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Bio: Chapter 24
Term | Definition |
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Speciation | The process by which one species splits into two or more species. |
Macroevolution | The broad pattern of evolution over long spans of time. |
Species | A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring. |
Reproductive Isolation | The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring. |
Hybrids | Offspring that result from an interspecific mating. |
Prezygotic Barriers | Block fertilization from occurring . |
Postzygotic Barriers | May contribute to reproductive isolation after the hybrid zygote is formed. |
Morphological Species Concept | Characterizes a species by body shape and other structural features. |
Ecological Species Concept | Views a species in terms of nits ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment. |
Phylogenetic Species Concept | Defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. |
Allopatric Speciation | Gene flow is interrupted when a population is divided into geographically isolated subpopulations. |
Polyploidy | When a species originates from an accident during cell division that results in extra sets of chromosomes. |
Autopolyploid | An individual that has more than two chromosome sets that are all derived from a single species. |
Allopolyploid | A sterile hybrid that is changed into a fertile polyploid by various mechanisms. |
Hybrid Zone | A region in which members of different species meet and mate, producing at least some offspring of mixed ancestry. |
Reinforcement | A process in which natural selection strengthens pre zygotic barriers to reproduction, thus reducing the chances of hybrid formation. Such a process is likely to occur only if hybrid offspring are less fit than members of the parent species. |
Punctuated Equilibria | In the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change. |
Punctuated Pattern | In a punctuated pattern, new species change most as they branch from a parent species and then change little for the rest of their existence. |