Finding new species in the Western Ghats

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o what is a species? In the seventeenth century, European thinkers proposed that a group of organisms that could breed with each other could be called a species. A century on, Carl Linnaeus, the pioneering Swedish naturalist, popularised the use of combining two Latin terms: first the name of the genus, then that of the species. The yellow-eyed bush frog has the name Raorchestes because it signifies the genus Raorchestes, which encompasses almost 65 species of bush frogs mostly from South Asia; flaviocularis is its species.

For all this time, scientists have been having furious arguments about the best way to classify species. There are presently more than 30 approaches to define a species, variously based in ancestry, ecology, appearances, even sound. The general consensus these days is to take an “integrative” approach. So Vijay started off with flaviocularis’s distinct looks––its morphology––and then worked on tracing its family tree in the DNA lab. The distinctiveness of its metallic calls, as well as its geographical distribution, helped along the hypothesis that flaviocularis was a species that hadn’t been described previously.

“Documenting the existence of a species is the first step to understanding our biodiversity,” Shanker said. It’s an exciting field because there is so much we don’t know. Ecologists have terms of art associated with these knowledge gaps. The Linnean Shortfall refers to the problem of undescribed lineages. A Wallacean Shortfall refers to the lack of information about a species’ geographical distribution. “These shortfalls are the starting point for our exploration of ecology and evolution. There are lots of questions that can be answered once both these knowledge gaps are addressed,” said Shanker.

One set of questions is evolutionary in nature: Where did a species originate? If it started from Africa, how did it find its way into Asia and diversify? That’s how we got Asian elephants for instance: fossil remains indicate that the first elephant ancestors originated in Africa during the geological epoch known as the Early Pliocene. Recent genetic and fossil studies now confirm that their descendants moved into Asia 2-4 million years ago, and gave rise to the modern Asian elephant just 2.5 lakh years ago.

Geographic barriers such as deep gorges and wide rivers also affect dispersal, and can isolate populations. The gaps and valleys of the Western Ghats explain why there are so many different kinds of bush frogs. A species’ own ability to move around determines the kind of places it eventually gets to: birds are likelier than frogs to move from one mountain to another, for example.

Then they could ask after ecological factors such as rainfall, temperature and altitude, gradients along which species can adapt and evolve into different groups.

Finally, there are questions related to conservation. Research may focus on the availability of a type of plant if it appears that a species relies on it for survival. This data is analysed to help us approach answers to speculative questions like: what could happen to the species a hundred years from now; how would they adapt to climate change?

One of the things that is clear after a couple of centuries of study is that the species richness of a region increases as you move from the poles to the tropics. Within the tropics, you get “biodiversity hotspots.” These are sites that represent only 2.4% of the earth’s land surface, support more than 40% of endemic fauna, and are threatened by human habitation.

The Himalayas, with an estimated 10,000 species of plants including more than 3,100 endemics, is one of them. The states of north-eastern India that form part of the larger Indo-Burma hotspot are another. But easily the most well-studied hotspot in India is the Western Ghats.

from Hacker News https://ift.tt/2YGgmT8