Chapter 27 Genetics HW

Population genetics is concerned with the ______.

extent of genetic variation within a group of individuals

Natural selection is the phenomenon in which certain phenotypes have ______ than other phenotypes.

greater reproductive success

Genetic drift is the _____ in a population.

random change of allele frequencies

Which of the following correctly defines a population of sexually reproducing species for the purposes of population genetics?

A group of individuals that occupy the same area and can interbreed with each other

The relative (compared to other genotypes) likelihood that a genotype will contribute its alleles to the next generation is known as

Darwinian fitness

In certain populations, natural selection can favor the maintenance of 2 or more alleles in a population. An example of this is ______ selection.

balancing

Which type of selection is also known as diversifying selection because it tends to favor the survival of two or more different phenotypes in a heterogeneous environment?

Disruptive selection

Over time, genetic drift can lead to the fixation of an allele. What types of alleles are usually fixed by drift?

Genetic drift is random, so deleterious, beneficial, or neutral alleles can become fixed.

Consider a single gene with two alleles in a population of wild birds. A situation in which the heterozygotes for that gene have higher fitness than the two homozygote genotypes is known as_________-- ___________In these situations, an equilibrium is reached, in which both alleles of the gene are maintained in the population.

Heterozygote Advantage

The genetics field that is concerned with the extent of genetic variation within a group of individuals and changes in that variation over time is

Population genetics

A scientist is studying two populations of the same species of birds - one in Michigan and one in Montana. Both populations are relatively large (with more than 10,000 individuals each). However, the Michigan population has a much lower genetic diversity than the Montana population. Which of the two populations is most likely to have experienced a bottleneck and which of the two populations is currently more susceptible to genetic drift?

The Michigan population likely experienced a bottleneck in the past. Both populations are equally susceptible to genetic drift.

Which of the following is the best definition of Darwinian fitness as it relates to population genetics?

The relative (compared to other genotypes) likelihood that a genotype will contribute alleles to the next generation

Consider a population and a gene that has two alleles in this population, designated as E and e. If you divide the number of all the copies of the e allele in the population by the total number of copies of both alleles (E and e) in the population, you will calculate the ______.

allele frequency of the e allele

In________selection, natural selection favors the maintenance of two or more alleles in a population. An example of that is the phenomenon of heterozygote advantage.

balancing

A healthy population can become highly susceptible to genetic drift if its size is dramatically reduced due to natural phenomena, such as earthquakes or droughts. This is known as the ______ effect.

bottleneck

In_________selection, individuals at one extreme of a phenotypic distribution are more likely to survive and reproduce in a particular environment.

directional

Sometimes individuals at one extreme of a phenotypic distribution are favored in a particular environment, for example, selection will strongly favor insects that have very high resistance to an insecticide. In such cases, the type of selection that operates is ______ selection.

directional

A population would be described as being in ______ if a high chi-square value is obtained when testing whether the allele and genotype frequencies are in Hardy-Weinberg equilibrium.

disequilibrium

When the hypothesis that the allele and genotype frequencies are in Hardy-Weinberg equilibrium is rejected, it can be stated that the population is in

disequilibrium

The Hardy-Weinberg equilibrium is a mathematical expression which predicts that, when certain requirements are met, the allele and genotype frequencies of a gene in a population ______.

do not change over the course of many generations

The Hardy -Weinberg equilibrium is used as a null hypothesis, i.e., if a population is in Hardy-Weinberg equilibrium, then ______.

evolutionary change is not occurring in this population

In order to derive the Hardy-Weinberg equation, the two scientists assumed that ______ population's gene pool..

gametes are independently chosen at random from the population's gene pool

The ________ ________of a population consists of all of the alleles of every gene in all of the individuals of that population.

gene pool

When the heterozygotes for a specific gene have higher fitness than either of the corresponding homozygous genotypes (assume a single gene with two alleles), we are observing a situation called ______.

heterozygote advantage

The change in a population's gene pool from one generation to the next is known as ______.

microevolution

According to the theory of ____ ____, individuals with alleles leading to greater reproductive success will be more likely to produce offspring and pass those alleles to the next generation.

natural selection

Which of the following is an accurate depiction of the Hardy-Weinberg equation for a gene with two alleles?

p2 + 2pq + q2 = 1

Most of the traits in a healthy natural population exhibit some level of variation, or_____________, that is, they are found in two or more forms.

polymorphism

When scientists study populations, they typically observe high levels of variation in many of the traits that characterize a species. In genetics, variations in traits at the population level are known as ______.

polymorphisms

In genetics a ______________of a sexually reproducing species consists of a group of individuals of that species, which occupy the same region, and can successfully interbreed with each other.

population

Consider a population of cheetahs, inhabiting a protected area in Africa. In 2012, there were 112 cheetahs in this population. During that year, 60 of those animals reproduced and 48 new cubs were born. What constitutes the gene pool of the new generation made of those 48 new cubs?

All of the alleles of all the genes that were passed from the 60 parents to the 48 new cubs

____________selection acts on quantitative traits determined by multiple genes. In this type of selection, individuals with intermediate phenotypes have higher fitness and are selected for, while extreme phenotypes are selected against.

stabilizing

Microevolution is best described as ______.

the change in a population's gene pool from generation to generation

In disruptive selection, ______.

two or more alleles are maintained in a heterogeneous environment

How is the allele frequency of a population calculated?

The number of copies of the allele in the population is divided by the total number of all the alleles for the same gene in the population.

Which type of selection tends to select against extreme phenotypes for a quantitative trait, because individuals with intermediate phenotypes have the highest relative fitness values?

Stabilizing selection