Exam 22: Speciation

Herbivorous bugs typically specialize on eating one or a few closely related species of plants, whereas predatory bugs tend to feed on many different species of insects.If there is a high diversity of potential host plants, we would expect to find

The morphology and natural history of a common and widely distributed butterfly was observed over a 25-year period in Costa Rica.Recent DNA barcoding (DNA sequence analysis) showed that what was once thought to be a single species is actually a complex of at least 10 species.Though caterpillars of these species eat different food plants and have somewhat different habitat preferences than their adult forms, their morphological differences are subtle.These butterflies would be considered _______ species.

Two different species of three-spined stickleback fish have been found together in each of five different lakes.Within the same lakes, the larger bottom-dwelling species with a large mouth feeds on large prey close to shore.A smaller surface-dwelling species feeds on small plankton in open water.DNA analysis shows that the two species in each lake are more closely related to each other than they are to any of the other species in the lakes.However, they are reproductively isolated.The habitat specialization of these species is consistent with which prezygotic mechanism that can lead to speciation?

The Isthmus of Panama cut off gene flow between Atlantic and Pacific populations of a species of fish.The cessation of gene flow led to the accumulation of genetic differences between the populations, which then led to reproductive isolation.Now, Atlantic and Pacific populations of this fish are separate species that cannot interbreed, even if they were again to come into contact with each other.The process described here is that of

Platyfish with spots have an X-linked gene that produces the spots.All platyfish have an autosomal repressor that inhibits the expression of the spot-producing gene.The closely related swordtail lacks both the spot-producing gene and the repressor.In backcrosses between these two species, some hybrids receive the spot-producing gene, but not the repressor.These individuals can develop malignant tumors, because the expression of the spot-producing gene is not properly regulated.This appears to be an example of

Refer to the table. The relationship between genetic divergence (in sequence divergence) and the extent of reproductive isolation is plotted for three lineages of frogs.Reproductive isolation is measured on a scale ranging from zero representing no isolation, to 1 representing complete isolation.What would be the likely amount of reproductive isolation of frogs in lineage B that have diverged by 4 percent in DNA sequence based on the observed data?

Refer to the table. The table shows five lineages of flies and provides some information on the areas that they have colonized and other notes on their biology.In which lineage would you expect an adaptive radiation to be most likely?

An evolutionary biologist makes decisions about whether to consider three different populations of copepods as separate species based on observations of the individuals with which these copepods will mate.All combinations of these populations are able to mate with one another, but none of the combinations produce viable offspring.This biologist is most likely employing the _______ species concept, and based on the application of this species concept to these results, there are most likely _______ species of copepods present.

Even trained biologists have difficulty telling females of Drosophila melanogaster and D.sechellia apart, yet these species are reproductively isolated.Thus, these species are considered _______ species.

Which situation would most likely pose a major difficulty for applying the biological species concept?

Levin's studies in Phlox showed that

Studies with Rhogeessa bats show that the Dobzhansky-Muller model

The C and the D loci interact in a Dobzhansky-Muller incompatibility, in which any combination of the C1 allele and the D1 allele would have reduced viability.If the parental populations are C0C0/D0D0 and C1C1/D0D0, the genotype of the hybrids would be _______, and would have high viability.

Despite inhabiting overlapping ranges, the western spotted skunk and the eastern spotted skunk do not interbreed.One reason is that the western species breeds in early fall and the eastern species breeds in late winter to early spring.This is an example of _______ isolation.

Which condition is most likely to lead to allopatric speciation?

A tetraploid fish is generated by autopolyploidy.Its haploid number is 27.It should thus have _______ chromosomes.

The strengthening of prezygotic barriers between two incipient species by natural selection is known as _______.

The classification of organisms based on appearance alone is known as the _______ species concept.

Autopolyploidy

Which statement about polyploidy is true?