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Summary: Ecology, 88(3), 2007, pp. 541549
Ó 2007 by the Ecological Society of America
DIVERSITY AND HOST RANGE OF FOLIAR FUNGAL ENDOPHYTES:
ARE TROPICAL LEAVES BIODIVERSITY HOTSPOTS?
A. ELIZABETH ARNOLD
1
AND F. LUTZONI
Department of Biology, Duke University, Durham, North Carolina 27708 USA
Abstract. Fungal endophytes are found in asymptomatic photosynthetic tissues of all
major lineages of land plants. The ubiquity of these cryptic symbionts is clear, but the scale of
their diversity, host range, and geographic distributions are unknown. To explore the putative
hyperdiversity of tropical leaf endophytes, we compared endophyte communities along a
broad latitudinal gradient from the Canadian arctic to the lowland tropical forest of central
Panama. Here, we use molecular sequence data from 1403 endophyte strains to show that
endophytes increase in incidence, diversity, and host breadth from arctic to tropical sites.
Endophyte communities from higher latitudes are characterized by relatively few species from
many different classes of Ascomycota, whereas tropical endophyte assemblages are dominated
by a small number of classes with a very large number of endophytic species. The most easily
cultivated endophytes from tropical plants have wide host ranges, but communities are
dominated by a large number of rare species whose host range is unclear. Even when only the
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