Convergent Evolution

Every type of species has its own characteristic traits. In order to survive in their natural habitat and the constantly changing environment, species have to undergo alterations in their structures. Quite often, two different species undergo similar modifications in their quest to adapt to the same environment. Thus, these species acquire similar body structures, although through independent course of changes. There are plenty of species exhibiting convergent evolution across various habitats of planet Earth.

Examples of Convergent Evolution

Sometimes, the features evolve out of a common feature in different species, like the wings of birds and bats. Wings are a similar pattern developed in them for the same purpose, which is flying. This part is a modification of the limbs, which altered over a period of time in both the species. Further, koalas found in Australasia have the same fingerprint pattern as that of human beings, although the two animal species have no evolutionary resemblance . The prickly extrusions on hedgehogs and porcupines are a form of this evolution. However, it is important to understand the difference between convergent evolution, evolutionary relay, and parallel evolution, to appreciate the peculiar nature of this type. Evolutionary relay refers to similar types of changes that take place in two species, but at different periods in time. The dorsal fins of an extinct ichthyosaur and a shark are the same type of adaptive alteration in the body feature of two distinct species, but a feature occurring at different times. On the other hand, a parallel evolution refers to changes occurring at the same period of time, but in related species. For example, the same prickly extrusions found on new world porcupines are also present on old world porcupines. In this case, the pattern adapted is by species belonging to the same family.

Convergent evolution is different in a way that, it occurs in the same time period, and essentially involves species of different ancestry. It can also occur as a result of ecological living patterns, like the food habits or hunting styles of two animals of different ancestry, and like the similarities found in marsupial animals and placental mammals. Both class have certain similarities arising out of their manner of living. Examples include, the saber-tooth formation in the cat family of both types and the flying squirrels. Characteristics that emerge as a result of this evolution are called analogs structures. The likeness that evolves in different species in accordance with this evolution is termed as homoplasy.

The degree of influence convergent evolution has in the development and adaptation is still a matter of ongoing debate between experts. One theory advocates the belief that there is no satisfactory reason why a particular change should occur in a species. This means, if the course of events were to reverse and the evolutionary process began all over again, there may be altogether a different set of changes than what are evident today. The opposing group of scientists argue that since the type of environmental changes or effects are same for different species, their adaptability would also be influenced equally and in the same form. This would result in exactly the same type of changes according to the environment as are evident now, no matter how many times the evolutionary cycle repeats.

The bottom line is that, convergent evolution is a real phenomenon but which cannot be conclusively credited to a given set of parameters as of today.