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Abstract Detail

Evolutionary insights from studies of geographic variation: Establishing a baseline and looking ahead to future change

Bellemare, Jesse [1], Moeller, David [2].

Non-equilibrium in the geographic ranges of plants: Ecological, evolutionary, and conservation implications.

Ecological and evolutionary models of geographic ranges and range edges are often premised on a dynamic equilibrium between species distributions and the environment.  For example, species distribution models typically assume that a species’ current native range represents the full set of abiotic conditions it requires for survival.  Similarly, evolutionary studies of range edges are often set within a dynamic equilibrium framework that seeks to understand the factors that might limit natural selection on traits allowing for further range expansion.  However, data from biogeographic studies, experimental transplants, and horticulture increasingly suggest that the distributions of many plant species might not be in close equilibrium with the environment.  Indeed, some species appear to thrive in environmental conditions and geographic regions far beyond their native ranges.  Although well known from research on inter-continental invasives, this type of non-equilibrium is becoming evident for intra-continental movements of native species, including some that might otherwise be considered highly vulnerable to climate change, like narrow endemics.  Here we present the results of a biogeographic analysis surveying the distribution and diversity of 189 small-ranged plant species endemic to the forests of eastern North America.  The ranges of these species are highly concentrated in the southeastern United States, with diversity dropping off substantially near the boundary of the Last Glacial Maximum, suggesting an important role for non-equilibrium processes like dispersal limitation in determining modern distributions.  To test this possibility, we have conducted a multi-year seed sowing experiment with the Southern Appalachian endemic Diphylleia cymosa (Berberidaceae), moving seeds to a series of 5 sites along a transect extending ~1000 km north of its native range.  Seed germination outside the range, as well as juvenile growth, have been comparable to or significantly higher than rates seen within the native range at several sites, indicating that highly suitable habitat for the species occurs under novel conditions outside its native range.  Taken together, the biogeographic analysis and experimental results suggest that non-equilibrium distributions might be common for some types of plant species.  For such species, native range boundaries might not reflect close environmental matching or evolutionary limits on further adaptation, but rather dispersal limitation or other historical factors.  Indeed, the fundamental niches and abiotic tolerances of some species appear to be substantially broader than would be inferred from their native ranges alone.  These findings have significant implications for conservation management and the role of evolutionary change as species respond to climate change.

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1 - Smith College, Dept. Of Biological Sciences, Clark Science Center, 44 College Lane, Northampton, MA, 01063, USA
2 - University of Minnesota, Dept. of Plant Biology, 250 Biological Science Center, 1445 Gortner Ave., St. Paul, MA, 55108, USA

Climate change
Geographic range
range limit.

Presentation Type: Symposium or Colloquium Presentation
Session: SY08
Location: Firs North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 10:45 AM
Number: SY08007
Abstract ID:399
Candidate for Awards:None

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