Exam 25: Evolutionary Processes

Which of the following is true?

Humans have domesticated a number of plants and animals.In the domestication process,a few individuals of a species are "captured" to have a starting population and then these are bred for many generations.This is an example of a ________ and you would therefore predict that domesticated organisms would show ________.

A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness.She hypothesizes that the population is experiencing

Mutation is the only evolutionary mechanism that

Currently the only predators of Galápagos marine iguanas are Galápagos hawks.Iguana body size is not correlated with risk of hawk predation,although small iguanas can sprint faster than large iguanas.If predators (e.g.,cats)that preferably catch and eat slower iguanas are introduced to the island,iguana body size is likely to ________ in the absence of other factors;the iguanas would then be under ________ selection.

Genetic drift occurs in a population.Which of the following statements might be true?

Which sex typically has more extreme sex-selected characteristics: males or females? Why? Give an example.

For a biologist studying a small fish population in the lab,which Hardy-Weinberg condition is easiest to meet?

Why doesn't inbreeding depression,by itself,cause evolution?

Researchers (Helle et al.,2004)analyzed rates of twin births in the Sami population of Northern Scandinavia during the eighteenth and nineteenth centuries.They found that (1)a baby born from a singleton pregnancy was more likely to survive to adulthood than a baby born from a twin pregnancy,and (2)the average number of offspring raised to adulthood was higher for women who had twins than for those who never had twins.These data suggest that in this population,human twinning rate was

Dark-eyed junco birds have white outer tail feathers that the males display during aggressive interactions and also during courtship displays.Males with more white in their tail are more likely to win aggressive interactions with other males,and females prefer to mate with males with more white in their tails.In the case of juncos,aggression (fighting)by males is a type of ________ selection;thus,we would expect that variation in reproductive success to be higher in ________ and this species should exhibit ________ sexual dimorphism.

Consider the following two scenarios: 1)A flash-flood sweeps through an area and random lemmings are killed,resulting in a change in lemming phenotype in subsequent generations;2)A flash-flood sweeps through an area and some lemmings are able to survive because they are able to hold their breath longer than other lemmings,resulting in a change in lemming phenotype in subsequent generations.What are the primary differences between the two scenarios?

Based on the information given above,which of the following types of selection was most likely initially involved in the evolution of white outer tail feathers in juncos?

Which of the following is FALSE with respect to natural selection and genetic drift?

Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years.If 9 in 10,000 newborn babies have the disease,what are the expected frequencies of the dominant (A₁)and recessive (A₂)alleles according to the Hardy-Weinberg model?

Which of the following describes what we should expect when a population is in Hardy-Weinberg genetic equilibrium?

Which of the following best describes the effect of the migration of individuals into a population?

In 1986,a nuclear power accident in Chernobyl,USSR (now the Ukraine),led to high radiation levels for miles surrounding the plant.The high levels of radiation caused elevated mutation rates in the surviving organisms,and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since.Based on your understanding of evolutionary mechanisms,which of the following most likely occurred in the rodent populations following the accident?

Given the information above,what is the frequency of the A₂ allele in this population?

Which of the graphs above best represents the relationship between the intensity of directional selection and the genetic variation present within a population?