Researchers have discovered that grazing animals such as deer
and rabbits are actually helping to spread plant disease -
quadrupling its prevalence in some cases - and encouraging an
invasion of annual grasses that threaten more than 20 million
acres of native grasslands in California. The findings run
contrary to what had been predicted by other theories, which had
suggested that 'consumers' such as deer would help to contain or
reduce disease. They point once again to the complexity of
natural ecosystems and the many ways in which plants, animals
and even viruses interact with each other. The work will be
published this week in Proceedings of the National Academy of
Sciences, by researchers from Oregon State University, Cornell
University and the University of North Carolina. 'We usually
think of a disease and its host as very tightly coupled, like a
flu virus that infects humans,' said Elizabeth Borer, an
assistant professor of zoology at OSU. 'But in natural
ecosystems we're finding it's not nearly that s