Chapter 24: Evolution of Populations Flashcards
change in nucleotide sequence of an organism’s DNA
____ ==> change in one base of gene
______ ==> delete, disrupt, or rearrange man loci at once
mutations
Point
Chromosomal
small scale; change in allele frequency in SINGLE population
microevoluton
Mechanism that shuffles alleles, genetic material is exchanged during between nonsister chromatids during prophase 1 of meiosis
Crossing Over
shuffled alleles are randomly distributed to gametes
independent assortment
brings gametes of individuals with different genetic sequences together
fertilization
genes available in population
population geneticss
group of individuals of the same species that live in the same area, interbreed, and produce fertile offspring
population
all the alleles for all the loci in all individuals of a population
gene pool
only one allele exists for a particular locus in a population
fixed allele
the frequency of allele and genotypes in a population will remain constant from generation-to-generation; only mendelian segregation and recombination of alleles are at work
Hardy-Weinburg Equilibrium
conditions of hardy-weinburg principle
no mutations random mating large population size no natural selection no gene flow
allele frequencies fluctuate unexpectedly from generation to generation
genetic drift
genetic drift that occurs when individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population
founder effect
genetic drift that occurs when the size of a population is drastically reduced because of natural disaster/human actions. The surviving population is not genetically representative of the original population
Bottleneck effect
transfer of alleles in or out of a population
gene flow
the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
relative fitness
Occurs when conditions favor individuals exhibiting one extreme curve of a phenotypic range
directional selection
conditions favor individuals of both extremes of a phenotypic range over individuals with intermediate phenotypes
disruptive selection
acts against both extremes and favors intermediate phenotypes
stabilizing selection
form of natural selection in which individuals w/ certain inherited traits are more likely to obtain mates
sexual selection
marked differences between the secondary sex characteristics of males and females
sexual dimorphism
Most eukaryotes are diploid. most genetic variation is hidden in recessive alleles
diploidy
heterozygotes have greater reproductive success than homozygotes, preserves variation in gene pools
heterozygote advantage
