BIOL 1442 UTA Exam 1

Members of two different species possess a similar-looking structure that they use in a similar way to perform about the same function. Which of the following would suggest that the relationship more likely represents homology instead of convergent evolution?

The two species share many genes and/or proteins.

A population of organisms will not evolve by natural selection if

all individual variation is due only to environmental factors

Which of the following statements describe the effect of natural selection on a population?

increasingly better match between a population and its environment

No two people are genetically identical, except for identical twins. The chief cause of genetic variation among human individuals is

the reshuffling of alleles in sexual reproduction.

The specific negative consequences of accidental attempts at hybridization between species .

postzygotic barriers

Members of two different species possess a similar-looking structure that they use in a similar way to perform about the same function. Which of the following would suggest that the relationship more likely represents homology instead of convergent evolution?

The two species share many genes and/or proteins.

Which is the best estimate of evolutionary fitness?

The number of offspring it produces over its lifetime that survive to breed

What are (evolutionary) adaptations?

inherited characteristics of organisms that enhance their survival

A population is defined as

all of the individuals of a species living within a specific area

The amino acid sequences of human and bonobo hemoglobin are almost identical, yet they differ considerably from the sequence of the hemoglobin of wolves. This fact indicates that

bonobos are more closely related to humans than to wolves.

Adaptive radiations are more likely to appear to follow which model for the pace of evolution when studied in the fossil record?

Punctuated equilibrium

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. That the actual forelimbs of these mammals do not seem to be optimally arranged is because

natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

Which statement about natural selection is most correct?

Well-adapted individuals leave more offspring, and thus contribute more to the gene pool of the next generation, than do poorly adapted individuals.

Which two people independently developed the theory of natural selection?

Alfred Russel Wallace and Charles Darwin

Guppies exhibit sexual dimorphism in some pools due to intersexual selection, but the frequency of brightly colored males in a population varies depending on environmental factors such as the presence or absence of predators in the pool. Which of the following would you predict would evolve in guppies that are taken from streams in Trinidad with predators and put into streams lacking predators?

Future generations will contain relatively more colorful male guppies.

Which of these definitions of species best matches the biological species concept?

Members of the same species can mate and produce fertile offspring.

Vocab Term: Adaptations which serve to prevent accidental hybridization between species.

prezygotic barriers

Best suited vocab term: This type of event led to the unusual diversity of finch types in the Galapagos, and also spawned the variety of ecological types of anole lizards in the Caribbean.

adaptive radiation

Best suited vocab term: The reproductive success of an individual, relative to others in the population.

relative fitness

Best vocab term: Autopolyploidy is a mechanism for this evolutionary event.

sympatric speciation

Examples include the human coccyx and appendix, the remnants of eyes in blind cave salamanders, and tiny hind limbs in transitional fossils of whale ancestors.

vestigial structure

The fact that whales have pelvic and leg bones indicates that

ancestral whales had legs.

Both natural selection and sexual selection result in organisms being better able to survive in their environments true or false

False

An allele frequency is the

relative proportion of a given allele in a population.

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele?

0.32

Nonrandom mating can happen by chance if a population is spread across a large geographical area

True

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer or more than this have reduced fitness. This is an example of

stabilizing selection

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake?

a genetic bottleneck

The process by which allele frequencies are altered in a population due to chance is called

genetic drift.

In the United States, approximately one child in 10,000 is born with PKU (phenylketonuria), a syndrome that affects individuals homozygous for the recessive allele (aa).

Calculate the percentage of carriers of the trait within the population.

approximately 2%

The interaction of genes and environment produces a specific

phenotype

Sexual dimorphisms are

Differences between males and females in traits

Suppose a population of flour beetles has 1,000 individuals. Normally the beetles are red; however, this population is polymorphic for a mutant autosomal body color, black, designated by bb. Red is dominant to black, so BB and Bb genotypes are red. Assume the population is at Hardy-Weinberg equilibrium, with equal frequencies of the two alleles. What would be the expected frequencies of the red and black phenotypes?

0.75 red; 0.25 black

If there are only two alleles at a given locus and the frequency of one allele is 0.3, what is the frequency of the other allele?

0.7

Natural selection can increase the frequency of beneficial alleles in a population or decrease the frequency of deleterious alleles in a population true or false

true

Organisms with large population size are more susceptible to genetic drift than natural selection

false

A population geneticist is studying a species of turtle. Which of the following would they be most interested in measuring?

How the turtle's diet impacts the hardness of their shell

Mutations that don't affect the organism are removed from the genome quickly true or false

false

When a species lives in a constant environment for a long time, the "average type" of individual may have the best chance of surviving and producing the most offspring. What type of selection is occurring?

stabilizing selection

Ka/Ks < 1

purifying/negative selection

Ka/Ks > 1

positive selection

Ka/Ks = 1

neutral selection

Approximately how much of the human genome consists of functional protein coding sequence?

