IndietroGeneral Biology: Evolution and Speciation Study Guide
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Evolution is the change in the genetic composition of a population over successive generations.
Descent with modification means that species change over time, giving rise to new species while sharing a common ancestor.
An adaptation is a heritable trait that increases an organism's fitness in its environment.
Natural selection is the process where individuals with advantageous traits are more likely to survive and reproduce.
Artificial selection is human-driven breeding to select for desired traits, differing from natural selection by intentional choice.
Homologous structures are anatomical features shared by species due to common ancestry, even if their functions differ.
Vestigial structures are remnants of features that served important functions in ancestors but are reduced or nonfunctional now.
Convergent evolution occurs when unrelated species evolve similar traits independently due to similar environments.
Analogous structures have similar functions but evolved independently, not from a common ancestor.
The fossil record provides chronological evidence of past life forms and evolutionary changes over time.
Biogeography studies the geographic distribution of species and how it supports evolution and common ancestry.
Microevolution is the change in allele frequencies within a population over time.
Genetic drift is random changes in allele frequencies, especially significant in small populations.
The founder effect occurs when a new population is established by a few individuals, reducing genetic variation.
The bottleneck effect is a sharp reduction in population size causing loss of genetic diversity.
Gene flow is the transfer of alleles between populations, which can reduce genetic differences.
Hardy-Weinberg equilibrium describes a non-evolving population where allele frequencies remain constant under five conditions.
Directional selection favors one extreme phenotype, shifting allele frequencies in one direction.
Disruptive selection favors two or more extreme phenotypes over intermediate ones.
Stabilizing selection favors intermediate phenotypes and reduces variation.
Sexual selection is natural selection for mating success, including intrasexual and intersexual selection.
The biological species concept defines species as groups of interbreeding populations reproductively isolated from others.
Reproductive isolation prevents gene flow between species through prezygotic or postzygotic barriers.
Prezygotic barriers prevent mating or fertilization and include habitat, temporal, behavioral, mechanical, and gametic isolation.
Postzygotic barriers reduce hybrid viability or fertility, or cause hybrid breakdown in later generations.
Allopatric speciation occurs when geographic isolation leads to reproductive isolation and new species formation.
Sympatric speciation occurs without geographic isolation, often through polyploidy or sexual selection.
Polyploidy is the presence of extra sets of chromosomes, which can cause instant reproductive isolation.
A hybrid zone is a region where different species meet and interbreed, producing hybrids with varying outcomes.