Living things are classified largely in accordance with degrees of ________.

All species are referred to by a two-part name, the first part of which is a species’ ________.

Under the biological species concept, species members are defined by their ability to ________ with each other in nature.

Name as many intrinsic isolating mechanisms as you can.

The critical factor leading to speciation is reduced ________ between two ________ of the same species.

The mule provides an example of the intrinsic isolating mechanism of hybrid ________.

Two factors always play a part in allopatric speciation: first, the development of ________ and second, the development of one or more ________.

Sympatric speciation is speciation that does not involve ________.

Living things are classified into a set of hierarchical categories. Why is this more useful to biologists than simply giving everything a one-word name (or a number) and eliminating some of the categories?

In the biological species concept, the factor that defines a species is:

a. geographical separation.

b. reproductive isolation.

c. hybridization.

d. cladogenesis.

e. its behavior.

Populations of some kinds of organisms may be isolated by a barrier as small as a roadway, while other organisms require a much larger physical barrier to block gene flow. What features of organisms might determine how readily they become geographically isolated? What impact might these features have on how often or how rapidly speciation is likely to occur in these groups?