smc_bio_202_week_03_v2

Microevolution

Changes in allele frequency in a population over time.

Macroevolution

Broad patterns of evolutionary change above the species level.

Speciation

The process by which one species splits into two or more species.

Biological Species Concept

Defines a species as a group of populations whose members can interbreed and produce viable, fertile offspring.

Morphological Species Concept

Defines a species based on structural features.

Ecological Species Concept

Defines a species in terms of its ecological niche.

Prezygotic Barriers

Barriers that prevent fertilization from occurring between different species habitat, temporal, behavioral, physical barrier

Postzygotic Barriers

Barriers that prevent the hybrid zygote from developing into a viable, fertile adult. sperm competition, mechanical, sterile, fitness of hybrid

Allopatric Speciation

Speciation that occurs when gene flow is interrupted or reduced due to geographic isolation.

Sympatric Speciation

Speciation that occurs in populations that live in the same geographic area.

Polyploidy

The presence of extra sets of chromosomes due to accidents during cell division.

Hybrid Zone

A region where members of different species mate and produce hybrids.

Reinforcement

Strengthening of reproductive barriers when hybrids are less fit than parent species.

Fusion

Weakening of reproductive barriers leading to the merging of parent species into a single species.

Stability

Continued formation of hybrid individuals in a stable hybrid zone.

Punctuated Equilibria

A model describing periods of apparent stasis punctuated by sudden change in the fossil record.