All Geology Terms for Final - All 3 session
Geology 110 with Shanan Peters at University of Wisconsin - Madison
About this deck
By: j f
Textbook:
The Origin of Species (Barnes & Noble Classics Series)
Created: 2009-12-18
Size: 277 flashcards
Views: 188
Textbook:
The Origin of Species (Barnes & Noble Classics Series)Created: 2009-12-18
Size: 277 flashcards
Views: 188
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Name three factors that affect the ?struggle for existence?.
predators, the amount of food, climate, the elements, epidemics, competition within
Name three factors that affect the ?struggle for existence?.
predators, the amount of food, climate, the elements, epidemics, competition within
Why did Darwin delay publishing?
Wanted more evidence, against religious notions of the time, worried about his darling wife
What is required for natural selection to occur?
Varition, heritability, differential reproduction
Give two reasons why Darwin thinks the absence of innumerable transitional forms does not disprove evolution by natural selection
slow process of natural selection; imperfection in the geologic record; intermediate generally has smaller population size and is thus more vulnerable; unconformities (periods of missing time between strata); chemical and physical weathering (i.e. erosion); have not explored many areas of the world; insufficient paleontological collections; preservational bias (terrestrial vs. marine for example)
What is bipedalism a good example of?
tendency for evolution to modify pre-existing parts
What was discovered before the theory of evolution by natural selection, can be used to order and subdivide geologic time and forms the basis of biostratigraphy?
faunal succession
What is sexual dimorphism? And why would organisms, generally males, evolve traits that may reduce survival?
?Traits that differe between males and females of a species ? such as tails, color and songs ? are called sexual dimorphism, from the Greek for ?two forms.?? ? Coyne If that trait means the organism could have greater reproductive success it is then beneficial. The ?goal? is to pass genes through generations, which can only be done by leaving viable progeny. The possibly decreased survival must be offset by increased reproduction.
The answer to this question involves types of selection. If a population starts out on the slope of an adaptive landscape with only one fitness peak that is static over time, what is the expected response of the population, assuming that natural selection can act on the relevant traits?
directional selection followed by stabilizing selection
Who was the main proponent of the reality of extinction?
Cuvier
These species have interbreeding populations with range endpoints that do not interbreed.
Ring species.
Name three ways a group of organisms may become reproductively isolated.
geographic barriers; different mating/flowering seasons (timing); different mating displays/phermones; different pollinators in plants; sterile hybrids; unviable embryos
These structures are derived from a common ancestor and can be modified for various uses in different linneages?
homologous structures
What is composed of a sugar-phosphate backbone bound to bases?
DNA
Approximately what percentage of the human genome codes for proteins?
Roughly 2%
Changes in the timing of developmental processes is called?
heterochrony
Where are proteins made using the mRNA? What is necessary to read the mRNA?
In the ribosome using tRNA anticodons
Where were all elements heavier than He produced?
Inside of Stars
What is the process where some isotopes are unstable and will spontaneously decay into new stable elements?
radioisotopic decay
Why is there ?extra? iron in the universe?
It is the end product of normal stellar nucleosynthesis
What are two key things we learn from meteorites?
some of our best constraints on the composition of the inner planets and age of the earth and solar system
Who organized the hierarchy of morphological similarity in nature?
Linaeus
Who used comparative anatomy to prove that extinction is real?
Cuvier
Who hypothesized that individuals acquire characteristics that are useful to their mode of life and those acquired traits are passed on to offspring via inheritance?
Lamarck (species persist indefinitely, but are constantly evolving)
Who used uniformitarianism to prove that Earth is very old?
Hutton
Name three of the major figures of the scientific revolution and what they contributed
Galileo Galilei ? elaborates on telescope design, saw planets moving around Jupiter (began decentralization of earth) Copernicus ? heliocentrism Kepler ? planetary motion astronomy Descartes ? analytical geometry, cogito ergo sum Newton ? mechanics, gravitation
In reality what were ?tongue stones??
shark teeth
What is a vestigial structure?
Features of organisms that have no apparent purpose or function, often resembling parts that are in use by other organisms. Often greatly reduced in size, modified from the original form.
What is biostratigraphy?
correlation of strata and determination of relative ages based on index fossils
What is the principle of faunal succession that William Smith came up with?
fossils follow each other through time in a predictable manner; relative aging tool; same types of fossils occur in many different rock types; temporal order is consistent and similarly repeated everywhere no matter what the rocks look like
What are the two problems that Steno had to deal with in regard to fossils? What were the two outstanding questions of the day?
1) Are fossils just ?similar? to organisms OR were they once part of living organisms? 2) If living, then by what MECHANISM did they get into and become part of rocks?
What is required for natural selection to occur?
variability, heritability, differential reproduction
What is natural selection?
The process by which favorable traits are preserved and unfavorable/harmful traits are eliminated over generations.
What is biological fitness?
Relative ability to contribute offspring to the next generation.
Name three types/forms of selection?
direction, disruptive, stabilizing, no selection (drift)
What is a homologous structure?
Anatomical parts that share similarities that are not functionally necessary.
What is an analogous structure?
Anatomical parts with functionally similar forms, constructed in different ways.
What is ?American degeneracy??
American quadruped size and diversity very low in comparison to Old World mammals. Hypothesized that this was due to ?unfavorable conditions.?
What is the difference between the typological and biological species concepts?
Typological: species are as many as were created in the beginning Biological: species are groups of interbreeding natural populations that are reproductively isolated from other such groups
Why do island species diminish in size and gain traits such as no fear of humans and how?
Typically a rare event to make it to an island which leads to isolating the individuals from the rest of the population. Are now in a different environment (different adaptive landscape). Change in size could be due to lack of predators or limited resources.
What is comparative anatomy?
Study of similarities and differences in the morphology of living and fossil organisms; based on the principles of correlation of parts and subordination of characters.
What is Neoplatonism?
Inter?connected universe; hidden bonds of analogy revealed by form; objects possess innate power related to their essence; living/non?living distinction unreal; ?the force?
What is Aristotelianism?
Living, non?living distinction more rigid; vegetative spirit cold cause spontaneous generation (organic interpretation of fossils not necessary)
What are Steno?s three principles of stratigraphy?
law of superposition; principle of original horizontality; principle of original continuity
Why did Darwin FINALLY publish on natural selection?
Wallace
What geologic formation did Darwin encounter in the middle of the ocean and correctly describe how they formed?
atolls - sinking valcanoes
Why was domestic breeding so important to Darwin?
Analogy between artificial and natural selection central to Origin. If humans can produce divergent morphologies in short time periods through selection, wouldn?t nature be able to produce the same over millions and millions of years of natural selection?
What are three of Darwin?s key observations while on the Beagle?
