Question 1

Which of the following reproductive barriers would prevent a mating attempt?

Accepted Answer

Behavioural isolation prevents mating attempts by preventing individuals from recognizing each other as potential mates.

Question 2

A researcher notices that in a certain moth species,some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes.Other females prefer to feed and lay eggs on wild solanaceous plants like Datura.Both male and female moths primarily use scent to find these plants from afar.Females tend to mate where they feed,and the researcher finds a genetic basis for scent preference in these moths.Based on the above information,what might be occurring in this moth species?

Accepted Answer

The divergence in feeding and scent preference between the two groups of females (those preferring domesticated versus wild solanaceous plants) suggests that the species may be undergoing sympatric speciation, whereby a single population diverges into two or more reproductively isolated groups in the same geographic location. The genetic basis for scent preference reinforces this possibility, as it suggests that the two groups of females have evolved different genetic adaptations to their preferred host plants.

Question 3

Which of the following reproductive barriers would prevent a hybrid zygote from developing into a viable,fertile adult?

Accepted Answer

Hybrid sterility refers to the inability of a hybrid offspring to produce viable gametes, which leads to infertility. This particularly affects species that have different numbers of chromosomes, which can create problems during meiosis and result in non-viable gametes in the hybrid offspring. Therefore, hybrid sterility is a post-zygotic reproductive barrier that prevents the development of viable, fertile adults. The other options listed are pre-zygotic barriers that prevent the formation of a hybrid zygote in the first place.

Question 4

A species of groundhog spreads through an environmentally varying region surrounding a lake;the different populations,each in their own environments,accumulate habitat-specific morphological traits.Which of the following is this an example of?

Accepted Answer

This is an example of the formation of subspecies, where populations of the same species accumulate distinct traits due to living in different environments. Allopatric speciation would involve the complete separation of populations, while a species cluster is not a recognized biological concept. The founder effect involves a small group of individuals colonizing a new area and their genetic makeup influencing the traits of the new population.

Question 5

You are studying lizards in the field.The range of the northern population,species 1,overlaps the range of the southern population,species 2.You find hybrids in the zone of overlap.What is happening?

Accepted Answer

The answer of You are studying lizards in the field.The...

Question 6

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysocelis is diploid,and Hyla versicolor is tetraploid.The frogs are identical in appearance,but their mating calls,which females use to find mates,differ.Which difference most likely evolved first?

Accepted Answer

Polyploidy likely evolved first, leading to reproductive isolation. The difference in mating calls could then evolve as a mechanism for species recognition, reinforcing the separation initiated by the change in ploidy.

Question 7

Imagine two North American ground cricket species that contact each other as the southern species moves northward during a period of global warming.These two species do not mate much,due to differences in their courtship songs.The northern cricket does not seem to tolerate the warmer temperatures well,but is limited in its ability to move north because it does not normally disperse much.Based on this information,which is the most likely outcome?

Accepted Answer

Based on the information given, it is likely that the northern ground cricket will not be able to adapt to the warmer temperatures and may eventually go extinct. The southern species may move northward, but due to the differences in courtship songs, they may not interbreed with the northern species enough to form a hybrid zone or create a new species. Reinforcement, which is the strengthening of prezygotic barriers to prevent interbreeding, is also unlikely since there is already limited mating between the two species. Therefore, the most likely outcome is the extinction of the northern species.

Question 8

Which of the following is FALSE regarding speciation?

Accepted Answer

Natural selection does not deliberately isolate populations, it is a result of the physical isolation and genetic divergence over time.

Question 9

The common edible frog of Europe is a hybrid between two species,Rana lessonae and Rana ridibunda.The hybrids were first described in 1758 and have a wide distribution,from France across central Europe to Russia.Both male and female hybrids exist,but when they mate among themselves,they are rarely successful in producing offspring.What can you infer from this information?

Accepted Answer

The fact that the hybrids are rarely successful in producing offspring when mating among themselves indicates the presence of postzygotic isolation, which refers to reproductive barriers that prevent the hybrid offspring from developing properly or from being fertile. This suggests that there are genetic differences between the two frog species that cause these barriers.

Question 10

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.What outcomes can occur where the ranges of two species overlap?

Accepted Answer

When the ranges of two closely related species overlap, there are multiple potential outcomes. Interspecific mating can occur, leading to hybridization and eventually fusion over time (option A). Alternatively, a stable hybrid zone can form if the hybrids are more adapted to the area of overlap than either parent species (option B). However, if the species are not successful in interbreeding, they may continue to diverge and become isolated by behavioral or genetic mechanisms (option C). Therefore, all of the listed outcomes are possible (option D). Option E, none of the above being possible, is not accurate as multiple potential outcomes are possible when species ranges overlap.

