Evolution Unit Review

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VIDA

• variation

• inheritance

• differential survival + reproduction

• adaptation

Natural selection

• prolific rep. of individuals w/ favorable traits that survive environmental change bc of those traits

• “inherited modifications”

• only known mech. for adaptive evolution

2 main mechanisms of genetic diversity

mutation & sexual reproduction

Mutation

change in DNA

outcomes of mutation

• reduced fitness

• beneficial effect on fitness

• no effect on fitness (neutral mutations)

how sexual reproduction leads to genetic diversity

2 parents = unique combination of alleles —> unique genotypes + thus phenotypes in offspring

Adaptation

hereditable trait that helps an organisms’s survival and reproduction in present environment

Divergent evolution

two species that evolve in diverse directions from a common point —> variation in form + function

ex. flowers all have a common ancestor

Convergent evolution

similar traits evolve independently in species that do not share a recent common ancestry

• trait in 2 species came to be similar in structure + have the same fuction but did so independently

ex. bats + incests can fly

Evidence of evolution

• fossils

• anatomy + embryology (bones)

• biogeography

• molecular biology

Homologous structures

bones shape + sizes change but they maintain the same overall layout

Vestigial structures

unused structures w/out function

ex. tailbone in humans

Analogy aka homoplasy

when similar characteristics occur bc of environmental constraints and not due to close evolutionary relationship

• happens bc of selection pressure

embryology

study of anatomy of an organism’s development into it’s adult form

• some organisms have structures in their embryonic form that disappear when they reach adult or juvenile form

biogeography

study of geographic distribution of organisms across the planet

• species can be region specific based on WHEN they developed (pre or post continental divide)

molecular biology

DNA’s universality + structural differences in ribosomes + membranes reflect common ancestry + decent w/ modification

gene duplication in evolution

allows new protein functions to evolve while maintaining the original function

Things to note

• INDIVIDUALS DO NOT EVOLVE

• IT ISN’T THE ORIGIN OF LIFE

• EVOLUTION IS NOT GOAL DIRECTED

3 primary sources of genetic variation

• mutation

• gene flow

• sex

Gene flow

any movement of genetic material from one population to another

Fitness

how good a particular genotype is @ levaing offspring in the next generation relative to otehr genotypes

artificial selection

when people select which organisms get to reproduce (instead of nature)

ex. farmers and breeders choosing traits

Thomas Malthus

economist who published essay explaining competition for resources among humans —> influenced Darwin + Wallace

Georges Cuvier

He established proof that many species had become extinct in past ages and that after catastrophes new species had been created —> influenced Darwin + Wallace

Charles Lyell

Geologist who provided geological and fossil evidence to support Darwin’s theory (long time span proven). He proposed that Earth is extremely old and processes that changed the Earth in the past are still @ work today

Charles Darwin

If you don’t already know what he did ur cooked. Biggest name in evolution EVER

Alfred Russel Wallace

Same thing as Darwin at the same time just doesn’t get credit

Modern synthesis

the coherent understanding of the relationship btwn natural selection and genetics

Microevolution

a change in gene frequency within a population (small scale)

Macroevolution

process that gave rise to new species + bigger taxonomic groups w/ widely divergent characters

evolution of groups larger than an individual. Macroevolution encompasses the grandest trends and transformations in evolution, such as the origin of mammals and the radiation of flowering plants

population genetics

study how selective forces change a pop. through changes in allele and genotypic frequencies

gene pool

sum of all the alleles in a population

genetic drift

when allele frequencies in a population changes randomly with no advantage to the pop. over existing allele freq.

founder effect

an event that initiates an allele freq. change in an isolated part of the pop. which is not typical of the original pop.