The answer is either A, the bottleneck effect or C, natural selection. The answer is most likely A because it is hinted that the predator fish was placed in the isolated stream. The predators eating the darters less than 5cm is natural selection though.
Estos pueden ser desde una tipología de rocas, un habitat natural, comunidades urbanas y rurales, cuerpos de agua y afuentes, elementos morfológicos(volcanes, sierras, montañas), coberturas vegeatles. Existe una gran diversidad y abundancia de organismos que habitan en nuestro planeta.
Answer:
The crust is not the thickest layer of earth
:)