1) variation in nature ? species consist of individuals and populations that vary in their traits 2) extinction: fossils of organisms that are similar to, but also distinct from living species are common 3) biogeography: species vary in their traits geographically; species that are very similar to one another are often separated in space 4) island biogeography: species on islands are often found only on those islands, but are also most similar to species found on nearby mainlands 5) dispersal: organisms can reach new, isolated habitats that separate them from the rest of the species and expose them to new environments 6) gradual change: power of very small, incremental changes to have large effects when operating over vast scope of geologic time
Neo-Platonism
Inter-connected universe, Hidden bonds of analogy revealed by form, Objects possess innate power related to their essence, and Living, non-living distinction unreal (Think Yoda) [ Organic interpretation of fossils is NOT NECESSARY ]
Aristotelianism
Living, non-living distinction more rigid, Vegetative spirit could cause spontaneous generation [ Organic interpretation of fossils is NOT NECESSARY ]
TYPOLOGICAL Species Concept
Species are as many as were created in the beginning?, Changes and mutabilities within species became viewed as part of a DIVINE PLAN
BIOLOGICAL Species Concept
Species are groups of interbreeding natural populations that are reproductively isolated from other such groups
RING Species Concept
Species with populations that interbreed continuously along a gradient, but the ends, which differ, don?t interbreed. Morphological gradients can be quite large, despite reproductive continuity, extinction of middle forms would create two completely distinct species
Parsimony
A principle that states that the simplest explanation that explains the greatest number of observations is preferred to more complex explanations". In the claytograms, the diagram with shortest number of steps is favored as the simplest explanation for the available data. May not be correct! But it is the best hypothesis until more data are available
Steno?s principles of stratigraphy
Law of superposition - strata are arranged in a temporal order, with oldest at bottom, youngest at top. ? Principle of original lateral continuity - strata originally deposited continuously unless interrupted by solid object; gaps in the same strata indicate rocks have been removed after they formed
Uniformitarianism
Processes operating today can be used to understand processes that operated in the past. i.e. Hutton used present as a key to understanding the past recorded in rocks
Types of Uniformity (4)
1. Uniformity of Law: natural laws (e.g., physics) are invariant in space and time 2. Uniformity of Process: only processes operating today operated in the past 3. Uniformity of Rate: changes take place at a constant rate or constant distribution of rates 4. Uniformity of State: dynamic equilibrium results in no net change, no directionality
Unconformity
Surface of erosion and/or non-deposition separating two rock bodies: represents missing TIME
Deformation
Faulting, tilting, and folding of originally flat rocks
Correlation of Parts
Animals are machine-like, Parts must be integrated into a functional whole, Species are real, fixed embodiments of distinct mode of life, and Anatomy of parts can be studied to understand the whole.
Subordination of Characters
All traits of an organism are important to survival; BUT....parts serving most vital functions are most important, and these should be the basis of classification and reconstruction
Comparative Anatomy
DEFINITION: study of similarities and differences in the morphology of living and fossil organisms; based on the principles of correlation of parts and subordination of characters. GOALS: to establish similarities between organisms that reveal patterns of affinity and the hierarchy of form in nature; reconstruct function from (incomplete) form
Pyrimidines
6 member ring DNA Base: Includes T (Thymine) and C (Cytosine)
4 DNA Bases
T (Thymine) and C (Cytosine) which are pyrimidines; also G (Guanine) and A (Adenine) which are the Purines
Purines
DNA Bases of fused 5 & 6 member rings : Includes G (Guanine) and A (Adenine)
DNA Connections
A to T (double bond) ; G to C (tripple bond) So GC is stronger
reverse transcription
transfer of information from RNA back into the complete DNA strand; this is the strategy employed by retroviruses, such as HIV
RNA replication
RNA can be replicated spontaneously in the presence of correct enzymes; this is used in RNA silencing and interference (& therapy)
What are Genes
regions of DNA that are transcribed and translated or that are involved in these processes
exons
get directly translated and determine the sequence of amino acids in proteins
introns
are pieces of DNA between exons - removed when making mRNA
promoters/enhancers
are regions of DNA that are involved in the initiation of transcription
gene expression
is the extent to which genes are transcribed into functional RNA and translated into proteins
Homeobox (Hox) genes
genes that code for transcription factors that initiate a regulatory cascade of gene expression, which in turn determines cell fate and differentiation. some of the most important roles of Hox genes involve body serialization and segment identity
Mutation Operations
Mutations occur by substitution, deletion, and insertion
Mutation Causes
1. copy errors 2. exposure to mutagenic agents (UV radiation, tobacco smoke, other chemicals)
Mutation Occurances
Mutations may occur in: somatic cells (may lead to cancer) germ cells (passed on to offspring)
synonymous mutations
mutations that DO NOT change the ?meaning? of a triplet are called silent or synonymous
non-synonymous mutations
mutations that result in the replacement of one amino acid for another are non-synonymous
sources of variation
there are two sources of variation in organisms: 1) mutation 2) recombination (happens during sexual reproduction)
Neo-Platonism
Inter-connected universe, Hidden bonds of analogy revealed by form, Objects possess innate power related to their essence, and Living, non-living distinction unreal (Think Yoda) [ Organic interpretation of fossils is NOT NECESSARY ]
Aristotelianism
Living, non-living distinction more rigid, Vegetative spirit could cause spontaneous generation [ Organic interpretation of fossils is NOT NECESSARY ]
TYPOLOGICAL Species Concept
Species are as many as were created in the beginning?, Changes and mutabilities within species became viewed as part of a DIVINE PLAN
BIOLOGICAL Species Concept
Species are groups of interbreeding natural populations that are reproductively isolated from other such groups
RING Species Concept
Species with populations that interbreed continuously along a gradient, but the ends, which differ, don?t interbreed. Morphological gradients can be quite large, despite reproductive continuity, extinction of middle forms would create two completely distinct species
Parsimony
A principle that states that the simplest explanation that explains the greatest number of observations is preferred to more complex explanations". In the claytograms, the diagram with shortest number of steps is favored as the simplest explanation for the available data. May not be correct! But it is the best hypothesis until more data are available
Steno?s principles of stratigraphy
Law of superposition - strata are arranged in a temporal order, with oldest at bottom, youngest at top. ? Principle of original lateral continuity - strata originally deposited continuously unless interrupted by solid object; gaps in the same strata indicate rocks have been removed after they formed
Uniformitarianism
Processes operating today can be used to understand processes that operated in the past. i.e. Hutton used present as a key to understanding the past recorded in rocks
Types of Uniformity (4)
1. Uniformity of Law: natural laws (e.g., physics) are invariant in space and time 2. Uniformity of Process: only processes operating today operated in the past 3. Uniformity of Rate: changes take place at a constant rate or constant distribution of rates 4. Uniformity of State: dynamic equilibrium results in no net change, no directionality
Unconformity
Surface of erosion and/or non-deposition separating two rock bodies: represents missing TIME
Deformation
Faulting, tilting, and folding of originally flat rocks
Correlation of Parts
Animals are machine-like, Parts must be integrated into a functional whole, Species are real, fixed embodiments of distinct mode of life, and Anatomy of parts can be studied to understand the whole.
Subordination of Characters
All traits of an organism are important to survival; BUT....parts serving most vital functions are most important, and these should be the basis of classification and reconstruction
Comparative Anatomy
DEFINITION: study of similarities and differences in the morphology of living and fossil organisms; based on the principles of correlation of parts and subordination of characters. GOALS: to establish similarities between organisms that reveal patterns of affinity and the hierarchy of form in nature; reconstruct function from (incomplete) form
The Archetype
Hypothetical fossil structure that is considered to be the blueprint of all vertebrates modified to become all species including ud; where all its transformations were predetermined by its divine creator
Homologous structures
Anatomical parts that share similarities that are not functionally necessary, i.e. hair is a homologous trait shared by all mammals
Analogous structures
Anatomical parts with functionally similar forms, constructed in different ways, NB: can be hierarchical (e.g., bird and bat wing homologous as limbs, not wings)
Vestigial structures
Features of organisms that have no apparent purpose or function, often resembling parts that are in use by other organisms. Often greatly reduced in size, modified from the original form. These were perplexing to pre-Darwinian scholars because seemed to imply waste by creator. E.G. snake legs, human tail parts.
