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Competition drives the evolution of new species, according to a new study on fish.

Scientists discovered that competition leads to the differentiation of new species within the highly diverse cichlid fishes of Lake Tanganyika in East Africa.

Researchers said the cichlid fish Telmatochromis temporalis shows two genetically distinct ecomorphs (local varieties of a species whose appearance is determined by its ecological environment) that differs significantly in body size and habitat.

"We found large-sized individuals living along the rocky shoreline of Lake Tanganyika and, in the vicinity of these shores, we found small-sized individuals, roughly half the size of the large ones, that live and breed in accumulations of empty snail shells found on sand," Dr. Martin Genner of the University of Bristol in UK said in a news release.

Researchers believe the bigger fish outcompete the smaller ones by driving them away from the preferred rocky habitats and into the neighboring sand, where the smaller fish find shelter in empty snail shells.

"In effect, big and small fish use different habitats; and because of this habitat segregation, fish usually mate with individuals of similar size. There is virtually no genetic said between the large- and small-bodied ectomorphs," Genner said.

Researchers said the speciation occurs when genetic differences between the two groups of fish accumulate over time. While there are no obvious obstacles to the movement and interaction of individuals in the case of Telmatochromis, researchers explain that the non-random mating between large- and small-bodied fish may trigger evolutionary play.

"The relevance of our work is that it provides experimental evidence that competition for space drives differential mating in cichlid fish and, in time, leads to the formation of new species. Nature has its ways - from body size differences to the formation of new species. And clearly, size does matters for Telmatochromis and for fish diversity," Genner concluded.

The findings are published in the journal Nature Communications.