According to the most accepted scientific hypothesis about the origin of two new species from a single common ancestor, most new species arise when
a. Many mutations occur
b. Populations of the ancestral species are isolated from one another
c. There is no natural selection
d. A supernatural creator decides that two new species would be preferable to the old one
e. The ancestral species decides to evolve

Which of the following is an example of a prefertilization barrier to reproduction?

a. A female mammal is unable to carry a hybrid offspring to term

b. Hybrid plants produce only sterile pollen

c. A hybrid between two bird species cannot perform a mating display

d. A male fly of one species performs a 'wing-waving' display that does not convince a female of another species to mate with him

e. A hybrid embryo is not able to complete development

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species. Recently, these birds have been classified as eastern and western forms of a single species, the yellow-rumped warbler. Which of the following pieces of evidence, if true, would be cause for this reclassification?

a. The two forms interbreed often in nature, and their offspring survive and reproduce well.

b. The two forms live in similar habitats and have similar food requirements.

c. The two forms have many genes in common.

d. The two forms are very similar in appearance.

According to the biological species concept, species are defined by their

a. Particular roles in a biological community.

b. Ability to interbreed and produce viable, fertile offspring.

c. Reproductive isolation from nearby populations.

d. Common ancestry.

If a cell were to use only 10 of the 20 possible amino acids, how much effect would you expect this to have on protein diversity? Calculate and compare the number of different sequences that can be generated by randomly assembling either 10 or 20 amino acids into peptides that are five residues long.

Which of the following factors would not contribute to allopatric speciation?

a. The separated population is small, and genetic drift occurs.

b. The isolated population is exposed to different selection pressures than the ancestral population.

c. Different mutations begin to distinguish the gene pools of the separated populations.

d. Gene flow between the two populations is extensive.

Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species that lived side by side in parts of their ranges. However, recent books show them as eastern and western forms of a single species, the yellow-rumped warbler. Most likely, it has been found that these two kinds of warblers

a. Live in similar habitats and eat similar foods.

b. Interbreed often in nature, and the offspring are viable and fertile.

c. Are almost identical in appearance.

d. Have many genes in common.

When the ranges of two different species meet, a stable 'hybrid zone' occupied by hybrid individuals may form. How is this possible?

a. Two diverged populations are capable of mating and producing viable and fertile offspring.

b. Hybrid individuals are always allopolyploid and are thus unable to mate with either of the original species.

c. Hybrid individuals may have reduced fitness and thus be strongly selected against.

d. One species has a selective advantage, so as hybridization continues, the other species will go extinct.

For two populations of organisms to be considered separate biological species, they must be

a. Reproductively isolated from each other

b. Unable to produce living offspring

c. Physically very different from each other

d. A and C are correct

e. A, B, and C are correct