Widespread hybridization in the introduced hog deer population of Victoria, Australia, and its implications for conservation

Abstract

In Australia, many species have been introduced that have since undergone drastic declines in their native range. One species of note is the hog deer (Axis porcinus) which was introduced in the 1860s to Victoria, Australia, and has since become endangered in its native range throughout South‐East Asia. There is increased interest in using non‐native populations as a source for genetic rescue; however, considerations need to be made of the genetic suitability of the non‐native population. Three mitochondrial markers and two nuclear markers were sequenced to assess the genetic variation of the Victorian population of hog deer, which identified that the Victorian population has hybrid origins with the closely related chital (Axis axis), a species that is no longer present in the wild in Victoria. In addition, the mitochondrial D‐loop region within the Victorian hog deer is monomorphic, demonstrating that mitochondrial genetic diversity is very low within this population. This study is the first to report of long‐term persistence of hog deer and chital hybrids in a wild setting, and the continual survival of this population suggests that hybrids of these two species are fertile. Despite the newly discovered hybrid status in Victorian hog deer, this population may still be beneficial for future translocations within the native range. However, more in‐depth analysis of genetic diversity within the Victorian hog deer population and investigation of hybridization rates within the native range are necessary before translocations are attempted.

Population genomics of free‐ranging Great Plains white‐tailed and mule deer reflects a long history of interspecific hybridization

“…Hybridization has been found to be relatively common between ungulate species, in large part due to detection using increasingly complex nuclear datasets, and often in combination with mtDNA that can highlight discordant genealogies, a common signature of interspecific gene flow (Hill, Linacre, et al, 2019;Hill, Havird, et al, 2019;Iacolina et al, 2019) Given the consistency of these results, we hypothesize that some sorting mechanism exists within the exome where critical functional genomic elements must remain true to species assignment through inheritance, and unfit allele combinations as a result of hybridization are purged. If so, this would indicate strong directional selective pressure on hybrids.…”

Bayesian modelling reveals differences in long-term trends in the harvest of native and introduced species by recreational hunters in Australia

“…However, in effect only the first three species are hunted because there are no wild populations of chital and rusa deer now present in Victoria. Hog deer (Axis porcinus) (Hill et al 2019) can only be hunted during April and only one male and one female may be taken by each hunter during the regulated season. Limited balloting allows selected hunters to take small numbers outside the April season.…”

Genetic analysis of hog deer (Axis porcinus) in Victoria, Australia, and its applications to invasive species and game management

“…The 'Snake Island' cluster, comprising all samples from Snake Island as well as individuals from Stratford and Loch Sport, showed very strong genetic differentiation to all other sampling sites in Victoria. No private alleles were observed in the Snake Island population, and previous research did not reveal any differences in mitochondrial or nuclear sequences when compared to other populations (Hill et al 2019). This observed genetic difference may be due to Snake Island being one of the initial hog deer release sites, undergoing a separate founder event and consequent genetic drift due to the long-lasting isolation from the mainland populations.…”

“…Assessment of the impacts of sustained harvesting in sites managed as game reserves, and historical hybridisation between hog deer and chital are also of interest, particularly in measurements of genetic diversity. Previous research has shown that hog deer hybridised with chital very early in the initial introduction of the species, with all hog deer tested comprising a chital mitochondrial haplotype, and analysis of mitochondrial DNA revealed local populations of hog deer to be monomorphic at the D-loop region (Hill et al 2019), suggesting diversity is very low in Victorian hog deer. The low levels of diversity at this mitochondrial region are likely due to founder effects and may be reflective of chital diversity at the time of hybridisation rather than hog deer.…”

“…Previous research has shown that genetic analysis using short tandem repeats (STRs) is effective at identifying invasion pathways, population connectivity, human mediated dispersal, and genetic variation in introduced populations of invasive species (Walker et al 2003;Rollins et al 2009;Yue et al 2010;LaRue et al 2011), and these markers are likely to be more informative than the mitochondrial markers that have been used in the past for hog deer (Hill et al 2019). Knowledge of dispersal and illegal translocation of hog deer can assist in invasive species management and will provide insight into the impact that natural dispersal and illegal translocations may have on the management of this species.…”