23. Speciation

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 __________.

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

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

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

Which of the following evolutionary mechanisms does not contribute to the process of allopatric speciation?

If a new species of plant is to be produced by means of allopolyploidy from two parental species that are 2n = 4 and 2n = 8, how many chromosomes would you expect in the somatic cells of the new species?

A new species can arise in a single generation __________.

The Galápagos finches collected by Darwin are thought to have descended from a very small parent population. Different species of finches that are confined to only one or two islands most likely arose by __________.

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

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

In the Lake Victoria cichlids, what appears to be contributing to fusion of different species?

What is the first thing that must happen in order for speciation 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?

According to the punctuated equilibrium model of evolution, __________.

Define 'biological species.'