Embryology
Study of embryos: ?evolution? of an individual (Development): individuals undergo profound change in morphology during development, early developmental stages of organisms that are very different as adults are very similar, and traits appear in embryo that are not part of adult
Faunal Succession
Relative aging tool, repeated temporal succession. The principle of faunal succession is that different strata each contain particular assemblages of fossils by which the rocks may be identified and correlated over long distances; and that these fossil forms succeed one another in a definite and habitual order. This law, together with the law of superposition of strata, enables the relative age of a rock to be deduced from its content of fossil faunas and floras.
Order of Eons (3)
Archean, Proterazoic, Phanerozoic [ Think Anchent 3 phases of life: Arkaic = Nothing, Some Prokaryotes found, Then they Phan out into everything else ]
Order of Phanerozoic Eras (3)
Paleozoic, Mesozoic, Cenozoic [ Think PMS but with a C ]
Order of Phanerozoic Periods (12)
Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Mississippian, Pennsylvanian), Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene
Two methods of dating:
1. Numerical, 2. Relative
Relative Dating
Age of events/rocks expressed in rank order relative to one another (i.e., first a then b)
Numerical Dating
Age of events/rocks expressed in units of time (i.e. a happened x years ago, b happened y years ago)
Biostratigraphy
Correlation of strata and determination of relative ages, based on INDEX FOSSILS
Development of Geologic Time
Biostratigraphy, Steno?s laws, cross-cutting relationships were original basis for subdivision of geologic time ?visible life? ?ancient life?, names in the geologice time scale some are named after places and tribes in Great Britain. Three major Eons, Archean, Protyerazoic, Phanerozoic. Three major Eras, Paleozoic, Mezzozoic, and Cenozoic. And 12 Major periods of the Phanerzoic Eon: Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Mississippian, Pennsylvanian), Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene
Atolls
Coral Reef structrure found by Darwin on Beagle Voyage: Circular, oval, or horseshoe-shaped arrays of coral reef that form sandy islands that are perched around an oceanic volcanic seamount and encircle a shallow lagoon.
Two types of artificial selection
1. Methodical ?purposeful? selection; and 2. Unconscious ?accidental? selection
Ontogenetic growth
Change in shape during ontogeny (maturation): 2 Types: Isometric growth (change in size only, proportions stay constrained), and Allometric growth (change in size and shape)
Isometric growth
Growth that occurs at the same rate for all parts (change in size only proportions stay constrained)
Allometric growth
Parts grow at different rates (change in size and shape)
Heterochrony
Changes in timing of development E.G. Micky Mouse: in this case, the slowing of the developmental trajectory so as to retain juvenile characteristics (paeodomorphosis)
Breeding
?artificial selection? for one trait, often causes changes in other traits as well
Heritability
Correlation between parent trait and offspring trait defines heritability. Ccorrelation = the extent to which one variable varies with another. Examples: Galapagos finches: there is a strong positive correlation between parent and offspring bill depth; heights of children are positively correlated with heights of their parents
Geographic variation
Populations of the same species often differ from place to place, variations often mirror some aspect of the local environment for that population, populations of the same species often differ from place to place,variation in geographically isolated, small populations are often more pronounced
Temporal variation
Populations of the same species can differ over time. Temporal variations often correlate to some aspect of the local environment for that population
Characteristics of population
Geographic distribution (area, connectedness), Population size (number of individuals; density = individuals/area), and Growth rate (positive or negative)
Population Growth Factors
The number of births per unit time (b/?t), the number of deaths per unit time (d/?t), immigration and emigration per capita, and birth and death per capita. N(t) = N0e(p - q)t = exponential change. There population checks that keep a population from growing too fast. Birth rates and GDP negatively correlated, Adding the level of education and, life control of women is even better predictor of birth rate. Pregnancy-related death rates, vary markedly geographically, women in developing countries are much more likely to die from pregnancy and childbirth related causes than women in Europe/USA.
Population Checks (2)
Density-independent checks (Doesn't Care about Density - Natural Disasters), and Density-dependent checks (Variable with the density of the population - amount of food)
Density-independent checks
Population growth check that doesn't Care about Density - Natural Disasters
Density-dependent checks
Population growth check in ways varying with the population density. (i.e. number of perditors to prey, food sources, climate change etc.). The change in growth rate is a common consequence of geometric growth in natural populations ? initial phase of unbridled exponential growth ? rate of growth slows as K is approached ? equilibrium achieved (P = Q)
Carrying capacity
Can reproduce too quickly to be sustainable, as population approaches environmental ?carrying capacity? (K),
Population Loss
LOSS != DEATH LOSS = NO OFFSPRING
Natural Selection
Survival of the fittest. The process by which favorable/beneficial variations are preserved and inherited by an organism?s offspring, while unfavorable/harmful variations are eliminated from the population. This disproves the idea of the continued creation of new species as well as the immutability of species.
What is required in order for natural selection to occur?
1) Variability - offspring not exact copies of parents and/or individuals in populations are not all identical. 2) Heritability - traits of parents are passed on to offspring. 3) Differential reproductive success - individuals with favorable/advantageous traits will contribute more offspring than others.
Variability
Offspring not exact copies of parents and/or individuals in populations are not all identical
Heritability
Traits of parents are passed on to offspring
Differential reproductive success
Individuals with favorable/advantageous traits will contribute more offspring than others
Biological Fitness:
Relative ability of an individual to reproduce and contribute offspring to the next generation, combines BOTH probability of survival and relative fecundity in population
Directional selection
Selection in favor of one end of distribution, directional change in population morphology towards optimum, need be no change in original variability of population
Stabilizing selection
Selection against extremes (end members) in population, results in the maintenance of status quo around an optimum, and can result in decreased variability in population, but it need not if rate of introduction of new variants is high relative to strength of selection
Disruptive selection
Selection for all extremes in population, results in divergence away from current mode in all directions, divergence of population into two+ discrete modes; typically results in an increase in the variability of a population
No selection (drift)
No differential reproduction, all forms equally successful. no change in mean morphology of population is expected. Always results in an increase in the variability of a population
Sexual dimorphism
males and females often differ in morphology
Sexual selection
Operates on characters that help organisms obtain mates, but are of little value, or possibly disadvantageous, in day-to-day survival; Two processes involved in sexual selection: 1) mate choice (usually female choice). 2) intrasexual selection (usually male-male combat)
Chromosomes
Genetic material in animals and plants is packaged into chromosomes. humans have 23 pairs. Chromosomes are paired (except in eggs and sperm).
