AP Biology Unit 7 Voacbs

Evolution

change in the allele frequency in a population over time

Microevolution

small changes in the allele frequency in a single population or species

Macroevolution

large evolutionary changes and explores common ancestry different species

Genetic drift

evolution due to random chance events that equally effect all members of the population regardless of their traits

Founder effect

small group of an existing population leaves to colonize a new area and exclusively breed with members of this new population

Population bottleneck

a natural disaster kills off a majority of the population, leaving few survivors behind

Sexual selection

selective changes where in allele frequency shifts due to selection of mates based on physical characteristics

Mutations

random change in allele frequency caused by changes in DNA sequence that result in phenotypic variation that can be acted upon by natural selection

Gene flow

random, non-selective change in allele frequency that occurs due to migration between populations

Evolutionary fitness

reproductive success; organisms that survive AND pass on their genes to the next generation

Natural selection

selective and adaptive change in allele frequency resulting from differential reproductive success in response to selective pressures from the environment; it is the major driving force behind evolution

Artificial selection

selective and adaptive change in allele frequency caused by humans selecting and breeding members of species for specific traits

Directional selection

selective pressure favors the alleles for one phenotype over the other

Stabilizing selection

selective pressures favor the allele that represents the mean, or most frequent phenotype; against extreme phenotypes

Disruptive selection

selective pressures favor the alles that represent the extreme phenotypes

Hardy-weinberg equilibrium

theory stating that the absence of any evolutionary driving forces, the allele frequency in the population will not change over time; population not in this experiences evolution

p + q = 1

measures the frequency of the alleles

p² + 2pq + q² = 1

represents the frequency of the genotypes

Speciation

formation of a new species from a common ancestor as a result of reproductive isolation

Common ancestor

species of organism from which one or more new species evolves; all organisms under it shares the same fundamental molecular and cellular features

Biogeography

evidence of evolution that is useful for illustrating patterns of common evolution among ancestors and their descendant species

Anatomical homologies

evidence of evolution that studies the similarities in physical traits

Homologous structures

structures that are similar in shape amongst related species, but do not serve the same purpose

Vestigial structures

structures that are inherited from a common ancestor, but serve no actual purpose in the present-day species

Developmental homologies

evidence of evolution that studies the similarities in the embryonic development between species

Molecular similarities

evidence of evolution regarding the DNA and amino acid sequences between species

Fossil

preserved remains of ancient species

Fossil record

evidence of evolution that shows the order in which ancient species evolved

Adaptive radiation

a single species of small group of species evolving into many different species in different habitats in a short period of time

Gradualism

slow steady rate of evolution in a single line of descent of species

Punctuated equilibrium

species experience periods of stasis (no evolution occurring), which are interrupted by periods of rapid evolutionary change

Phylogeny

visual representations of speciation eventa and hypothesized evolutionary relationships between species

Cladograms

grouping of organisms based on shared characteristics present in more than one species

Phylogenic tree

grouping of organisms based on shared characteristics OR genetic sequence similarity; length of branches represent evolutionary time scale and amount of change

Node

most recent common ancestor

Species

a group or organisms capable of mating, exchanging genetic material, and producing viable, fertile offspring

Allopatric speciation

speciation that occurs when members of population are geographically isolated and then become reproductively isolated

Sympatric speciation

speciation that occurs when members of a population stay in the same geographic area but still become reproductively isolated

Reproductive barriers

term that refers to the various ways that organisms can become repoductively isolated

Prezygotic barrier

reproductive barrier that occurs prior to fertilization, preventing formation of offspring

Postzygotic barrier

reproductive barrier that occurs after fertilization occurs, leading to inviability or infertility

Habitat isolation

prezygotic barrier that results in the physical separation that prevents members of two species from mating and producing offspring; can be allopatric or sympatric

Temporal isolation

prezygotic barrier; timing of the mating season prevent members of different species from mating and producing offspring

Behavioral isolation

prezygotic barrier; differences in behaviors, mating rituals, and mating calls prevent members of different species from mating and producing offspring

Mechanical isolation

prezygotic barrier; differences in reproductive anatomy prevent members of different species from mating and producing offspring

Gametic isolation

prezygotic barrier; differences in gametes prevent members of different species from mating and producing offspring

Reduced hybrid viability

postzygotic barrier where a negative interaction between genes of the two parent species causes offspring to be frail and unable to mate

Reduced hybrid fertility

postzygotic barrier where the hybrid offspring is viable, but are infertile and cannot produce their own offspring

Hybrid breakdown

postzygotic barrier; first generation of hybrid offspring are viable and fertile, but the offspring of this generation are non-viable or infertile