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Genetic differentiation and phylogeography of partially sympatric species complex Rhizophora mucronata Lam. and R. stylosa Griff. using SSR markers.

Wee AK, Takayama K, Chua JL, Asakawa T, Meenakshisundaram SH - BMC Evol. Biol. (2015)

Bottom Line: Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them.Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species.These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. alisonwks@xtbg.ac.cn.

ABSTRACT

Background: Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity, management units, and genetic structure. Here, we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range, by employing a suite of 20 informative nuclear SSR markers.

Results: Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids, and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata, a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait, South China Sea and Northwest Pacific Ocean). In R. stylosa, the genetic break was located more eastward, between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents, thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow.

Conclusions: Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.

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Map depicting the location of study sites. Yellow circles denote Rhizophora mucronata populations; red squares denote Rhizophora stylosa populations.
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Fig1: Map depicting the location of study sites. Yellow circles denote Rhizophora mucronata populations; red squares denote Rhizophora stylosa populations.

Mentions: To resolve these problems on the genetic distinctiveness between R. mucronata and R. stylosa, we collected both species from their entire distribution range (Figure 1, Table 1) and genotyped them with 20 rapidly-mutating nuclear microsatellite (SSR) loci. The sample collection was conducted through an unprecedented level of international collaboration among mangrove scientists, whereby field identification and sampling in every site involved both local and international representatives of the cooperative network, using a standardized sampling protocol across a large geographical area. Specifically, we aim to determine the degree of genetic distinctiveness between these two species and their respective genetic structure.Figure 1


Genetic differentiation and phylogeography of partially sympatric species complex Rhizophora mucronata Lam. and R. stylosa Griff. using SSR markers.

Wee AK, Takayama K, Chua JL, Asakawa T, Meenakshisundaram SH - BMC Evol. Biol. (2015)

Map depicting the location of study sites. Yellow circles denote Rhizophora mucronata populations; red squares denote Rhizophora stylosa populations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4389924&req=5

Fig1: Map depicting the location of study sites. Yellow circles denote Rhizophora mucronata populations; red squares denote Rhizophora stylosa populations.
Mentions: To resolve these problems on the genetic distinctiveness between R. mucronata and R. stylosa, we collected both species from their entire distribution range (Figure 1, Table 1) and genotyped them with 20 rapidly-mutating nuclear microsatellite (SSR) loci. The sample collection was conducted through an unprecedented level of international collaboration among mangrove scientists, whereby field identification and sampling in every site involved both local and international representatives of the cooperative network, using a standardized sampling protocol across a large geographical area. Specifically, we aim to determine the degree of genetic distinctiveness between these two species and their respective genetic structure.Figure 1

Bottom Line: Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them.Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species.These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. alisonwks@xtbg.ac.cn.

ABSTRACT

Background: Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity, management units, and genetic structure. Here, we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range, by employing a suite of 20 informative nuclear SSR markers.

Results: Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids, and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata, a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait, South China Sea and Northwest Pacific Ocean). In R. stylosa, the genetic break was located more eastward, between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents, thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow.

Conclusions: Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.

Show MeSH