Locus
Along each member of pair are genes that code for the same trait a given site on the chromosome is called a locus (plural = loci)
Alleles
Genes may be identical, or may vary slightly alternative forms of the same gene are called alleles. Homozygous = 2 alleles are identical. Heterozygous = 2 different alleles
Mendelian genetics
1) one gene (with two alleles, one from each parent) codes for one trait. 2) some alleles are dominant to others. 3) each pair of alleles behaves independently of other pairs, can therefore predict outcomes of matings. BUT, these ?rules? are often broken! many genes behave in ?non-Mendelian? fashion. Some non-Mendelian characteristics: 1) incomplete dominance of alleles (snapdragons: cross of white with red yields pink). 2) codominance of alleles both A and B are fully expressed (human blood type gene has three alleles (A, B, O) O is recessive A and B are codominant). 3) many alleles for one gene (in a population)
Pyrimidines
6 member ring DNA Base: Includes T (Thymine) and C (Cytosine)
4 DNA Bases
T (Thymine) and C (Cytosine) which are pyrimidines; also G (Guanine) and A (Adenine) which are the Purines
Purines
DNA Bases of fused 5 & 6 member rings : Includes G (Guanine) and A (Adenine)
DNA Connections
A to T (double bond) ; G to C (tripple bond) So GC is stronger
reverse transcription
transfer of information from RNA back into the complete DNA strand; this is the strategy employed by retroviruses, such as HIV
RNA replication
RNA can be replicated spontaneously in the presence of correct enzymes; this is used in RNA silencing and interference (& therapy)
What are Genes
regions of DNA that are transcribed and translated or that are involved in these processes
exons
get directly translated and determine the sequence of amino acids in proteins
introns
are pieces of DNA between exons - removed when making mRNA
promoters/enhancers
are regions of DNA that are involved in the initiation of transcription
gene expression
is the extent to which genes are transcribed into functional RNA and translated into proteins
Homeobox (Hox) genes
genes that code for transcription factors that initiate a regulatory cascade of gene expression, which in turn determines cell fate and differentiation. some of the most important roles of Hox genes involve body serialization and segment identity
Mutation Operations
Mutations occur by substitution, deletion, and insertion
Mutation Causes
1. copy errors 2. exposure to mutagenic agents (UV radiation, tobacco smoke, other chemicals)
Mutation Occurances
Mutations may occur in: somatic cells (may lead to cancer) germ cells (passed on to offspring)
synonymous mutations
mutations that DO NOT change the ?meaning? of a triplet are called silent or synonymous
non-synonymous mutations
mutations that result in the replacement of one amino acid for another are non-synonymous
sources of variation
there are two sources of variation in organisms: 1) mutation 2) recombination (happens during sexual reproduction): a) crossing-over b) reshuffling of chromosomes ** = ** 223 = 8,388,608 possible combinations for one set of parents (without crossing-over)
genes are
portions of DNA that are transcribed to mRNA, which transports the code to other parts of the cell; genes consist of protein coding exons, non-coding introns, and segments involved in RNA polymerase activation; humans have ~25,000 genes
what is tRNA, mRNA, rRNA
? tRNAs specific to one of 20 amino acids align with 3 base pair codon on mRNA (transcribed from DNA); translation of genetic code to make protein takes place in ribosomes, which are composed of protein and rRNA 3-letter genetic code is highly redundant; 64 codons identify just 20 amino acids; some mutations in genes have no effect ? only a small fraction of the genome actually gets translated into proteins; in humans < 2%
the three main types of speciation
allopatric, parapatric, and sympatric speciation
punctuated equilibrium
s a theory in evolutionary biology which proposes that most sexually reproducing species will experience little evolutionary change for most of their geological history (in an extended state called stasis).
gradualism
is a speciation hypothesis rooted in uniformitarianism. The hypothesis states that species continue to adapt to new environmental and biological selection pressures over the course of their history, gradually becoming new species. Phyletic gradualism holds that a species population changes gradually and that there is no clear line of demarcation between an ancestral species, that is a descendant species unless a splitting (cladogenetic) event occurs or the gradually-changing lineage is divided arbitrarily.
What are the effects of gaps in the rock record?
Hypothesis: rock truncations ( gaps (hiatuses) in the rock record ) cause false/artificial species truncations | Means: Gaps in the rock record reflect important environmental change!
human genetic disorders can tell us about:
? how genes work ? building proteins ? regulating development ? how selection works
How many chromesomes, autosomes, and sex chromososes do humans have?
humans have 23 pairs of chromosomes: 22 pairs of autosomes 1 pair of sex chromosomes (X, Y)
autosomes
a chromosome that is not a sex chromosome ? that is to say there are an equal number of copies of the chromosome in males and females.[1] For example, in humans, there are 23 pairs of autosomes, but the X and Y chromosomes are sex chromosomes.
Reproductive Isolation
? reproduction results in the continuity of information (genes) between generations ? REPRODUCTIVE ISOLATION is critically important to the process of speciation because it permits local adaptation and drift to cause divergence
Characteristics of the Hawaiian biota
? The Hawaiian islands have fewer types of organisms than surrounding mainlands, but some of those types are extremely diverse; many species (>10,000) are endemic to the islands ? The Hawaiian islands lack many types of animals and plants; for example, they have NO native amphibians, reptiles, or conifers ? Only TWO mammals are native to the Hawaiian islands (bats, seals) ? Marine organisms are ~25% endemic terrestrial organisms >90% endemic
Cichlid fish of East African Rift Lakes
? the diversity of ecological strategies among lake fish species today is very high ? morphological characteristics, including color, are closely related to these ecological strategies due to environmental factors ? high ecological diversity is likely the result of adaptive radiation and niche partitioning Malawi | Lake Malawi has > 500 species, Tangawikisi has > 200 species ? East African lakes have two main bottom habitat types: sandy and rocky ? optimal ecological strategies between these two habitats are different ? environmental heterogeneity contributes to variability in the adaptive landscape and promotes diversification ? sexual dimorphism and ritualistic mating behavior is widespread in cichlid fish ? color and display are key components ? variation in mate preferences and sexual selection has contributed to reproductive isolation of populations within a lake ? fish in each rift lake are reproductively isolated at the present time - have been for many generations ? each lake has it?s own unique characteristics, but the environments are largely similar ? fish occupying similar niches in different lakes are remarkably similar to one another, despite being completely separate species and lineages ? this is an example of convergent evolution and iterative evolution
What are some of the characteristics of the fossil record?
? morphology only ? reproductive continuity and genetic similarities/differences cannot be measured in the fossil record ? limited temporal resolution ? in general, the temporal resolution of the rock record is much coarser than generations ? the rock record is also incomplete and discontinuous
Measuring rates of evolution: morphological
? there is no ?model of evolution? or assumption about evolution in this diagram; it simply shows the empirical pattern of tooth shape through stratigraphic levels (i.e., over time) ? data show anagenesis (evolutionary change WITHIN A LINEAGE) and cladogenesis (splitting of one lineage into two lineages)
stasis
an extended state of punctuated equalibrium is called stasis
Patterns of evolution in the fossil record
? anagenetic changes in morphology within lineages are commonly short relative to the duration of the lineage ? a random walk is a pattern of change over time which is generated by the addition of random variation in each time increment ? the same random walk can produce a very wide range of outcomes; it is therefore difficult to reject as a NULL HYPOTHESIS
Frequency of evolutionary modes
? sustained, directional evolution in fossil record is rare ? most patterns in fossil record reflect stasis or a random walk; shape traits are more likely to be static than size
How is evolutionary changes mesured?
evolutionary change can be measured genetically and morphologically
measuring morphology
morphological rates of evolution are measured as change relative to variability in the population per generation; one Haldane is a change of one standard deviation in one generation ? rates measured in the lab and in nature typically range from 0.1 to 0.2 Haldanes; this is VERY fast when long time scales are considered
Haldane
? the amount of change from one generation to the next should be measured relative to some aspect of the population, not in absolute terms ? because variation is the fundamental feature of the population acted upon by natural selection, reference should be to variability in the population ? the HALDANE is a rate unit: change in standard deviations per generation | So h = change in mean / standard deviation
Rates of evolution
rates of evolution are fast on short timescales, slow on long
Physical characteristics of Hawaii
? Hawaii is the most recent end in a chain of seamounts and islands that were formed by HOTSPOT volcanism and sea floor spreading ? islands sequentially pop out of water as lava and are completely devoid of life; everything on the islands must get there via DISPERSAL
Adaptive radiation
is a rapid evolutionary radiation characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage. Phenotypes adapt in response to the environment, with new and useful traits arising.[1] This is an evolutionary process driven by natural selection.
