unit 6 - evolution Flashcards
(42 cards)
what is evolution
a change in the inherited characteristics of a population of organisms over generations
artificial selection
process by which individuals display specific traits through selective breeding (eg. dog breeding)
natural selection
process by which individuals w/ advantageous genetic characteristics for a particular environment survive and reproduce at a higher rate than others
are adaptions always beneficial
not always beneficial since there can be changes in environmental conditions (eg. drought and then extreme rain)
how do fossils help with evolution understanding
strongest evidence since they can reconstruct earth’s history by showing how organisms changed over time
common ancestry
an organism from which many species have evolved from
homologous traits
a feature that is common across species because of common descent
vestigial traits
a feature that is inherited from a common ancestor but is no longer used
how do homologous and vestigial traits support common ancestry theory
demonstrate shared evolutionary history and modification of structures over time
how does embryonic development relate to evolution
similarities in embryonic development across species show traits inherited from common ancestors
pieces of evidence that prove common ancestry
x-rays, chromosome banding patterns, embryonic development, fossil evidence,
three types of selection
directional, stabilizing, disruptive
direction selection
individuals at one phenotypic extreme of a trait have an advantage over others
stabilizing selection
individuals with phenotypes in the middle have an advantage
disruptive selection
those with both extreme phenotypes have an advantage over others
convergent evolution
evolution that results in organisms that have different genetics but appear very similar
analogous trait
feature that is shared across a species due to convergent evolution, not due to modification by common descent
analogous traits vs homologous traits
analogous traits are developed by unrelated organisms due to similar issues whereas homologous traits share evolutionary orgin and not necessarily same function
sexual selection
natural selection in which a trait increases an individuals chance of mating even if it might decrease survival rates
gene flow
exchange of alleles between populations
genetic drift
change in allele frequencies produce by random differences in survival and reproduction in a small population
one way genetic bottleneck can happen
drop in population size leads to a loss of genetic variation in the new rebounded population
founder effect
small group of individuals establish population isolated from the original, larger population leading to a loss of genetic variation
Darwin’s theory of evolution by natural selectin
if a population contains variation and if ht e variation is at least partly heritable and if some variants survive to reproduce at higher rates than others, then the population will evolve
