Chapter 23 Vocab Flashcards
population genetics
investigative processes that cause changes in allele and genotype frequencies in populations
gene pool
all the alleles of all the genes in a certain population
inbreeding
mating between closely related individuals
deleterious allele
alleles that decrease fitness
inbreeding depression
decline in average fitness that may take place when homozygosity increases and heterozygosity decreases in a population
sexual selection
favors individuals with traits that increase their ability to obtain mates
ecological selection
favors individuals with heritable traits that enhance their ability to survive and reproduce in certain physical and/or biological environment, excluding ability to obtain a mate
genetic variation
number and relative frequency of alleles that are present in a particular population
purifying selection
decreases frequency of, or even eliminates, deleterious alleles
intersexual selection
between species, one sex is selecting the other sex for mating
intrasexual selection
within a sex, competing among members of the same sex for mating
territory
actively defended area where owner has exclusive or close to exclusive use
sexual dimorphism
any trait that differs between male and female
- make and female usually look different
sexual polymorphism
any trait that occurs in 2 or more forms among females and males in population
genetic drift
change in allele frequencies in a population that is due to chance
sampling error
selection of a nonrepresentative sample from some larger population, due to chance
founder effect
change in allele frequencies that occurs when a new population is established from a small group of individuals due to sampling error
bottleneck effect
if large population experiences sudden reduction in size
genetic bottleneck
sudden reduction in diversity of alleles in population resulting from sudden decrease in size of population
gene flow
movement of alleles between populations
point mutation
change in a single base pair
chromosome level mutation
change in number or composition of chromosomes
lateral gene transfer
transfer of genetic information from one species to another, rather than from parent to offspring
beneficial allele
allele from a mutation that allows individual to produce more offspring increase fitness
neutral allele
allele from a mutation that has no effect on fitness
Hardy-Weinberg principle
genotype frequencies in large population do not change from generation to generation in absence of evolutionary process and nonrandom mating
what do the quantities mean for Hardy-Weinberg
p= frequency of A alleles
q= frequency of “a” alleles in same gene pool
directional selection
- average phenotype of population changes in 1 direction
- shift
- tends to decrease genetic diversity
stabilizing selection
genetic variation in population is reduced but there is no change in average value of a trait over time
disruptive selection
- eliminates phenotypes near average value
- favors extreme phenotypes
- overall genetic variation is increased
- can play a role in speciation
balancing selection
- no phenotype has distinct advantage
- heterozygous advantage
- frequency dependent selection
heterozygous advantage
heterozygous individuals have increased fitness than homozygous
frequency dependent selection
certain alleles are favored when they are rare, but not when they are common