Examples of Adaptive radiation on Hawaii
? original grosbeak probably arrived about 6 Myr ago ? divergence in bill size and shape is greater than in any other songbird family ? relationships between species well established based on morphological and genetic analyses - all consistent with descent from a single ancestral lineage ? phylogeographic pattern consistent with widespread island hopping, but in an overall direction that reflects age of islands ? many species appeared since origin of modern islands
what is a geologic rift?
? in plate tectonics, the separation of two plates causes the formation of a rift ? when a continent is pulled apart, the crust of the continent sinks, and fills with water ? eventually, a new ocean might be formed between two isolated continents
Combining DNA and geology
? molecular distances between cichlid fish can be measured using DNA sequencing ? diagram of relationships (cladogram) shows pattern of nested relationships; molecular distances between species represented by branch length ? Lake Tanganyika ?superflock? identified by a large number of species with very little molecular distance ? geographic patterns of genetic differences and similarities reveals dispersal pathways and historical biogeographical structure ? exchanges between lakes are relatively rare, but occur via connections with rivers and other dispersal mechanisms (e.g., birds) ? with geological control on the age of reproductive isolation, molecular clock can be used to estimate divergence times ? both geological evidence AND the molecular distance evidence indicate rapid speciation of East African
characteristics of the fossil record?
? morphology only ? reproductive continuity and genetic similarities/differences cannot be measured in the fossil record ? fortunately, this is usually ok? morphologically-identified species are often reproductively isolated species ? morphological differences are also positively correlated with genetic distances in all organisms that have been studied.? limited temporal resolution ? in general, the temporal resolution of the rock record is much coarser than generations ? the rock record is also incomplete and discontinuous
Measuring rates of evolution: morphological
? collect fossil specimens, record their position in the stratigraphic section; multiple specimens per level required ? measure the morphology of those specimens, estimate variability in each stratigraphic level ? plot change in morphology from level to level (i.e., through time) ? there is no ?model of evolution? or assumption about evolution in this diagram; it simply shows the empirical pattern of tooth shape through stratigraphic levels (i.e., over time) ? data show anagenesis (evolutionary change WITHIN A LINEAGE) and cladogenesis (splitting of one lineage into two lineages) ? in order for accurate determination of evolutionary rate, need an estimate of the time in number of generations; this is difficult to do in most sedimentary deposits
How do we measure time?
In evolution, the relevant time scale is always the generation ? evolutionary change is measured from one generation to the next
Measuring rates of evolution: molecular
? a molecular clock can be used to determine the time of reproductive isolation between two extant species ? requires measuring genetic distance and calibration with historical/geological/fossil record ? assumes that rates of mutation are stochastically constant ? molecular clock estimates almost always predict an age for divergence that is slightly to moderately older than what is suggested by the fossil record.
Physical characteristics of Hawaii
A primer on plate tectonics: hotspots ? hot, buoyant magma from core-mantle boundary rises to base of lithosphere, melting lithosphere and making conduit to surface ? sea floor spreading moves the lithosphere relative to the hotspot; result is a chain of volcanos that start above sea level and then sink as they cool ? Hawaii is the most recent end in a chain of seamounts and islands that were formed by HOTSPOT volcanism and sea floor spreading ? as the islands move away from hotspot, they subside and erode, eventually sinking beneath the sea to form atolls. ? islands sequentially pop out of water as lava and are completely devoid of life; everything on the islands must get there via DISPERSAL
Why is Hawaii so diverse
? relationships between species well established based on morphological and genetic analyses - all consistent with descent from a single ancestral lineage ? diversity reflects filling of available niches by evolution of one ancestral species ? an ADAPTIVE RADIATION is a relatively rapid increase in morphological and ecological diversity within a single lineage. ? being first to arrive on a new volcanic island means encountering a completely ?empty? ecological landscape ? provided that Pr(event per generation) ~ 0, then survival of new individuals will depend only on availability of resources and INTRA-SPECIFIC COMPETITION ? geometric increase in population will quickly make competition a dominant force.
Adaptive radiation Points
? being first to arrive on a new volcanic island means encountering a completely ?empty? ecological landscape ? provided that Pr(event per generation) ~ 0, then survival of new individuals will depend only on availability of resources and INTRA-SPECIFIC COMPETITION ? geometric increase in population will quickly make competition a dominant force.? founder species, if successful at all, can adapt to local conditions, but eventually competition may become the strongest selective pressure ? successive bouts of disruptive selection may prevail, pushing species into new ecological territories ? in Hawaii, the possible new ecological territories are greatly exaggerated by the diversity of the physical environment? Patchy populations of Drosophila silvestris on Hawaii are exposed to very different environmental conditions ? gene flow is also limited and populations are diverging genetically - speciation is happening! -- Island Hoping Vicariance
Island Hoping Vicariance
? in archipelagos, like the Hawaiian islands, allopatry is not limited to dispersal from the mainland ? dispersal of organisms between islands can result in a radiation driven primarily increases in the frequency of allopatric speciation ? dispersal among islands repeats this process multiple times, resulting in high species-level diversity within the ?type? that originally colonized the region? inversions occur when molecular mechanisms repair DNA damage, but flip the DNA segment with no vital effect ? once relationships of genetic divergence are established, biogeographic patterns of dispersal can be inspected ? phylogeographic pattern of dispersal consistent with widespread island hopping, but in an overall direction that reflects age of islands ? also implies that extinction is a prominent process
Undoing evolution
? Hawaii?s isolation has resulted in the evolution of unique ecosystems; by introducing species to the islands, humans have altered the course of evolution ? feral pigs, introduced >1000 years ago, have ravaged the local biota? in 1992 a large storm took out some chicken farms on Kauai (oldest island) and some of the damn things got loose; may have also been let out before then ? they are now all over the island and completely altering the biological community in ways never experienced in 5 million years. ? basically, the Hawaiian biota is screwed ? humans have greatly increased the rate of introduction of new species (approximately 2,000,000x); the result is catastrophic for the local biota ? species introductions are, in the opinion of this prof, far and away the #1 bad thing we are doing to our planet...makes global warming look silly
What is evolution?
? change in DNA sequence over time ? change in gene/allele frequencies over time ? change in fitness over time ? change in morphology over time ? formation of new species over time all of these involve change over time among groups of organisms
Reproductive Isolation: What two main classes of mechanisms
1. PRE-ZYGOTIC ISOLATION - union of egg and sperm never occurs because gametes never encounter one another 2. POST-ZYGOTIC ISOLATION - egg and sperm encounter one another but the zygote is either not viable or gives rise to individuals that cannot reproduce or that have very low fitness
Pre-zygotic reproductive isolation - ecological
? ECOLOGICAL ISOLATION occurs when environmental preference reduces the frequency of interbreeding ? a very well documented example is the expansion in the past 200 years of Rhagoletis pomonella (apple maggot) ? females prefer to lay eggs in the fruit they grew up in and males tend to look for mates in the fruit they grew up in ? genetic differences between these two ecological groups are already emerging. ? SYMPATRIC SPECIATION occurs when there is divergence and evolution of new species from populations that overlap in space ? host shift in Rhagoletis is causing reproductive isolation of populations and genetic divergence - we are seeing speciation in action!? example is competition for coral habitats among Gobiodon, which promotes shifts to different coral host species and the formation of reproductively isolated populations. ? PARAPATRIC SPECIATION occurs when there is no specific barrier to gene flow between populations, but environmental gradients or distances result in different selective pressures ? example is a grass that occurs near acid mine drainages; these environments have lots of heavy metals and grasses with genes that make them tolerant are favored; timing of flowering is also changing
PARAPATRIC SPECIATION
occurs when there is no specific barrier to gene flow between populations, but environmental gradients or distances result in different selective pressures ? example is a grass that occurs near acid mine drainages; these environments have lots of heavy metals and grasses with genes that make them tolerant are favored; timing of flowering is also changing
SYMPATRIC SPECIATION
occurs when there is divergence and evolution of new species from populations that overlap in space ? host shift in Rhagoletis is causing reproductive isolation of populations and genetic divergence - we are seeing speciation in action!? example is competition for coral habitats among Gobiodon, which promotes shifts to different coral host species and the formation of reproductively isolated populations.
