Carlson, Sara E. , Evans, Margaret E.K. , Donoghue, Michael J. .
The influence of climate on dispersal and life history evolution in Lomelosia (Dipsacaceae).
Climate may play a key role in driving the evolution of important life history traits such as dispersal and the perennial and annual habit. We investigated evolutionary relationships between dispersal traits, habit, biogeography, and climate in the plant clade Lomelosia (Dipsacaceae), which includes both annuals and perennials with “wing” and “pappus” diaspore types that occur in different habitats of the Mediterranean basin. We first reconstructed the phylogeny of 35/ca. 50 Lomelosia species based on chloroplast (atpB-rbcL, trnL-trnF, trnSUGA-trnGGCG) and nuclear (ITS, ETS) DNA markers using Bayesian methods and used the inferred phylogeny in subsequent comparative analyses. Next, we described variation in diaspore morphology using phylogenetic principle components analysis and inferred ancestral character states for diaspore type and habit using Bayesian methods, and ancestral geographic ranges using maximum likelihood. To investigate correlations between climate traits and evolutionary transitions in diaspore type and habit, we used climatic niche modeling to generate species means for 19 climate variables (“Bioclim” variables) and tested for correlations with diaspore type and habit using phylogenetically independent contrasts. Our morphometric results reveal that the majority of variation in diaspore morphology is described by overall diaspore size and the relative length of the pappus, and generally recover the observed wing and pappus diaspore types. Winged diaspores evolved multiple times from pappus-bearing ancestors, and annuals evolved multiple times from perennials, but we found no correlation between diaspore type and habit. Similarly, neither diaspore type nor habit was associated with particular biogeographic regions. However, both traits were correlated with climate features. Winged diaspores were correlated with milder winters, and evolutionary transitions to the annual habit were correlated with summer heat and drought and decreased annual precipitation, which is consistent with a drought-avoiding evolutionary strategy. Our findings indicate that different climate pressures are acting on diaspore and habit evolution, and we discuss the implications of these results in the context of adaptation to particular ecological and environmental conditions.
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1 - University of Neuchâtel, Department of Evolutionary Botany, rue Emile Argand 11, Neuchâtel, CH-2009, Switzerland
2 - Ecole Normale Super, Ecology Lab, Unit Math Ecoevolutionary Biology, Paris, F-75230 , France
3 - Yale University, Ecology & Evolutionary Biology and Peabody Museum of Natural History, PO Box 208106, New Haven, CT, 06520-8106, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 556B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 1:45 PM