Crash of a living fossil: conservation genetic assessment for horseshoe crabs around East Asia

The horseshoe crab, a living fossil, is a marine species that has lived on earth for more than 400 million years. Three of four species horseshoe crabs distributed in Asia were under long-term stress due to coastal... [ view full abstract ]

The horseshoe crab, a living fossil, is a marine species that has lived on earth for more than 400 million years. Three of four species horseshoe crabs distributed in Asia were under long-term stress due to coastal development, marine pollution and over-harvest. The conservation assessments for their population and habitat are evaluated by IUCN SSC horseshoe crab specialist group. Otherwise, loss of genetic variation within a species may affects its ability to adapt to changing environmental conditions but currently lacks explicit considerations of range-widegenetic condition in conservation assessments. 

In this study, population demography, habitat and genetic condition of horseshoe crab in Asia were compared. Generally, the populations with related higher genetic diversity were found in south east Asia compared to northwestern Pacific area. The full loss of genetic diversity were found in some populations in Taiwan and Japan due to population crash. Temporal haplotypes shift and loss of genetic connectivity in T. tridentatus at Kinmen were also found due to construction of port through a 13 years genetic data tracked from 2002 to 2014. Marine protected area network can also be designed based on genetic connectivity along China coast. 

Long term and regional scale population monitoring are not easily applied on each locations, but conservation genetic assessment may make a contribution on broader view of population status.