Award: OCE-1234345

Connecting genetic diversity to ecosystem functioning: links between genetic diversity, relatedness and trait variation in a seagrass community Seagrass ecosystems provide important services to coastal regions including primary production, nutrient cycling, habitat for fisheries species, and erosion control. Considerable effort is aimed at conservation and restoration of these ecosystems to ensure the continued provision of these important ecosystem services. Our prior research showed that genetic diversity of the seagrasses themselves enhances the reliability of these important services, but genetic diversity is declining in many places due to human influences. Restoration success of seagrasses is limited in part by a lack of understanding of exactly why genetic diversity is important and whether specific genotypes are needed or if diversity per se is sufficient to create a healthy grass bed. Our project fostered a predictive approach to understanding the consequences of diversity loss in seagrass beds dominated by eelgrass, Zostera marina, by integrating physiological, community, and genetic approaches. First, we characterized the relationship between genetic relatedness and trait similarity among individual genotypes of eelgrass, and found that in fact relatively small genetic changes could lead to large functional differences so that the was no easy predictive relationship between overall genetic similarity and similarity in ecological traits such as growth rate, nutrient uptake, root length and heat tolerance. At very small scales we found that very similar genotypes could coexist very well due to shared environmental tolerances. However, at the scale of even a meter-square patch, the environment was sufficiently variable that many genotypes were required to achieve maximum shoot density and growth rates. When we did experiments manipulating the diversity of eelgrass assemblages in natural field settings, we found that different dimensions of diversity made independent contributions to predicting the effects of diversity on eelgrass health. The number of genotypes and the extent to which these were equally abundant in an assemblage both increased eelgrass population growth whereas high relatedness among genotypes decreased growth. Thus healthy and resilient eelgrass beds are characterized by high genetic diversity, low relatedness among individuals, and high diversity in important growth and survival related traits. This allows them to maintain high growth rates and density in the face of seasonally and interannually varying conditions in the same way that species diversity in other systems provides a hedge against an uncertain future. We have shown that this approach enhances the success of restoration activities in Indonesian seagrass beds and have used expertise from this project to advice the California Ocean Protection Council on the potential use of seagrass as a means to combat ocean acidification by removing CO2 from coastal waters. We?ve also engaged in outreach to local K-12 schools and helped put on exhibits in local museums like the Exploratorium in San Francisco. The project has trained a number of undergraduate, graduate and postdoctoral researchers and interfaced with other programs at UC Davis that enhance training of underrepresented minorities in STEM fields to build scientific capacity in the areas of plant genetics, plant physiology and ecology. Last Modified: 01/30/2018 Submitted by: John J Stachowicz