Exam 22: Speciation

Polyploidy that arises from a combining of the chromosomes of two different species is known as _______.

The different finch species in the phylogeny shown in the 22.8 of the textbook have all evolved on islands of the Galápagos archipelago within the past 3 million years.Molecular clock analysis (see Chapter 23) has been used to determine the dates of the various speciation events in the phylogeny.Geological techniques for dating rock samples (see Chapter 24) have been used to determine the ages of the various Galápagos islands.The table shows the number of species of Darwin's finches and the number of islands that have existed in the archipelago at several times during the past 4 million years. If no more islands form in the Galápagos archipelago, do you think that speciation by geographic isolation will continue to occur among Darwin's finches? Why or why not? What additional data could you collect to test your hypothesis (without waiting to see if speciation occurs)?

What is the most likely sequence of events in allopatric speciation?

Except in cases of polyploidy, sympatric speciation usually requires the action of _______ selection.

Refer to the table showing the relationship between prezygotic reproductive isolation and genetic distance for both allopatric and sympatric pairs. Drosophila species that have been crossed with each other allow evolutionary biologists to make general inferences about their evolution.Species pairs that are sympatric accumulate more prezygotic reproductive isolation at a faster rate than those that are allopatric.There is no such effect on postzygotic reproductive isolation: sympatric and allopatric pairs accumulate postzygotic isolation at the same rate.What is the likely explanation for the patterns observed?

Refer to the figure. The figure shows two species, a fire-bellied toad and yellow-bellied toad, which occupy different areas of Europe.A small area of overlap between these regions constitutes a hybrid zone.If individuals from the two populations overcome prezygotic reproductive barriers, additional postzygotic barriers may prevent the formation of stable hybrids.Based on this data, which statement is true?

Suppose two species of morning glories are reproductively isolated because their flowers bloom at different times.This would be an example of _______ isolation, which is a form of prezygotic isolation.

Which characteristic is least likely to be used to determine the difference between two cryptic species of Hyla treefrogs?

Females of the species Drosophila pseudoobscura respond less well to courtship signals from males of their close relative D.persimilis than they do to those of males of their own species.This is an example of

You begin a study of colorful spiders on the Hawaiian islands of Oahu, Molokai, Maui, and Hawaii.Examining only their appearance, you discover that populations on these four islands share most anatomical features but have a variety of patterns on their abdomens.Without any further information, you might conclude that these populations are different species, on the basis of which species concept?

A fly is separating into two different groups-one that lays eggs on cherries and one that lays eggs on apples.The two types of flies, which are found in the same locality, prefer to mate with their own type.This fly species is most likely demonstrating

Which of the following examples does not illustrate possible routes to behavioral reproductive isolation?

The original host of apple maggot fly in North America was hawthorn, but it has since evolved to live on apple.This is an example of the early stages of _______ speciation.

When hybrid offspring in amphibians are at a fitness disadvantage and reinforcement does not take place, what event or process is likely to occur?

Two closely related beetles are in the same location.They exhibit reproductive isolation, and they are both diploid.Biologists are arguing about which is more likely, that they evolved via sympatric or allopatric speciation.Which statement presents the best argument for what is occurring?

Which statement about prezygotic barriers is false?

Of the three species concepts, the application of the _______ species concept is most likely to be constrained by computational power.

The sperm of species A dies when it comes in contact with the female reproductive tract of species B.This is an example of the phenomenon known as

Rank the following isolating mechanisms with respect to their time of occurrence in the life cycle, from earliest to latest.

In 1928, a Russian plant geneticist crossed cabbage (Brassica) with radish (Raphanus).Fusion of gametes produced mostly infertile hybrids, but a few fertile plants contained a complete set of cabbage (n = 9) and radish (n = 9) chromosomes (n = 18).Fusion of their gametes in turn produced fertile 36-chromosome plants with cabbage-like roots and radish-like leaves.These plants could interbreed, but not with cabbage or radish ancestors.Production of this species, which can also occur naturally, is called