It is created by the direct action of natural selection.
It arises in response to changes in the environment
It must be present in a population before natural selection can act upon the population.
It tends to be reduced by the processes involved when diploid organisms produce gametes.
A population that has a higher average heterozygosity has less genetic variation than one with a lower average
The population is diploid.
Heterozygotes can come about in two ways.
The population is doubling in number.
Heterozygotes have two alleles.
Change in allele or gene frequency
Change in gene expression
Change in average heterozygosity
Must happen, due to organisms’ innate desire to survive.
Must happen whenever a population is not well-adapted to its environment
Can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.
Requires the operation of natural selection.
Requires that populations become better suited to their environments.
All of the above
Only A and B
It represents the result of selection for acquired characteristics.
It is synonymous with the process of gene flow.
It is descent of humans from present-day great apes
It is the differential survival and reproduction of the most-fit phenotypes.
Genetic variation among individuals
Variation among individuals caused by environmental factors
Three of the responses are correct
Two of the responses are correct
Mechanical . . . postzygotic
Behavioral . . . prezygotic
Mechanical . . . prezygotic
Temporal . . . prezygotic
Gametic . . . postzygotic
New mutations that occurred in the preceding generation.
Genetic drift due to the small size of the population.
Reshuffling of alleles in sexual reproduction.
Geographic variation within the population.
Reduced hybrid fertility
The formation of new species
The extinction of species
Dramatic biological changes, such as the origin of flight, within a taxon
The generation of biodiversity
A change in allele frequencies within the gene pool of a population
The postzygotic barrier called hybrid inviability
The postzygotic barrier called hybrid breakdown
The prezygotic barrier called hybrid sterility
The species is now extinct.
Speciation occurred instantaneously.
Speciation occurred in one generation.
Speciation occurred rapidly in geologic time.
The species will consequently have a relatively short existence, compared with other species
Occurs at such a slow pace that no one has ever observed the emergence of new species.
Occurs only by the accumulation of genetic change over vast expanses of time.
Must begin with the geographic isolation of a small, frontier population. must begin with the geographic isolation of a small, frontier population.
And microevolution are synonymous.
Can involve changes to a single gene.
The goal of natural selection is speciation.
When reunited, two allopatric populations will interbreed freely if speciation has occurred.
Natural selection chooses the reproductive barriers for populations.
Prezygotic reproductive barriers usually evolve before postzygotic barriers.
Speciation is a basis for understanding macroevolution.
The number of chromosomes in the gene pool must change.
Changes to centromere location or chromosome size must occur within the gene pool.
Large numbers of genes that affect a single phenotypic trait must change.
Large numbers of genes that affect numerous phenotypic traits must change.
At least one gene, affecting at least one phenotypic trait, must change.