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Population genetics
Refers to the study of evolution via the observation and modeling of allele frequencies and genetic change in populations of organisms TERM 2
Gene pool
DEFINITION 2 The total of all genes in the population at any one time TERM 3
Allele frequency
DEFINITION 3 The proportion of a specific allele at a given locus, considering that the population may contain from one to many alleles at that locus TERM 4
What is the smallest unit that can
evolve
DEFINITION 4 a population TERM 5
Genotype frequency
DEFINITION 5 The proportion of a specific genotype at a given locus, considering that many different genotypes may by possible
Phenotype frequency
The proportion of individuals in a population that exhibit a given phenotype TERM 7
Microevolution
DEFINITION 7 Applies to small genetic changes due to changing allelic frequencies in populationsOccurs continuouslyCan transform into macroevolution TERM 8
Macroevolution
DEFINITION 8 Refers to genetic change that is sufficient to form a new speciesCan happen gradually TERM 9
Stasis
DEFINITION 9 A lineage that appears to remain the same over time TERM 10
Hardy-Weinberg equilibrium
DEFINITION 10 A population that is not changing geneticallyNo natural selectionNo genetic drift or random allele frequency changesNo gene flowNo mutationRandom matingLarge PopulationA violation of one or more = evolved population
Genetic variation
Refers to the number and relative frequency of alleles that are present in a particular populationLack or variation can make populations less able to respond successfully to changes in the environment TERM 17
Stabilizing selection
DEFINITION 17 Occurs when individuals with intermediate traits reproduce more than othersThere is no change in the average value of the trait over timeGenetic variation in the population is reduced TERM 18
Disruptive selection
DEFINITION 18 Occurs when intermediate phenotypes are selected against and extreme phenotypes are favoredCan cause speciation, the formation of new species TERM 19
Balancing selection
DEFINITION 19 No single allele has a distinct advantage and increase in frequencyThere is a balance among several alleles in terms of their fitness and frequency TERM 20
Heterozygote
advantage
DEFINITION 20 Heterozygous individuals have higher fitness than homozygous individuals do, thus maintaining genetic variation in the population
Genetic Drift
Any change in allele frequencies in a population due to change (sampling error). Occurs in every population, in every generation.Causes allele frequencies to drift up and down randomly over timeUsually reduces average fitnessRandom with respect to fitnessMost pronounced in small populations TERM 22
What are the two factors that may cause
genetic drift?
DEFINITION 22 Bottleneck effectFounder effect TERM 23
Bottleneck Effect
DEFINITION 23 May lead to reduce genetic variability following some large disturbance that removes a large portion of the population. The surviving population often does not represent the allele frequency in the original population TERM 24
Founder Effect
DEFINITION 24 May lead to reduced variability when a few individuals from a large population colonize an isolated habitat TERM 25
Gene Flow
DEFINITION 25 The movement of alleles from one population to another, occurs whenever individuals leave one population, join another, and breedMay increase or decrease average fitness
Inbreeding depression
A decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population TERM 32
Does Inbreeding cause evolution?
DEFINITION 32 No because allele frequencies do not change in the population as a whole TERM 33
Sexual selection
DEFINITION 33 Occurs when individuals within a population differ in their ability to attract mates. Favors individuals with heritable traits that enhance their ability to obtain matesLeads to evolutionResponsible for the phenotypic differences between males and females TERM 34
Sexual dimorphism
DEFINITION 34 Any trait that differs between males and females of the same speciesMale and female lions
