Genetics Week 14

Migration of a random few individuals from one population to a new area to establish a new population is an example of __________.

founder effect

What type of cladogenesis can occur through the founder effect?

Allopatric speciation

Which of the following types of selection favors one extreme of a phenotypic distribution?

Directional selection

Heritability may be calculated as which of the following?

Genetic variance divided by total variance

The formula p2 + 2pq + q2 = 1 is associated with which of the following?

Hardy-Weinberg equilibrium

The biological species concept was introduced by __________.

Mayr

Of the five factors that contribute to microevolution, which is most likely impact Hardy-Weinberg Equilibrium in a population? Justify your answer. (There is more than one possible correct answer here, but not all five factors have a significant impact. Be sure to be thoughtful and take the time to review the notes and analyze the situation.)

Migration would most likely impact Hardy-Weinberg Equilibrium, as migration causes for a loss of alleles for one population and an addition of alleles to the receiving population. For the receiving population, the addition of alleles can increase the diversity and overall increase the number of alleles in the population. On the other hand, the population that lost the alleles may have a decrease in diversity, and their overall alleles is decreased for the population

A gene which displays a single trait is said to be...

Monomorphic

What is the difference between multiple alleles and additive alleles?

Multiple alleles are different forms of the same gene. Additive alleles are alleles of different genes, all of which affect the same trait

Which of the following will alter the frequency of alleles in the population the least?

Mutation

The discipline within evolutionary biology that studies changes in allele frequencies is known as...

Population genetics

Which of the following types of selection favors the survival of individuals with the intermediate phenotype?

Stabilizing selection

The formation of polyploids in plants is an example of which model of cladogenesis?

Sympatric speciation

While the distribution ranges of the eastern and western warbler overlap, they reproduce at different times of the year. This is an example of which of the following isolating mechanisms?

Temporal isolation

If a population is tested to see if the 2 alleles for a gene are in Hardy-Weinberg equilibrium and the chi square for the population is 22 what is your conclusion?

The alleles are not in equilibrium.

What is true concerning a quantitative trait?

The phenotypic variation for the trait is continuous

What does narrow sense heritability (h2) estimate

The proportion of phenotypic variation that is due to additive genetic variance

The equation that describes the relationship between phenotypic variance, genetic variance and environmental variance is __________.

VP = VG + VE

Polygenic inheritance may result in a continuum of phenotypes because __________.

as the number of genes controlling a trait increases and the influence of environment variation becomes greater, there is a blurring of discreteness

(T/F) The sum of all of the values for a trait, divided by the total number of individuals, is called the standard deviation.

false

Which of the following terms describes all of the alleles of a population that contribute to the next generation?

gene pool

Genetic drift has a greater influence on __________ populations.

small

The square root of the variance is called the __________.

standard deviation

Molecular paleontology __________.

studies the DNA of extinct species

It is currently believed that apple maggot flies are undergoing a divergence into two separate species. Two hundred years ago these maggot flies laid their eggs only on the hawthorn fruit, but after apples were introduced in the Americas, some maggot flies started laying their eggs on apples. Today, females generally lay their eggs on the type of fruit they grew up in, and male flies end up mating on the type of fruit they grew up in. Therefore hawthorn flies mate with hawthorn flies and apple flies mate with apple flies. If genetic changes between the hawthorn maggot flies and the apple maggot flies continue until the flies are different species, this would be an example of ___________.

sympatric speciation

Compare and contrast direction selection, stabilizing selection, and disruptive selection.

- Directional Selection: this type of selection favors one extreme phenotype, that is more adapted to the environment compared to other phenotypes. This type of selection also affects Hardy-Weinberg equilibrium, as it favors one extreme phenotype. - Stabilizing Selection: this type of selection favors intermediate phenotypes instead of extreme phenotypes. This selection also causes for a decrease in genetic diversity. - Disruptive Selection: this type of selection favors two of more different genotypes that have different phenotypes. - All three selections select for a specific phenotype that is survivable in a particular environment.

Which of the following is true concerning a population in equilibrium according to the Hardy-Weinberg rule?

- The population size is very large. - There is no migration into or out of the population. - Individuals of the population mate randomly. - There is no mutation in the population.