Pre-zygotic reproductive isolation - geographic
? ALLOPATRIC SPECIATION occurs when populations become physically separated from one another by a geographic barrier ? examples include isolation on islands (e.g., Darwin?s finches) and isolation by other physical geographic barriers (e.g., mountains, oceans, rivers, etc.). ? example is populations of lizards separated by rivers; there is a greater morphological dissimilarity between these populations for a given distance than those not separated. ? example is 2 species of ground squirrel in Grand Canyon- one lives on north rim, the other lives on the south rim; other species that can cross canyon (e.g., birds) are not different.
Pre-zygotic reproductive isolation three main geographic mechanisms
? ALLOPATRIC SPECIATION: complete separation of populations ? PARAPATRIC SPECIATION: divergence occurs in broadly continuous region ? SYMPATRIC SPECIATION: no spatial separation, but reproductive isolation
ALLOPATRIC SPECIATION
occurs when populations become physically separated from one another by a geographic barrier ? examples include isolation on islands (e.g., Darwin?s finches) and isolation by other physical geographic barriers (e.g., mountains, oceans, rivers, etc.). ? example is populations of lizards separated by rivers; there is a greater morphological dissimilarity between these populations for a given distance than those not separated. ? example is 2 species of ground squirrel in Grand Canyon- one lives on north rim, the other lives on the south rim; other species that can cross canyon (e.g., birds) are not different.
Post-zygotic reproductive isolation - zygote mortality
? ZYGOTE MORTALITY occurs when a successfully fertilized egg begins process of development, but the zygote is not viable and dies prior to complete development ? prevents interbreeding between populations, but also involves investment. ? HYBRID INVIABILITY occurs when gametes fuse, development progresses, but the offspring cannot survive to adulthood ? example is offspring of the occasion cross between Rana pipiens and Rana sylvatica - offspring do not last more than a few days. ? HYBRID STERILITY occurs when gametes fuse, development progresses, and offspring survive to adulthood, but cannot themselves reproduce ? example is cross between D. melanogaster and D. pseudoobscura; adults are made from this cross, but the males have atrophied testes and cannot reproduce. ? example is cross between Equus ferus and E. africanus; strong mules are made from this cross, but males cannot reproduce and females can only do so rarely because their chromosomes do not permit production of viable gametes
Post-zygotic reproductive isolation - low fitness
? LOW HYBRID FITNESS occurs when gametes fuse, development progresses, and offspring survive to adulthood and can reproduce, but have very low fitness in the wild ? example is dog-wolf hybrids; these are perfectly viable but are considered to be poor pets and are almost always rejected and killed by wild wolf packs
Regulation of gene expression
? gene expression is the extent to which genes are transcribed into functional RNA and translated into proteins ? any step in the process of transcription and translation may be used to regulate expression ? by regulating gene expression, cell identity and function can be specified; so, with ONE genome, there are MULTIPLE possibilities
? Lasting legacy
o??? Plastic and garbage, mixing of biosphere (HE BELIEVES WORST THING), disruption of surface, shift in carbon cycle
Are we experiencing another mass extinction
o Extinction rates today may be higher than background rates but we have not yet measured them in an appropriate way o Some extinction is always happening o Climate change is not the main problem
Are We are cooler now than most of the phanerozoic
Phanerozoic cooling of the planet due in part to burial of carbon in sediments
Global temperature is going up and we are the cause
burning fossil fuel we are releasing CO2 trapped in rocks during the Phanerozoic
Biotic consequences of sea level change
o Decrease in shelf area, loss of unique epicontinental sea habitats, change in avg connectedness of epicontinental seas, correlated/causal environmental and climate changes
Causes of Permian Mass Extinction
Kill Mechanism - the thing that actually kills individuals. Trigger - the evernt that leads to lethal conditions. o Trigger is Bolide Impact: Kill Mechanisms is loss of primary production, widespread fire, acid rain o Trigger is Volcanism and Siberian Traps: Kill Mechanisms is Global Warming (CO2 doubled) and CO2 poisoning o Trigger is drop in sea level: Kill mechanism is species-area effect, loss of habitats, decimation of reefs, widespread anoxia o Trigger is Pangea: Kill Mechanisms is Loss of Geographic Barriers, Dry climate on land o Trigger is Change in Depositional Mode: Kill Mechanisms is no long able to grow shells and skeletons
? Walter Alvarez
o Iridium on surface but rained down on earth in form of dust and meteorites on K/Pg surface o Found concentration of iridium many times greater than expected at Gubbio section o Then go other places o Found that K/Pg boundary represents and impact and should be other evidence ? Iridium found globally and impact must have put a lot more than just iridium in atmosphere ? Found crater on Yucatan Peninsula Mexico ? E=0.5mv^2=2.3x10^23 Joules o Mankinds best effort to blow us up is 2x10^17 ? Problem with theory is that many taxa survive
? Cretaceous/Paleogene Mass extinction
o Marine effects ? 76 percent of all marine invertebrate animal species went extinct ? Planktonic skeletal microbes devastated forams ? Bivalves, corals, ammonites to name a few ? Many marine vertebrates severely affected ? Plesiosaurs/pliosaurs, ichthyosaurs, mosasaurs o Terrestrial effects o Non avian dinosaurs, pterosaurs, 50 percent of all plant species in some areas, few mammal groups affected ? Dinosaur diversity very high in Late Cretaceous o Most diverse and successful tetrapods groups nearly eliminated ? Few hypotheses why dinosaurs went extinct o Disease, evolution of new types of plants, they got too big, changing sex ratios, thin eggshells, magnetic reversal, sea level fall, global cooling, volcanism, competition from mammals
Types of extinction
o Normal-extinction due to many different taxonspecific causes and to chance continuously happening; accounts for MOST extinctions o Mass extinctions- wholesale elimation of many unrelated taxa on a global scale; extinction rate is significantly higher than normal; the rules of who lives and dies change; constitutes a small proportion of total extinctions over time, but have disproportionate effects; usually thought to be driven by unusual/rare events
? Big Five extinctions
o Permian/Triassic- 95 percent species loss on land and in sea o Ordovician/Silurian- 85 percent species loss in sea, too few land metazoans to make any estimates o Triassic/Jurassic- 80 percent species loss, land and sea o Cretaceous/Paleogene- 76 percent of all species went extinct; non avian dinosaurs go extinct o End Devonian- estimates vary
Dinosaur Extinction
? Causes ? Out competed by other organisms ? Competition for the same resources ? Unable to keep pace in an evolutionary arms race, specialists generally favored over generalists o Enviromental Change o Unable to tolerate change, unable to migrate to favorable climate, unable to adapt by evolutionary change, generalists generally favored over specialists ? Evolution o Species exist in TIME and can evolve does evolution cause extinction o Evolutionary change within a single lineage called anagenetic evolution posses a problem when trying to count extinctions ? Chance o Sometimes doesn?t matter how adapted you are o Random processes alone can result in extinction
Theropods
o meat eating, bipedal, constant tooth replacement like crocodiles, warm blooded, avian-like breathing system ? Dinosaur eggs are just almost undistusihable from bird eggs in thin section ? Theropods evolved into birds
Sauropods
o bipedal ancestors, incease in size until the Early Cretaceous, specialized breathing ? air sacs, long tails, long neck
Marginocephalia
o diverse clade of horned dinosaurs, elaborate elongation of back of skull, defensive and/or display, throughout Late Cretaceous, most derived ornithischian o Cerotopsians
Ornithopods
o Diverse group of creseted dinaosaurs, immense tooth batteries for grinding plant material, domnate late cretaceous herbivore o Hadrosaurs (duck billed)
Thyreophera (armored dinosaurs)
o Herbivorous, tall plates along neck and back, tail and shoulder spikes o Symmetrically aligned dermal armor along entire back and midline, o Ankylosaurs
Basal ornithischians
Heterodontosaurs, different teeth (canine like) capable of tearing and hind teeth for grinding, omnivorous and eocursor
What is a dinosaur?
