Demographic and genetic structure of a severely fragmented population of the endangered hog deer (Axis porcinus) in the Indo-Burma biodiversity hotspot

Introduction The hog deer (Axis porcinus) is an ‘endemic’ species, geographically confined to South and Southeast Asia. There are two subspecies—the Southeast Asian subspecies (A. p. annamiticus) and the Indian subspecies (A. p. porcinus). The Southeast Asian subspecies originally occurred in Thailand, China, Laos PDR, Vietnam and Cambodia whereas the Indian subspecies occurred in India, Nepal, Bangladesh, Bangladesh and Burma [1]. It was once widespread, but the population has declined rapidly across its geographic range. It is estimated that the global decline rate over the last 21 years is 50% and that the species has declined by more than 90% within its Southeast Asian range [2]. The species has completely disappeared from Thailand, Laos and Vietnam [2]. In India, the species is distributed throughout the northern plains and in the Northeast region [3]. The latter has emerged as a stronghold for the species, with large local subpopula- tions in Assam and West Bengal [4] and in Manipur, where a small, secure subpopulation sur- vives [5, 6]. Nevertheless, the species is estimated to have undergone a decline of 30–40% or more in the country over the last 21 years [7]. On the basis of these estimates (the average for the species in three generations), the species has been listed as “Endangered” in the IUCN Red List [7]. Hunting, habitat loss and habitat degradation have been the major drivers of the decline [2]. The extant population is now patchily distributed and highly fragmented [8]. The relict populations are found in low alluvial

grasslands in the Brahmaputra flood plains and in Nepal, Bangladesh and Southwest Yunnan Province, in China [2], and are probably suffering from inbreeding depression [9, 10]. Phylogenetic analysis using both the mitochondrial and the nuclear DNA suggests that the hog deer belongs to the subfamily Cervinae [11]. Little empirical information is available on the ecology and conservation genetics of this species. In order to design successful and effective conservation strategies for this species, information about its genetic variability and structure is crucial. Northeast India is particularly significant in terms of the lineage and genetic diversity of the hog deer, being a stronghold of the species [4] and possibly holding a link between the Indian subspecies and the Southeast Asian subspecies. The localised and isolated hog deer populations in the state of Manipur are not well studied, and, therefore, little is known about the status of these populations and their genetic structure. Recent studies have also revealed that the hog deer population in Keibul Lamjao National Park, Manipur is the Southeast Asian subspecies (A. p. annamiticus) [12]. Isolated populations such as these are likely to be more vulnerable to local extinction because they are at higher risk of genetic, demographic and environmental sto- chasticity [10, 13, 14, 15]. Understanding the population dynamics of any species requires a combination of demographic, genetic and ecological studies. The effective population size and

the number of individuals that actually contribute to the gene pool are key factors in the dynamics [16]. In view of the aforementioned, this research was carried out to examine the demographic status and genetic structure of the hog deer in Keibul Lamjao National Park (KLNP), Manipur, India. Materials and methods Study area The study was conducted in KLNP, Manipur, India, located on the south-eastern fringes of Loktak Lake, which is also a Ramsar site [17]. KLNP extends between latitudes 24˚270N and 24˚310N and longitudes 93˚530E and 93˚550E, in the Barak-Chindwin river basin. Loktak Lake is a wetland of international importance (Ramsar site) [18]. Presently the park has an extent of Demographic and genetic structure of hog deer in the Indo-Burma biodiversity hotspot PLOS ONE | https://doi.org/10.1371/journal.pone.0210382 February 6, 2020 2 / 16 decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.