title: High speciation rate at temperate latitudes explains unusual diversity gradients in a clade of ectomycorrhizal fungi.
abstract: Understanding the patterns of biodiversity through time and space is a challenging task. However, phylogeny-based macroevolutionary models allow us to account and measure many of the processes responsible for diversity buildup, namely speciation and extinction. The general latitudinal diversity gradient (LDG) is a well-recognized pattern describing a decline in species richness from the equator polewards. Recent macroecological studies in ectomycorrhizal (EM) fungi have shown that their LDG is shifted, peaking at temperate rather than tropical latitudes. Here we investigate this phenomenon from a macroevolutionary perspective, focusing on a well-sampled group of edible EM mushrooms from the genus Amanita-the Caesar's mushrooms, which follow similar diversity patterns. Our approach consisted in applying a suite of models including (1) nontrait-dependent time-varying diversification (Bayesian analysis of macroevolutionary mixtures [BAMM]), (2) continuous trait-dependent diversification (quantitative-state speciation and extinction [QuaSSE]), and (3) diversity-dependent diversification. In short, results give strong support for high speciation rates at temperate latitudes (BAMM and QuaSSE). We also find some evidence for different diversity-dependence thresholds in "temperate" and "tropical" subclades, and little differences in diversity due to extinction. We conclude that our analyses on the Caesar's mushrooms give further evidence of a temperate-peaking LDG in EM fungi, highlighting the importance and the implications of macroevolutionary processes in explaining diversity gradients in microorganisms.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, Ontario, M5S 3B2, Canada. santiago.snchez@gmail.com.|Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada. santiago.snchez@gmail.com.
authors.forename: Santiago
authors.initials: S
authors.lastname: Sánchez-Ramírez
authors.affiliation: Community and Conservation Ecology and Centre for Ecological and Evolutionary Studies, University of Groningen, Box 11103, 9700 CC, Groningen, The Netherlands.
authors.forename: Rampal S
authors.initials: RS
authors.lastname: Etienne
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, Ontario, M5S 3B2, Canada.|Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Moncalvo
mesh_terms: D000545:Amanita / Q000235:genetics* / Q000502:physiology; D001499:Bayes Theorem; D044822:Biodiversity; D005075:Biological Evolution; D002980:Climate; D049810:Genetic Speciation; D038821:Mycorrhizae / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D011157:Population Dynamics
keywords: Amanita; BAMM; Caesar's mushrooms; Ornstein-Uhlenbeck; QuaSSE; diversity-dependent diversification; macroevolution; speciation and extinction