PARENT SESSION
OOS 1: Genetic Explorations of the Seascape: Using Molecules and Experiments to Understand Marine Biodiversity.
Organized by: E Sotka and R Thacker
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room E 141 .
Genetic diversity enhances seagrass ecosystem function by mediating disturbance.
Hughes, A. Randall*,1, Stachowicz, John1, 1 University of California - Davis, Davis, CA
ABSTRACT- Empirical and theoretical research suggest that more speciose systems exhibit enhanced productivity, nutrient cycling, or resistance to invasion relative to systems with fewer species. However, many ecosystems are dependent on one or a few key habitat-forming species (e.g., kelps, corals, trees) that support a highly diverse assemblage of associated organisms. Such foundation species also perform many of the ecosystem functions associated with multiple species in other systems. Thus, individual-level diversity in foundation species may perform a comparable role to species diversity in speciose systems. Currently, few data exist to assess the effects of within species genetic variability on ecological processes and community structure. To evaluate the importance of genetic diversity in the habitat-forming seagrass species (Zostera marina) for the function of this system, we genotyped individual shoots using DNA microsatellites and transplanted them into the field to produce plots of equivalent initial shoot density but varying from one to eight genotypes. We show that increasing genotypic diversity in Z. marina enhances community resistance to natural and artificial disturbances. During the recovery process, sediment nutrient concentrations decreased with increasing genotypic diversity, suggesting that enhanced resource utilization could be responsible for the rise in productivity with diversity. Genotypic diversity had no effect on any ecosystem processes in the absence of disturbance. These results suggest that the greatest value of biodiversity may lie in enhancing the consistency and reliability of ecosystems in the face of environmental change. As human-associated disturbance intensifies, biodiversity seems increasingly likely to play a critical role in sustaining the integrity of our ecosystems.
Key words: genetic variation, seagrass, biodiversity, disturbance