Exam 24: The Origin of Species

You want to study divergence of populations, and you need to maximise the rate of divergence to see results within the period of your grant funding. You will form a new population by taking some individuals from a source population and isolating them so the two populations cannot interbreed. What combination of characteristics would maximise your chance of seeing divergence in this study? 1) Choose a random sample of individuals to form the new population. 2) Choose individuals from one extreme to form the new population. 3) Choose a species to study that produces many offspring. 4) Choose a species to study that produces a few, large offspring. 5) Place the new population in the same type of environment as the source population. 6) Place the new population in a novel environment compared to that of the source population.

According to the punctuated equilibria model,

Use the following description to answer the question. 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 320 kilometres away. At higher elevations, and only on Sao Tomé, is found the very closely related Drosophila santomea. The two species can hybridise, 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. 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 ________.

Two researchers experimentally formed tetraploid frogs by fertilising diploid eggs from Rana porosa brevipoda with diploid sperm from Rana nigromaculata. When they mated these tetraploid frogs with each other, most of the offspring that survived to maturity were tetraploid, with chromosome sets of both diploid parent species. Based on these results, if this type of tetraploid formed in the wild, what would be the result?

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

Three populations of crickets look very similar, but the males have courtship songs that sound different. What function would this difference in song likely serve if the populations came in contact?

How are two different species most likely to evolve from one ancestral species?

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new 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?

Which statement describes unity within a species?

What does the biological species concept use as the primary criterion for determining species boundaries?

Suppose that a group of male pied flycatchers migrated from a region where there were no collared flycatchers to a region where both species were present. Assuming events like this are very rare, which of the following scenarios is least likely?

Other than predation by introduced Nile perch, the most likely explanation for the recent decline in cichlid species diversity in Lake Victoria is ________.

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago. In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. - Which habitats should harbour snapping shrimp species with the greatest degree of genetic divergence from each other? Divergence from each other?

In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10 million years ago. The oceans were completely separated by the isthmus about 3 million years ago. In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean on the right (side B). The seawater on either side of the isthmus is separated into five depth habitats (1-5), with 1 being the shallowest. - Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus? Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?

Which of the following factors would not contribute to allopatric speciation?

The production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) is an example of ________.

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences. What is the best way to promote fusion between two related populations of mosquitofish, one of which lives in a predator-rich pond and the other of which lives in a predator-poor pond?

Most causes of speciation are relatively slow in that they may take many generations to see changes, with the exception of ________.

Which of the following describes the most likely order of events in allopatric speciation?