(Choose the closest value)

less than 2%

To calculate Ka/Ks we must compare ______________ sequences.

orthologous

Which type of nucleotide substitution is LEAST likely to be neutral (i.e. not under selection)?

Non-synonymous

A synonymous mutation (or substitution) will change the amino acid sequence of a protein.

False

The last common ancestor of Species 1, Species 2, and Species 3 had two genes (Gene A and Gene B) that arose by gene duplication. Gene B is a duplicate of Gene A. When Species 1, 2, and 3 evolved from this common ancestor, each one inherited Gene A and Gene B so that:

Species 1 carries Gene A1 and Gene B1

Species 2 carries Gene A2 and Gene B2

Species 3 carries Gene A3 and Gene B3

In this scenario, Genes A1 and A2 are

orthologs

What is the most common fate of new gene duplicates?

Pseudogenization

Which of the following best explains variation in genome size?

Transposable elements

Migration

Genome wide differences in allele frequencies (variation) among populations

Random Genetic Drift

Genome wide reduction in variation

Natural Selection

Reduced nucleotide variation, but only for the gene under selection

The last common ancestor of Species 1, Species 2, and Species 3 had two genes (Gene A and Gene B) that arose by gene duplication. Gene B is a duplicate of Gene A. When Species 1, 2, and 3 evolved from this common ancestor, each one inherited Gene A and Gene B so that:

Species 1 carries Gene A1 and Gene B1

Species 2 carries Gene A2 and Gene B2

Species 3 carries Gene A3 and Gene B3

In this scenario, Genes A2 and A3 are

Orthologs

Which is true of frame shift indels?

usually deleterious

The last common ancestor of Species 1, Species 2, and Species 3 had two genes (Gene A and Gene B) that arose by gene duplication. Gene B is a duplicate of Gene A. When Species 1, 2, and 3 evolved from this common ancestor, each one inherited Gene A and Gene B so that:

Species 1 carries Gene A1 and Gene B1

Species 2 carries Gene A2 and Gene B2

Species 3 carries Gene A3 and Gene B3

In this scenario, Genes A3 and B3 are

Paralogs

Natural selection is the dominant driver of evolutionary change in DNA sequences and All mutations have a beneficial or deleterious effect

Selectionist Theory

Genetic drift is the dominant force driving evolutionary change in DNA sequences and Most mutations have no effect on fitness

Neutral Theory

Most mutations have a small beneficial or deleterious effect and Population size affects the relative importance of natural selection versus genetic drift in driving evolutionary change in DNA sequences

Nearly neutral theory

In corn, kernel color is governed by a dominant allele for white color (W) and by a recessive allele (w). A random sample of 100 kernels from a population that is in Hardy-Weinberg equilibrium reveals that 9 kernels are yellow (ww) and 91 kernels are white.

Calculate the percentage of this population that is homozygous dominant (WW).

0.49

Ultimately, all genetic variation (or variance) comes from new mutations. These occur

at random within the genome, whenever gametes are produced.

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele?

0.32

A high proportion of the cats on the island of Key West have extra toes (polydactyly). What is the most likely explanation?

founder effect

The Hardy-Weinberg principle is often referred to as Hardy-Weinberg equilibrium. In this context, what does the term "equilibrium" refer to?

Without evolutionary forces acting, a population's allele and genotype frequencies will remain the same over time

An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically determined, what effect has the ground-squirrel population experienced during the earthquake?

a genetic bottleneck

Deviations from the Hardy-Weinberg equilibrium

occur when evolutionary forces are operating on the population.

Genetic drift can eliminate an allele from a population (t/f)

true

Genetic variation (or variance) in a natural population is the result of

random mutations of the DNA.

For a diploid population that meets the assumptions of the Hardy-Weinberg equilibrium at a particular locus,

The allele's frequency should not change from one generation to the next.

Natural selection can increase the frequency of beneficial alleles in a population or decrease the frequency of deleterious alleles in a population (t/f)

true

The founder effect and the bottleneck effect are both forms of adaptive evolution. (t/f)

False

Imagine that hobbits and humans have been living on separate continents for so many generations that they cannot produce offspring together.

allopatric speciation

Imagine within a population that over time, hobbits with medium-sized feet became common while those with large or small feet became rare.

stabilizing selection

Imagine that within a population over time, hobbits with large feet became more and more common.

directional selection

Imagine that hobbits from a village on one side of a mountain moved to a village on the other side of the mountain, and intermarried with the locals.

gene flow

Imagine that hobbits that live near the river have very large feet, while hobbits that live farther uphill from the river have progressively smaller feet.

cline