Evolutionary Mechanisms Questions

Why is microevolution (or population genetics) an important topic for any biologist?

It can be used to track small generation to generation changes in a population, It can affect the genetic health of human populations., It is the initial cause of larger evolutionary changes., It can affect the genetic health of populations of endangered

The different birds shown here are all subspecies of the dark-eyed junco (Junco hyemalis), a bird that spends the winters in Kansas. Why would biologists consider them to be the same species even though they look different and occur in different areas?

They can still interbreed.

Evolution within populations (or microevolution) is defined as ____________________.

a change in allele frequency from one generation to the next

Evolution by natural selection requires

genetic variation among individuals.

Male deer (bucks) in a given population are reaching sexual maturity with smaller antlers than they did in the past because antler growth rate has decreased. Some biologists suggest that this change is related to hunting because bucks with larger antlers

Bucks that reproduce with smaller antlers are likely to have more chances to reproduce because they are not as likely to be taken by hunters. They then pass on their slower antler growth rate to their offspring.

In a large population of flowers, the frequency of a trait'srecessive allele is 0.4. What is the frequency of the trait's dominant allele?


T/F: If a population is large enough, has no mutations, has no new individuals migrating in, and has no differences in survival or reproduction among individuals; then it could not evolve in any way.


T/F: The naturalist, Lamarck, who hypothesized the inheritance of acquired characteristics, had a hypothesis about evolution before Charles Darwin did.


In small populations, gene frequencies can change drastically by chance alone. This phenomenon is called

genetic drift

Darwin's main principle of natural selection was that

every organism has the potential to produce more offspring than can survive and those individuals that are better suited to their environment are more likely to survive.

If there are only two alleles at a given locus and the frequency of one allele is 0.6, what is the frequency of the other allele?


A small population of sawflies that was once connected to a larger population but is now isolated is no longer experiencing

Gene flow

T/F: traits that are not controlled by genes can evolve


What evidence for natural selection and speciation did Alfred Russell Wallace find in Malaysia?

Marsupial mammals are on the islands in Malaysia that are closer to Australia, where their ancestors likely lived.

Small populations are _______ likely to fit the predictions of a Punnett Square than large populations, because genetic drift is _______ important in small populations.


Darwin and Wallace were the first to state the idea of evolution by natural selection, but what was really their main question?

where do species come from?

Which of the following are evidence that evolution has caused the diversity of species and forms that we now see:

Fossils of ancient species similar but different from modern species,
Geographical distribution of species, and
DNA of similar-looking species is more similar

the ultimate origin of genetic variation is


In Mendel's peas, tall and short plant variants resulted from differences at a single genetic locus, with tall being dominant to short. The height of the plant is called its


disruptive selection for body size would most likely occur when

intermediate-sized individuals are less able to find a food source

In addition to Darwin, who do we credit for formulating the theory of evolution by natural selection?

Alfred Russel Wallace

a small population of saw flies that once connected to a larger population but is now isolated is no longer experiencing

gene flow

Three different alleles (b1, b2, and b3) at the b locus exist in a hypothetical population of juniper trees. If the frequency of b1 is 0.4, what can be said about the frequency of b3?

cannot be greater than 0.6

In a population of 200 individuals at Hardy-Weinberg equilibrium, 72 are homozygous recessive for the character of eye color (cc). One hundred individuals from this population die from a fatal disease. Thirty-six of the survivors are homozygous recessive.


What is the primary distinction between artificial selection and natural selection?

artificial selection acts on specific traits, regardless of their effect on survival and reproduction

The horn sizes in males of a particular beetle have an interesting distribution: the highest frequencies are around 15 millimeters and 30 millimeters, with few individuals in between. Based on this observation, which mode of selection is most likely to be

disruptive selection

It may be that red hair evolved in Neanderthals and then was introduced into human populations via interbreeding. If this is so, this would be an example of

gene flow

A population of 600 horses has 70 individuals that are AA and 160 that are Aa at a locus involved in immune response. Assuming that these are the only alleles at that locus, what is the frequency of a?


If variation at a given locus has no effect on the phenotypes of individuals, which evolutionary process will still occur at that locus?

genetic drift

a genetic locus has two alleles. one has a frequency of 0.12; the other has a frequency of


If a population is monomorphic for an allele at one locus, the population is _______ for that allele, and the frequency of the allele is _______.


In a population of 200 individuals at Hardy-Weinberg equilibrium, 72 were homozygous recessive for the character of eye color (cc). One hundred individuals from this population died from a fatal disease. If 36 of the survivors are homozygous recessive, ho


The average size of downy woodpeckers in North America gradually increases as one moves north. What term best describes this phenomenon?

clinal variation