Upright stance, hinged ankle, open acetabulum
Pterosaurs
o Flying reptile o 50cm to 13 m wingspan o Not ancestors of birds
Dinosauromorphs
Almost dinosaurs, lack open hip joint, middle Triassic
Therapsids
o Greatly expanded infratemporal fenestra o Teeth divided into nipping incisors, biting canines, and grinding cheek teeth o Forelimbs more powerfully developed than hindlimbs
Archosaurs
o An antorbital and mandibular fenestrae (air chambers) o Semi-erect posture: so that they could move sometimes without having to twist from side to side o Interlocking gastralia: to help pump extra oxygen through the body belly breathing
Crurotarsi
crocodilians and everything more closely related to crocodilians than to birds Aetosaurs: heavy armor crocs
Scleromochlus
Digitigrades, erect posture, fast runner, jumper
Ornithodira
o Erect posture: hindlimbs positioned directly underneath the body rather than sprawling to the sides o Simple hinge like ankle joints o Digitigrades posture
Measuring rates of evolution; morphological
o Collect fossil specimens, record their position in the stratigraphic section; need multiple specimens per level o Measure the morphology of those specimens, estimate variability in each stratigraphic level o Plot change in morphology from level to level o Anagenesis-evolutionary change within a lineage o Cladogenesis-splitting of one lineage into two o In order to accurate determine evolutionary rate we need an estimate of the time in number of generations this is difficult to do in most sedimentary deposits
Random walk
o Is a pattern of change over time which is generated by the addition of random variation in each time increment ? Directional evolution in fossil record is rare most reflect random walk
How / Why Are Paleontological collections are imperfect
o About 2% are complete o Measure perfection by total fossil sp/total sp ever lived o Gaps in the rock record cause artificial species truncations ? Unconformitites are correlated with fossil species truncations ? Duration of gap predicts amount of species truncation is false
Rock Record / Age of the Earth
o Without a way to estimate numerical ages of sedimentary rocks there is usually no way to accurately measure the rates of evolution in real time o James Ussher put a date to the formation of earth according to the bible on Saturday, 22 October 4004BC
Saltiness of ocean
o Rivers carry water and solutes dissolved from land to oceans o Evaporation returns water back to land, solutes left behind o Concentrations of solute in ocean and river used to calculate age
Erosion
o Rates of erosion can be measured and compared to amount of erosion observed o Steno?s laws require every landscape has a long history of erosion o Using uniformitarianism, modern erosion rates can be used to estimate amount of time required to form the landscape
Law of Thermodynamics
o Energy cannot be created or destroyed o Entropy in a closed system never decreases o Absolute zero entropy of everything is same
Kant?s nebular hypothesis
o Solar system formed by gravitational collapse of dust and gas in a planetary nebula o Gravitational contraction resulted in increase in temperature, impacts of asteroids into other bodies converted kinetic energy to heat o Given open system of solar system and law of conservation. System must cool down
Age of the earth
o Assumptions ? Earth cooled from originally molten mass, mixing achieves equilibrium, center solidifies firs, no other energy inputs, uniform temperature o 1st date was 400 million years
Measuring age of earth
o Requires making measurements, geological estimates requires assumptions of uniformitarianism; physics-based estimates missed key components of physics o Radioisotopic decay ? Isotope is same number of protons but different number of Neutrons ? Some isotopes are unstable and will decay into new stable elements ? To make unstable isotope energy must be expended ? To make an isotope measure the time it takes to decay (half-life) ? Many different radio isotopes are used by geologists to age minerals ? Any mineral that can include radionuclides in its lattice at time of formations and then hold onto daughter nuclei after decay can be aged ? Age tells us the last time the mineral cooled ? Measurement of ration of parent to daughter nuclei ? Biostratigraphy and other relative aging techniques are combined with radioisotopic ages to build the geological timescale
? Raw materials (How to build a habitable planet)
? 92 naturally occurring elements ? After big bang only H and He existed and no planet can not be around without the remaining elements ? Nucleosynthesis: stellar fusion ? Stars are nuclear reactors that balance inward force of gravity and dissipative force of heat generated by fusion ? In order for fusion reactions to occur temperatures need to be high ? Leads to extra iron
Sun (How to build a habitable planet)
o Made from ? Photons are emitted from atoms when their electrons are excited to higher energy levels and then fall back down to lower levels ? The wavelength of the absorbed/emitted light depends on the specific change in energy state of the electrons ? Because different elements have different electron configurations they have different emission spectra ? Naturally occurring elements synthesized in red giant stars (2nd generation) o Rather small star, not enough mass to go supernova, barely has enough to be He o In 5 Ga it will run of H fuel and begin to collapse
Planetary nebula (How to build a habitable planet)
o Gravity causes collapse of compositionally homogenous gas and dst in a nebula o Small variations in motion within cloud get transferred to rotational motion during collapse, cloud flatten into a disk o Gravitational fields created by orbiting particles result in accumulation of ever-larger masses around central mass
Meteorites (How to build a habitable planet)
o Best constraints on the composition of the inner planets o Most of fragments are left over from planetary nebula, some from impacts on other planets o Provides best age for earth (4.55 Ga) o Many different ones have been ages and all have ages that are similar to one another
55 Cancri solar system
5 confirmed planets and one is thought to be an earth like one
Moon (How to build a habitable planet)
o After formation of earth a mars sized planet impacted the earth o Material ejected from earth eventually coalesced to form moon o Large amount of angular momentum in earth-moon system today
Planitary Modifications (How to build a habital planet)
? Gravitational, density-driven segregation of earth resulted in formation of a heavy Fe-rich core and light rocky mantle ? Some elements preferentially concentrated in Fe-rich core (Ni) other elements concentrated in scum at surface (Si) NICE Diagram on page 12 out of 13 ? Gases like H2O and CO2 expelled to form early atmosphere ? Differentiation of earth set up conditions necessary for production of a strong magnetic field which deflects solar wind ? Light elements near the surface (O, Si, Al) and heavy elements (Fe, Ni) in core ? Plate tectonics moves continents around and recycle/release material at earth?s crust ? Process is driven by transfer of heat from interior to exterior by convection and by density contrasts created by cooling lithosphere ? Light, buoyant continental crust floats on mantle (rarely recycled), Heavy less buoyant sea floor sinks into mantle (recycled frequently
Oldest surviving rock
? Is in Acasta Gneiss in the oldest portion of North America ? Rock has been repeatedly heated and deformed indicating a long and complex history ? Older rocks must have existed, but these have been destroyed by erosion and by plate tectonics
Controls of Planet?s temperature
o Luminosity of star, distance from star, reflectivity of surface, compostion of atmosphere
Inner planets get the volatiles through degassing
o Some minerals in mantle are capable of holding a large amount of H2O o Earth?s atmosphere accumulated from volcanic emissions o Plate tectonics continuously supplies gases to our atmosphere
Atmospheric gases trap thermal energy
