23 Flashcards
how does natural selection act on individuals
each individual’s combination of traits affects its survival and reproductive success compared to other individuals
____ are selected; ____ evolve
individuals; populations
microevolution
evolutionary change on its smallest scale; change in the genetic makeup of a population from generation to generation
darwin didn’t have a satisfactory explanation for
how the heritable variations required for natural selection appear in populations or how organisms transmit these variations to their offspring
model proposed by gregor mendel
particular hypothesis of inheritance
stated that parents pass on discrete heritable units that retain their identities in offspring
darwin considered the raw material for natural selection to be
“quantitative” characters – those characteristics in a population that vary along a continuum
mendel and other early geneticists worked only with
discrete “either-or” traits
geneticists later determined that
quantitative characters are influenced by multiple genetic loci and that the alleles at each of these loci follow Mendelian patterns of inheritance
population genetics
the study of how populations change genetically over time
population genetics gave rise to ____
modern synthesis
modern synthesis
a comprehensive theory of evolution that integrated ideas from many other fields
population
a localized group of individuals that are capable of interbreeding and producing fertile offspring
populations of the same species may be isolated from one another, thus exchanging genetic material only rarely. such isolation is common for populations
confined to different,. widely separated islands or lakes
individuals near the population center are more likely to breed with
members of their own population than other populations and thus on average are more closely related to one another than to members of other populations
gene pool
the aggregate of genes in a population at any one time
the gene pool consists of
all alleles at all gene loci in all individuals of the population
if only one allele exists at a particular locus in a population,
that allele is said to be FIXED in the gene pool, and all individuals are homozygous for that allele
if there are 2 or more alleles for a particular locus in a population,
individuals may be either homozygous or heterozygous
when there are 2 alleles at a particular locus, the convention is to
use p to represent the frequency of one allele and q to represent the frequency of the other allele
at loci that have more than 2 alleles,
the sum of all allele frequencies must still equal 1
hardy-weinberg theorem was derived in the year
1908
the hardy-weinberg theorem describes
the properties of gene pools that aren’t evolving
the hardy-weinberg theorem states that
the frequencies of alleles and genotypes in a population’s gene pool remain constant from generation to generation, provided that only mendelian segregation and recombination of alleles are at work
the hardy-weinberg theorem describes how
mendelian inheritance preserves genetic variation from one generation to the next in populations that aren’t evolving