Soay sheep

Coltman, D.W., Pilkington, J.G., Smith, J.A. and Pemberton, J.M. (1999) Parasite-mediated selection against inbred Soay sheep in a free-living, island population. Evolution 53, 1259-1267. 

To date, little difficulty has been observed in livestock grazing fine fescues, though circumstantial evidence suggests that their EA may have dramatic effects on populations of feral Soay sheep in the Outer Hebrides (115). On the island of Hirta, the Soay sheep undergo population crashes of 40-65% every 3-5 years, and red fescue (Festuca rubra) infection by E. festucae correlates with grazing pressure. Furthermore, mock herbivory (clipping) induced production of 8 in plants from the island, whereas 8 was undetectable in control plants. Thus, 8 appears to be an inducible defense in red fescue - E. festucae symbiota. 

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