a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value.

* selection that favors heterozygous

when sexually reproducing organisms mate with individuals not like them

* Results in stabilizing natural selection

when sexually reproducing organisms mate with individuals that are like themselves.

* Results in disruptive natural selection

Causes changes in allele and genotype frequencies within population.

1. mutations

2. sexual selection/ non-random mating

3. natural selection

4. gene flow

5. genetic drift

a mathematical theory that predicts genotype frequencies from observed allele frequencies. 

** Purpose: can do a test for evolutionary change

the fitness of a particular genotype depends on its frequency population

when one species evolves in to many species in a short time period, usually in response to ecological niches

ex. galapagos finches, lizards, NA wood warblers

the movement of individuals from one population to another with mating (really, this is allele flow)

With lots of gene flow-- prevents populations from becoming genetically different; therefore, gene flow prevents speciation.

With no gene flow-- populations become genetically different; can cause speciation

NOT THE SAME AS GENE FLOW

- seasonal movements of populations from one geographic locality to another

sampling error in the production of zygotes from a gene pool

a) not adaptive

b) decreases frequency of heterozygotes, increases frequency of homozygotes

c) reduces genetic variation

d) big problem in small population

when a small number of individuals starts a new population.

- genetic variation small compared to original population

the average number of indivuduals in a population that contribute genes equally to the next generation

-- usually smaller than the actual population size

Beneficial mutations are rare.

Most evolutionary changes at the molecular level are caused by random drift of selectively neutral mutants.

if most mutations are neutral, then the rate of molecular evolution should be roughly constant over time, ticking along like a clock.

- can use to predict time since divergence

- a tree showing evolutionary relationships and history of a group of organisms

Main idea: close branches mean close evolutionary relationships

organisms are similar because they are closely related

Ex. blue jay, scrub jay, gray jay

organisms are similar because they evolved the same characters independently via natural selection as adaptations to the same selective forces

ex. stork, turkey vultures, griffon vulture, fish eagle

a change in allele frequencies of one species in response to a change in allele frequencies in another species.

ex. moths

structures that have lost their original function.

ex. your appendix

- leg bones in pythons

- leg bones in fossil whales

"throwbacks " - genes present but normally turned off

ex. supernumary nipples

examples:

antibiotic resistance/ pesticide resistance

a closely related species that is not part of the ingroup

-- characters in outgroup assumed to be ancestual

a character found in the ingroup and in the outgroup or can found in the outgroup only

* USELESS

a character that is shared by two or more members of the ingroup, but not with the outgroup

** VERY USEFUL

a character found in only one species

** USELESS

- warm-blooded/endothermic

** - mammary glands + milk to nourish offspring

** - hair made of keratin

- four-chambered heart

- well-developped brain

- specialized teeth

** - neocortex region of brain

- sweat glands

- three middle ear bones used in hearing

young develop in a marupium (a pouch)

** Austrailia = marsupials found most on this continent

CHARACTERISTICS

a) Have a big toe separated from other toes, except humans

b) thumb is separate from fingers

c) binocular 3D vision

d) large brains and short jaws

e) flat nails on fingers and toes, no claws

monkeys, apes, and humans of both new and old worlds

3 MAIN GROUPS OF ANTHROPOIDS

a) new world monkeys -- prehensile** tail, all species arboreal***, nostrils open to the side

b) old world monkeys: no prehensile tail, arboreal and terrestrial species, nostrils open downward.

c) great apes --- no tail, arboreal and terrestrial species, large body size, nostrils open downward

1. Ardpithecus ramidus

2. Australopithecus afernsis (lucy)

3. Homo Habilis

- skull was less than half the size of modern human

4. Homo erectus

ex. Peking man 

5. homo neanderthalensis

- Did not interbreed with homosapiens

6. Homo sapiens

ex. cro-magnon man: name for the earliest modern humans that lived in europe

1. homoerectus leaves africa 1-2 my to colonize asia, europe and australasia

2. by 100,000 years ago, all homoerectus populations evolved into homosapiens at the same time

3. lots of gene flow between populations

1. homoerectus leaves africa 1-2 mya to colonize europe, asia, and australasia

2. homosapiens evolve in africa 200,000 years ago

3. homosapiens leave africa 100,000 years ago and replaces (outcompetes) all homoerectus populations

**Supported by molecular and skeletal data

what an animal does and how it does it

** influenced by both genetic and environmental factors

"instinctive" behaviors are developmentally fixed and not modified by environmental factors

- these are usually behavior for which there are no opportunities for learning

ex. baby monkeys holding on to mom

- a sequence of innate behaviors that is unchangeable and once, initiated, is carried to completion.

-- ex. the egg rolling behavior in geese.

