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Metadata provide insights on patterns of epiparasitism in mistletoes (Santalales), an overlooked topic in forest biology

2016; Canadian Science Publishing; Volume: 95; Issue: 3 Linguagem: Inglês

10.1139/cjb-2016-0264

1916-2804

Carol Wilson, Clyde L. Calvin,

Plant and Fungal Species Descriptions

Mistletoes are aerial-branch parasites belonging to one of five families in the Santalales. Usually, mistletoe hosts are autotrophic, but if the hosts themselves are parasitic, the plant parasitizing the host is an epiparasite. Three categories of epiparasites are recognized, chance-, obligate-, and auto-epiparasites. Loranthaceae and Viscaceae comprise about 97% of mistletoe species and also the largest number of epiparasites. We report frequencies and biogeographical distributions of epiparasite – parasite host combinations for Loranthaceae and Viscaceae, and we summarize epiparasitism in other mistletoe families. Parasitic hosts are primarily recruited from Loranthaceae, whereas most epiparasites are members of Viscaceae. Twenty-seven species are considered likely to be obligate epiparasites. Data suggest species abundance influences whether mistletoes serve as host to other mistletoes. We found no reports of epiparasitism in Misodendraceae and only a few reports for Santalaceae, although Santalaceae are often root-parasitic hosts. In Phacellaria (Amphorogynaceae) all species are obligate epiparasites, mainly on Loranthaceae. Epiparasitism occurs worldwide and is most common in the tropics and subtropics. The greatest number of reports is from Oceania, the smallest from Africa. Epiparasitism in mistletoes has received little research attention, yet our research shows that this life form contributes to species and structural diversity in forest ecosystems across the globe.