Kinship and genetic diversity of the Critically Endangered giant shovelnose ray (Glaucostegus typus) in the eastern Indian Ocean

In this study, single nucleotide polymorphisms (SNPs) were used to investigate kinship, genetic diversity and inbreeding within a globally significant area for the Critically Endangered giant shovelnose ray, Glaucostegus typus (Anonymous [Bennett] 1830). Sampling for G. typus was conducted in the eastern Indian Ocean, along an expansive (~ 1000 km) stretch of the Western Australian coastline. Single-read sequencing was performed using a Glaucostegus DArTseq™ platform, with a high-density assay of 2.5 million sequence reads. Kinship, genetic diversity and inbreeding were investigated for G. typus using between 564 and 4126 SNPs. Four full and four half sibling dyads were detected amongst 90 genotyped G. typus, including one pair of half siblings separated by > 600 km of coastline, providing evidence of long-distance, likely parental, movement. Observed heterozygosity (H_O = 0.29–0.30) and gene diversity (H_S = 0.32–0.33) were relatively low compared to other rays, although a lack of previous studies using SNP data may reduce the effectiveness of comparisons. Moderate levels of inbreeding were detected at each site (F_IS = 0.07–0.13) and across all sites, combined (F_IS = 0.09). Long-distance movement of G. typus between sampled assemblages reduces the risk of localised extinctions across the study area; additional work is required to determine whether the sampled assemblages are genetically distinct from one another, as well as other G. typus populations throughout its Indo-West Pacific range.