Exam 26: Speciation

Imagine two North American ground cricket species that contact each other as the southern species moves northward during a period of global warming.These two species do not mate much,due to differences in their courtship songs.The northern cricket does not seem to tolerate the warmer temperatures well,but is limited in its ability to move north because it does not normally disperse much.Based on this information,which is the most likely outcome?

You are studying two populations of spiders of the Dolomedes genus,characterized by a light stripe down each side of the body.One population lives in a pond,while another nearby population lives in the trees.Which of the following species concept would you be using if you determined that these were two different species?

Natural selection for traits that keep distinct populations from reproducing with each other is called reinforcement.When is reinforcement beneficial?

Which of the following reproductive barriers would prevent a hybrid zygote from developing into a viable,fertile adult?

If the isthmus formed gradually rather than suddenly,what pattern of genetic divergence would you expect to find in these species pairs?

Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall.They spend the winter in these warmer areas,where they feed and prepare for the spring migration north and another breeding season.Two hypothetical species of sparrow,A and B,overwinter together in mixed flocks in Costa Rica.In spring,species A goes to the east coast of North America,and species B goes to the west coast.What can you say about the isolating mechanisms of these two species?

Two researchers experimentally formed tetraploid frogs by fertilizing 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? (Y.Kondo and A.Kashiwagi.2004.Experimentally induced autotetraploidy and allotetraploidy in two Japanese pond frogs.Journal of Herpetology 38(3):381-92.)

The common edible frog of Europe is a hybrid between two species,Rana lessonae and Rana ridibunda.The hybrids were first described in 1758 and have a wide distribution,from France across central Europe to Russia.Both male and female hybrids exist,but when they mate among themselves,they are rarely successful in producing offspring.What can you infer from this information?

The snake family Typhlopidae consists of small,burrowing species with vestigial eyes.They are found in Australia,sub-Saharan Africa,India and some adjacent areas,and South America.What is the most likely explanation for this distribution?

Which of the following is FALSE regarding speciation?

What keeps the two populations separate?

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.What outcomes can occur where the ranges of two species overlap?

Most causes of speciation are relatively slow,in that they may take many generations of organism to see changes,except

Which of the following is a disadvantage of the morphological species concept?

Male frogs give calls that attract female frogs to approach and mate.Researchers examined mating calls of closely related tree frogs in South America.If reinforcement of prezygotic isolation is occurring,what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

The sister populations on opposite sides of the isthmus are true species under which species concept?

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

When the Isthmus of Panama formed,a land bridge resulted between North and South America.What opportunities for colonization did this land bridge offer?

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?

Figure 26.1 -Refer to Figure 26.1.Which of the following forms a monophyletic group?