Two populations of a species of frog live around the gulf of california. one population has a brown back, and lives on rocky islands with brown rocks and little vegetation. a second population lives on the mainland among the vegetation and has a back that is speckled with green and brown spots. if, after many generations, a reproductive isolating mechanism evolves, what type of speciation most likely occurred?
a. sympatric
b. postzygotic isolation
c. habitat isolation
d. allopatric

D. Allopatric

Explanation:

Allopatric speciation is the process of formation of new species from the populations that live in different habitats. In the given example, one population resides on rocky islands and is adapted to the surroundings while the other population lives on the mainland.

Accumulation of genetic variations among the individuals of these geographically isolated populations would isolate them reproductively.

Since both the populations are present in different habitats, it represents the allopatric speciation.  

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.