Fungal endophyte-grass symbioses are rare in the California floristic province and other regions with Mediterranean-influenced climates

Research on agronomic grasses has shown that Class 1 fungal endophytes (Neotyphodium/Epichloe; Clavicipitaceae) can have profound effects on host plant fitness. However, in natural systems, even basic ecological knowledge of most endophyte symbioses is lacking. Here, I describe the distribution and abundance of endophytes across 36 native (or naturalized) grasses in a previously unsurveyed region, the California Floristic Province. Symbiosis was generally low: 8.33 % of species and 18.75 % of genera hosted endophytes. I then compared the proportions of symbiotic species and genera found in California and other Mediterranean regions to the proportions found in non-Mediterranean regions. Surveys of Mediterranean-influenced regions showed significantly lower proportions of species (similar to 66 % lower) and genera (similar to 65 % lower) hosting endophyte than surveys of nonMediterranean regions. This pattern suggests that selection in Mediterranean climates may not favor endophyte symbioses. (C) 2011 Elsevier Ltd and The British Mycological Society. All rights reserved.