Comparative Analysis of Stability—Genetic Diversity in Seagrass (Posidonia oceanica) Meadows Yields Unexpected Results

• Published in: Estuaries and coasts Vol. 33; no. 4; pp. 878 - 889
• Main Authors: Arnaud-Haond, Sophie, Marbà, Núria, Diaz-Almela, Elena, Serrâo, Ester A., Duarte, Carlos M.
• Format: Journal Article
• Language: English
• Published: New York Spring Science + Business Media 01.07.2010; Springer-Verlag; Springer Nature B.V; Springer Verlag
• Subjects: Aquaculture; Aquatic plants; Biodiversity; Coastal Sciences; Comparative analysis; Demography; Diversity of citizenship; Earth and Environmental Science; Ecological genetics; Ecology; Environment; Environmental Management; Evolutionary genetics; Freshwater & Marine Ecology; Genetic diversity; Life Sciences; Marine; Marine ecology; Meadows; Mortality; Population genetics; Population growth; Posidonia oceanica; Sedimentation & deposition; Sedimentation rates; Species diversity; Water and Health; Mediterranean Sea; MED, Western Mediterranean; MED; Clonality; Seagrass; Demography; Diversity–stability; Genetic richness
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-009-9238-9

The diversity-stability relationship is the subject of a long-standing debate in ecology, but the genetic component of diversity has seldom been explored. In this study, we analyzed the interplay between genetic diversity and demographic responses to environmental pressures. This analysis included 30 meadows formed by the Mediterranean endemic seagrass, Posidonia oceánica, showing a wide range of population dynamics ranging from a near equilibrium state to steep decline due to strong environmental pressures close to aquaculture installations. Our results show that sedimentation rates are much better predictors of mortality than clonal or genetic components. An unexpected positive trend was observed between genotypic diversity and mortality, along with a negative relationship between allelic richness and net population growth. Yet such trends disappeared when excluding the most extreme cases of disturbance and mortality, suggesting the occurrence of a threshold below which no relationship exists. These results contrast with the positive relationship between genotypic diversity and resistance or resilience observed in previous manipulative experiments on seagrass. We discuss the reasons for this discrepancy, including the difficulties in designing experiments reflecting the complexity of natural meadows.