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===Examples of Convergent Evolution===

===Examples of Convergent Evolution===

One of the best examples<ref> http://cas.bellarmine.edu/tietjen/Evolution/convergent_evolution_examples.htm</ref> of convergent evolution involves how birds, bats, and pterosaurs (all different species that evolved along distinct lineages at different times) learned to fly. Importantly, each species developed wings independently. These species did not evolve in order to prepare for future circumstances, but rather the development of flight was induced by selective pressure imposed by similar environmental conditions, even though they were at different points in time. The development potential of any species is not limitless, primarily due to inherent constraints in genetic capabilities. Only changes that are useful in terms of adaptation are preserved. Yet, changes in environmental conditions can lead toward less useful functional structures, such as the appendages that might have existed before wings. Another change in environmental conditions might result in alterations of the appendage to make it more useful, given the new conditions.

An obvious example of convergence would be that of birds, bats, pterosaurs, and flying insects (all different species that are on distinct evolutionary lineages), all of which can fly, but for which their postulated common ancestors could not fly. Thus each species is considered to have developed wings independently. Species do not evolve in order to prepare for future circumstances, but rather the development of flight is considered to be induced by selective pressure imposed by similar environmental conditions, even though they are supposed to be at different points in time. The development potential of any species is not limitless, primarily due to inherent constraints in genetic capabilities. Only changes that are useful in terms of adaptation are preserved. Yet, changes in environmental conditions can lead toward less useful functional structures, such as the appendages that might have existed before wings. Another change in environmental conditions is though to result in alterations of the appendage to make it more useful, given the new conditions, although changes which involve the generation of new genetic information have never been observed.

For example, the wings of all flying animals are very similar because the same laws of aerodynamics apply. These laws determine the specific criteria that govern the shape for a wing, the size of the wing, or the movements required for flight. All these characteristics are irrespective of the animal involved or the physical location. Understanding the reason why each different species developed the ability to fly relies on an understanding of the possible functional adaptations, based on the behavior and environmental conditions to which the species was exposed. Although only theories can be made about extinct species and flight since these behaviors can be predicted using by fossil records, these theories can often be tested using information gathered from their remains. Perhaps the wings of bird or bats were once appendages used for other purposes, such as gliding, sexual display, leaping, protection, or arms to capture prey.

For example, the wings of all flying animals are very similar because the same laws of aerodynamics apply. These laws determine the specific criteria that govern the shape for a wing, the size of the wing, or the movements required for flight. All these characteristics apply irrespective of the animal involved or the physical location, except for insects, which have wings that are more marked differences. Evolutionists think that understanding the reason why each different species developed the ability to fly relies on an understanding of the possible functional adaptations, based on the behavior and environmental conditions to which the species was exposed. Although only theories can be made about extinct species and flight, since these behaviors can be predicted using by fossil records, these theories can often be tested using information gathered from their remains. Evolutionists believe that perhaps the wings of bird or bats were once appendages used for other purposes, such as gliding, sexual display, leaping, protection, or arms to capture prey.  Creationists, on the other hand, point out that the joints and muscles required for capturing prey, for example, are quite different to those required for flying.

In various species of plants, which share the same pollinators, many structures and methods of attracting the pollinating species to the plant are similar. These particular characteristics enabled the reproductive success of both species due to the environmental aspects governing pollination, rather than similarities derived by being genetically related by descent.

In various species of plants, which share the same pollinators, many structures and methods of attracting the pollinating species to the plant are similar. These particular characteristics enabled the reproductive success of both species due to the environmental aspects governing pollination, rather than similarities derived by being genetically related by descent.

Convergent evolution is supported by the fact that these species come from different ancestors, which has been proven by DNA analysis. However, understanding the mechanisms that brings about these similarities in characteristics of a species, despite the differences in genetics, is more difficult.

Evolutionists believe that convergent evolution is supported by the "fact" that these species come from different ancestors, but that is itself part of the evolutionary story.  They claim that this has been proven by DNA analysis, although such analysis does not exclude the possibility that similar creatures were created with similar DNA. Evolutionists admit, however, that understanding the mechanisms that brings about these similarities in characteristics of a species, despite the differences in genetics, is more difficult.

==Parallel Evolution ==

==Parallel Evolution ==