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 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.
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 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.
Hardy-Weinberg equilibrium describes a non-evolving population where allele frequencies remain constant under specific conditions.
Directional selection favors one extreme phenotype, shifting the population's trait distribution.
Disruptive selection favors both extreme phenotypes over intermediate ones.
Stabilizing selection favors intermediate phenotypes, reducing variation.
Sexual selection is natural selection for traits that increase mating success.
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, which can cause instant reproductive isolation.
A hybrid zone is a region where two species meet and interbreed, producing hybrids with varying outcomes.
Punctuated equilibrium describes rapid evolutionary change followed by long periods of stability.