- when organisms prefer an excessive stimulus to the normal stimulus

ex. a bird that wants to incubate the biggest egg it can find, even if it is just a big rock

the recognition, response, ant attachment of young to a particular adult or object.

-- irreversible usually

-- ex. ducks & geese will imprint on humans

the loss of responsiveness to unimportant stimuli.

ex. the "cry wolf" effect

-- ex. habituation to unpleasant smalls

- the ability of many animals to learn to associate one stimulus with another

ex. pavlov's dog learned to associate the sound of a bell with food and would drool even if it only heard the bell

trial & error learning. -- an animal learns to associate one of its own behaviors with reward or a punishment 

- ex. when a dog does something you like, the dog wants to keep doing it

reasoning. formulating a course of action by understanding the relationships between the parts of the problem. 

-- common only in primates, especially humans.

- difference in gamete size in males and females.

-- eggs are large and costly; sperm are small and cheap

** females protect their investment in reproduction (more choosy)

** males try to fertilize as many as eggs as possible (be promiscuous)

-evolve because sometimes males and females must cooperate to successfully raise offspring

one male, one female.

usually mate for life.

sexes often monomorphic (look alike) both sexes "jealous"

protecting your investment in reproduction by not allowing your partners to mate with other individuals.

-- often seen as PDA

- one male, many females.

harem (brothel) tend to form when territories or other resources are limiting

sexes dimorphic: males showy, females cryptic

- one female, multiple men

sexes dimorphic: females showy, males cryptic

when females are promiscuous, males evolve strategies to ensure they fertilize her eggs.

in many species, females store sperm for a later time

- some species can store sperm for a week or more

most recent male fertilizes most of the eggs.

-- explains why mate guarding evolves

chimps and macaque's are polyandrous, but humans and gorillas are usually monogamous

in species where females mate with multiple males, natural selection should favor males with competitive sperm.

some species produce many small sperm-- others produce a few giant sperm.

- female accepts the 1st mate that meets a minimum that threshold

- occurs when males are scarce or spread out over a large geographic area

- female accepts the best male among those available

- usually involves a simultaneous comparison of several males

lek: an arena where males display for females

- Mhc genes may act like pheromones

- warning if someone is too closely related to you

- DIFFERENT is good!

- parents take care of young only as long as they need to

-- after that, it's just competition

- parents force other individuals to raise their offspring

ex. cuckoo and cowbird

- your fitness plus the fitness of your close relatives

*** WHY ANIMALS COOPERATE

clumped

**most common

- organisms together in patches, herds, flocks, etc

ex. caterpillars, wilderbeast

- equal spacing among individuals

- ex. gannet breeding colony

No pattern

- ex. dandelions

proportion of individuals alive during a given time interval

a) type I: high survivorship through early and middle-ages

(humans)

b) type II: relatively constant survivorship throughout life

(birds)

c) type III: low survivorship early in life

(plants)

the traits that affect an organism's schedule of survival and reproduction

ex. how long to live?

when to reproduce?

how many eggs/seeds to make?

ex... dandelion

- many small seeds

....coconut

- few large seeds

a) survival and reproduction

ex. red deer females that reproduce die younger than those that don't reproduce

b) offspring quality versus offspring number

population size controlled by disease, competition, parasites, predators, territorality, accumulation of wastes.

**Factors become more intense as population size increases.

populations size affected by natural disasters, climate changes.

** Factors affect large and small populations equally

- mammals living in the cold have shorter faces and limbs than mammals living in warmer area

ex. red fox vs. arctic fox

- Warm-blooded animals that live in cold areas are biggers than those that live in warm areas

ex. canadian geese are bigger because they flock to canada where it's cold

Dark pigments are more living in warm, humid environments than in cool, dry ones

ex. song sparrows --> light in cool north

darker in warm south

- an interaction that benefits one species, but has no affect on the other

ex. Bird's nest

- epiphytes - plants that grow on other plants

- an interaction that benefits both species

ex. african birds pick parasites off mammals

- shrimp will pick parasites off

OLDEST MUTUALISM -- eukaryotic cell - mutualism between archaen & bacterial cell

- nobody benefits

- competition between individuals of the same species

** limits population size

- One organism feeds on the living tissues or another organism

- Parasite doesn't always kill the host

- warns of poison

-- orange, blue, red

- poisonous prey species all evolve bright warning colors (orange, blue, red)

-- poisonous predators usually does not

when a harmless species mimics (imitates) a harmful species

ex. hover fly, hornet moth, wasp beetle.

"batman"

- the chronological colonization of a habitat by a series of different communities

ex. annual plants, perennial plants and grasses, shrubs, softwood trees, hardwood trees

**if you stop mowing your lawn, the area changes what it looks like over time (stages of different growth)