Severino G. Salmo

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

BackgroundMangrove 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.ResultsOur 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.ConclusionsOur 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.

Bruguiera hainesii, a critically endangered mangrove species, is a hybrid between B. cylindrica and B. gymnorhiza (Rhizophoraceae)

Bruguiera hainesii (Rhizophoraceae) is one of the two Critically Endangered mangrove species listed in the IUCN Red List of Threatened Species. Although the species is vulnerable to extinction, its genetic diversity and the evolutionary relationships with other Bruguiera species are not well understood. Also, intermediate morphological characters imply that the species might be of hybrid origin. To clarify the genetic relationship between B. hainesii and other Bruguiera species, we conducted molecular analyses including all six Bruguiera species using DNA sequences of two nuclear genes (CesA and UNK) and three chloroplast regions (intergenic spacer regions of trnL-trnF, trnS-trnG and atpB-rbcL). For nuclear DNA markers, all nine B. hainesii samples from five populations were heterozygous at both loci, with one allele was shared with B. cylindrica, and the other with B. gymnorhiza. For chloroplast DNA markers, the two haplotypes found in B. hainesii were shared only by B. cylindrica. These results suggested that B. hainesii is a hybrid between B. cylindrica as the maternal parent and B. gymnorhiza as the paternal one. Furthermore, chloroplast DNA haplotypes found in B. hainesii suggest that hybridization has occurred independently in regions where the distribution ranges of the parental species meet. As the IUCN Red List of Threatened Species currently excludes hybrids (except for apomictic plant hybrids), the conservation status of B. hainesii should be reconsidered.

Development and characterization of 15 polymorphic microsatellite loci in Sonneratia alba (Lythraceae) using next-generation sequencing

A set of 15 new microsatellite loci was developed and characterized for the widespread mangrove tree species Sonneratia alba (Lythraceae) by using next-generation sequencing. Forty-eight S. alba samples from seven populations in the Indo-West Pacific region were genotyped; all loci were polymorphic, with the number of alleles ranging from three to eight. The mean observed heterozygosity per locus was 0.21 for a population from Sabah, Malaysia. No null allele or significant linkage disequilibrium was detected, indicating the robustness of the markers. Only one locus (SA103) showed deviation from Hardy–Weinberg equilibrium. As characterization of these microsatellite loci was done with samples covering most of the species’ distribution range, the markers can be applied to genetic diversity studies over the broad geographical range of the species.

Isolation and characterization of 14 microsatellite markers for Rhizophora mucronata (Rhizophoraceae) and their potential use in range-wide population studies

A set of 14 new microsatellite markers was developed for mangrove species Rhizophora mucronata (Rhizophoraceae) by using pyrosequencing. Fifty-six samples from 9 populations of R. mucronata in the Indo-West Pacific region were genotyped; all loci were polymorphic, with the number of alleles ranging from 2 to 9. The mean expected heterozygosity per locus was 0.16 in a population from Sabah, no significant linkage disequilibrium was found among loci, and significant deviation from Hardy–Weinberg equilibrium was found in 3 loci. The polymorphic microsatellite markers with samples covering most of the species’ distribution range can be applied in genetic diversity studies covering a broad geographical range of the species.

Development of 11 polymorphic microsatellite markers for Xylocarpus granatum (Meliaceae) using next-generation sequencing technology

Human impacts have seriously damaged mangroves, and conservation of mangroves will require information on local and regional population genetic structures. Here, we report the development and polymorphism of eleven novel microsatellite markers, developed using next-generation sequencing on 56 samples of widespread mangrove species Xylocarpus granatum (Meliaceae) from nine populations across the Indo-West Pacific region. All loci were found to be polymorphic, with the number of alleles per locus ranging from four to 19. In a population from Sabah (Malaysia), the mean observed and expected heterozygosity per locus was 0.59 and 0.58, respectively. No null allele, significant linkage disequilibrium or deviation from Hardy–Weinberg equilibrium was detected among all loci. The eleven markers developed can be valuable tools to conservation genetics of this species across its distributional range.

Reach and messages of the world's largest ivory burn

Recent increases in ivory poaching have depressed African elephant populations. Successful enforcement has led to ivory stockpiling. Stockpile destruction is becoming increasingly popular, and most destruction has occurred in the last 5 years. Ivory destruction is intended to send a strong message against ivory consumption, both in promoting a taboo on ivory use and catalyzing policy change. However, there has been no effort to establish the distribution and extent of media reporting on ivory destruction events globally. We analyzed media coverage of the largest ivory destruction event in history (Kenya, 30 April 2016) across 11 nation states connected to ivory trade. We used an online-media crawling tool to search online media outlets and subjected 5 of the largest print newspapers (by circulation) in 5 nations of interest to content analysis. Most online news on the ivory burn came from the United States (81% of 1944 articles), whereas most of the print news articles came from Kenya (61% of 157 articles). Eighty-six to 97% of all online articles reported the burn as a positive conservation action, whereas 4-50% discussed ivory burning as having a negative impact on elephant conservation. Most articles discussed law enforcement and trade bans as effective for elephant conservation. There was more relative search interest globally in the 2016 Kenyan ivory burn than any other burn in 5 years. Ours is the first attempt to track the reach of media coverage relative to an ivory burn and provides a case study in tracking the effects of a conservation-marketing event.

State of the Mangroves in Southern Luzon: A Synthesis of Experiences, Lessons, and Management Recommendations

Mangrove forests were reported to provide various services commonly ranging from socio-economic to ecological services. Socio-economic services include provision of food and other products for human consumption or as a source of income. Common products are wood for charcoal or as housing material, fish, clams and shellfish; other products are honey, vinegar and traditional medicine. Aside from these products, tourism was also reported to be an additional source of income for the provinces of Marinduque, Romblon, Oriental Mindoro, Palawan, Batangas, and the National Capital Region (NCR).

Nekton communities as indicators of habitat functionality in Philippine mangrove plantations

In the present study, we investigated the changes to nekton communities with increasing mangrove forest age and relationships between nekton and the mangrove vegetation, mangrove sediments and environmental variables. The nekton community was assessed as a potential indicator for evaluating habitat functionality of mangrove planting programs. In all, 99 species from 52 families were captured, including crabs, shrimp, squid and fish. The crustacean assemblage was dominated by Portunidae and Penaeidae, whereas the fish assemblage was dominated by Atherinidae, Apogonidae, Hemirhamphidae, Tetraodontidae, Congridae, Sphyraenidae, Murraenidae, Ambassidae, Gerreidae, Clupeidae, Platycephalidae, Gobiidae, Mullidae and Plotosidae, with these families accounting for 90% of all individuals collected. The species composition, abundance and biomass of the nekton community were not significantly correlated with mangrove vegetation and sediment variables, but were significantly associated with environmental variables, particularly proximity to reef and tidal inundation. The lack of correlations suggests that the whole nekton assemblage was not a useful indicator in evaluating the progress of restoring habitat functionality in these planted mangroves. However, a significant interaction with mangrove vegetation was found for non-fish components of the nekton. As such, crustaceans, particularly of the Portunidae and Penaeidae families, were useful indicators for determining the habitat functionality of planted mangroves.

Where We Stand: A Synthesis of Status Reports of Mangroves in Northwestern Luzon

Northwestern Luzon has over 8,600 km of the Philippine shoreline, and is composed of 8 cities, 73 municipalities and 909 barangays. It is part of the northern section of the West Philippine Sea biogeographic region and is home to over 14.5 million individuals (14,240,907), around 10% of whom live in coastal areas (Table 26). Table 26. Provinces in northwestern Luzon showing the total (and % coastal population) per province