Exam2

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genotype

Back 1

the entire set of genes in an organism; a set of alleles that determines trait expression

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phenotype

Back 2

the physical appearance of an organism from expression of its genotype

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allele

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one member of a pair of genes that controls the same trait

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population

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a group of organisms of one species that interbreed and live in the same place at the same time

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gene

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the fundamental, physical, and functional unit of heredity

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locus

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the position on a chromosome

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inbreeding

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the mating of closely related individuals, which tends to increase the number of individuals that are homozygous for a trait and therefore increases the appearance of recessive traits

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genetic bottleneck

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sharp reduction in the size of a population due to environmental events or human activities

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adaptation

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the change or the process in which an organism becomes better suited for its environment

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heritability

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estimates how much variation in a phenotypic trait in a population is due to genetic variation among individuals in that population

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relative fitness

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way of measuring the reproductive success of organisms within a population

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absolute fitness

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measure of biological fitness expressed as the total number of gene copies transmitted to the subsequent generation or the total number of surviving offspring that an individual produces during its lifetime

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heterozygote superiority

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the case in which the heterozygote genotype has a higher relative fitness than either dominant/recessive homozygote genotypes; heterozygote advantage due to a single locus is “overdominance”

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directional selection

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a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing allele frequency to shift over time in the direction of that phenotype

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stabilizing selection

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type of natural selection in which genetic diversity decreases and the population mean stabilizes on a particular trait value

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inbreeding depression

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reduced biological fitness in a given population as a result of inbreeding. Population biological fitness refers to an organism’s ability to survive and perpetuate its genetic material. Often results in a population botteneck.

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genetic drift

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variation in the relative frequency of different genotypes in a small population, owning to the chance disappearance tof particular genes as individuals die or do not reproduce

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genotype

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genetic constitution of an individual organism

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deleterious mutation

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a genetic alteration that increases an individual’s susceptibility or predisposition to a certain disease or disorder. When such a variant or mutation is inherited, development of symptoms is more likely, but not certain. Also called disease-causing mutation, pathogenic variant, predisposing mutation, and susceptibility gene.

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migration/gene flow

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the movement and exchange of genes or alleles from one population of species to another. EX: members of a population of particular species migrating to a new habitat could use gene flow to occur when they mate with the members of a population already existing in the habitat.Better definition: movement and exchange of genes from one population to another; the movement of genes between interbreeding populations of a particular species

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disruptive selection

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changes in a population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups.

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frequency-dependent selection

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term given to an evolutionary process where the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population (positive- the fitness of a phenotype increases as it becomes more common)

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polygamy

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having more than one mate

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polygyny

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mating system in which one males lives and mates with multiple females , but each female only mates with a single male

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founder effect

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reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors

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direct fitness

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results from personal reproduction

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indirect fitness

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results from additional reproduction by relatives that is made possible by an individual’s actions

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inclusive fitness

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the representation of some of an individual's own alleles will increase with increased fitness of its relatives

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polyandry

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rare- one female mates with several males in a breeding season; usually males take on most paternal duties and females compete for mates

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sexual selection

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natural selection arising through preference by one sex for certain characteristics in individuals of the other sex

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sperm competition

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physical competition between the sperm of two separate males to fertilize the eggs of a lone female. A male’s fitness is usually measured as a function of the number of females inseminated, however in many animal species fertile females mate with many male partners.

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altruism

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action of an individual increases the fitness of another individual (or group) with cost to personal fitness

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kin selection

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natural selection that favors the spread of alleles that increase indirect fitness

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eusociality

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living in a cooperative group in which usually one female and several males are reproductively active and the non-breeding individuals care for the young or protect and provide for the group (termites, ants, naked mole rats)