Understanding how evolutionary mechanisms work has always been a fundamental aim for biologists. Genetic and phenotypic variation and diversity are in fact constantly maintained in natural populations by a complex system of ecological factors. Since Darwin started to consider the major causes of divergence, suggesting ecological opportunity and competition as the main ones, studies and researches have been conducted to achieve a deeper knowledge on them. Adaptive radiations are now determined to be the forces which have generated the larger part of ecological diversity on earth, shaping the morphologies and physiologies of organisms so that they could fit different environments.