mimic non venomous.
adaptive if model is common
features of an organism that:
help them survive and reproduce.
created through evolution by natural selection
wrote origin of species in 1859.
introduced natural selection.
Darwin's three postulates
for adaptation to occur there must be:
1. struggle for existence
2. variation in fitness
3. inheritance of variation.
this is also definition of natural selection.
HMS beagle voyage
Thomas Malthus: principle of populations.
Charles Lyell principles of geology
Carolus Linnaeus : systems nature.( counter to Darwin's ideas)
john baptist lamark: essentialism. (counter to Darwin)
Alfred Russell wallace
came up with same idea as Darwin before origin of species was published
physician and naturalist. interested in evolution.
arise through accumulation of small changes.
improbable with just random variation.
probable when changes are additive and intermediate steps favored by natural selection.
rate of evolution
complex adaptations can arise slowly or quickly .
the same anatomical feature can evolve at diff. times quickly or slowly.
slow changes easier to observe in fossil record.
born in Czech.
conducted experiments on inheritance in peas.
mendelian genetic 1866. ignored until 1900.
eventually eliminates variability.
everything becomes intermediate form.
Mendel's conclusions from pea experiment
traits of an organism:
determined by two genes.
equally likely to be transmitted when gametes produced.
diploid vs haploid
diploid: 2n=46. after meiosis you get a diploid zygote.
haploid: gametes: egg and sperm are haploid. n=23.
contains genes that allow traits to be transmitted.
portion of chromosome that has a recognizable effect on phenotype.
variety of genes with the same effect on an organism.
variant of a gene
combo of genes and alleles an indiv. carries
building blocks of proteins.
AA and aa
2 of the same allele for the same gene.
from genotype to phenotype
sequence of paired bases:
g with c
t with a
mrna : takes DNA message from nuc to cyto.
tRNA: strings together
similar structure to dna: T replaced by U
chains of amino acids.
body is made of proteins:
coding sequences: ie like the ones that code for proteins.
introns: gene sequences that code for nothing.
regulatory sequences: determine condition under which genes express themselves. shapes?
change message of DNA
can change proteins.
can change phenotype
some are deleterious.
some create variability natural selection can work with.
forces of evolution
natural selection: change in phentype due to selective pressure.
gene flow: exchange of genes between populations of the same species.
genetic drift: changes in population gene frequencies by random chance
change in population gene freq by random chance.
chance increases in small population sizes:
ie. founders effect
genetic drift caused by small population breaking off from the larger one. ie: bottleneck
genes that code for a range of traits or behavior.
ex soapberry bugs and mate guarding. put a leash on ya chick! jk
in Oklahoma sex ratios vary necessitating plastic behavior.
in Florida the population is stable=canalized no plastic behavior
constraints on adaptation
laws of physics and chem.
natural selection may lead to maladaptation:
things that can lead to maladapt:
pleiotrophy: a gene has affect on more than one trait.
ex birds beak width and depth.
adaptive lag: environment change to fast.
changes in population gene frequencies.
processes that lead to development of new species and higher taxonic levels.
biological species concept: 1942
species are populations of orgs. that can interbreed and are reproductively isolated.
gene flow inhibits evolution of new species
formation of new species.
new species arise from existing ones .
physical environmental barriers creating 2 separate populations.
allopatric speciation is reinforced because
there is selection against matings that produce hybrids.
hybrids usually less viable than non hyb offspring.
strong selection for did phenotypes in neighboring habitats.
hybrid zones occur at boundaries of habitats with selection against hybrid traits between the neighboring zones. .. don't know if my wording makes sense to anyone else.
strong selction even without geographic separation
when a single type of organism diversifies through macroevolution to fill a variety of niches.
occurs when there are empty niches.
ex. mammals after extinction of dinosaurs
all organisms can be classified to taxonomic principles
kingdom: most inclusive
subspecies most exclusive
human taxonomy(not all) common English names
tribe : hominin
species: recent humans
sub species: anatomically modern humans
classification of primates
apes and humans:
super family= hominoidea
great apes: orangutans gorillas chimps:
humans and recent ancestors:
humans and apes/ chimps split at tribe level: hominini
similarities that orgs share because of common ancestry.
reconstructing evolutionary relationships among orgs.
phylogeny and its use
basis for identification and classification of species.
helps explain why a species evolved certain adaptions and others didn't.
we can deduce function of morphological features or behaviors by comparing traits of diff species.
transcription vs translation
translation:process in which DNA strand is copied by mRNA and then transferred outside the nucleus by tRNA for translation.
transcription: the copied segment contain anticodons which bond with codons to create a chain of amino acids and or proteins
long term study of chimps from 1960.
classification of primates
prosimians: lemurs, lorises, tarsiers
anthropoids:platyrrhines: new world monkeys
cattarrhines: cercopithecoids old world monkeys
hominoids apes and humans.
ancestral # fingers and toes.
feet have opposable big toes
nails instead of claws
adaption for aboreality?
promote trends 2
increased importance of sight. decrease import. of smell.
vision: stereoscopic . color
brain: portion for sought larger, portion for smell smaller
brain size proportionally larger than other mammals
teeth: 2 incisors 1 canine 3 molars
primate trends 3
parental investment increased.
typically live in groups:
adaptive: provides support for parental inv.
grooming common: social relationships
types of natural selection
directional : changes avg value. takes away one extreme
stabilizing selection: normalizes
disruptive: selective pressure against the avg. instead extremes favored