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http://www.newscientist.com/article/dn18912-fat-lips-evolve-at-record-speed.html --- In Baraya_Sunda@yahoogroups.com, "Remi" <rsyaif...@...> wrote: > > > Fat lips evolve at record speed > > 18:18 14 May 2010 by Andy Coghlan > For similar stories, visit the Evolution Topic Guide > Fish in a remote crater lake in Nicaragua are splitting into separate species > at breakneck speed. > > It has taken the lake cichlids just 100 generations and as many years to > evolve an entirely new physical feature: very fat lips. Most estimates of how > fast species evolve new features are based on models, which generally > indicate that it could take up to 10,000 generations. Some models suggest > just tens of generations are enough, but such rapid change has never been > documented before. > > Axel Meyer at the University of Konstanz in Germany and his team say the > fat-lipped fish occupy a different ecological niche from their thin-lipped > cousins, despite living in the same lake, which fills a volcanic crater > formed 1800 years ago. They don't eat the same diet and observations of > captive fish in a tank suggest they avoid mating with each other though lab > experiments show they can still interbreed. Meyer says the fact that if they > avoid mating with each other in the wild, as seems likely, they are well on > the way to becoming separate species. > > The new variety have narrower, pointy heads, ideal for nibbling insects and > larvae from crevices in the volcanic rock, and fat lips to cushion their > ventures into the sharp crags. The thin-lipped variety have sturdier jaws and > extra teeth to crack the shells of the snails they feed on. > > "When scientists catch incipient species in the process of divergence, it is > important, because it is difficult to catch the process in action," says Todd > Streelman of the Georgia Institute of Technology in Atlanta, who also studies > cichlid evolution. "This new work nicely matches theories developed in the > 1990s suggesting that species could develop rapidly even when they share the > same environment." > > Journal reference: BMC Biology, vol 8, p 60 >
