convergent evolution

Examples:

• many of the Australian mammals look like counterparts in other parts of the world, even though, unlike these, they are all marsupials;
• before the mammals existed, giant birds took the top of the food chain in some places
• before mammals and birds outcompeted them (a process that is still continuing), many types of reptiles existed that look much like certain modern birds or mammals
• eyes with very similar designs have provably developed independently in very different types of animals, but the set of designs in actual use is limited
• the sabretooth tiger developed and died out in North America at least 4 times (each time from smaller species of felines)
• vertebrates have a tendency to learn how to fly, and the results are limited by functional constraints: Pteranodon looks much like a pelican in overall shape, and its wings are much like a bat's

Apparently, function dictates form, and environmental stability dictates function.

It describes a family of anole lizards in the Caribbean. Each island has a set of specialized lizards dwelling in different habitats, like on the trunks of trees, in the grass and in the forest canopy. According to the article, these lizards have all developed on the islands seperately, as DNA tests show that lizards on each island are more closely related that similar specialists on other islands. Nonetheless, the same specialists on different islands look almost identical.