Abstract Detail

Empirical Approaches to Phylogenetic Comparative Methods in Plant Science

Humphreys , Aelys M [1], Linder, H Peter [2].

Understanding plant distributions using a combined experimental and historical approach: cold tolerance in grasses (Danthonioideae).

Grasses (Poaceae) occupy among the warmest and coldest environments on earth. Temperature has long been considered an important determinant of biodiversity distribution patterns and yet the role of cold tolerance evolution in generating the distribution of grasses is poorly understood. Grasses are also generally easy to cultivate and thus an ideal group for studying the relationship between climate tolerances and distribution patterns using both experimentation and modelling in an evolutionary framework. Here we study whether the distribution of a clade of primarily Southern Hemisphere temperate grasses (Danthonioideae) is limited by its degree of cold tolerance. Specifically we ask whether their relative absence in the Northern Hemisphere can be explained by the more extreme cold temperatures experienced there. First, differences in cold tolerance among 10 species from different continents, grown in a common winter garden, were determined and the relationship between measured cold tolerance and that predicted by species’ ranges assessed. Next, temperature conditions in species’ ranges were used together with an almost completely sampled phylogeny (~281 species, >80% sampled) to study how and when cold tolerance evolved across the entire clade. Species’ ranges were found to generally underestimate cold tolerance but still tended to be a meaningful representation of relative cold tolerances, i.e., differences in cold tolerance among species. Cold tolerance evolution was inferred to have commenced at the onset of danthonioid diversification in the Oligocene and to have subsequently increased both in pace and extent during the Miocene, in certain lineages. Finally, interspecific variation in cold tolerance was found to be better accounted for by spatial than phylogenetic distance. These results together suggest that temperature – low termperature in particular – does not limit the distribution of this temperate clade. Competition, time or dispersal limitation might better explain its relative absence from northern temperate regions.

1 - Imperial College London, Department of Life Sciences, Silwood Park Campus, Ascot, Berkshire, SL57PY, UK
2 - University of Zurich, Institute of Systematic Botany, Zurich, 8008, Switzerland

Keywords:
cold tolerance
distribution
grasses
niche evolution
common garden experiment
Character evolution.

Presentation Type: Symposium or Colloquium Presentation
Session: C1
Location: Summit/Boise Centre
Date: Monday, July 28th, 2014
Time: 1:30 PM
Number: C1001
Abstract ID:348
Candidate for Awards:None