Convergent evolution
Species that live in similar environments that evolve similar adaptations but do not have a common ancestor
Differential reproductive success
When individuals with phenotypes that give them a survival advantage are more likely to survive and reproduce.
Directional Selection
One end of the range of phenotypes is favored by natural selection, causing the frequency of that phenotype to increase over time
Stabilizing selection
The intermediate phenotype is favored and extreme phenotypes are selected against.
Disruptive selection
Individuals on both ends of the phenotypic ranges are likelier to survive and reproduce than individuals with an intermediate phenotype.
Artificial selection
Selectively breeding domesticated plants or animals to produce populations with desired traits.
sexual selection
When individuals with certain characteristics are more likely to attract mates than other individuals
gene flow
transfer of alleles from one population to another, caused by the migration of individuals into a population.
genetic drift
random loss of alleles in a population, more likely to occur in smaller populations
bottleneck effect
When the size of the population is greatly reduced for one or more generations, reducing number of different alleles.
founder effect
When members of a larger population start a new population, decreasing genetic diversity
speciation
evolution of new species
adaptive radiation
The evolution of organisms into separate species that occupy different ecological niches.
Gradualism
The slow and constant pace of speciation is due to a stable environment and less selective pressure on populations.
Punctuated equilibrium
Long periods of stability in species are interrupted by periods of rapid evolution.
Allopatric speciation
Larger populations become geographically separated, and the smaller subgroups diverge and become separate species.
Sympatric speciation
Speciation occurs in the same geographic area and is due to prezygotic and postzygotic reproductive barriers.
Habitat isolation
When organisms live in different habitats and do not come in contact with each other, resulting in no mating/formation of a zygote
Temporal isolation
When organisms live in the same habitat but have different times for being active or different breeding seasons.
Behavioral isolation
Some species will interbreed only with others who perform compatible mating behaviors, such as mating calls or dances.
Mechanical isolation
If the sexual organs of the organisms are incompatible and prevent the transfer of gametes
Gametic isolation
If two organisms can successfully copulate ,but have incompatible gametes
Reduced hybrid viability
When two organisms that can form a zygote but the zygote does not survive till adulthood or age of reproduction
Reduced hybrid fertility
When the zygote survives till adulthood but is infertile
Hybrid breakdown
When the zygote is viable and fertile, future generations of the hybrid become weaker and less robust and eventually die out.