Tigers of Sundarbans in India: is the population a separate conservation unit?
The Sundarbans tiger inhabits a unique mangrove habitat and are morphologically distinct from the recognized tiger subspecies in terms of skull morphometrics and body size. Thus, there is an urgent need to assess their ecological and genetic distinctiveness and determine if Sundarbans tigers should be defined and managed as separate conservation unit. We utilized nine microsatellites and 3 kb from four mitochondrial DNA (mtDNA) genes to estimate genetic variability, population structure, demographic parameters and visualize historic and contemporary connectivity among tiger populations from Sundarbans and mainland India. We also evaluated the traits that determine exchangeability or adaptive differences among tiger populations. Data from both markers suggest that Sundarbans tiger is not a separate tiger subspecies and should be regarded as Bengal tiger (P. t. tigris) subspecies. Maximum likelihood phylogenetic analyses of the mtDNA data revealed reciprocal monophyly. Genetic differentiation was found stronger for mtDNA than nuclear DNA. Microsatellite markers indicated low genetic variation in Sundarbans tigers (He= 0.58) as compared to other mainland populations, such as northern and Peninsular (Hebetween 0.67- 0.70). Molecular data supports migration between mainland and Sundarbans populations until very recent times. We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries. Demographic analyses suggest that Sundarbans tigers have diverged recently from peninsular tiger population within last 2000 years. Sundarbans tigers are the most divergent group of Bengal tigers, and ecologically non-exchangeable with other tiger populations, and thus should be managed as a separate "evolutionarily significant unit" (ESU) following the adaptive evolutionary conservation (AEC) concept.
Department of Biology, University of Oulu, Oulu, Finland; Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Dehradun, India.
Sujeet Kumar
SK
Singh
Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Dehradun, India.
Sudhanshu
S
Mishra
Department of Biology, University of Oulu, Oulu, Finland.
Jouni
J
Aspi
Department of Biology, University of Oulu, Oulu, Finland.
Laura
L
Kvist
Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Dehradun, India.
Parag
P
Nigam
Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Dehradun, India.
Puneet
P
Pandey
Population and Conservation Genetics, Instituto Gulbenkian de Ciência, Rua da Quinta, 6, P-2780-156, Oeiras, Portugal.
Reeta
R
Sharma
Department of Animal Ecology and Conservation Biology, Wildlife Institute of India, Dehradun, India.
Surendra Prakash
SP
Goyal
D000220:Adaptation, Biological; D000818:Animals; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000032:analysis; D019143:Evolution, Molecular; D051456:Gene Flow; D014644:Genetic Variation; D007194:India; D018895:Microsatellite Repeats; D010802:Phylogeny; D058974:Phylogeography; D011157:Population Dynamics; D046010:Tigers / Q000145:classification / Q000235:genetics* / Q000502:physiology
D004272:DNA, Mitochondrial