Abstract
Vital for many marine and terrestrial species, and several other environmental services, such as carbon sink areas, the mangrove ecosystem is highly threatened due to the proximity of large urban centers and climate change. The forced fragmentation of this ecosystem affects the genetic diversity distribution among natural populations. Moreover, while restoration efforts have increased, few studies have analyzed how recently-planted areas impact the original mangrove genetic diversity. We analyzed the genetic diversity of two mangroves species (Laguncularia racemosa and Avicennia schaueriana) in three areas in Brazil, using inter-simple sequence repeat (ISSR) markers. Using the local approach, we identified the genetic diversity pool of a restored area compared to nearby areas, including the remnant plants inside the restored area, one well-conserved population at the shore of Guanabara Bay, and one impacted population in Araçá Bay. The results for L. racemosa showed that the introduced population has lost genetic diversity by drift, but remnant plants with high genetic diversity or incoming propagules could help improve overall genetic diversity. Avicennia schaueriana showed similar genetic diversity, indicating an efficient gene flow. The principal component analysis showing different connections between both species indicate differences in gene flow and dispersal efficiencies, highlighting the needed for further studies. Our results emphasize that genetic diversity knowledge and monitoring associated with restoration actions can help avoid bottlenecks and other pitfalls, especially for the mangrove ecosystem.
Highlights
The mangrove forests are widely distributed in the tropical and subtropical areas of the world, where they occupy muddy intertidal environments [1]
The GST was high for Lumnitzera racemosa, a sister species of the Indo-Pacific mangroves assessed with the same markers, in the South China Sea (0.337) and in the East Indian Ocean (0.402) [47]; our work focused on a more limited area, which is very alarming for the conservation of Laguncularia racemosa in the southeastern region of Brazil
Genetic diversity studies are important to measure the success of environmental restoration, during or after restoration, and before, in order to identify new and better strategies for genetic enrichment and avoid unwanted effects due to genetic drift, such as bottlenecks and the founder effect
Summary
The mangrove forests are widely distributed in the tropical and subtropical areas of the world, where they occupy muddy intertidal environments [1]. They are one of the most important ecosystems globally, and serve as nurseries for many marine and terrestrial species [2]. Diversity 2018, 10, 27 and fauna, is an important source and sink for sediments, organic matter and nutrients [1]. It is among the most carbon-rich biomes, being important in the atmospheric carbon sequestration/capture [5,6]. Up to 70 true mangrove species worldwide belong to 17 families, of which 11 species qualified for a Red List threatened category, according to different classifications [11,12]
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