l'oliva di mare: disturbance and genetic diversity

Seagrasses are important ecosystem-engineers of coastal regions around the world. Previous work has demonstrated the correlation of high genotypic diversity with resistance (e.g., Hughes and Stachowicz 2004) and resilience (e.g., Reusch et al. 2005).
In a recently accepted paper in Molecular Ecology, Jahnke, Olsen and Procaccini (2015) performed a meta-analysis of 56 meadows of Posidonia oceanica in which they tested for correlations of disturbance with genetic diversity.

© www.thelivingmed.org

© www.thelivingmed.org

Anthropogenic disturbances are the main threat to seagrass populations, but, P. oceanica  is a long-lived species. Past climate change may generate complex phylogeographic patterns that might result in

particular vulnerabilities under rapidly changing environmental stress.

Moreover, the longevity of species, like P. oceanica, can result in a temporal mismatch. In other words, a meadow may be characterized as healthy, but the allelic diversity may be slowly deteriorating.  
The authors advocate the necessity of placing genetic estimates from a single meadow in the context of a meta-population. The ability to sample at fine-scales and combine these data with connectivity matrices will be the way forward and enable an

understanding [of] the causes behind and evolutionary meaning of genetic diversity metrics for application in conservation management.

Hughes AR, Stachowicz JJ (2004) Genetic diversity enhances the resistance of a seagrass ecosystem to disturbance. PNAS, 101, 8998-9002.
Jahnke M, Olsen JL, Procaccini G (2015) A meta-analysis reveals a postive correlation between genetic diversity metrics and environmental status in the long-lived seagrass Posidonia oceanica. dpi: 10.1111/mec.13174
Reusch TBH, Ehlers A, Hämmerli A, Worm B (2005) Ecosystem recovery after climatic extremes enhanced by genotypic diversity. PNAS, 102, 2826-2831.

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