Chapter 10 review questions (BIO 1104)

Which statement best describes how homologous structures evolve?

A basic structure inherited from a common ancestor may evolve different variations in different species.

Which scenario describes an example of genetic drift?

A drought killed many of the orchids living on a small island. By chance, only the pink and purple varieties survive, whereas the white‑flower variety is lost completely.

Which scenario describes an example of founder effect?

A small number of British colonists occupied a small island between South America and Africa during the early 1800s, establishing a new population. This population has different allele frequencies from the original population of Britain.

Which scenario describes an example of gene flow?

A species of snake is spread across a wide area of the country living in separate populations within relatively close proximity to one another. Migration between the populations prevents speciation from occurring.

Which statement best describes how natural selection affects the genetic equilibrium of a population?

Allele frequencies are altered due to differences in the survival and reproductive success of individuals carrying different genotypes.

Which statement describes an example of genetic equilibrium?

Allele frequencies do not change in a population from one generation to the next.

What is the difference between artificial selection and natural selection?

Artificial selection requires human intervention, whereas natural selection does not require human intervention.

_____ selection favors organisms with phenotypes that are at one extreme relative to the average phenotype.

Directional

How do analogous structures arise in different species?

Distantly related species independently develop similar structures in response to similar environmental pressures.

Which statement about natural selection is true?

Environments can change more quickly than natural selection can adapt organisms in a population.

A change in allele frequencies that occurs in a population is:

Evolution

Which statement best explains the difference between homologous and analogous structures and traits?

Examples of homologous structures would be a human arm and a bat wing, whereas examples of analogous structures would be a flying mammal and a flying insect.

Generalist Species vs Specialist Species

Generalists - Species with a broad ecological niche. -They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Specialists - Species with a narrow ecological niche. - They may be able to (1) live in only one type of habitat, (2) tolerate only a narrow range of climatic and other environmental conditions, or (3) use only one type or a few types of food.

Species evolve traits that allow them to survive and thrive in certain habitats. Classify each trait in the habitat where it would be most favorable. Habitats - Hot desert - Tropical rainforest Traits - Active at dusk to avoid extreme daytime heat - Short wings to maneuver through trees - Beak that can crack large nuts and seeds - A strong prehensile tail - Many plants have spines or thorns for protections - Burrows beneath sand to minimize sun exposure

Hot desert habitat - Active at dusk to avoid extreme daytime heat - Burrows beneath sand to minimize sun exposure - Many plants have spines or thorns for protection Tropical rainforest habitat - A strong prehensile tail - Short wings to maneuver through trees - Beak that can crack large nuts and seeds

Natural selection is the primary process responsible for adaptive evolution.

Individuals with adaptive inherited traits are more likely to survive and produce offspring.

Select the definition of sexual selection.

Individuals with certain inherited traits are more appealing to potential mates, making them more likely to reproduce than those without the traits.

What does having higher fitness mean in an evolutionary sense?

Individuals with genotypes favorable for current conditions are more likely to survive and reproduce.

Select the definition of sexual dimorphism.

Males and females of one species possess distinct traits.

Which statement describes an important difference between natural selection and genetic drift?

Natural selection involves differential reproductive success in the struggle for existence in an environment, whereas genetic drift does not.

Which scenario is an example of natural selection?

Over generations, predation by cheetahs causes a herd of antelopes to become faster.

Determine whether the following statements pertain to a population or to an organism - It can change through evolution -Natural selection acts on a phenotype to change reproductive success -A new phenotype results from a novel mutation -Natural selection can cause allele frequencies to change over time

Population - Natural selection can cause allele frequencies to change over time - It can change through evolution Organism - Natural selection acts on a phenotype to change reproductive success - A new phenotype results from a novel mutation

Which statement describes a way that scientific understanding of the world changed following the publication of Charles Darwin's The Origin of Species?

Populations of organisms can change over time.

What happens in divergent evolution?

Populations or species develop in different ways from a common point.

If a population is in Hardy-Weinberg equilibrium, what does this imply?

