Exam 26: Speciation

House finches were found only in western North America until 1939,when a few individuals were released in New York City.These individuals established a breeding population and gradually expanded their range.The western population also expanded its range somewhat eastward,and the two populations have recently come in contact.If the two forms were unable to interbreed when their expanding ranges meet,what would this situation definitely illustrate?

Use the following information when answering the corresponding question(s). About 3 million years ago,the Isthmus of Panama (a narrow strip of land connecting North and South America)formed,dividing marine organisms into Pacific and Caribbean populations.Researchers have examined species of snapping shrimp on both sides of the isthmus.Based on the morphospecies concept,there appeared to be seven pairs of species,with one species of each pair in the Pacific and the other in the Caribbean.The different species pairs live at somewhat different depths in the ocean.Using mitochondrial DNA sequences,the researchers estimated phylogenies and found that each of these species pairs,separated by the isthmus,were indeed each other's closest relatives.The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other,and any that did mate almost never produced fertile offspring.(N.Knowlton,L.A.Weigt,L.A.Solorzano,D.K.Mills,and E.Bermingham.1993.Divergence in proteins,mitochondrial DNA,and reproductive incompatibility across the Isthmus of Panama.Science 260:1629-32. ) -Which of the following describes the most likely order of events in speciation?

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

What keeps the two populations separate?

A storm brings two formerly separated populations of beetles together.They look very similar.Under the biological species concept,which of the following would show that the two populations are different species?

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?

Which of the following statements about human races is correct?

Two groups of lizards that have long been living in allopatry have recently been reintroduced in the wild.When members of opposite groups mate,the hybrids are almost always inviable.Which of the following could be expected to occur over the long term if the populations remain in sympatry?

Use the following information when answering the corresponding question(s). About 3 million years ago,the Isthmus of Panama (a narrow strip of land connecting North and South America)formed,dividing marine organisms into Pacific and Caribbean populations.Researchers have examined species of snapping shrimp on both sides of the isthmus.Based on the morphospecies concept,there appeared to be seven pairs of species,with one species of each pair in the Pacific and the other in the Caribbean.The different species pairs live at somewhat different depths in the ocean.Using mitochondrial DNA sequences,the researchers estimated phylogenies and found that each of these species pairs,separated by the isthmus,were indeed each other's closest relatives.The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other,and any that did mate almost never produced fertile offspring.(N.Knowlton,L.A.Weigt,L.A.Solorzano,D.K.Mills,and E.Bermingham.1993.Divergence in proteins,mitochondrial DNA,and reproductive incompatibility across the Isthmus of Panama.Science 260:1629-32. ) -Refer to the paragraph about the formation of the Isthmus of Panama.If the isthmus formed gradually rather than suddenly,what pattern of genetic divergence would you expect to find in these species pairs?

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

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

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 postzygotic isolation is occurring,what would you expect if you compare the calls of the two species in zones of sympatry versus zones of allopatry?

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?

There is an island in the middle of a large river that houses a large population of ants.Damming of the river causes the island to flood and only the highest points of the island are now above water.The ants cannot swim,so are now in multiple isolated populations.Which of the following best describes this event?

You want to study divergence of populations,and you need to maximize the rate of divergence in order 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.

Which of the following statements explains why animals are less likely than plants to speciate by polyploidy?

Use the following information when answering the corresponding question(s). About 3 million years ago,the Isthmus of Panama (a narrow strip of land connecting North and South America)formed,dividing marine organisms into Pacific and Caribbean populations.Researchers have examined species of snapping shrimp on both sides of the isthmus.Based on the morphospecies concept,there appeared to be seven pairs of species,with one species of each pair in the Pacific and the other in the Caribbean.The different species pairs live at somewhat different depths in the ocean.Using mitochondrial DNA sequences,the researchers estimated phylogenies and found that each of these species pairs,separated by the isthmus,were indeed each other's closest relatives.The researchers investigated mating in the lab and found that many species pairs were not very interested in courting with each other,and any that did mate almost never produced fertile offspring.(N.Knowlton,L.A.Weigt,L.A.Solorzano,D.K.Mills,and E.Bermingham.1993.Divergence in proteins,mitochondrial DNA,and reproductive incompatibility across the Isthmus of Panama.Science 260:1629-32. ) -Refer to the paragraph about the formation of the Isthmus of Panama.The sister populations on opposite sides of the isthmus are true species under which species concept?

Why is speciation by polyploidy more likely in plants than in animals?

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?