In de evolutie zijn er verschillende processen geweest waar veel discussie over heeft bestaan, zo ook over de bouw en de vorming van een organisme. De tak van de evolutieleer die zich hierover buigt noemen we morfologie. Het is duidelijk dat er organismen zijn die een identieke evolutionaire oorsprong hebben en daarom een grote mate van gelijkvormigheid vertonen.

Convergence

Some species of animals look alike because they are closely related. The characteristics they share are called homologous. Some species have characteristics that are similar, but their origin is different. The species are not related and are living in different parts of the world, but in similar habitats and climates. These characteristics are called converging and are the result of parallel evolution. The same habitat in different places of the world selects for the same characteristics.
A short list of species with converging characteristics is given.
Besides this some unrelated species share characteristics with a certain goal for one of them. One species imitates the other, because this last one is for instance poisonous or tastes nasty. This is called mimicry. It is not convergence, because on the contrary, the different species have to live close to each other, otherwise imitation wouldn’t make sense.
Shared characteristics of different species of reptiles and amphibians often tell us something about shared characteristics of their habitats and thus how we should keep our animals.