Authored by Tom Williams
Reptile Evolution
Evolution has always captured my imagination, especially in reptiles which first appeared on Earth over 300,000,000 years ago. A programme recently aired in the UK called “The Decades Top 10 New Species” depicted 10 new species of animal that have been discovered this decade. Including the Langkawi bent-toed gecko. This small species of gecko was first discovered in 2008 on an island near North West Malaysia by Dr Lee Grismer of La Sierra University in California.
Picture courtesy of BBC website.
The most amazing discoveries surrounding this gecko is that it may be going through an evolutionary change right before our eyes. The geckos have now been discovered living in Limestone caves, different to their known forest habitats. Geckos from the two habitats are noticeably different in appearance including different patterings, head shape and eye size. One explanation for the geckos migration to new habitat may be to avoid predation by Pit Vipers living in the forests or a lack of food for the geckos possibly brought about by human activities. Potentially these changes may lead to the forest dwelling species dying out and being replaced solely by the cave dwelling species.
All species, not just reptiles experience a level of background extinction, one species dying out usually to be replaced by another in a better evolved form. More suited to the modern habitats available to it. Thanks to fossil records it is known that 99 percent of species that have ever lived on planet Earth are now extinct yet 1.75 million species of bacteria, vertebrates, fungi, protoctista, plants and insects have been described and many more estimated to exist.
So why are reptiles in particular so succesful at evolution and how did they come about? Its is now thought that about 300,000,000 years ago Global Warming, yes it existed back then too, caused a collapse in the rainforests of what was then the super continent of Euramerica. This caused fragmentation of forests creating different groups of reptiles divided by smaller ‘islands’ of forests. This caused an evolutionary burst as reptiles altered their diet and breeding techniques to suit the nearly formed habitats as the temperature rose still. Reptiles have clearly been evolving and adapting to altering conditions for many moons. Several reasons have been given for their awesome evolution skills compared to those such as amphibians, which suffered badly as the Earth warmed and wetlands dried up. Reptiles lay eggs with a relatively hard shell that is easier to adapt to different habitat and warmer climates, not needing damp or wet lands like those of most amphibians. Secondly reptiles hard, scaly skin protection holds in moisture and lets them live in more arid environments. These advantages freed them of the aquatic environments that they most likely originated from.
So during these days of Climate Change and human habitat destruction, lets hope that our reptiles and other animals of the world can begin to evolve quicker and keep up with humans appetite for destruction.