adaptation and natural selection

adaptation

a characteristic that helps an organism survive and reproduce in its environment. structures and behaviors for finding food, a mate, protection, or moving place to place

snake

jaw that can unhinge to swallow prey whole/ basks in the sun to warm cold-blooded body

kangaroo

large ears to hear predators/ powerful back legs to jump long distances

spider

easily sense vibrations in the ground

monkey

opposable thumbs for grasping items/ prehensile tail for hanging from trees

cheetah

spots to camouflage from predators and prey

elephant

trunk used to bathe,drink,and wash themselves/ large tusks for defense

Origin of species hypothesis 1

aristotle believed all plants and animals had been placed on earth since the beginning and none have ever changed/ tgus idea lasted 2000 years

Origin of species hypothesis 2/ A. Lamark/ Law of use and disuse

the more often a body part is used, the more developed it will be. The less it is used the less developed it will be

origin of species hypothesis 2/ A.Lamark/ inheritance of aquired characteristics

the more developed or underdeveloped traits are passed onto their children. if giraffe uses its neck a lot, it grows longer, and when it has a kid, the kids neck is automatically longer.

disproving Lamark’s theory/ august weismann experiment

august weismann cut tails off 20 generations of mice.

disproving lamarks theory. what was weismann’s hypothesis?

if lamarck is correct, then after 20 generations the mice will have, small, underdeveloped tails because of the law of use and disuse , and inheritance of aquired characteristics.

what was the result of disproving lamarcks theory?

there was no change in the tail length and size of the mice

Origin of species hypothesis 2/ Darwins theory of evolution

evolution happens because of natural selection

natural selection

organisms possessing traits that are highly suited for their environment have a great chance of survival and higher rate of reproduct success.

what are the 4 key conditions necessary for natural selection to occur?

struggle for survival, inheritable variation, variation of fitness, lots of time