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speciation: 12 recap
as part of AS91605 NCEA L3 Biology
| Term | Definition |
|---|---|
| Adaptation | An inherited structural, behavioural or physiological trait which increases an organism’s fitness |
| Allele | alternate version of a gene. e.g. code for red, brown, black hair |
| Allele frequency | The proportion of a particular allele in the gene pool of a population (as a %). |
| Common Ancestor | Original species from which others develop through divergent evolution |
| Competition | When organisms use energy to acquire the same (finite) resource. |
| Directional selection | When the intermediate and one extreme phenotypes are selected for and one extreme selected against. |
| Disruptive selection | when the phenotypes at both extremes are selected for and the intermediate selected against |
| Endemic species | Species restricted to one area only (e.g. endemic to N.Z.) |
| Evolution | Changes in a gene pool over successive generations. |
| Extinction | Occurs when all members of a species die out. |
| Fitness | The relative ability of an individual to survive and reproduce in an environment. |
| Founder effect | When a small founding population becomes isolated, carrying a small unrepresentative sample of the original population’s alleles. |
| Gene flow | Exchange of alleles between populations by immigration and emigration. |
| Gene pool | The collective alleles of all members of a population. |
| Genetic drift | Changes in the allele frequencies of a gene pool due to CHANCE. The effects are greatest in small populations. |
| Introduced species | A species that does not naturally occur in a given area, but has been introduced to it by humans. |
| Mass extinction | When a large number of species and major groups of organisms disappear over a relatively short time. |
| Mutation | A sudden, permanent change in the DNA of an organism (could affect a gene, chromosome or sets of chromosomes). |
| Native species | A species that naturally occurs in a given area. |
| Natural selection | phenotypes best suited to the environment have greater survival and reproductive success |
| Population | A group of organisms of the same species living in the same location, at a set point in time. |
| Selection pressure | Any factor that affects the survival and reproductive success of an individual |
| Speciation | The process of forming distinct new biological species from existing species. |
| Species | A group of organisms that normally interbreed in nature to produce fertile offspring over successive generations. |
| Stablising selection | Selection against organisms at the extreme ends of the range of variation of phenotypes. |
| Stasis | A period of little or no evolutionary change in a species |
| Subspecies | a distinct population within a species that shows consistent genetic or physical differences from other populations, but can still interbreed with them to produce fertile offspring. |
| Variation | Differences between individuals (e.g. in phenotypes and therefore genotypes). The raw material on which selection acts. |
| Sexual selection | Where one sex chooses the other sex to mate with based on the most successful phenotype. |
| Population bottleneck | population becomes dramatically reduced in size, so that only a small number survive carrying an unrepresentative sample of the original alleles. |
| Genetic variation | range of alleles and allele combinations in a population |
Created by:
NZARoberts
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