23. Speciation

Which of the following conditions is necessary for speciation to occur?

Prezygotic barriers __________.

According to the experiment of Diane Dodd, can adaptive divergence of allopatric fruit fly populations lead to reproductive isolation?

Lake Victoria, in Africa, is home to a group of related fishes known as cichlids. Many of these fishes are similar in appearance but have different feeding habits. What is the best method for scientists to determine conclusively whether the fish are members of a population that has a lot of variation or members of entirely different species?

In a hybrid zone, which of the following would tend to lead to reinforcement?

In which of the following pairs of populations is allopatric speciation most likely to occur?

Comparison of human fossils with living humans seems to show that there have been no significant physical changes in Homo sapiens in 30,000 to 50,000 years. What might an advocate of punctuated equilibrium say about this?

Sometimes two phenotypically different populations interbreed to a limited extent, so that it is difficult to determine whether they are clearly separate species. This is not a concern to scientists because this __________.

Three species of frogs, Rana pipiens, Rana clamitans, and Rana sylvatica, all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a __________ barrier, called __________.

In the case of the Lake Victoria cichlids, sympatric speciation has been shown to be driven by __________.

At which point in the adaptation of a population is it clear that speciation has occurred?

The time interval between speciation events is typically __________.