How do fish migrate to isolated lakes?
One biological mystery that has engaged biologists for centuries is the question of how isolated water bodies come to have fish. If they are isolated, they should be devoid of fish life, right? After all fish do not fly nor do they walk overland. How then do fish reach isolated lakes of water? One of the commonest methods is by human interference. Humans stock water bodies with fish and once they are there, the fish can breed, undergo evolution and carry on normal biological processes. But where there has been no human interference, the problem is a little more difficult. Let us discount floods that wash fish species from elsewhere to an isolated lake and concentrate only on biological processes. One common theory was proposed more than a century and a half ago by the likes of Charles Darwin, and Alfred Wallace, and several others. They suggested that fish eggs could travel as passengers on the feathers and feet of aquatic birds from one water body to another. This...