Planted mangroves reflect low genetic diversity of natural stands in Southern Cameroon
In: Forest Ecology and Management. Elsevier/Elsevier Science: Amsterdam; Lausanne; New York; Oxford; Shannon; Tokyo. ISSN 0378-1127; e-ISSN 1872-7042, more
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| Author keywords |
Ecosystem restoration;Revegetation;Planted mangroves;Resilience;Restoration genetics;Conservation genetics;Mangrove rehabilitation;Restoration practices;effective population-size;linkage disequilibrium;allele frequency;computer-program;r-package;n-e;restoration;software;forests;rescue |
| Abstract |
Planting is a common mangrove restoration practice. Yet, evidence from increasing planting failure rates around the globe emphasize the need for initial assessments and planning to determine which restoration strategies are appropriate for any given region. When and where planting is necessary, sourcing seedlings to maximize genetic diversity is crucial for the resilience of restored sites to environmental perturbations. Our primary objective was to assess how genetic diversity at restored sites compared to natural sites and to determine the origin of propagules used in restoration. In many grassroots restoration projects, it may be easier to source propagules from a few local founders, which will make restored sites genetically depauperated. To investigate this hypothesis, we genotype 189 individuals from three Rhizophora racemosa mangrove plantations and compared them to 108 individuals from four natural sites in southern Cameroon, using 10 microsatellite markers. Our results show similarly low levels of genetic diversity in natural and planted sites, which impeded individual-level assignments of planted individuals. Such low levels of genetic diversity coupled to low relatedness, and low kinship coefficients (FIJ), suggests propagules used in planting may have originated from multiple mother trees from nearby natural sites; as supported by structure analyses. Small effective population sizes (Ne), evidence of recent bottlenecks, and loci deviation from Hardy Weinberg expectations indicate genetic drift at play in the planted sites. Locally sourcing germplasm usually is a low-risk and high-reward approach. Nevertheless, to augment genetic diversity, a cautious approach to 'genetic rescue' may be explored. |
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