Exam 12: Mechanisms of Evolution

The population of a cactus species in a particular area has two to seven spines with an average of four spines per square centimeter of surface area.Cacti with fewer than four spines per square centimeter are more easily eaten by the wild boars thriving in the area.Over time,the population of this cactus species in this area have an average of six spines per square centimeter of surface area.This is an example of

Which of the following statements concerning evolution is FALSE?

Around 12,000 years ago,a massive extinction event decimated about 75 percent of the world's large mammal populations.A small number of cheetahs survived this event and began to reproduce.Discuss the implications of this event on the genetic diversity of today's cheetah population.

Which of the following is NOT a mode of natural selection?

A used car is shipped from Australia to the United States.Stowed away in the trunk of the car is a piece of wood infected with Australian termites.Once in the United States,the buyer of the car finds the rotting wood and dumps it on the side of the road.The termites survive and establish a colony on the side of the road but do not mate with local termite populations.This is an example of

Provide an example of analogous traits in two organisms and explain how/why those traits evolved in such distantly related organisms.

How do natural selection and sexual selection differ?

Natural selection and other mechanisms of evolution act upon the ________ that result from the novel genotypes produced by mutations.

Disruptive selection operates whenever

If the size of a population drops for at least one generation and causes a loss of genetic variation,a ________ occurs.

When similar environmental pressures,such as permafrost in low-altitude tundra and permafrost in high-altitude alpine tundra,cause genetically distantly related organisms to evolve similar structures for survival and reproduction under similar conditions,________ has occurred.

Insecticides are used to kill insects.However,insecticide-resistant insects are being found.What is the mechanism for this new insect trait?

Bacteria often store genes on small,circular pieces of DNA called plasmids.The process of transmitting these plasmids and the genes they contain to other bacteria is called ________ and is an example of gene flow.

Propose an explanation for why the circumference of newborn babies' heads would act as a stabilizing selective force in a population of humans that does not have access to modern medical care.

Alex is a student with Strep throat (caused by a strain of bacterium)who is given a prescription for an antibiotic and is told to take the drug for two weeks.After a week,he feels better and stops taking the drug.Two months later,Alex again shows symptoms of Strep throat and decides to finish the leftover antibiotic rather than going to the doctor again.Two months after that,he develops Strep throat for a third time and returns to the doctor.This time,the antibiotic does not work.The doctor runs a test and discovers that the bacterial strain Alex is carrying is antibiotic resistant.What most likely happened?

The wings of a bird and the wings of a bat both form from the front appendages (arms).The bird wing is covered by feathers,and the bat wing consists of a thin layer of skin stretched between the "finger" bones.Are the wings of the bird and bat homologous or analogous?

Which of the following is true with regard to mutations?

Two populations of mice exist: one lives in an area with light rocks and the other lives in an area of dark rocks.A dark mouse from the population living on dark rocks migrates to the area of light rocks and breeds with mice there.Will this alter the allele frequency in the population? Discuss changes that may or may not be seen in the next generation and in following generations.

During gene flow,

While on a camping trip,Brian collects a white tadpole from a pond and takes it home.The tadpole develops into a white bullfrog.When the frog gets too big,he releases it into a local pond.The next year,several white bullfrogs are observed in the pond.This is an example of