EVOLUTION: stories our freshwater fishes tell

Well over 2.5 million Sri Lankans visit national parks each year.

- BY ROHAN PETHIYAGODA & HIRANYA SUDASINGHE

We can conclude from this that a great many of us love nature and want it conserved. For the most part, we see nature primarily through the lens of species which, together with landscapes and ecosystems, constitute what we commonly call 'biodiversity'. We rarely stop to think, however, of the processes that give rise to our astonishing biodiversity. Evolution by natural selection, the most important of these processes, was discovered by Charles Darwin 165 years ago. But despite the passage of so much time, scientists continue to be perplexed by some of the mechanisms by which species evolve.

Sudasinghe & Pethiyagoda

Taking Sri Lanka's freshwater fishes as an example, this month's Nations Trust-WNPS lecture will seek to unravel the evolutionary processes by which this remarkable diversity came to be. The lecture, written in collaboration with Hiranya Sudasinghe, will be delivered by Rohan Pethiyagoda. Aged just 33, Sudasinghe has been exploring freshwater fishes since his childhood. He eschewed a career in medicine to study zoology, securing a first-class in his BSc at Peradeniya and going on to an MPhil in fish systematics. He has discovered and named seven new species and three new genera of fishes, and despite his youth, is the author of more than 30 papers in international journals. He also went on to rediscover two species which were long thought to be extinct. He is presently in the final year of his PhD programme at the University of Bern, Switzerland.

Rohan Pethiyagoda first came to national attention in 1991, when he published his landmark book