Competitors can pose more of a threat than predators

Date: November 27, 2015

Source: EAWAG: Swiss Federal Institute of Aquatic Science and Technology

When the biodiversity of an ecosystem is reduced by invasive species, competition for food plays a more important role than has previously been supposed. This was the conclusion of research conducted by Eawag and Bern University scientists on cichlid species in Lake Victoria, which suffered mass extinction following the introduction of the fish-eating Nile perch in the 1950s. The study also demonstrates the threat which rapid environmental changes pose to highly specialized species.

Although an evolutionary innovation can open up new ecological niches, traits which are essentially beneficial can put species at a disadvantage in the context of rapid environmental changes. The costs of specialization are highlighted in an article published this week in Science on fish-eating cichlids in Lake Victoria which became extinct following the proliferation of the Nile perch, introduced around 60 years ago.

In the article, the evolutionary and fish biologists Matt McGee and Ole Seehausen report that, because of a specialized jaw structure, fish-eating cichlids in Africa's largest lake take a long time to swallow their prey and are thus no match for competitors that can feed much more rapidly.

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