Evolution Flashcards
evolution
a change in genotype frequencies in a population over time
natural selection
the process by which a selective force causes some individuals in a population to survive and reproduce to a greater degree than others, which can lead to evolutionary change
fitness
the level of ability to survive and reproduce
adaption
any trait that makes the organism more likely to survive and repreoduce
fecundity
reproductive success measured by counting the number of surviving offspring
divergent evolution
when 2 or more species evolve from a common ancestor
convergent evolution
similar conditions can cause the evolution of similar traits
homologous structures
structures that have similar parts due to shared common ancestry, which may or may not have similar functions
vestigial structures
structures that have no apparent function and are likely from an ancestor that did have a function for it
microevolution
changes within a species
biological species concept
group of populations whose members have the potential to interbreed in nature and produce fertile offspring
organisms that can breed and produce offspring
morphological species concept
defines species by physical traits, doesn’t require mating
ecological species concept
defines species by their role within the environment
phylogenetic species concept
any group of organisms that have shared common ancestry, also uses physical traits
allopatric speciation
when two species are physically separated
sympatric speciation
When populations live in the same habitat but gene flow has been eliminated through reproductive isolation
reproductive isolation
when a species is reproductively independent from other species; behavior, location, or reproductive barriers may cause this to happen
prezygotic barrier
mechanism that occurs before zygote formation
postzygotic barrier
mechanism that occurs after zygote formation
reinforcement
when hybrids are less fit than parental species- maintain species
fusion
when hybrids are more fit than parental species causing two species to fuse into one
stability
when hybrids continue to be produced and are maintained
hybrid zones
regions where two species have the opportunity to meet and produce offspring
adaptive radiations
when one species rapidly diversifies into a large number of descendant species
equilibrium
no evolutionary forces acting on a population
allele
gene variation that arises by mutation
locus
fixed position on a chromosome where a gene is located
population genetics
it investigates how genotype frequencies in an offspring generation are related to the genotype frequencies of the parents
sexual selection
a form of natural selection, where the selective force is either a choice or competition in mates
intrasexual selection
competition between members of the same sex
intersexual selection
choice in one sex for mates of the opp sex
mutation
variation in the sequence of the gene
migration
gene flow, tends to homogenize populations, but asymmetry can occur
genetic drift
the tendency for sampling error among genes in small populations
stabilizing selection
centering pop around the mean
directional selection
taking the population and centering it somewhere else, when individuals have higher fitness on the end of the curve than in the middle
diversifying selection
selection that favors extreme over the average
frequency-dependent selection
selection that favors phenotypes that are either common or rare
types of genomic mutations
single base pair substitution (point mutation), frame shift, deletion, insertion
example of frequency-dependent selection
host/parasite coevolution, predator/prey coevolution
population
populations evolve multiple organisms of the same species
