Question 1

Babies that are at a low birth weight are more likely to have health problems,while women will have difficulty delivering babies with high birth weight.Together this leads to ______ for babies of average birth weight.

Accepted Answer

Stabilizing selection. This is because natural selection favors babies with an average birth weight, as they are more likely to survive and reproduce successfully. Babies with either very low or very high birth weights have lower survival rates and may have health problems, so natural selection will act against these extremes, leading to stabilizing selection for babies with average birth weights.

Question 2

Natural selection acts on

Accepted Answer

Natural selection acts on populations because it is the population that evolves over time. Alleles, genotypes, individuals, and communities are all components of a population, but they are not the units of evolution.

Question 3

Figuer:  
-In figure (a),what was the dependent variable?

Accepted Answer

The dependent variable in figure (a) is the mean weight of harvested fish. This can be inferred from the y-axis which shows the weight of fish in grams.

Question 4

Carriers of cystic fibrosis have some protection against intestinal infections such as cholera.However,people with two copies of the cystic fibrosis allele develop a life-threatening disease.The mutant allele is very common in people of northern European descent because of

Accepted Answer

Heterozygote advantage explains why the cystic fibrosis allele persists in the population, especially among people of northern European descent. Carriers of one copy of the allele (heterozygotes) have some protection against certain intestinal infections, which can confer a survival advantage in environments where such diseases are prevalent. This advantage does not extend to individuals with two copies of the allele, who suffer from the severe symptoms of cystic fibrosis.

Question 5

Figuer:  
-In figure (b),what was the independent variable?

Accepted Answer

The answer of Figuer:  
-In figure (b),what was the...

Question 6

The founder effect occurs when

Accepted Answer

The founder effect occurs when a small group of individuals leave their home population and establish new settlements, mating only among themselves. This results in a loss of genetic diversity and unique genetic variations in the new population.

Question 7

The bottleneck effect occurs when

Accepted Answer

The bottleneck effect occurs when a large population is greatly reduced in size, resulting in a loss of genetic diversity. This can happen due to natural disasters, disease outbreaks, or human activities. The smaller the population becomes, the less likely it is to contain a full range of genetic variation, which can cause long-term genetic consequences for the population.

Question 8

Darwin's theory was strongly founded on the geographic distances travelled by migrating species,or occupied by their populations.A theory of "Island Biogeography" was introduced in 1967,further elaborating on importance of the distances travelled,or areas occupied by populations.A specialized field of "Landscape Ecology" concerns patches of habitat,and distances between them,along with movement corridors,or barriers to movement.With all of these,the individuals that move about and successfully reproduce in the population

Accepted Answer

All of the answer options are correct as possibilities for different species. Gene flow can counteract trends in selection and other allele frequency changes, human construction of cities or modification of vast landscapes can block movement, construction of artificial corridors of movement can aid movement, and movement can reunite smaller groups of the species population that were previously isolated.

Question 9

A population declines when

Accepted Answer

When the death rate exceeds the reproductive rate, there are fewer offspring being born than there are individuals dying, leading to a decline in population size over time.

Question 10

Figuer:  
-What did the researchers conclude based on the data shown in figure (b)?

Accepted Answer

The answer of Figuer:  
-What did the researchers conclude...

Question 11

The North American bison was hunted to near extinction in the 1800s,and has since recovered,but with decreased genetic diversity.This is an example of

Accepted Answer

The hunting of the North American bison in the 1800s led to a bottleneck event where the population was drastically reduced, resulting in decreased genetic diversity. This is a classic example of a bottleneck event in population genetics.

Question 12

Figuer:  
-The heritability of body size is 0.2 in Atlantic silversides.What would happen in figure (b)if this heritability was 0.8?

Accepted Answer

A higher heritability (0.8) would mean that more of the variation in body size is due to genetics, thus changes in average size would occur more rapidly as offspring size would more closely resemble the size of their parents.

Question 13

Historically fishermen kept larger fish and left smaller juvenile fish.Over time the average size of the fish would

Accepted Answer

Selectively targeting larger fish and leaving smaller juveniles would result in natural selection favoring smaller fish. This is because the larger fish are more likely to be caught and removed from the population, while the smaller fish have a greater chance of survival and reproduction. Over time, this continual selection pressure would result in an overall decrease in the size of the fish population.

Question 14

Alleles conferring red plumage to male cardinals are common because red plumage

Accepted Answer

Female cardinals typically prefer males with bright red plumage, as it is a signal of good health and genetic quality. This drives the frequency of genes for red plumage higher in male cardinal populations through sexual selection.

Question 15

When Conover and Munch harvested small fish,large fish,or random sizes of fish,what hypothesis were they testing?

Accepted Answer

Conover and Munch were testing the hypothesis that harvesting larger fish would decrease the size of fish in future generations. They found that this was indeed the case, as the remaining smaller fish were able to grow and reproduce, passing on their smaller size to future generations.

Question 16

Ancestors of giraffes with shorter necks could not reach branches high up in trees for food.This led to ____ for longer necked giraffes.

Accepted Answer

The situation describes directional selection, where the selection pressures are driving the population towards one extreme of a particular trait (in this case, a longer neck) in response to a changing environment. The individuals with longer necks were better adapted to reach the higher branches and thus had a greater chance of survival and passing on their genes.

Question 17

The few ancestors of the Galàpagos finches who colonized the islands would be an example of

Accepted Answer

The few ancestors of the Galàpagos finches who colonized the islands would be a classic example of founder effect, where a small group of individuals separate from a larger population and establish a new population with a different gene pool due to chance events leading to genetic drift. This can lead to unique genetic characteristics in the new population compared to the original population.

Question 18

A male peacock has enormous tail feathers that it uses in mating displays to attract females.While the tail feathers are an advantage in mating,what is the potential disadvantage of these feathers to the male?

Accepted Answer

The large tail feathers of a male peacock require a lot of energy to produce, which can be a potential disadvantage to the male as it takes away resources that could otherwise be used for survival or reproductive purposes.

Question 19

Ancestors of the Galàpagos finches had two different types of seeds to eat on some islands.Some seeds were very small,and required small beaks to handle,other seeds were very large and required large strong beaks to crack.This led to ____ among the Galàpagos finches.

Accepted Answer

Disruptive selection occurs when extreme values for a trait are favored over intermediate values, leading to the population being divided into two distinct groups. In the case of the Galápagos finches, the presence of two types of seeds (very small and very large) favored birds with either small beaks or large strong beaks, thus leading to disruptive selection.

Question 20

Hunting magazines,hunting show hosts,and avid hunters often weave stories of letting smaller white-tailed deer pass by,waiting for the larger "prize bucks." Given what you know about possible changes in allele frequencies of populations,and assuming these reported hunting behaviors are true,

Accepted Answer

By selecting only larger "prize bucks" for hunting, the population is under directional selection for larger body size traits. Smaller deer may survive and reproduce, but over time their frequencies may decrease as the larger deer are more desirable for hunting. This may eventually result in a decrease in the availability of "prize bucks" in the population.

Quiz 12: The Forces of Evolutionary Change