MB Chapter 13

Consider a population of snowshoe hares in Montana. Their fur color changes in response to changes in day length. During the long summer days, they have brown fur, but as the days shorten in the fall, their fur turns white in preparation for winter. Then as the days get longer in the spring, their fur turns brown again. Their fur coloration acts as camouflage from predators. As climate change brings warmer fall temperatures to Montana, colder temperatures with snowfall are coming later in the year, and there may be less snowfall overall. As a result, the hares' fur color may be mismatched to the color of their surroundings, making them more visible to predators. Which snowshoe hares would have a reproductive advantage in this changing environment?

Hares with a mutation that causes them to change color in response to temperature rather than day length

Which one of the following statements is TRUE?

Natural selection works on variation already present in a population.

While on his voyage on the HMS Beagle, Darwin was strongly influenced by this book.

Principles of Geology by Charles Lyell: This book strongly influenced Darwin, because Lyell presented evidence that the Earth is millions rather than thousands of years old. This helped Darwin understand how evolutionary changes could occur over long periods of time.

Which of the following is a true statement?

Species with nucleotide sequences that match closely share a common ancestor.: Species that have a large number of sequence differences are probably not related.

Small lizards have difficulty defending their territory, but large lizards are more likely to be preyed upon by owls. Which type of selection would act on body size in these lizards under these conditions?

Stabilizing selection: does not change the mean of the population; only the extreme phenotypes (large and small lizards) become less common

fact (images)

The digits of a cat are homologous to those of these whale bones.

matching

The phrase Darwin used to describe his broad theory of evolution is ''descent with modification.'' 2. All of life is related through common ancestry, accounting for the unity of life. 3. The diversity of life arises from the adaptation of species to different habitats over long spans of time. 4. Darwin proposed a mechanism for how evolution occurs, which he called natural selection. 5. Two key observations underlying natural selection are that members of a population vary in their inherited traits and that all species can produce more offspring than the environment can support. 6. Darwin inferred that those organisms with traits best suited to the environment tend to leave more offspring than other members of a population. 7. This unequal reproduction in a population leads to the gradual accumulation of adaptations to the environment.

A population of small fish lives in a lake with a sandy bottom. Large shore birds prey on these fish. Although most of the fish are the same light brown color as the sandy lake bottom, about 10% are mottled. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which outcome would you predict?

The proportion of mottled fish in this population will increase over time.

As in the previous question, suppose there is a population of 100 rabbits that have different fur patterns. In this population several generations ago, there were 60 FF rabbits, 20 Ff rabbits, and 20 ff rabbits. Over time, the population changed, and now there are 40 FF rabbits, 40 Ff rabbits, and 20 ff rabbits. Has microevolution occurred? Why or why not?

Yes because the allele frequencies have changed

Natural selection can be defined as ________.

a process in which organisms with certain inherited traits are more likely to survive and reproduce than individuals with other traits

Which mechanism for evolution was proposed by Lamarck?

evolution by inheritance of acquired characteristics

The wing of a bat is homologous to the _____ of a whale.

flipper

Consider a population of birds living on an island. Suppose several individuals of the same species from a different population migrate to the island. Due to the arrivial of the new birds, the allele frequencies in the original population change. What mechanism of microevolution is at work in this example?

gene flow

Generation-to-generation change in the allele frequencies in a population is _____.

microevolution

Which one of the following can create new alleles?

mutation

A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than individuals with other characteristics is called _____.

natural selection: explains how life evolves

While on the Beagle, Darwin was influenced by a book by Charles Lyell that suggested that Earth was ________ and sculpted by geologic processes that ________ today

old... continue

What do we call scientists who study fossils?

paleontologists

The study of comparative anatomy __________.

provides information about the evolutionary history of species: A good example is the study comparing the forelimbs of humans, cats, whales, and bats.

What does evolutionary fitness measure?

relative reproductive success

Natural selection ________.

results in evolutionary adaptation

Which of the following is the most recent example of an evolutionary change in populations?

the development of pesticide-resistant insects

Which of the following is an example of natural selection that has been seen in our lifetime?

the evolution of antibiotic-resistant bacteria

In evolutionary terms, an organism's Darwinian fitness is measured by its __________.

contribution to the gene pool of the next generation: Those organisms with adaptations best suited to the current environment will make the most significant contribution to the next generation.

A challenge to traditional (pre-1860) ideas about species came from embryology, where it was discovered that __________.

embryos of dissimilar organisms, such as sharks and humans, resemble each other: Early in development, the similarities among all vertebrate embryos are more apparent than the differences.

Which of the following are causes of evolutionary change?

mutation genetic drift natural selection gene flow

In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat,which type of selection would act on shell color in these snails?

Disruptive selection: causes both extreme phenotypes (light and dark shells) to be favored over the intermediate phenotype.

matching

A(n) mutation is a change in the nucleotide sequence of DNA. A(n) allele is an alternative version of a gene. A(n) population is a group of individuals of the same species living in the same area that interact with each other. The total collection of alleles in a population at a given time is the population's gene pool. Changes in allele frequencies in a population over time is microevolution.

Which of the following is the study of the geographic distribution of species on Earth?

biogeography

Homology is evidence of ________.

common ancestry

The similarity of the embryos of fish, frogs, birds, and humans is evidence of ________.

common ancestry

Suppose there is a population of 100 rabbits. In this population, 60 rabbits are FF, 20 are Ff, and 20 are ff.

0.7

matching

1. A change in allele frequencies in a population over a span of generations is microevolution. 2. Evolution that occurs by natural selection results in nonrandom reproductive success and adaptive change. 3.Evolution that occurs by genetic drift results in a change in a population's gene pool due to chance. 4. Evolution that occurs by gene flow results in a change in a population's gene pool due to the movement of individuals into and out of the population.

In 1859, Charles Darwin wrote, "The affinities of all the beings of the same class have sometimes been represented by a great tree... As buds give rise by growth to fresh buds, and these if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications." At the base of the evolutionary tree of all life is __________.

an organism that is a common ancestor to all living organisms: All living organisms arose from a common ancestor. This is reflected in the structure of an evolutionary tree of life.

matching

1. Stabilizing selection favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation. 2. Disruptive selection favors phenotypes at both ends of a range over intermediate phenotypes. This type of selection may occur when the habitat is varied. 3. Directional selection favors phenotypes at one end of a range and is common in periods of environmental change. 4. In sexual selection, individuals with certain inherited characteristics are more likely to obtain mates than other individuals. This often results in sexual dimorphism, differences between the sexes in size, appearance, and behavior. 5. Intrasexual selection is a type of sexual selection in which individuals of one sex (usually males) compete directly for mates. This may involve ritualized displays or physical combat. 6. In a type of sexual selection often called mate choice, individuals of one sex (usually females) are choosy in selecting their mates. This choice is often based on the showy appearance or behavior of the male.

Why is natural selection considered to be the most important mechanism of microevolution?

Natural selection is the only mechanism that consistently leads to adaptive changes in populations.