Exam 24: The Origin of Species

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?

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

Two species of tree frogs that live sympatrically in the northeastern United States differ in ploidy: Hyla chrysoscelis is diploid, and Hyla versicolor is tetraploid. The frogs are identical in appearance, but their mating calls, which females use to find mates, differ. Which difference most likely evolved first?

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?

According to the punctuated equilibria model,

If biological species are defined in terms of reproductive compatibility, the formation of a new species hinges on ________.

Speciation ________.

You want to study divergence of populations, and you need to maximize 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 maximize 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.

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

What happens to the hybrid zone when gene flow is established?

Which statement describes unity within a species?

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?

Which postzygotic barriers prevent formation of hybrids beyond the first generations?

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?

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be ________.

A hybrid zone is properly defined as ________.

How is length of time for speciation estimated?

Which of these animals could overcome the geographic barrier of water that causes allopatric speciation?

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. Why should deepwater shrimp on different sides of the isthmus have diverged from each other earlier than shallow-water shrimp?