Exam 17: The Means of Evolution: Microevolution

Male guppies are known for their bright colors.Having bright colors attracts mates,but it also attracts predators.So in an environment with a lot of predators,male guppies have more dull colors.In an experiment,guppies were removed from an area with predators to an area without predators.Over a period of 12 months the population became much more colorful.This is an example of a response to:

If within a large population no mutations occur,no migration occurs,all mating is random,and each individual has an equal chance of reproducing,which of the following will probably happen?

African black-bellied seedcracker finches have beaks that are either large or small.Only large-beaked birds can crack open hard seeds,and small-beaked birds are more adept at handling small seeds.Both have an advantage over intermediate-sized beaks.This is an example of a response to:

The only known population of a reptile species lives on an African mountain.The population is relatively large,but no close relatives of this species are known.Suppose you could stop all mutations within the population and all emigration out of this population.Which statement best describes the probable future of this population?

Shrews have been documented to travel across frozen lakes and establish populations on previously uninhabited islands; thus,the shrews have a limited gene pool.If this limited gene pool has allele frequencies that are very different from the allele frequencies found in the original population,then this would be an example of:

A bottleneck may be dangerous to a population because:

The genetic makeup of any organism is its ________,which determines the physical characteristics called its ________.

List five mechanisms by which gene frequencies in a population can be altered.Describe each briefly.

Imagine a population of monkeys in South America whose habitat has been reduced to the point where only 25 monkeys survive.This is an example of:

For a particular character,natural selection can favor an average phenotype or extreme phenotypes.In order to do this,a character must be:

Which of the following possibilities is the best indicator of an organism's evolutionary fitness?

Male long-tailed widowbirds have unusually long tails,about 20 inches in length,whereas the females have short tails.In an experiment with long-tailed widowbirds,one group of males had their tails clipped to 5 inches,a second group were left with normal 20-inch tails,and a third group had their tails lengthened to 30 inches by gluing on feathers clipped from the tails of other birds.If sexual selection is responsible for the males having such long tails,predict what will happen when similar numbers of females are placed in the territories of each group of males.

The concept of evolution has always been connected with some notion of progress-natural selection pushing populations toward better and better adaptations to create "perfect organisms." How would you argue that evolution does not craft perfect organisms?

Which of the following is ultimately responsible for introducing new alleles into a population?

Genetic drift has a much more significant effect on small populations than on large populations.

How have Caesarean sections and intensive neonatal (near-birth)medical care likely affected the average birth weight of American babies?

In order for migration to alter allele frequencies in another population:

The basic units that evolve are species.

Which of these humans is the "fittest" as far as natural selection is concerned?

The most immediate effect of sexual displays and contests in animals (such as bighorn sheep bashing their heads together)is: