The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is

The most likely explanation for the high rate of sympatric speciation that apparently existed among the cichlids of Lake Victoria in the past is 

A) sexual selection.
B) habitat differentiation.
C) polyploidy.
D) pollution.
E) introduction of a new predator.








Answer: A

Which of these should decline in hybrid zones where reinforcement is occurring?

Which of these should decline in hybrid zones where reinforcement is occurring? 

A) gene flow between distinct gene pools
B) speciation
C) the genetic distinctness of two gene pools
D) mutation rate
E) hybrid sterility






Answer: A

A hybrid zone is properly defined as

A hybrid zone is properly defined as 

A) an area where two closely related species' ranges overlap.
B) an area where mating occurs between members of two closely related species, producing viable offspring.
C) a zone that features a gradual change in species composition where two neighboring ecosystems border each other.
D) a zone that includes the intermediate portion of a cline.
E) an area where members of two closely related species intermingle, but experience no gene flow.








Answer: B

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and 

A) their chromosomes are no longer homologous enough to permit meiosis.
B) a constant number of viable, fertile hybrids is produced over the course of generations.
C) the hybrid zone is inhospitable to hybrid survival.
D) an increasing number of viable, fertile hybrids is produced over the course of generations.
E) a decreasing number of viable, fertile hybrids is produced over the course of generations.








Answer: D