Mitochondrial phylogeography reveals high haplotype diversity and unique genetic lineage in Indian dugongs (Dugong dugon)

Abstract

India plays a significant role in dugong conservation by having the largest population within South Asia. The status of dugongs in India is largely unknown due to a paucity of reliable ecological data. This study generated mitochondrial control region sequences from ~10% of dugong individuals from existing populations within India. Furthermore, data generated in this study were compared with the global data to assess genetic lineages, population structure, and genetic diversity of Indian populations. Multiple analyses suggest that the Indian dugong populations are part of a single genetic cluster, comprising South Asia, North‐west Indian Ocean, and South‐west Indian Ocean populations. Despite small population size, they retain high genetic diversity with unique mitochondrial DNA haplotypes within South Asia. Within India, novel haplotypes are observed from all dugong habitats sampled, with overall high haplotype diversity (0.85 ± 0.04) but low nucleotide diversity (0.005 ± 0.001). Indian populations exhibit genetic differentiation with higher within‐population variance (63.41%) than among populations (36.59%). Two of the haplotypes observed in India are shared with Sri Lanka, implying genetic connectivity between these populations. The genetic data from Indian dugong populations provide critical insights into the identification of dugong corridors and important dugong conservation zones in India. We suggest site‐specific interventions, including the creation of new marine protected areas and boundary reorganization and expansion of other existing protected areas, to ensure population connectivity. In addition, simultaneous efforts towards seagrass meadow restoration, reduction of dugong mortalities, and community participation in dugong conservation are recommended for population recovery of this threatened marine herbivore.

Spatio-temporal analysis identifies marine mammal stranding hotspots along the Indian coastline

“…Media reporting is also often erroneous, which can further confuse species identification and stranding causes. High D. dugon strandings have been reported through focused surveys 42 and formation of volunteer networks 45 , 46 from isolated pockets of dugong distribution along the Indian coast. This absence of quality information collection on stranding events arises due to lack of appropriate facilities and trained personnel to report strandings and conduct necropsies throughout the Indian coastline.…”

Scars of hope and forewarn of a bleak future: Post-mortem findings of dugongs (Dugong dugon) belonging to a relict population in the Gulf of Kachchh, India

“…x 40.40 mm) (Fig 1 (4)). Nematode, Paradujardinia halicoris, a common endoparasite in dugongs 8,9 , and manatees 10 , was found in the stomach of the animal.…”

“…The current range of dugongs in the country is restricted to parts of the Gulf of Kachchh (Gujarat), Palk Bay, Gulf of Mannar (Tamil Nadu), and Andaman & Nicobar Islands (across the islands except for Great Nicobar). Several research advances related to the Tamil Nadu and Andaman and Nicobar Islands' dugong populations pertaining their foraging behaviour 2 , abundance 3,4 etc. There is a significant lack about the ecological background information regarding dugong population of the Gulf of Kachchh (GoK).…”

Opportunistic gut sampling indicates differential diet and plastic ingestion risk in Indian dugongs

“…Recent efforts at isolated pockets of their distribution along the Indian coastline (Gulf of Kutch in Gujarat; Gulf of Mannar and Palk Bay in Tamil Nadu; and Andaman and Nicobar Islands) have helped generate some crucial ecological data on Indian dugongs including their distribution, important habitats, genetic diversity and connectivity, threats etc. (Sivakumar & Nair, 2013; D’Souza et al, 2013; Rajpurkar et al, 2021; Srinivas et. al, 2020).…”

“…Despite a vast global distribution spanning from the east African coast to Australia (Indo-Pacific Ocean region), their populations are declining due to various human-mediated drivers (Marsh et al, 2012). These drivers include mortalities arising from fishnet entanglement, boat strikes, hunting for meat, seagrass habitat loss due to increased sedimentation and pollution (Marsh & Sobztick, 2019), which push the dugong populations towards localised extinctions (Hines et al, 2005;Pusineri et al, 2013;Srinivas et al, 2020). Dugongs employ two major feeding techniques viz; cropping and excavation of seagrasses, depending on species morphology and substratum (Wirsing, 2007;Rasheed et al, 2016;Marsh et al, 2018).…”