o Sunlight warms the surface of the earth, energy re-emitted as longer wavelength radiation o A body of the avg temperature of earth will emit energy in a predictable pattern; departures from this pattern reflect the effect of energy trapping by greenhouse gases
Atmospheric moisture trap
o Most water on earth derives from degassing of the mantle o Vapor from surface cannot easily escape into upper atmosphere due to temperature drop at tropostratophere boundary o Temperature change acts as a moisture barrier that prevents H2O from making it out of atmosphere o Huge amount of CO2 is in sedimentary rocks- active tectonics and liquid H2O permits this
Oldest sedimentary rocks record hydrologic cycle
o 3.85 Ga (Greenland) o because life takes up light isotope all organic matter is depleted in the heavy isotope o light graphite is found in these rocks suggesting life made the carbon
Life as a chemical reactor
o Bacteria and archaea are fast acting chemical reactors that radically change the chemistry of the entire planet
Oldest fossils on earth
o Apex Chert (3.4 Ga) Australia o Oldest actual fossils of organisms are small prokaryotes o Fossils are preserved as carbon films within chemically precipitated sediment
Chemolithotrophs
Use inorganic compounds as an energy source
Photolithotrophs
Use light as an energy source in photosynthesis
Origin of Life
o Bacteria and archea are simple in terms of basic construction o Key elements are barrier to external environment, DNA/RNA, and ribosomes o Complexity is mostly in their metabolic diversity o Organic compounds are quite common in the universe o Left handed amino acids are used by life most abundant in space o Original atmosphere contain abundant of carbon and hydrogen rich compounds o Compound Synthesis-Organic compouns are common in the universe and easily synthesized inorganically on earth but they need to concentrated in order to form the precursors of life. --- Clay minerals have large surface areas that can serve as a template for organizing relatively simple molecules into more complex molecules
Compartmentalization
o Inorder to be viable a cell must have a way to isolate its interior chemistry from the exterior environment o Fatty acid bilayers are perfect for this because they are fluid and can allow molecules to enter and exit
Replication
o Key to life and evolution o RNA under some chemical conditions can replicate without enzymatic mediators o Fatty acid membranes will separate into two vesicles spontaneously as they grow in size o Replication of the information system (RNA) and the compartment system (fatty acid membranes) likely occurred independently, later combined functionally
Oldest stromatolites record biological activity
o 3.5 Ga, most formed by sediment trapped in cyanobacterial mats ? Before evolution of photosynthesis there was no free oxygen in atmosphere way to reactive, Fe was soluble in water when oxygen wasn?t present, for oxygen to build up is atmosphere oceans had to rust
Eukaryotes fossils
o Oldest are single celled most likely made by algae o Organelles were derived from the cooperative association of multiple prokaryotic cells o Origin of eukaryotes believed to be the enclosure of some prokaryotic cells by another larger prokaryotic cell ? Size of organelles within eukaryotic cells is nearly identical to the size of free-living prokaryotes to which they are metabolically similar ? Organelles of eukaryotes have their own DNA, RNA, and ribosomes; sequences are similar to prokaryotes ? Organelles have their own independent mechanisms of reproduction during division of eukaryotic cell ? Mitochondria are susceptible to antibiotics
Earths Very Compact Timeline
o 4,550,000,000 yr- Earth forms from planetary nebula (from meteorites) o 4,404,000,000 yr-oldest know object from earth o 4,030,000,000 yr-oldest surviving rocks o 3,465,000,000 yr-oldest visible fossils:prokaryotes o 2,300,000,000 yr-oxygen accumulates in atmosphere o 2,100,000,000 yr-oldest macroscopic fossils: eukaryotes o 710,000,000 yr-earth freezes over: snowball earth o 600,000,000 yr-oldest multicellular animal fossils o 542,000,000 yr-cambrian explosion of animals o 240,000,000 yr-first archosaurs o 65,500,000 yr-K/Pg mass extinction o 2,600,000 yr-Genus homo (H. habilis) appears o 10000 yr-last glaciers in WI o 233 yr-American Independence
Precambrian Life
? The Precambrian living world is a microbial metabolic world ? Virtually all metazoan phyla don't appear untill early in the Cambrian
The Early Cambrian
Small shelly fossils, burrowing by bilaterians, first trilobite in NA (eofallotaspis)
Middle Cambrian
Lingulide brachiopods, eocrinoids
Trilobite evolution
o Arthropods with durable external skeletons that readily fossilize o Bodies divided into distinct regions (head, thorax, tail) o In order to grow all arthropods must shed their exoskeletons which meanst that lots and lots of fossils record the growth of the species o Variation in development can be compared within and between species o One trait that varies is the number of segment in the adult form known as polymorphism o Number of polymorphisms within species is much higher earlier in the Cambrian o Rates of diversification are very high in Cambrian o Hox genes are conserved across all arthropods o Rare but fossils of trilobites that preserve soft parts (legs and antennae) * Provide additional info about development and evolution of arthropod body plans
Cambrian Explosion summary
o Most animal phyla have stem groups that appear relatively abruptly in the lowest fossiliferous strata in the Phanerozoic o There is still plent of time for evolution 10s of millions of years separate the first traces of bilaterians and the abundant fossil record of animals o Our knowledge of the Cambrian explosion has been greatly enhanced by the occurrence of several key lagerstartten
What caused the Cambrian explosion
o Hypotheses ? Biological factors ? Developmental Trigger-the evolution of HOX genes and the differentiation and patterning of animal body plans ? Ecological Trigger-the evolution of predators and an evolutionary arms race ? Physical Factors o Oxygen trigger-oxygen threshold reached permitting evolution of large bodied animals with active lifestyles o Snowball Earth-the deepfreeze of the earth did something to prompt the evolution of animals with shells
Ordovician radiation
Marine life diversifies, but few major new types of animals appear, variations of those appeared in Cambrian
Paleozoic Marine Revolution
Devonian-------sea lilies regenerate their arms just like starfish, frequency of predation events on crinoids ( sea lilies) are caused by fish. Increase in frequency of predation in Devonian
Problems getting onto land
Gravity and water, must have structural features to support body, must have structural features to prevent desiccation
Land Invasion: plants pave way
o Ordovician and siliurian o Forests by Devonian
Land invasion by animals
o Silurian-Devonian o Arthropods get there first ? Insects rule sky o Flying by carboniferous ? Lobe-finned fish o Appear in Devonian o Fleshy lobes with well developed skeleton in fin, Nostrils and lungs, living examples include lungfish and coelacanths ? Tetrapods (amphibians) appear in Devonian o Four limbs for walking
Tetrapods
(amphibians) appear in Devonian. -- o Four limbs for walking o Digits on limbs from 4 to 12 o Hinge like wrist and knee joints o Pelvis attached to vertebrae for support o Eggs without shell, laid in water o 1st tetrapods retain many lobe-finned features
Reptiliomorph amphibians
o Larger limbs much more robust; body held higher off ground o Reptile like in many respects but lack key reptilian trait
First amniotes (egg layers)
o Eggs free tetrapods from water o Anapsid reptiles? Synapsids: pelycosaurs and mammal-like reptiles ? Diapsids: reptiles
About this deck
By: j f
Textbook: The Origin of Species (Barnes & Noble Classics Series)
Created: 2009-12-18
Size: 277 flashcards
Views: 188
Textbook:
The Origin of Species (Barnes & Noble Classics Series)Created: 2009-12-18
Size: 277 flashcards
Views: 188
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Kathy
Kathy