AP® biology unit 7 Flashcards
AP® biology unit 7
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What is natural selection? The process by which organisms better adapted to their environment tend to survive and produce more offspring. Define genetic drift. A mechanism of evolution that involves random changes in allele frequencies in a population. What is the bottleneck effect? A sharp reduction in the size of a population due to environmental events or human activities. Explain the founder effect. When a new population is established by a very small number of individuals from a larger population. What is gene flow? The transfer of genetic variation from one population to another. Describe adaptive radiation. The diversification of a group of organisms into forms filling different ecological niches. What is speciation? The formation of new and distinct species in the course of evolution. Define allopatric speciation. Speciation that occurs when biological populations are physically isolated by an extrinsic barrier. What is sympatric speciation? Speciation that occurs without physical separation of members of the population. Explain the concept of a phylogenetic tree. A diagram that represents evolutionary relationships among organisms. What is a homologous structure? Structures in different species that are similar because of common ancestry. Define convergent evolution. The process whereby organisms not closely related independently evolve similar traits. What is a vestigial structure? A structure in an organism that has lost all or most of its original function in the course of evolution. Describe the Hardy-Weinberg principle. A principle that states allele and genotype frequencies in a population will remain constant in the absence of evolutionary influences. What is a mutation? A change in the DNA sequence of a gene or chromosome of an organism. Explain the role of sexual selection in evolution. A mode of natural selection where typically members of one gender choose mates of the other gender to mate with. What is an ecological niche? The role and position a species has in its environment. Define coevolution. The influence of closely associated species on each other in their evolution. What is punctuated equilibrium? A theory that proposes that once species appear in the fossil record they will become stable, showing little evolutionary change. Describe the concept of genetic variation. Differences in DNA sequences among individuals within a population.