Of frogs and sharks...

...or how DNA research gives clues to the longevity of speciation and the subsequent effect in real terms of the loss of species.

Phew..after making that title I think I need to lie down. So, this article from Stony Brook University gives us an insight into a soon to be published paper in the jouirnal "Ecology Letters" which attempts to explain why it is that certain areas contain more species than others, despite having similar ecosystem characteristics; for example, some tropical rainforests outside of the Amazon basin have no more species than some sites in temperate North America. The reason for the high diversity in the Amazon is not due to the warm and humid conditions as we might expect, but the length of time that the species have been in the area, developing over an enormous time span greater than 50 million years. It seems the later in history that a colonisation occurs, the lower the species diversity will be in that region. Although this particular study used tree frogs as a study group, the report states that the findings could have implications for other species such as trees, birds and insects - and why indeed not for sharks?

This next report highlights the ability of DNA to pinpoint the home range of sharks when they are targetted and sold in the fin markets. By analysing DNA scientists have been able to identify a difference between sharks of the same species living along different continents. This allows the science and conservation community to identify shark fins sourced in world markets and identify whether these are being illegally sourced from protected regions.

There is a considerable link between the two articles. By trading strongly in low fecund species, we are not just risking the temporary absence of one or other type of shark, we are disturbing the development of species that has taken millions upon millions of years to occur. As we know, apex predators play a vital role in the trophic pyramid and so if we remove a key species, we are not just removing one organism from time, we are disturbing the building blocks of our most critical environment - the ocean. If that one building block took, let's say, 200 million years to develop, then how many blocks and mortar will fall around it, and how many millions of years of ecological constitution are we undoing? How serious, how long lasting, how never-mending will be the cascade?