PARENT SESSION
Oral Session # 75: Biodiversity II.
Presiding: K Kirkman
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 100.

The coincident evolution of dispersal and specialization: Consequences for diversity.

Friedenberg, Nicholas^*,1, ¹ University of Florida, Gainesville, FL, USA

ABSTRACT- Both dispersal rates and local adaptation may evolve in response to the spatial and spatiotemporal heterogeneity of a species' potential habitats. Increasing spatial heterogeneity should select for lower dispersal rates and increased local adaptation. Increasing spatiotemporal fluctuations in the environment should select for a higher dispersal rate and favor a broad range of tolerance over strong local adaptation. Both characters are proposed mechanisms for the determination of species diversity. I allowed dispersal propensity and the degree of local adaptation to evolve independently in an individual based model. Individuals occupy a linear landscape of patches that differ by a fixed degree, representing a transect along an environmental gradient. Individuals belong to ancestral lineages and to derived lineages that arise randomly with a fixed probability, much like a simplistic model of speciation. I find that increased dispersal rates accelerate the loss of lineages, ancestral and derived, whereas the relationship between local adaptation and diversity is contingent upon spatial heterogeneity. Above a threshold level of spatial heterogeneity, an increase in the severity of patch fluctuations leads to a negatively correlated change in dispersal and local adaptation and a loss of ancestral and derived lineages. I will discuss these results in terms of diversity both within and between species.

Key words: species ranges, individual based model, spatial heterogeneity