A geneticist is studying sexual reproduction of a species of…

A geneticist is studying sexual reproduction of a species of butterfly that lives in a very cold climate.  He hypothesizes that there should be low genetic diversity because it is well adapted to the cold climate but does not seem to be able to colonize surrounding areas with warmer climates.  What important principle is he using to formulate his hypothesis?

On this temperature versus precipitation graph, the four are…

On this temperature versus precipitation graph, the four areas plotted represent the ranges of temperatures and precipitations typical of four major types of biomes. Which choice correctly identifies the temperature and precipitation profiles for each type of biome?