Exam 18: Macroevolution

If an environmental change happens too suddenly, a population may go extinct because:

All members of the golden hamster species known today are descendants of a single litter collected in Syria in 1939. Its diploid chromosome number is 44. Two other species of hamster, each with a diploid number of 22, overlap in Syria. The golden hamster is thought to be a new species that developed following the mating of a male and female of the two other hamster species. What mechanism might explain this recent event of speciation?

When the London underground (subway) system was built in the nineteenth century, mosquitoes moved into the tunnels and became adapted to biting the customers and small animals that inhabit the subway system. Like people, mosquitoes can freely enter and leave through the tunnel entrances. Recently, DNA analysis and attempts to cross-breed above-ground mosquitoes with underground mosquitoes indicate that there are now two different species. The underground insects are visibly larger. Which term best describes what has happened?

Gaps in the fossil record are predicted by the theory of :

Polyploid speciation is about as common in plants as it is in animals.

Refer to the following scenario and then answer the questions that follow. A European species of marsh grass called Sparitina maritima has 2n = 60. A similar species native to North America, S. alterniflora, has 2n = 62. In 1835, the North American species was found growing near the European species near Southampton, England, having been accidentally imported. Occasional sterile hybrids were noted. In 1895, a new species, S. anglica, was first identified at Southampton and subsequently became very common. The new species has been identified as a fertile hybrid of the original two species. -What is the 2n chromosome number of the new species, S. anglica?

Which of the following "species cannot be tested via the biological species concept to determine whether the mentioned organisms are in fact a single species?

In the fossil record, species suddenly appear, remain more or less unchanged for varying periods of geologic time, and then disappear from the record. This trend best supports the theory of:

Label the steps of polyploidy in the figure below.

Two populations of mountain-dwelling salamanders are separated by an impassable valley. The populations are:

Thinking of the examples in your book of adaptive radiation (Galapagos finches, for one), in which of the following environments might you be most likely to find adaptive radiation?