Evolution of ectomycorrhizas as a driver of diversification and biogeographic patterns in the model mycorrhizal mushroom genus Laccaria.
A systematic and evolutionary ecology study of the model ectomycorrhizal (ECM) genus Laccaria was performed using herbarium material and field collections from over 30 countries covering its known geographic range. A four-gene (nrITS, 28S, RPB2, EF1α) nucleotide sequence dataset consisting of 232 Laccaria specimens was analyzed phylogenetically. The resulting Global Laccaria dataset was used for molecular dating and estimating diversification rates in the genus. Stable isotope analysis of carbon and nitrogen was used to evaluate the origin of Laccaria's ECM ecology. In all, 116 Laccaria molecular species were identified, resulting in a near 50% increase in its known diversity, including the new species described herein: Laccaria ambigua. Molecular dating indicates that the most recent common ancestor to Laccaria existed in the early Paleocene (56-66 million yr ago), probably in Australasia. At this time, Laccaria split into two lineages: one represented by the new species L. ambigua, and the other reflecting a large shift in diversification that resulted in the remainder of Laccaria. L. ambigua shows a different isotopic profile than all other Laccaria species. Isotopes and diversification results suggest that the evolution of the ECM ecology was a key innovation in the evolution of Laccaria. Diversification shifts associated with Laccaria's dispersal to the northern hemisphere are attributed to adaptations to new ecological niches.
Chicago Botanic Garden, Plant Science and Conservation, 1000 Lake Cook Road, Glencoe, IL, 60022, USA.|Sam Mitchel Herbarium of Fungi, Denver Botanic Gardens, 909 York Street, Denver, CO, 80206, USA.
Andrew W
AW
Wilson
Department of Botany, National Museum of Nature and Science, Tsukuba, Ibaraki, 305-0005, Japan.
Kentaro
K
Hosaka
Chicago Botanic Garden, Plant Science and Conservation, 1000 Lake Cook Road, Glencoe, IL, 60022, USA.
Gregory M
GM
Mueller
D044822:Biodiversity; D005075:Biological Evolution; D002247:Carbon Isotopes; D019992:Databases as Topic; D055399:Laccaria / Q000502:physiology*; D008954:Models, Biological; D038821:Mycorrhizae / Q000502:physiology*; D009587:Nitrogen Isotopes; D058974:Phylogeography; D013045:Species Specificity
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes
biogeography; diversification; ectomycorrhiza; evolutionary ecology; molecular dating; new species; stable isotopes; systematic evolution