Analysis of rRNA sequences led to the proposal of what main branches of life?

- bacteria - archaea - eukaryotes

Select the prezygotic isolating mechanisms.

- temporal isolation - habitat isolation - mechanical isolation - behavioral isolation - gamete isolation

Calculate the narrow-sense heritability of height between aunts and nieces if the observed phenotypic correlation coefficient is 0.1.

0.4

In a given population of Drosophila, curly wings (c) is recessive to the wild-type condition of straight wings (c+). You isolate a population of 35 curly winged flies, 70 flies that are heterozygous for straight wings and 45 that are homozygous for straight wings. What is the frequency of alleles in this population?

46.7% c; 53.3% c+

If the frequency of allele A is 0.8 and the frequency of a is 0.2 within a population given the fitness values below what will be the relative frequencies for the different genotypes in the next generation? Fitness values: AA 1.0 Aa 0.75 aa 0.25

AA 0.64/ Aa 0.24/ aa 0.01

Explain how artificial selection utilizes the principles of natural selection, but why they are not the same processes.

Artificial selection utilizes the principle of natural selection, in that it is still selecting for the most fit organisms in the particular environment. The difference with artificial selection is that the parents are specifically chosen to mate and reproduce. These parents usually contain genes that the other does not, and they are able to produce an offspring with all of the viable genes from both parents. This specific selection allows for even more fit offspring to be produced and hopefully the offspring are able to survive and reproduce as well.

Allopatric and parapatric speciation have similar roots. Describe what aspects are shared between them, but why ultimately, they are different modes of speciation.

Both allopatric and parapatric speciation involve some kind of geographical change between species. For both cases, the geographical change causes for the divergence of evolution of the species affected. The difference is the type of geographical change. With allopatric, the species are completely separated by geographical processes, while parapatric does not completely separate the species. The geographical process in parapatric speciation may have a small divide that allows for the species to interbreed.

Why are phylogenetic studies that compare extant and extinct species (e.g. the flightless birds) important for evolutionary biology?

Comparing the extant and extinct species is important for evolutionary biology because it shows the relationship and similarities between the different species. It also allows for the genetic changes that caused for the divergence of different species during their evolution to be identified.

Which of the following is most typical of a case of quantitative inheritance?

Continuous variation in phenotypes

Which type of selection would lead to two distinct phenotypes?

Disruptive selection

Heterosis is __________.

an increased vigor of hybrids resulting from the crossing of inbred strains

The characteristics of a given population over time are ________.

dynamic

The best definition for genotype-environment interactions is __________.

environmental effects on the phenotype differ with genotype

(T/F) Microevolution is the term given to evolutionary changes that produce new species and groups of species.

false

(T/F) The production of sterile offspring is an example of a prezygotic isolation mechanism.

false

Molecular clocks are based on __________ mutations.

neutral

In the construction of a phylogenetic tree, a __________ considers the overall similarities among a group of species without trying to understand their evolutionary history, whereas a __________ considers the possible pathways of evolution to find the best possible tree.

phenetic approach; cladistic approach

A group of individuals from the same species that occupy the same region and can interbreed with one another is the definition of a ________.

population

After several generations of artificial selective breeding, a plateau is reached where artificial selection is no longer effective. This is called the __________.

selection limit

The plant species Erythranthe peregrina arose from a duplication of all of the chromosomes of a sterile triploid hybrid called E. x robertsii. E. peregrina most likely arose by __________.

sympatric speciation

The degree of relatedness of two members of a pedigree is calculated using __________.

the inbreeding coefficient

Your professor wants you to construct a phylogenetic tree of maple trees. He gives you tissue from 14 maple species and an oak species. What is the most likely reason he gave you the oak?

to serve as an outgroup

(T/F) Heritability is the amount of genetic variation in a particular population and a particular environment.

true

(T/F) Homologous genes are derived from the same ancestral gene.

true

(T/F) Many organisms used in modern agriculture are a result of artificial selection.

true

(T/F) One definition of species is a group of individuals whose members have the potential to interbreed and produce viable, fertile offspring.

true

(T/F) Random genetic drift is due to chance events that alter the allele frequency in a population.

true