PARENT SESSION
Oral Session #30: Landscape Ecology: Dynamics and patterns. Presiding: A. Hansen.
Tuesday, August 7, 2001. 1:00 PM to 5:00 PM. Madison Ballroom D.
Environmental suitability across the geographic distribution of marine intertidal invertebrates.
Gonzalez, Laura1, Gaines, Steven2, Dugan, Jennifer2, 1 2
ABSTRACT- A central question in ecology, biogeography and conservation biology is understanding how individual fitness interacts with spatial variation in population density and habitat characteristics across species geographic ranges. Because abundance is usually higher towards the center of the range, scientists believe that environmental conditions are more suitable, on average, in sites closer to the center of the range. Nonetheless, high abundance may not be a good predictor of individual fitness because of density-dependence effects. Moreover, abundance can be determined as much by dispersal regimes as by local environmental conditions. In the present study, we want to determine to what extent abundance and position within the range are related to performance of individuals within local sites. We have used fluctuating asymmetry, parasite load and estimates of reproductive output to assess the performance of individuals across sites. To assess the importance of dispersal regimes in the patterns observed, we have studied a species with planktonic larvae (Emerita analoga) and one with non-planktonic larvae (Idotea montereyensis). We expect a stronger association of performace with abundance and position within the range in Idotea montereyensis. We will use partial correlation analysis to determine the relationship of the performance values with abundance and position within the range. We will use spatial correlation analysis to determine the similarity of individual performance across sites. We will discuss the results and their ecological, evolutionary and conservation implications.
KEY WORDS: habitat suitability, fluctuating asymmetry, position within the range, individual performance