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Eco Evo Exam 2 (c.7)
Definitions
| Term | Definition |
|---|---|
| Deoxyribonucleic acid (DNA) | A molecule composed of two strands of nucleotides that are wound together into a shape known as a double helix. |
| Chromosomes | Compact structures consisting of long strands of DNA that are would around proteins. |
| Alleles | Different forms of a particular gene. |
| Polygenic | When a single trait is affected by several genes. |
| Pleiotropy | When a single gene affects multiple traits. |
| Epistasis | When the expression of one gene is controlled by another gene. |
| Heterozygous | When an individual has two different alleles of a particular gene. |
| Homozygous | When an individual has two identical alleles of a particular gene. |
| Codominant | When two alleles both contribute to the phenotype. |
| Dominant | An allele that masks the expression of the other allele. |
| Recessive | An allele whose expression is masked by the presence of another allele. |
| Gene pool | The collection of alleles from all individuals in a population. |
| Random assortment | The process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent. |
| Mutation | A random change in the sequence of nucleotides in regions of DNA that either comprise a gene or control the expression of a gene. |
| Recombination | The reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material. |
| Genetic drift | A process that occurs when genetic variation is lost because of random variation in mating, mortality, fecundity, and inheritance. |
| Bottleneck effect | A reduction of genetic diversity in a population due to a large reduction in population size. |
| Founder effect | When a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation. |
| Selection | The process by which certain phenotypes are favored to survive and reproduce over other phenotypes. |
| Stabilizing selection | When individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes. |
| Directional selection | When individuals with an extreme phenotype experience higher fitness than the average phenotype of the population. |
| Disruptive selection | When individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype. |
| Microevolution | The evolution of populations. |
| Artificial selection | Selection in which humans decide which individuals will breed and the breeding is done with a preconceived goal for the traits of the population. |
| Industrial melanism | A phenomenon in which industrial activities cause habitats to become darker due to pollution and, as a result, individuals possessing darker phenotypes are favored by selection. |
| Macroevolution | Evolution at higher levels of organization including species, genera, families, orders, and phyla. |
| Speciation | The evolution of new species. |
| Phylogenetic trees | Hypothesized patterns of relatedness among different groups such as populations, species, or genera. |
| Allopatric speciation | The evolution of new species through the process of geographic isolation. |
| Sympatric speciation | The evolution of new species without geographic isolation. |
| Strength of selection | The difference between the mean of the phenotypic distribution before selection and the mean after selection, measured in units of standard deviations. |
| Heritability | The proportion of the total phenotypic variation that is caused by genetic variation. |