The frequencies of recessive and dominant alleles are not changing over time.

What happens in convergent evolution?

Two distantly related species acquire similar traits independently.

Over evolutionary time, two divergent species gradually accumulate differences in their DNA sequences. This is referred to as:

a "molecular clock."

A population is:

a group of individuals of the same species that live in the same general location and have the potential to interbreed.

A fossil is defined most broadly as:

any preserved remnant or trace of an organism from the past.

Natural selection can only act on traits that:

are heritable.

Select the option that best completes the sentence.

populations, not individual organisms.

Individuals of a fish species living in a river have varying oxygen level requirements. A nearby factory accidentally releases pollutants into the river, causing oxygen levels in the water to decrease. Within a few generations, the percentage of fish with lower oxygen requirements has increased in the river. Conversely, the percentage of fish with higher oxygen requirements has decreased.

directional selection

A white‑winged butterfly population is easily visible against green vegetation. A few individuals in the population have red spots on their wings that resemble the red spots on a species that their predators avoid. A few other individuals have a speckled‑gray pattern on their wings that blends well with the vegetation. Over time, the proportions of red‑spotted and gray‑speckled butterflies increase in the population. Conversely, the proportion of pure white butterflies decreases in the population.

disruptive (diversifying) selection

In which type of selection does the frequency of intermediate traits decrease and the frequency of extreme traits increase?

disruptive or diversifying selection

The migration of reproductive individuals between populations results in a movement of alleles called:

gene flow.

The longer that two species have been evolving on their own, the:

greater the genetic differences that accumulate between them.

Disruptive selection occurs when:

individuals with extreme values of a trait have greater fitness than individuals with intermediate values of the trait.

For a population to evolve through natural selection:

its members must possess inheritable variation.

According to Darwin's theories and observations on "the struggle for existence," organisms better suited to an environment have a greater probability of surviving and will also:

leave more offspring.

Gene flow means most nearly the same as:

migration.

Imagine a population of moths. Yellow moths are easier for birds to see and eat. Gray moths blend into their surroundings, so they are less visible to birds than yellow moths. As a result, gray moths are more likely to survive and reproduce, enabling the gene for gray coloration to be passed on to the next generation. This increases the frequency of genes for gray coloration in the population.

natural selection

Several different types of predators hunt a population of rabbits. The smallest rabbits cannot run as fast as the larger rabbits and are often caught. The largest rabbits must spend more time foraging for food in the open and are also often caught. As a result, the majority of rabbits have an intermediate body size.

stabilizing selection

Which phrase describes a type of natural selection in which the average characteristics of a population are preserved?

stabilizing selection

Evolution is a change in allele frequencies within a population. It often occurs by four different mechanisms: mutation, genetic drift, migration, and natural selection.

take home Message

Fitness is a measure of reproductive output of an individual with a particular phenotype, compared with the reproductive output of individuals with alternative phenotypes. An individual's fitness can vary, depending on the environment in which it lives.

take home Message

Genetic drift is a random change in allele frequencies within a population, unrelated to the alleles' influence on reproductive success.The effects of genetic drift are most significant in small populations. The effects of genetic drift are most significant in small populations.

take home Message

Knowing the frequency of each allele in a population, we can predict the genotype sand phenotypes we should see. If there is random mating and no evolution is occurring in a population, recessive allele sand dominant alleles do not change their frequencies.

take home Message

Mutation is the only way that new alleles can be created within a population. Mutation is an alteration of the base-pair sequence in an individual's DNA. If such an alteration changes an allele in an individual's gamete-producing cells, the frequency of alleles in the population changes, and the population evolves.

take home Message

Natural selection is a mechanism of evolution that occurs when there is heritable variation for a trait,and individuals with one version of the trait have greater reproductive success than do individuals with a different version of the trait.

take home Message

The characteristics of individuals present in a population can change over time.

take home Message

We can observe such change in nature and can even cause it to occur.

take home message

If evolution has occurred:

the allele frequencies in a population have changed.

Which statement best defines "adaptation"?

the process by which organisms become better matched to their environment