Chapter 20

According to the biological species concept, two populations belong to the same species if (a) their members freely interbreed (b) individuals from the two populations produce fertile offspring (c) their members do not interbreed with individuals of different species (d) a and c (e) a, b, and \(c\).

A prezygotic barrier prevents (a) the union of egg and sperm (b) reproductive success by an interspecific hybrid (c) the development of the zygote into an embryo (d) allopolyploidy from occurring (e) changes in allometric growth.

The reproductive isolating mechanism in which two closely related species live in the same geographic area but reproduce at different times is (a) temporal isolation (b) behavioral isolation (c) mechanical isolation (d) gametic isolation (e) hybrid inviability.

Interspecific hybrids, if they survive, are (a) always sterile (b) always fertile (c) usually sterile (d) usually fertile (e) never sterile.

The process by which populations of one species evolve into separate species is known as (a) the evolutionary species concept (b) speciation (c) behavioral isolation (d) ploidy (e) hybridization.

The first step leading to allopatric speciation is (a) hybrid inviability (b) hybrid breakdown (c) adaptive radiation (d) geographic isolation (e) paedomorphosis.

The pupfishes in the Death Valley region are an example of which evolutionary process? (a) background extinction (b) allopatric speciation (c) sympatric speciation (d) allopolyploidy (e) paedomorphosis.

Sympatric speciation (a) is most common in animals (b) does not require geographic isolation (c) accounts for the evolution of the Hawaiian goose (the nene) (d) involves the accumulation of gradual genetic changes (e) usually takes millions of years.

Which of the following evolutionary processes is associated with allopolyploidy? (a) gradualism (b) allometric growth (c) sympatric speciation (d) mass extinction (e) preadaptation.

According to the punctuated equilibrium model, (a) populations slowly diverge from one another (b) the evolution of species occurs in spurts interspersed with long periods of stasis (c) evolutionary novelties originate from preadaptations (d) reproductive isolating mechanisms restrict gene flow between species (e) the fossil record, being incomplete, does not accurately reflect evolution as it actually occurred.

The evolutionary conversion of reptilian scales into feathers is an example of (a) allometric growth (b) paedomorphosis (c) gradualism (d) hybrid breakdown (e) a preadaptation.

Adaptive radiation is common following a period of mass extinction, probably because (a) the survivors of a mass extinction are remarkably well adapted to their environment (b) the unchanging environment following a mass extinction drives the evolutionary process (c) many adaptive zones are empty (d) many ecological niches are filled (e) the environment induces changes in the timing of development for many species.

Adaptive radiations do not appear to have ever occurred (a) on isolated islands (b) in birds such as honeycreepers (c) in environments colonized by few species (d) in plants such as silverswords (e) in environments with many existing species.

The Hawaiian silverswords are an excellent example of which evolutionary process? (a) allometry (b) preadaptation (c) microevolution (d) adaptive radiation (e) extinction.