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Definition
| a chain of ancestors and their descendants |
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| any change in the inherited traits of a population that occurs from one generation to the next |
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| a mechanism that can lead to evolution, whereby differential survival or reproduction of individuals causes some genetic type to replace others |
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| the independent origin of similar traits in separate lineages |
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| Homologous Characteristics |
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Definition
| similar in two or more species because they are inherited from a common ancestor |
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Definition
| derived from a trait that is shared by a group of related species (evolved in common ancestor of group and inherited by all descendants) |
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| a visual representation of the evolutionary history of populations, genes, and species |
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Definition
| any change in the genomic sequence of an organism |
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| evolution arising from random changes in the genetic composition of a population from one generation to another |
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Definition
| measurable aspects of organisms such as morphology. Genes interact with other genes and the environment during the development of phenotpyes. observable |
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| The simultaneous occurrence of two or more discrete phenotypes within a population. In the simplest case each phenotype results from a different allele or combination of alleles of a single gene. |
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Definition
| a trait for which multiple, discrete phenotypes can arise from a single genotype depending on environment circumstances |
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Definition
| the genetic makeup of an individual |
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Definition
| alleles that produce the same phenotype whether they are paired with an identical allele or a different allele |
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Definition
| alleles that produce their characteristics phenotypes only when they are paired with an identical allele |
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Definition
| measurable phenotypes that vary among individuals over a given range to produce a continuous distribution of phenotypes. |
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Definition
| a signalling molecule that flows between nearby cells and acts directly to alter expression of target genes |
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Definition
| changes in phenotype produced by a single genotype in different enviroments. |
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Definition
| the specific location of a gene or piece of DNA sequence on a specific chromosome |
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Definition
| the study of the distribution of alleles within populations and the mechanisms that can cause allele frequencies to change over time. |
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Definition
| a mathematical statement that has been proven based on previously established theorems and axioms. they are deductive reasoning and show that a statement necessarily follows from a series of statements or hypotheses. |
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Term
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Definition
| am allele becomes fixed in a population when all the alternative alleles have disappeared. No genetic variation exists at a fixed locust within a population because all the individuals are genetically identical at that locus. |
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Definition
| events in which the number of individuals in a population is reduced drastically reduced |
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Definition
| a type of genetic drift describing the loss of allelic variation that accompanies founding of a new population from a very small number of individuals. |
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Definition
| the success of an organism at surviving and reproducing and thus contributing offspring to future generations |
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Term
| Average Excess of Fitness |
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Definition
| the difference between the average fitness of individuals bearing the allele and the average fitness of the population as a whole |
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Definition
| the condition when a single mutation from a single gene affects the expression of many different phenotypic traits |
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Definition
| selection that decreases the frequency of alleles within a population. it occurs whenever the average excess for fitness of an allele is less than zero |
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Term
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Definition
| Selection that increases the frequency of alleles within a population. Positive selection occurs whenever the excess for fitness of an allele is greater than zero |
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Term
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Definition
| Occurs when the effects of an allele at one genetic locus are modified by alleles at one or more loci |
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Term
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Definition
| an allele that yields twice the phenotypic effect when two copies are present at a given locus than when only a single copy is present. |
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| Negative Frequency dependent selection |
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Definition
| rare genotypes have higher fitness than common genotpyes. maintains genetic variation. |
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Definition
| selection that favors more than one allele. it acts to maintain genetic diversity in a population by keeping alleles at frequencies higher than would be expected by chance or mutation alone. |
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Definition
| the probability that two alleles at any locus in an individual will be identical by descent. |
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Definition
| a reduction in the average fitness of inbred individuals relative to that of outbred individuals. it arises because rare alleles become expressed in a homozygous state where they can detrimentally affect the performance of individuals |
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Definition
| the study of continuous phenotypic traits and their underlying evolutionary mechanisms |
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Definition
| a statistical measure of the dispersion of trait values about their mean. |
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Term
| Narrow Sense Heritability |
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Definition
| the proportion of total phenotypic variance of a trait attributed to the additive effect of alleles. this is the component that causes offspring to resemble their parents and it causes populations to evolve predictability in response in selection. |
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Definition
| a measure of the strength of phenotypic selection. |
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Definition
| stretches of DNA that are correlated with variation in a phenotypic trait. these regions contain genes or are linked genes that contribute population differences in a phenotype |
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Definition
| the pattern of phenotypic expression of a single genotype across a range of environments. in a sense, reaction norms depict how development maps the genotype into phenotype as a function of the environment. |
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