Critically endangered Singapore freshwater crab lives in genetically isolated populations

phys.org | 6/1/2018 | Staff
hakimi308hakimi308 (Posted by) Level 4
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Researchers from NUS and National Parks Board (NParks) have established that the critically endangered Singapore freshwater crab (Johora singaporensis) does not mix or breed between different populations, and has overall low genetic diversity.

The International Union for Conservation of Nature (IUCN) considers the Singapore freshwater crab to be one of the 100 most endangered species worldwide. It is uniquely from Singapore and not found anywhere else in the world. Only a few hundred mature individuals of this pebble-sized freshwater crab are known to exist. They live in a few isolated populations in very small areas (less than 0.01 km2) within Singapore that are vital to the survival of the species. As part of the national conservation strategy formulated in 2015, one immediate concern was to establish if these crabs are experiencing inbreeding within their own isolated populations, which may cause them to lose genetic diversity.

Research - Team - Prof - Rudolf - MEIER

A research team led by Prof Rudolf MEIER from the Department of Biological Sciences and Lee Kong Chian Natural History Museum, NUS, partnering the NParks has found that the Singapore freshwater crabs from the remaining populations are indeed physically isolated and unlikely to move and breed between populations.

Presently, levels of genetic diversity are low. Cutting-edge genomic tools were used to analyse the genetic variation of the crabs for this study. The genetic information, together with their migration patterns, were compared with a more widespread and common species, the lowland freshwater crab (Parathelphusa maculata) that often lives in the same places as the Singapore freshwater crab. The researchers used 2,617 and 2,470 genome-wide SNPs (Single Nucleotide Polymorphisms, a common type of genetic variation) from the two groups of about 90 individuals each, with each group belonging to either of the two crab species mentioned above. The study also showed that the dispersal of individuals between populations for both...
(Excerpt) Read more at: phys.org
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