Tiny predators unleashed

A water flea infected by a yeast parasite. Image: Meghan Duffy

Water fleas (Daphnia dentifera) are evolving. Researchers at Georgia Institute of Technology discovered that water fleas allow outbreaks of  the virulent yeast parasite Metschnikowia bicuspidata to improve their chances of survival. After the outbreak, the host population (Daphnia) becomes more resistant to the parasite — although, depending of the size of the outbreak, they could become more susceptible.

“It’s a pretty amazing result that hosts can evolve to become more susceptible to parasites that ultimately kill them, but it does make sense if hosts trade off resistance to infection with capacity to make more offspring,” said associate professor Spencer R. Hall in a press release from Indiana University.

The results, which were published in Science, also provide an insight into predation pressure and productivity of ecosystems. The researchers will repeat the experiment to assess the changes on the genotypes.

“Anthropogenic manipulation of ecosystems, such as culling of predators or eutrophication, can noticeably boost disease prevalence. This factors can also profoundly influence genetic composition of hosts, a less visible but still important consequence,” said Hall.

Source: Indiana University




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