Exam 14: The Origin of Species

Speciation has occurred when

The geographic isolation of a population from other members of the species and the subsequent evolution of reproductive barriers between it and the parent species describes ________ speciation.

Which of the following types of reproductive barriers separates two flowering plant species that could interbreed but for the fact that one has a deep flower tube and is pollinated by bumblebees whereas the other has a short, narrow flower tube and is pollinated by honeybees?

Most polyploid species arise from

When plants undergo allopatric speciation, an initial reproductive barrier is often

Two species interbreed occasionally and produce vigorous, fertile hybrids. When the hybrids breed with each other or with either parent species, however, the offspring are feeble or sterile. These species are affected by

One of the finest available sequences of fossils shows how horses have changed slowly and by subtle steps from small shrub-browsing ancestors to the large, grass-grazing modern horse. A large number of fossil species have been named, and it is often difficult to decide on the identity of a fossil horse because transitional forms are common. This record of evolution best fits the idea of

In a hybrid zone, ________ can occur if the reproductive barrier between two species is weak, as seen among cichlids in the murky waters of modern Lake Victoria.

Which of the following would a biologist describe as microevolution?

The ________ suggests that speciation occurs in brief spurts.

After reading the paragraph below, answer the questions that follow. In the North Pacific Ocean, two groups of the same species of killer whales (Orcinus orca) appear to be forming two different species based on what they eat. One group eats fish and the other eats mammals such as seals. Scientists can tell what they eat based on their teeth, because whales that feed on fish have significantly different wear patterns. -Another difference between the two groups is in how they hunt. Whales that hunt fish tend to travel in large pods (groups of whales)and vocalize often. Whales that hunt seals, however, tend to travel in very small groups and vocalize very little, likely because of the excellent hearing ability of seals. If these differences brought about speciation, the separation would be considered

One of the key contributions of the punctuated equilibrium model is that it helps explain

Which provides the most general and correct description of the idea of a reproductive barrier?

The emergence of a new plant species over a brief period of time followed by a long period of little change is consistent with which of the following theories?

For speciation to occur there must be

A new plant species may arise in a single generation by

Which of the following types of reproductive barriers separates two species of sea cucumbers whose sperm and eggs often bump into each other but do not cross-fertilize because of incompatible proteins on their surfaces?

Ancestral diploid wheat species had 2n = 14 chromosomes. What happened when two of these species hybridized?

Organisms that possess more than two complete sets of chromosomes are said to be

Two species that sometimes mate and produce vigorous but sterile offspring are affected by