Scientists and Evolution Notes Flashcards

b/c he studied fossils and he thought that the earth was old b/c of how some ancient animals are similar to modern ones, but not exactly alike.

he says that adaptive characteristics are developed fro use or disuse use of a body part

ex) elephant stretching it's trunk to make it longer b/c it wanted to be more suiting for it's environment

WRONG

The environmental pressures change the species

ex) Darwin's finches, and the drought and flood. These environmental changes caused the birds beaks to change to match what was best to eat the foods available - the drought would have brought bigger harder seeds, so birds with big beaks would survive rather than birds with small beaks

he says that adaptive characteristics are based natural selection

ex) there was a mutation within the size of elephants trunks. The mutation making on elephants trunk longer. The one with the longer trunk would have fit the environment better, meaning it would have more offspring.

2 distantly related species

share 2 very distant common ancestors

they evolve a similar trait due to environmental pressures (ex. predators, climate change, human activity, fossil fuel burning)

ex) bat and bee (analogous)

2 species that share a more recent common ancestor

develop differently b/c of environmental pressures

ex) Darwin's finches (vestigial structures or homologous structure)

1) an animal struggles to survive (struggle for existence)

2) there are natural variations from mutations, and these variations can improve the organisms chance of survival (an adaptation)

3) the animal will have better fitness, meaning they can survive and have a lot of offspring

4) the bad variation is naturally selected against

shows how the earth is old, traces the evolution of modern species from extinct ancestors

similar structures support the idea of common decent

shows how animals have changed over time from common ancestors (environmental pressures)

can show scientifically how similar an organism is to another

same structure, different function

ancient lobe - finned fish < frog / horse

common function, different structure

ex) fly and bird = both fly, but one is membrane vs flesh/bone/blood

inherited from ancestors but lost much or all of it's function

moles eyes = blind or humans wisdom teeth = not used

certain conditions prevent mixing

ex) physical incapability (Chihuahua vs Great Dane)

different mating habits (calls, breeding ground or courting)

causes speciation

ex) the gran canyon and squirrels, the gran canyon eventually forms separating the squirrels into 2 dif species

a group of organisms that can breed and produce offspring (ex. people and dogs)

the finches came from the mainland, and landed on an island. Eventually they spread through other islands. The dif geography conditions make the birds adapt, creating a new species

some individuals become isolated and establish a new population

ex) the Pennsylvanian Amish -> incest caused mutations

a change in environment reduces population size

ex) cheetahs got poached = decreased population, causing certain alleles to disappear -> genetically similar

has a half-life of 5730 years

meaning 25% at 11460 years

12.5% at 22920 years

Offspring are not successful

the hybrids are sterile and unable to make more offspring

natural selection in which an extreme phenotype is favored over other phenotypes, causing the alleles causing that phenotype to be favored and shift over time in the direction of that phenotype

ex) if there is a large environmental change causing an abundance of only a certain type of seed (and not the other). Then only a certain type of bird will be able to survive making the graph move left or right

natural selection in which intermediate forms of a trait are favored and more extreme values are selected against

ex) the birds with the medium beak could get more food with less energy than birds with extreme size beaks

natural selection in which extreme forms of a trait are favored over intermediate values. Variance of the trait increases and the population becomes divided into 2 groups -> can cause speciation

ex) the birds with medium beaks couldn't get enough food so they died off leaving 2 dif groups making 2 new species

a group of organisms all from the same common ancestor

same as a clade but "missing" some organisms in the group

organisms being studied

"old" trait that everyone has

"newer" or novel trait derived more recently

branch representing a speciation event

everything above the node has the trait

top of the tree ; current organism

bottom of the tree ; representing common ancestor

explained George Buffon's observations

life evolves or changes due to adaption