Hybridised and extinct..could this happen to lake creatures?

Fish hybridise themselves extinct in Alpine lakes

15:05 16 February 2012 by Michael Marshall

Extract:

When the going gets tough, species start merging. Lake-dwelling fish species that once lived separately began interbreeding when pollution forced them together.After the last ice age, whitefish (Coregonus) in Europe's Alpine lakes split into several species, each with a specialised appearance and lifestyle. They first separated because they spawned in different places, some favouring the lake bottom and others the surface layers. That all changed when the lakes became polluted in the mid-20th century, says Ole Seehausen of Eawag: Swiss Federal Institute of Aquatic Science and Technology in Kastanienbaum and the University of Bern, Switzerland.

The number of species in the lakes has fallen 38 per cent since the 1920s, and the remaining species have become more similar in shape. What's more, lakes that have experienced more eutrophication have fewer species. Seehausen found that the remaining species sometimes carry genetic markers previously found only in extinct species, suggesting that those species have hybridised themselves out of existence.

Read rest here: http://www.newscientist.com/article/dn21482-fish-hybridise-themselves-extinct-in-alpine-lakes.html

It begs the question are lake creatures a hybrid or have they bred themselves almost to  extinction, which is why so few are seen? A hybrid would explain a lot and would explain how they are still here .Thought for the  week there .