bio chapter 24

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.
C) I and III
What is generally true of two very closely related species that have diverged from each other quite recently?
They shared a common ancestor recently in evolutionary time.
Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?
biological
Which species concept is currently most popular among most biologists?
phylogenetic
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?
biological
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?
ecological
What was the species concept most used by Linnaeus?
morphological
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?
morphological
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.
behavioral
One species lives only in tree holes; another species lives only in streams.
habitat
Females of one species choose mates based on song quality; females of another species choose mates on the basis of size.
behavioral
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.
temporal
Males of one species are too small to perform amplexus (an action that stimulates ovulation) with females of all other species.
mechanical
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?
habitat isolation
Rank the following from most general to most specific:
1. gametic isolation
2. reproductive isolating mechanism
3. pollen-stigma incompatibility
4. prezygotic isolating mechanism
2, 4, 1, 3
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?
the postzygotic barrier called hybrid inviability
Theoretically, the production of sterile mules by interbreeding between female horses and male donkeys should
strengthen postzygotic barriers between horses and donkeys.
The biological species concept is inadequate for grouping
asexual organisms.
Which example below will most likely guarantee that two closely related species will persist only as distinct biological species?
reproductive isolation from one another
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.
III only
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
1 through 4
A defining characteristic of allopatric speciation is
geographic isolation.
A rapid method of speciation that has been important in the history of flowering plants is
polyploidy.
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?
They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.
The difference between geographic isolation and habitat differentiation is the
relative locations of two populations as speciation occurs.
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
2 and 4
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?
sympatric speciation, habitat differentiation
The origin of a new plant species by hybridization, coupled with accidents during nuclear division, is an example of
sympatric speciation.
The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and
an increasing number of viable, fertile hybrids is produced over the course of
generations
The constantly changing nature of the Appalachian ground crickets ( Allonemobius fasciatus and Allonemobius socius) hybrid zone favors
extinction of both species as the hybrids persist.
A hybrid zone is properly defined as
an area where mating occurs between members of two closely related species, producing viable offspring.
Which of these should decline in hybrid zones where reinforcement is occurring?
gene flow between distinct gene pools
The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is
sexual selection.
The most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is
fusion.
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?
The alleles heterozygosity should be higher among the hybrid toads there.
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,
hybrid sterility
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
descended from an original colony of D. yakuba, of which there are no surviving members. The current island D. yakuba represent a second colonization event from elsewhere.
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
I & III
According to the concept of punctuated equilibrium, the sudden appearance of a new species in the fossil record means that
speciation occurred rapidly in geologic time.
According to the concept of punctuated equilibrium,
a new species accumulates most of its unique features as it comes into existence.
Which of the following would be a position held by an adherent of the punctuated equilibrium theory?
A new species forms most of its unique features as it comes into existence and then changes little for the duration of its existence.
Speciation
Speciation is a basis for understanding macroevolution.
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?
one that affects the compatibility of male pollen and female reproductive parts
In order for speciation to occur, what is true?
At least one gene, affecting at least one phenotypic trait, must change.
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?
V; shared a common ancestor with X most recently