BackGeneral Biology: Evolution and Speciation
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Terms in this set (29)
Evolution is the change in the genetic composition of a population over time.
Descent with modification means 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, despite different functions.
Analogous structures have similar functions but evolved independently, not from a common ancestor.
Vestigial structures are remnants of features that served important functions in ancestors but are reduced or nonfunctional now.
Molecular homology refers to similarities in DNA or protein sequences indicating common ancestry.
Convergent evolution occurs when unrelated species evolve similar traits due to similar environmental pressures.
The fossil record provides chronological evidence of past life forms and evolutionary changes over time.
Biogeography studies the geographic distribution of species, supporting evolution through patterns like continental drift.
Microevolution is the change in allele frequencies within a population over generations.
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.
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 both extreme phenotypes over intermediate ones, potentially leading to speciation.
Stabilizing selection favors intermediate phenotypes, reducing variation.
Sexual selection is natural selection for traits that increase mating success, causing sexual dimorphism.
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 after fertilization.
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, common in plants and a mechanism of sympatric speciation.
A hybrid zone is a region where two species meet and interbreed, producing hybrids with varying outcomes.