Chp 25-27 Biology

The biological species concept can be applied only to which of the following groups?

reptile species living today

The ease with which humans travel across the globe is likely to increase _____.

gene flow

Which evolutionary mechanism always increases genetic variation in a population?

mutation

Which type of selection tends to increase genetic variation?

Disruptive selection

Do individuals change when natural selection occurs? Why or why not?

No. Individuals do not change, but the population does.

Why do related species share homologous traits?

Related species inherited homologous traits from a common ancestor.

Which is an example of a structural homology?

Vertebrate forelimbs have the same number and arrangement of bones.

Which statement about vestigial traits is correct?

Vestigial traits are similar to functional traits in closely related species.

Which form of natural selection is most likely to play a role in speciation?

disruptive selection

What term is defined as the change in allele frequencies that occurs when a new population is established?

founder effect

How might the timing of when fruit falls from a tree be important in sympatric speciation?

Apple fruit drops earlier than hawthorn fruit to reduce the interaction of the fly species in time.

Which assumption must be correct for a population in Hardy-Weinberg equilibrium for a specific gene?

No genetic drift can affect allele frequencies for the gene

Which mechanism causes postzygotic reproductive isolation?

hybrid sterility

Which concept(s) for identifying species CANNOT be applied to asexual or fossil species?

Biological species concept

Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?

Directional selection Directional selection drives the average of the population in one direction, in this case, toward longer necks.

Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?

Disruptive selection causes both extreme phenotypes (large and small beaks) to be favored over the intermediate phenotypes.

What is plausible evidence supporting the hypothesis that birds evolved from dinosaurs?

Fossilized transitional forms are discovered that possess features of birds and dinosaurs yet are difficult to classify into either group.

Why don't the biggest and strongest individuals in a population always produce the most offspring? Why don't the biggest and strongest individuals in a population always produce the most offspring?

In some environments, being big and strong lowers fitness.

How might gene flow be important in managing an endangered species?

It increases genetic diversity by introducing alleles from one population into another.

How is a hybrid zone most likely to change over time if hybrid offspring have higher fitness than both parental populations?

It should expand into the ranges of both parental populations.

Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?

Stabilizing selection causes no change in the average of the population; extreme phenotypes (in this case, large and small babies) become less common.

Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?

Stabilizing selection causes no change in the average of the population; extreme phenotypes (large and small lizards) become less common.

Which of the situations below describes vicariance?

The Grand Canyon forms, separating two populations of squirrels on the North rim and the South rim.

In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?

The value of a particular characteristic; characteristics of an organism can include such traits as size and color.

In biology, an adaptation is defined as _____.

a heritable trait that increases the fitness of an individual in a particular environment

All the genes in a population are that population's _____.

gene pool

Modern travel along with migration reduces the probability of _____ having an effect on the evolution of humans

genetic drift

In what sense is the Hardy-Weinberg principle a null hypothesis?

if evolutionary processes and nonrandom mating are not occurring.

Which is the first step in allopatric speciation?

physical isolation of two populations

In biology, fitness is defined as _____.

the ability of an individual to produce surviving offspring

Genetic drift is a process based on _____.

the roll of chance

A mutation occurs when _____.

there is a change in the DNA sequence of a gene