Abstract Detail



Ecology

Dungey, Michael [1], Eckert, Christopher [2].

A broad-scale test of whether constraints on dispersal contribute to the northern range limit of a Pacific coastal dune plant.

Species are expected to occur where environments allow for population self-replacement, and be limited where biotic and abiotic conditions shift outside their recognized niche. However, many systems lack the declines in fitness towards their range edges expected under niche limitation and even show persistence beyond them, suggesting a role of dispersal limitation in maintaining species' ranges. For species that exist within patchy environments, dispersal limitation can occur through increases in heterogeneity of suitable habitat, as opposed to absolute dispersal barriers. Reductions in habitat patch size and greater patch isolation can increase the cost of dispersal along a gradient, with a range limit forming where colonization can no longer match stochastic patch extinction. We tested this hypothesis across the northern range of a Pacific coastal dune endemic, Camissoniopsis cheiranthifolia (Onagraceae). This species occur in patchy dune habitat, and previous studies of beyond-range transplants strongly suggest that dispersal may limit the northern range. By surveying all coastal dune habitat in the northern half of the species' range and quantifying habitat suitability and occupancy and at > 7000 randomly distributed 5x5 m plots, we tested the predictions that towards the northern range limit: (1) availability of suitable habitat decreases, (2) inter-patch distance increases, and (3) occupancy of suitable habitat patches decreases. Initial results suggest that available, suitable habitat declines with increasing proximity towards the range limit, and future steps incorprating habitat resistance metrics onto plot distances may yield further conclusions on dispersal constraints across the northern range. 


Related Links:
Eckert Lab Website


1 - Queen's University, Biology, 100 Wellington St Unit 5, Kingston, ON, K7L3C7, Canada
2 - Department Of Biology, Department Of Biology, Queen's University, 116 Barrie Street, Kingston, ON, K7L 3N6, Canada

Keywords:
Range limits
dispersal
metapopulation.

Presentation Type: Oral Paper
Number: ECO4006
Abstract ID:385
Candidate for Awards:None


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