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EVEN SLIGHT CHANGES CAN HARM ANIMALS

SHARE EVEN SLIGHT CHANGES CAN HARM ANIMALS

Slight damage to the environment can have a more dramatic effect on animal populations than previously thought, researchers reported Wednesday.

Ilkka Hanski and colleagues at the University of Helsinki said their studies of butterflies showed that populations grow or decline in sudden leaps.Observation of Glanville fritillary butterflies on islands in southwest Finland showed that more factors affecting specific groups - such as overall population size, rate of immigration from other communities and grazing by sheep and cows - meant more instability in numbers.

This meant that populations "may collapse unexpectedly to extinction even in landscapes degrading only slowly," they wrote in the science journal Nature.