Gene flow is the exchange of alleles between two or more populations. For this reason it is sometimes referred to as allele flow or gene migration. While migrating animals often carry new alleles from one population to another, they must interbreed with the new population for gene flow to occur. In the image below, a beetle from a population of brown beetles migrates into a population of green beetles.
There are two kinds of food chains one starting with autotrophs, the grazing food chain, and the other starting with dead organic matter, the detrital food chain.