Question 11

A storm brings two formerly separated populations of beetles together.They look very similar.Under the biological species concept,which of the following would show that the two populations are different species?

Accepted Answer

Under the biological species concept, different species are defined by reproductive isolation. All the options (A, B, and C) indicate mechanisms of reproductive isolation, thus supporting the idea that the two populations are different species.

Question 12

A population of ground squirrels is separated by a glacier.Changes in which of the following would most likely result in reproductive isolation if the two populations came into contact several generations later?

Accepted Answer

A change in the gene encoding of a receptor on the egg-cell surface in one group is most likely to result in reproductive isolation when the two populations come into contact. This is because it can lead to changes in the ability of the sperm of one population to fertilize the egg of the other population, causing a barrier to successful reproduction. Changes in fur colour, diet, and alarm calls are less likely to result in such a barrier.

Question 13

Natural selection for traits that keep distinct populations from reproducing with each other is called reinforcement.When is reinforcement beneficial?

Accepted Answer

Reinforcement is beneficial when hybrids have lower fitness than either parent population, as it strengthens reproductive barriers to prevent the production of less fit hybrids.

Question 14

Six potential species of seaside sparrows were genetically analyzed to determine their phylogenetic relationships.DNA analysis revealed that there were only two monophyletic groups with individuals from three subspecies making up each group.The three Altantic coast subspecies formed one monophyletic group,while the three Gulf coast subspecies made up the other monophyletic group.If you could only save two subspecies of the seaside sparrows from extinction,would you choose two subspecies from the Atlantic coast,two from the Gulf coast,or one each from the Atlantic and Gulf coasts?

Accepted Answer

Saving one subspecies from each coast will preserve more genetic diversity and maintain the two distinct monophyletic groups identified by the DNA analysis. Saving two subspecies from only one coast would result in loss of diversity within each monophyletic group, and may also disrupt the natural geographic distribution of the sparrows.

Question 15

Which of the following is a disadvantage of the morphological species concept?

Accepted Answer

The morphological species concept relies on the physical characteristics of organisms to define species, and thus is subject to variation in interpretation and subjective differences of opinion that may not be fully resolved by empirical data.

Question 16

If a plant species with 2n = 14 forms an allopolyploid with a plant species with 2n = 18,what would be the likely diploid (2n)number of the allopolyploid?

Accepted Answer

C)Student must visualize an error in duplication at a different stage than that depicted in Figure 26.11.

Question 17

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.If reinforcement of prezygotic isolation is occurring,what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

Accepted Answer

If reinforcement of prezygotic isolation is occurring, we would expect the two closely related tree frog species to evolve differences in their mating calls in areas of sympatry (where the two species overlap and potentially mate) compared to areas of allopatry (where the two species are geographically separated and do not mate). This is because if interbreeding occurs between the two species in sympatry, there may be reduced fitness of hybrid offspring due to genetic incompatibility between the two species. Therefore, natural selection would favor individuals with mating calls that differ from those of the other species to reduce the likelihood of interbreeding. Thus, we would expect the calls of the two species to be more different in areas of sympatry compared to allopatry.

Question 18

A small number of birds arrive on an island from a neighboring larger island.This small population begins to adapt to the new food plants available on the island,and their beaks begin to change.About twice a year,one or two more birds from the neighboring island arrive.What effect do these new arrivals have?

Accepted Answer

The answer of A small number of birds arrive on...

Question 19

You are studying two populations of spiders of the Dolomedes genus,characterized by a light stripe down each side of the body.One population lives in a pond,while another nearby population lives in the trees.Which of the following species concept would you be using if you determined that these were two different species?

Accepted Answer

The ecological species concept would be used here, as it defines species based on their ecological niches and adaptations to different environments, such as living in a pond versus living in trees.

Question 20

Which of the following evolutionary processes is not acting when two groups of organisms are identified as different species according to the Biological Species Concept?

Accepted Answer

The Biological Species Concept defines species as groups of organisms that are reproductively isolated from each other, meaning gene flow between them is not occurring. Therefore, gene flow is not acting when two groups of organisms are identified as different species according to this concept. Genetic drift, natural selection, mutation, and sexual selection could all still be acting in both groups separately.

Quiz 26: Speciation