AP bio unit 7

Biogeography

-study of patterns in the geographic distribution of species

-critters have diff features depending on their environment

comparative morphology

study of body plans and structures

fossils

pieces of evidence of the views of several scientists contradicted the popular belief regarding age of Earth

Charles Darwin

- English naturalist

Galapagos Islands

- close together, but have very different climates

- Hutton and Lyell

- Malthus

Hutton(1785) and Lyell(1833)

- geologists

- Theory of uniformity(Lyell)

- the idea that Earth has always changed in uniform ways and that the present key to the past

- gradual repetitive change that shaped earth

- took place of catastrophism idea(Cuvier 1800)

-Earth is millions of years old, and is still changing

Hutton(1785) and Lyell(1833) and Darwin

- If Earth could change, so could life!

- For life to change, it would take a long time

- earth is old enough to do this

Lamarck(1809)

- a naturalist before Darwin

- Lamarck believed that...

- organisms change over time

- species descended from other species

- Critters acquired or lost traits during their lifetime, and traits then passed onto offspring

- BIG IDEA: environment forces change on an organism and that change gets passed on

Lamarck(1809) and Darwin

- organisms change over time

Darwin agreed!

- species descended from other species

Darwin agreed!

- Critters acquired or lost traits during their lifetime, and traits then passed onto offspring

Darwin didn't agree!

Giraffe Example (Lamarck vs. Darwin)

Lamark: The giraffe stretched out its neck by using it constantly over its lifetime. It passed on its stretched neck to its offspring, which stretched out its neck more. Over time, you get a population of giraffes that all have longer necks.

Darwin: The lengths of giraffes' necks vary. The giraffes with longer necks live to reproduce, and they pass on their long-necked trait. B/c the long-necked giraffes reproduce, all giraffes eventually have longer necks.

Malthus(1798)

- economist

- connected pop size and demands on the environment

- if humans continued to grow unchecked, will run out of food/space.. humans need to compete

-Darwin applied this to plants and animals

-not all individuals of pop are exactly the same

-is variation connected to survival?

-majority of species' offspring will die

-which factors decide which survive and reproduce?

Natural Selection

1) There exists VARIATION within a pop

(born with diff alleles)

2) Not all offspring will survive

(Limited resources, predators, etc.)

3) Those best suited to environment survive longer and reproduce more

(survival of the fittest)

4) Descent with Modification

(Survivors pass on genes to next generation)

Artificial Selection

- not the same as natural selection

- nature provides variation

- naturally...the fittest survive

- artificially...humans select what's useful

Fossil Record

- fossils found in different layers of rock

- shows how species change over long periods of time

- use radiometric dating to determine age of fossil and rock

- C14 use

Tiktaalik- Missing link fossil Lobe-finned fish

- fossils are tools to show how organisms are related to each other

- life on earth started in the ocean

- whales return back to water

- animals moved got and but went back to water

- missing fossil was evidence of fish with fins providing push force which could have provided support force to help it propel on land

- likewise, some animals have returned to the ocean like whales and dolphins (another missing link)

-whales use tail for movement in ocean but have no hindlegs

-whales have hip bones(vestigial structure) though

-looking for evidence of four legged creature that had legs but legs that were used for swimming

Homologous body structure

- may have different mature forms

vestigial organ

structure no longer used by animal

EX: appendix, tailbone

vestigial organs/structures

semilunar fold

- sharks have it to protect their eye from being poked while hunting for food

Ear-wiggling muscles

- three small muscles above the ear

Tail

- present in human and all vertebrate embryos

- in humans, the tail is reduced; most adults only have three to five tiny tail bones

Wisdom teeth

- molars that are often useless and sometimes even trapped in the jawbone

- some people never develop wisdom teeth

Wrist tendon

- 10-15% don't have it

in order to become a new species,

gene pools of two pops must become isolated in order to become a new species

gene pool

collection of all genes and alleles found in a pop

Steps to Speciation

1) Founders arrive from South America

2) Allopatric Speciation

-geographic isolation

-different environments(dry, wet, high, low)

3) Pop adapts(Natural Selection)

-food source

-predators

-habitat

4) Reproductive Isolation Results

-Behavorial Isolation- diff mating calls

-Temporal Isolation- mate at diff times of they year

5) Abracadabra...

-Evolution has formed two different species

allopatric speciation

geographic isolation

Sympatric Speciation

Divergent evolution in a pop without barrier

Punctuatted Equilibrium

long stable periods interrupted by brief periods of rapid change

Gradualism

gradual change

speciation rates occur faster when...

new habitats open up