PARENT SESSION
Contributed Oral Session 14: Evolutionary Ecology: Theory; Modeling
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 521 A, Level 5, Palais des congrès de Montréal
Niche versus neutrality in forest sedges: phylogenetic evidence.
Lechowicz, Martin*,1, Waterway, Marcia 2, Bell, Graham1, 3, 1 Department of Biology, Montreal, Qc, CANADA2 Department of Plant Science, Ste-Anne-de-Bellevue, Qc, CANADA3 Redpath Museum, Montreal, Qc, CANADA
ABSTRACT- Sixteen clades within the genus Carex (Cyperaceae) are represented among the 55 Carex species occurring in the old-growth forests of the Gault Nature Reserve on mont St. Hilaire in southern Quebec, Canada. Different forest types and a high level of physiographic and edaphic diversity in the reserve provide ample potential for niche-dependent patterns of sedge distribution and abundance. Seven of the clades include species of sufficient abundance that their environmental affinities can be reliably assessed using a battery of field measurements and GIS-derived environmental variables. We took advantage of this rich array of co-occurring congeners to test the degree to which species distribution and abundance can be predicted from neutral- as opposed to niche-models. The phylogeny of a truly neutral community should have no ecological structure – environmental affinities within and among clades will be indistinguishable. If there is significant diversification among clades in their environmental affinities, this is strong evidence for non-neutral community assembly. We test the within- and among-clade variance in environmental affinities at the scale of quarter-hectare grid cells over the full 10 km2 extent of the reserve. There is some phylogenetic structure in the environmental affinities of the sedge community in this forest understory, but the results are not unambiguous at the scale sampled. We discuss other lines of evidence that can refine the estimate of phylogenetic structure and emphasize the value of phylogenetic data in assessing niche versus neutral explanations for community composition.
Key words: Carex (Cyperaceae), community assembly, ecological specialization, neutral model