Bryological and Lichenological Section/ABLS
Sérusiaux, Emmanuël , Villarreal, Juan Carlos , Wheeler, Timothy , Goffinet, Bernard .
Species of Nephroma endemic to Macaronesia belong to two strongly supported clades each comprizing a widespread holarctic species and all are of recent origin.
The lichen genus Nephroma (Peltigerales) is widespread all over boreal, temperate and tropical-montane habitats world-wide with c. 35 species. Five species are endemic to Macaronesia (comprizing three archipelagos : Canary Is, Madeira and the Azores). Their phylogenetic position in a comprehensive topology of the genus inferred from three loci sequences (nLSU, mtSSU, and nITS) demonstrate : (a) all endemic species belong to two strongly supported clades, each comprizing a widespread holarctic species (N. laevigatum and N. parile) ; (b) a radiative pattern is demonstrated for a strongly supported group of three species, each one being endemic to a different archipelago within Macaronesia.
Divergence dates were estimated using a relaxed molecular clock implemented in BEAST : a first analysis was performed with two calibrations based on islands ages and a second one was based on ITS evolution rate in the Erysiphales. Both converge to a recent divergence of all endemic species (divergence always younger than the archipelagos) and thus support a neo-endemism status. Furthermore, these inferences suggest that the diversification of the most common recent ancestor to the populations of both widespread species occurred almost in parallel to the diversification and speciation of the common ancestor to the endemic taxa in each clade.
This is the first evidence drawn from phylogenetic reconstructions and estimating date of divergences for neoendemism in insular lichen taxa. Furthermore, our data suggest that disjunct distributions in widespread taxa likely resulted from recent long distance dispersal rather than from ancient vicariance events.
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1 - University of Liège, Plant Taxonomy and Conservation Biology, Sart Tilman B22, Liège, 4000, Belgium
2 - University of Connecticut, Ecology and Evolutionary Biology, 75 Northeagleville road, Storrs, CT, 06269-3043, USA
3 - 6060 Jocko Canyon Road, Arlee, MT, 59821 , USA
Presentation Type: Oral Paper:Papers for Sections
Location: 554A/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:45 PM