week 12 population genetics

What is the average number of generations likely to be required to achieve fixation of a new allele arising in a population of 400 individuals?

1600

What is the average number of generations likely to be required to achieve fixation of a new allele arising in a population of 2000 individuals?

8000 (*4)

Repetitive sequences are composed of a certain sequence that is repeated many times throughout the genome of a species. What is the typical size of the sequence that is being repeated?

A few to a few thousand base pairs

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

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 every gene that were passed from the 60 parents to the 48 new cubs

Human individuals can be characterized by analyzing the presence and sizes of repetitive sequences in their DNA, a technique known as ______.

DNA fingerprinting

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

Darwinian fitness

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

A group of individuals from a larger population can migrate to a new area and establish a colony, which will be highly susceptible to genetic drift. This is known as the ______ effect.

Founder*

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 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

A founding population usually has lower genetic diversity than the original population it came from. For those alleles that are shared by the two populations, how are allele frequencies different (or similar)?

Usually, the allele frequencies in the founding population are very different from those of the original population.

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

allele; p allele

For random mating to occur, individuals must choose their mates irrespective of their genotype/phenotype. When this condition is violated, non-random mating is occurring, also known as ______ mating.

assortative

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

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

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

The ______ effect is observed when a population's size is dramatically reduced due to natural events, such as earthquakes and flood, or due to human destruction of habitat.

bottleneck/founder

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

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

directional selection

If a high chi square value is obtained when comparing observed and expected genotypes in a population, we can state 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 ______ over the course of many generations.

do not change

The term genetic ______ refers to any random change in the frequencies of alleles in a population.

drift

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 DNA _____, an individual is characterized based on the repetitive sequences in his or her genome.

fingerprinting

A group of individuals from a larger population can migrate to a new area and establish a colony, which will be highly susceptible to genetic drift. This is known as the ______ effect

founder

Sometimes populations become susceptible to genetic drift via the ______ effect. This happens when a small group of individuals separates from a larger population and migrates to a different site, where it establishes a colony.

founder's

Sometimes populations become susceptible to genetic drift via the ________ effect. This happens when a small group of individuals separates from a larger population and migrates to a different site, where it establishes a colony.

founder_

When individuals migrate, alleles can be transferred from one population to another population. This is commonly referred to as ____ ______

gene flow

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

gene pool

Suppose a chi square analysis is performed to test whether the observed genotypes in a population are consistent with the predictions of Hardy-Weinberg equilibrium. Which type of chi square value will be obtained if a population is in disequilibrium?

high

During ______ gene transfer, genetic material from a donor organism is incorporated into a recipient organism which is not the donor's offspring.

horizontal

The transfer of genetic material from one species to another (regardless of the exact mechanism) is called ______.

horizontal gene transfer

The founding population typically has less genetic diversity than the original population. The founding population typically has very different allele frequencies from those of the original population.

important results of the founder effect on the newly founded population.

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

microevolution

A ______ is any change in the DNA of an organism, for example, a change in DNA sequence or the structure and number of chromosomes.

mutation

The mechanism of evolution through _______ ______ states that those individuals better adapted to their environment are more likely to survive and reproduce

natural selection

The mechanism of evolution through ______ _______ was proposed by Charles Darwin and Russel Wallace in the 1850s.

natural_selection

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

Which field of genetics would study the extent of genetic variation within groups of people over time?

population genetics

The field of _______ genetics studies the extent of genetic variation within groups of people over time.

population__

In ______ assortative mating, individuals tend to choose mates with similar phenotypes. In ______ assorting mating, individuals tend to choose mates with dissimilar phenotypes.

positive, negative

Genetic drift is the ______ in a population.

random change of allele frequencies

Most eukaryotic species contain short sequences, typically a few base pairs to a few thousand base pairs long, that are repeated many times throughout the genome. The general name for these types of sequences is ______ sequences.

repetitive

Individuals must migrate from one population to another. Migrants must be fertile and pass their genes to the next generation.

required for gene flow to occur

Mutations occur when the DNA of an organism changes. Changes often happen in gene _______, but may also involve the structure and number of chromosomes.

sequences

______ 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

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

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