bio chapter 24

Which of the following statements about species, as defined by the biological species concept, is (are) correct? I. Biological species are defined by reproductive isolation. II. Biological species are the model used for grouping extinct forms of life. III. The biological species is the largest unit of population in which successful reproduction is possible.

What is generally true of two very closely related species that have diverged from each other quite recently?

Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?

Which species concept is currently most popular among most biologists?

There is still some controversy among biologists about whether Neanderthals should be placed within the same species as modern humans, or into a separate species of their own. Most DNA sequence data analyzed so far indicate that there was probably little or no gene flow between Neanderthals and Homo sapiens. Which species concept is most applicable in this example?

A biologist discovers two populations of wolf spiders whose members appear identical. Members of one population are found in the leaf litter deep within the woods. Members of the other population are found in the grass at the edge of the woods. The biologist decides to designate the members of the two populations as two separate species. Which species concept is this biologist most closely utilizing?

What was the species concept most used by Linnaeus?

You are confronted with a box of preserved grasshoppers of various species that are new to science and have not been described. Your assignment is to separate them into species. There is no accompanying information as to where or when they were collected. Which species concept will you have to use?

Several closely related frog species of the genus Rana are found in the forests of the southeastern United States. The species boundaries are maintained by reproductive barriers. In each case, match the various descriptions of frogs below with the appropriate reproductive barrier listed. 9) Males of one species sing only when its predators are absent; males of another species sing only when its predators are present.

One species lives only in tree holes; another species lives only in streams.

Females of one species choose mates based on song quality; females of another species choose mates on the basis of size.

One species mates at the season when daylight is increasing from 13 hours to 13 hours, 15 minutes; another species mates at the season when daylight is increasing from 14 hours to 14 hours, 15 minutes.

Males of one species are too small to perform amplexus (an action that stimulates ovulation) with females of all other species.

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

Rank the following from most general to most specific: 1. gametic isolation 2. reproductive isolating mechanism 3. pollen-stigma incompatibility 4. prezygotic isolating mechanism

Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?

Theoretically, the production of sterile mules by interbreeding between female horses and male donkeys should

The biological species concept is inadequate for grouping

Which example below will most likely guarantee that two closely related species will persist only as distinct biological species?

Races of humans are unlikely to evolve extensive differences in the future for which of the following reasons? I. The environment is unlikely to change. II. Human evolution is complete. III. The human races are incompletely isolated.

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. If some of these fleas develop a strong preference, instead, for cattle blood and mate only with fleas that, likewise, prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas habitat? 1. reproductive isolation 2. sympatric speciation 3. habitat isolation 4. prezygotic barriers

A defining characteristic of allopatric speciation is

A rapid method of speciation that has been important in the history of flowering plants is

two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of the following is not a possible outcome when they meet?

The difference between geographic isolation and habitat differentiation is the

Among known plant species, which of these have been the two most commonly occurring phenomena leading to the origin of new species? 1. allopatric speciation 2. sympatric speciation 3. sexual selection 4. polyploidy

Beetle pollinators of a particular plant are attracted to its flowers bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?

The origin of a new plant species by hybridization, coupled with accidents during nuclear division, is an example of

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and

The constantly changing nature of the Appalachian ground crickets ( Allonemobius fasciatus and Allonemobius socius) hybrid zone favors

A hybrid zone is properly defined as

Which of these should decline in hybrid zones where reinforcement is occurring?

The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is

The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is

In the narrow hybrid zone that separates the toad species Bombina bombina and Bombina variegata, what is true of those alleles that are unique to the parental species?

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island s lowlands, and is also found on the African mainland, located about 200 miles away. At higher elevations, and found only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridize, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n=4 in both species). Sao Tomé rose from the Atlantic Ocean about 14 million years ago. 36) Which of these reduces gene flow between the gene pools of the two species on Sao Tomé,

The observation that island D. yakuba are more closely related to mainland D. yakuba than island D. yakuba are to D. santomea is best explained by proposing that D. santomea

If a speciation event occurred on Sao Tomé, producing D. santomea from a parent colony of D. yakuba, then which terms apply? I. macroevolution II. allopatric speciation III. sympatric speciation

According to the concept of punctuated equilibrium, the sudden appearance of a new species in the fossil record means that

According to the concept of punctuated equilibrium,

Which of the following would be a position held by an adherent of the punctuated equilibrium theory?

Speciation

Upon undergoing change, which of these genes is most likely to result in speciation while a geographic barrier separates two populations of a flowering-plant species?

In order for speciation to occur, what is true?

which of these five species is the extant (i.e., not extinct) species that is most closely related to species X, and why is this so?