Natural Selection
Which of the following best illustrates natural selection?
-An organism with favorable genetic variations will tend to survive and breed successfully.
Which of these would have the least effect on natural selection in a subspecies of giraffes that is geographically isolated from other subspecies of giraffes?
-Chromosome number •Chromosome number is not a factor that influences natural selection. The other three choices represent factors that drive the process of natural selection.
A small population of chimpanzees lives in a habitat that undergoes no changes for a long period. How will genetic drift probably affect this population?
-It will reduce genetic diversity. •Genetic drift is a change in the frequency of alleles due to change. Typically, genetic drift decreases genetic diversity in a population.
Over time, the climate of an island became drier, which resulted in changes to the populations of various island finch species. Finch populations with a certain beak shape thrived, while those not having that beak shape decreased. Which of the following describes a necessary condition for these changes in the finch populations to occur?
-Limited food resources •Limited resources are a major driving factor for natural selection. Since there was not enough food for all of the finches, the finches that had beaks which allowed them to get food more easily were more likely to survive and reproduce.
Mutations within a DNA sequence are
-Natural processes that produce genetic diversity •Random mutations in DNA provide genetic variation in a population of species and allow for natural selection to occur.
In his book On the Origin of the Species, Charles Darwin described how species change over time. Which of the following is NOT part of his observations that describes the mechanisms of natural selection?
-Species today descended with modifications from ancestral species. •This answer represents evolution as a whole, not the process of natural selection.
Theodosius Dobzhansky discovered that successful species tend to have a wide variety of genes that do not appear to be useful to the species in its present environment. What did this discovery help explain about genetics and the changes that occur in a species over time?
-Species with greater genetic diversity adapt more easily to changing environments. •Greater genetic diversity allows for a wide range of environmental changes to occur without harming the population of organisms.
