Unit 2

Considers that a species is a group of organisms that interbreed freely under natural conditions

> More based on behavior and location, more of a biological concept than morphological

> the secies is defined by whether or not they can interbreed

1) can take 2 forms (geographic and behavioral)

2) isolation concentrates genetic info or traits, which then leads to divergence

Africa; lions and tigers have interbred

even though they have behavioral differences (tigers are solitary, lions are social)

MN; bobcats and lynx

Canada; polar bears and grizzly bears

1) Relationships between organisms based on ancestor-descendant relationships

2) Really key = we can understand species that are extinct based on teh ones we can see today

1) a diagram that tracks traits through time and ancestry

2) reflects common ancestry

1) feb 12 1809-apr 19 1882

2) left england dec 27 1831

3) five year voyage when 22

4) origin of species, pub 1859

Wallace's line in se asia: "similar species should be native to similar habitats"

      > found that deep trenches kept animals from going across the line

1) Biogeography

2) Paleontology

3) Morphology

      a. Homologous Structures

      b. Vestigial Structures

4) Embryology

1) superficially different but fundamentally similar versions of a single organ or trait shared by dissimilar species

2) reconfigured for different uses over time

3) ex: feet structures in humans, cats, whales, and bats

a trait that recurs in an organism that had elminiated it

    ex: legs on a snake

1) takes many generations to projuce substantial (speciation) evolutionary change

2) doesn't imply an even rate of change--some could be rapid, some more slow

Tracing ancestry backward in time to a shared/common ancestor

the proposition that genotypic ratios resulting from random mating remain unchanged from one generation to another, provided natural selection, genetic drift, and mutation are absent

* allows us to figure out

Beneficial: speed... you survive

Harmful: white fur... if you hunt in the dark, you won't catch anything

A condition where a gene pool is not changing in frequency because the evolutionary forces acting upon the allele are equal, thus, resulting in a population to not evolve even after several generations.

1) lack of mutations

2) large populations

3) complete isolation from other populations

4) allele under study has no effect on survival or reproduction

5) mating within the population is random

1) mutations

2) Genetic drift

3 main conditions for occurence:

1) variability

2) heritability (traits must be passed from parents to offspring)

3) differential reproduction (selection)

requires a selection mechanism (something in the external environment that actos on any particular allele and has an influence on survival and reproduction (temp, speed of predator, coloration of environment)

pop. size not all that important

1) selection tends to shift the genetic variation in one direction

2) Selection eliminates traits on one end of range

3) Mostly what we think of with respect to natural selection

1) Selection eliminates extreme forms of genes

2) Both sides of the range of values

Random fluctuation in allele frequency over time, due to chance alone without any influence by natural selection; important in small populations

> no selection mechanism is needed

> caused solely by chance

> has no memory

> has no memory

> accumulates

> causes/leads to a loss of genetic variability within a population

> leads to an increases in variability between populations (over many generations)

> similar organisms were nearby eachother

> spatial pattern/geographic distribution of organisms`

> fossil record

> relationships of organisms patterns through time

> strtigraphy (organisms changing through time)

      a. Homologous Structures

      b. Vestigial Structures

those things that we have but don't need, ex: tail bones in humans

cat fetus vs. human fetus

A population started by a few individuals or a small set of individuals will contain only a small subset of the alleles of the larger population

Move to a new place... like an island (and tend to have weird patterns)

a reduction in population size

ex: spotted owls; habitat was being destroyed (but then destruction stopped) yet population still decreased because of lack of variation and inbreeding didn't help with diseases

the formation of a new species in the same geographic area

very rare

diff from allopatric in that it's behavioral

"It takes all the running you can do to keep in the same place"

extinction can drive evolution

example of adaptive radiation

their beaks vary in length

somehow a bird with a short beak ended up in hawaii

example of sympatric speciation

the behavioral mechanism of feeding time affect lemurs

one kind started to be able to eat bamboo with cyanide (stenophagous)

>Red Queen Hypothesis

> Ex: wolves and deer and wolves needing to evolve to be faster

    > must involve unrelated species who evolve together

> mountain example

When animals go extinct, they can free up resources for other animals to use

    Ex: dinosaurs went extinct and more animals start to breed and caused them to start speciation

1) gene flow

2) genetic drift

3) natural selection

4) Mutation

> related to source and sink

> it's genes flowing from one population to another