According to darwin’s theory of natural selection australian marsupial is an example of parallel radiation.Parallel evolution is the development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.One of the most spectacular examples of parallel evolution is provided by the two main branches of the mammals, the placentals and marsupials, which have followed independent evolutionary pathways following the break-up of land-masses such as Gondwanaland roughly 100 million years ago. In South America, marsupials and placentals shared the ecosystem (prior to the Great American Interchange); in Australia, marsupials prevailed; and in the Old World the placentals won out. However, in all these localities mammals were small and filled only limited places in the ecosystem until the mass extinction of dinosaurs sixty-five million years ago. At this time, mammals on all three landmasses began to take on a much wider variety of forms and roles. While some forms were unique to each environment, surprisingly similar animals have often emerged in two or three of the separated continents. Examples of these include the litopterns and horses, whose legs are difficult to distinguish; the European sabre-toothed cat (Machairodontinae) and the South American marsupial sabre-tooth (Thylacosmilus); the Tasmanian wolf and the European wolf; likewise marsupial and placental moles, flying squirrels, and (arguably) mice.

Convergent evolution describes the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups.Flying insects, birds, and bats have all evolved the capacity of flight independently. They have "converged" on this useful trait.For example, Several groups of ungulates have independently reduced or lost side digits on their feet, often leaving one or two digits for walking. That name comes from their hooves, which have evolved from claws several times. Among familiar animals, horses have one walking digit and domestic bovines two. Various other land vertebrates have also reduced or lost digits.

Adaptive radiation is a process in which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges and opens environmental niches. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits with which they can exploit a range of divergent environments. An exceptional example of adaptive radiation would be the avian species of the Hawaiian honeycreepers. Via natural selection, these birds adapted rapidly and converged based on the different environments of the Hawaiian islands.