Genetic Structure and Phylogeography of the Leopard Cat (Prionailurus bengalensis) Inferred from Mitochondrial Genomes

Ancestry dynamics and trait selection in a designer cat breed

The Bengal cat breed was developed from intercrosses between the Asian leopard cat, Prionailurus bengalensis, and the domestic cat, Felis catus, with a last common ancestor approximately 6 million years ago. Predicted to derive ∼94% of their genome from domestic cats, regions of the leopard cat genome are thought to account for the unique pelage traits and ornate color patterns of the Bengal breed, which are similar to those of ocelots and jaguars. We explore ancestry distribution and selection signatures in the Bengal breed by using reduced representation and whole-genome sequencing from 947 cats. The mean proportion of leopard cat DNA in the Bengal breed is 3.48%, lower than predicted from breed history, and is broadly distributed, covering 93% of the Bengal genome. Overall, leopard cat introgressions do not show strong signatures of selection across the Bengal breed. However, two popular color traits in Bengal cats, charcoal and pheomelanin intensity, are explained by selection of leopard cat genes whose expression is reduced in a domestic cat background, consistent with genetic incompatibility resulting from hybridization. We characterize several selective sweeps in the Bengal genome that harbor candidate genes for pelage and color pattern and that are associated with domestic, rather than leopard, cat haplotypes. We identify the molecular and phenotypic basis of one selective sweep as reduced expression of the Fgfr2 gene, which underlies glitter, a trait desired by breeders that affects hair texture and light reflectivity.

First mitogenome phylogeny of the sun bear Helarctos malayanus reveals a deep split between Indochinese and Sundaic lineages

The sun bear Helarctos malayanus is one of the most endangered ursids, and to date classification of sun bear populations has been based almost exclusively on geographic distribution and morphology. The very few molecular studies focussing on this species were limited in geographic scope. Using archival and non-invasively collected sample material, we have added a substantial number of complete or near-complete mitochondrial genome sequences from sun bears of several range countries of the species' distribution. We here report 32 new mitogenome sequences representing sun bears from Cambodia, Thailand, Peninsular Malaysia, Sumatra, and Borneo. Reconstruction of phylogenetic relationships revealed two matrilines that diverged ~295 thousand years ago: one restricted to portions of mainland Indochina (China, Cambodia, Thailand; "Mainland clade"), and one comprising bears from Borneo, Sumatra, Peninsular Malaysia but also Thailand ("Sunda clade"). Generally recent coalescence times in the mitochondrial phylogeny suggest that recent or historical demographic processes have resulted in a loss of mtDNA variation. Additionally, analysis of our data in conjunction with shorter mtDNA sequences revealed that the Bornean sun bear, classified as a distinct subspecies (H. m. euryspilus), does not harbor a distinctive matriline. Further molecular studies of H. malayanus are needed, which should ideally include data from nuclear loci.

Mitogenome Phylogeny Including Data from Additional Subspecies Provides New Insights into the Historical Biogeography of the Eurasian lynx Lynx lynx

Previous molecular studies of the wide-ranging Eurasian lynx Lynx lynx focused mainly on its northern Palearctic populations, with the consequence that the reconstruction of this species’ evolutionary history did not include genetic variation present in its southern Palearctic distribution. We sampled a previously not considered Asian subspecies (L. l. dinniki), added published data from another Asian subspecies (L. l. isabellinus), and reassessed the Eurasian lynx mtDNA phylogeny along with previously published data from northern Palearctic populations. Our mitogenome-based analyses revealed the existence of three major clades (A: Central Asia, B: SE Europe/SW Asia, C: Europe and Northern Asia) and at least five lineages, with diversification in Lynx lynx commencing at least 28kyr earlier than hitherto estimated. The subspecies L. l. isabellinus harbors the most basal matriline, consistent with the origin of Lynx lynx in this subspecies’ current range. L. l. dinniki harbors the second most basal matriline, which is related to, and may be the source of, the mtDNA diversity of the critically endangered Balkan lynx L. l. balcanicus. Our results suggest that the Anatolian peninsula was a glacial refugium for Eurasian lynx, with previously unconsidered implications for the colonization of Europe by this species.

Phylogeography and population genetic structure of red muntjacs: evidence of enigmatic Himalayan red muntjac from India

BACKGROUND

Identifying factors shaping population genetic structure across continuous landscapes in the context of biogeographic boundaries for lineage diversification has been a challenging goal. The red muntjacs cover a wide range across multiple vegetation types, making the group an excellent model to study South and Southeast Asian biogeography. Therefore, we analysed mitogenomes and microsatellite loci, confirming the number of red muntjac lineages from India, gaining insights into the evolutionary history and phylogeography of red muntjacs.

RESULTS

Our results indicated the Northwestern population of red muntjac or the Himalayan red muntjac (M. aureus) in India as genetically diverse and well-structured, with significant genetic differentiation implying a low level of gene flow. The phylogenetic, population genetic structure, as well as species delimitation analyses, confirm the presence of the lineage from Western Himalayan in addition to the previously identified red muntjac lineages. Relatively low genetic diversity was observed in M. aureus compared to M. vaginalis, M. malabaricus and M. muntjak. The M. aureus and M. vaginalis lineages have split during the late Pleistocene, ~ 1.01 million years ago (Mya), making M. aureus the youngest lineage; whereas, M. malabaricus split earlier, ~ 2.2 Mya and appeared as the oldest lineage among red muntjacs.

CONCLUSIONS

Pronounced climate fluctuations during the Quaternary period were pivotal in influencing the current spatial distribution of forest-dwelling species' restriction to Northwestern India. Our finding confirms the distinct Himalayan red muntjac (M. aureus) within the red muntjac group from Northwestern India that should be managed as an Evolutionary Significant Unit (ESU). We recommend a reassessment of the conservation status of red muntjacs for effective conservation and management.

Evolutionary history of Carnivora (Mammalia, Laurasiatheria) inferred from mitochondrial genomes

The order Carnivora, which currently includes 296 species classified into 16 families, is distributed across all continents. The phylogeny and the timing of diversification of members of the order are still a matter of debate. Here, complete mitochondrial genomes were analysed to reconstruct the phylogenetic relationships and to estimate divergence times among species of Carnivora. We assembled 51 new mitogenomes from 13 families, and aligned them with available mitogenomes by selecting only those showing more than 1% of nucleotide divergence and excluding those suspected to be of low-quality or from misidentified taxa. Our final alignment included 220 taxa representing 2,442 mitogenomes. Our analyses led to a robust resolution of suprafamilial and intrafamilial relationships. We identified 21 fossil calibration points to estimate a molecular timescale for carnivorans. According to our divergence time estimates, crown carnivorans appeared during or just after the Early Eocene Climatic Optimum; all major groups of Caniformia (Cynoidea/Arctoidea; Ursidae; Musteloidea/Pinnipedia) diverged from each other during the Eocene, while all major groups of Feliformia (Nandiniidae; Feloidea; Viverroidea) diversified more recently during the Oligocene, with a basal divergence of Nandinia at the Eocene/Oligocene transition; intrafamilial divergences occurred during the Miocene, except for the Procyonidae, as Potos separated from other genera during the Oligocene.

Mitochondrial DNA Profiling Reveals Two Lineages of Sun Bears in East and West Malaysia

Sun bear populations are fragmented and at risk from habitat loss and exploitation for body parts. These threats are made worse by significant gaps in knowledge of sun bear population genetic diversity, population connectivity, and taxonomically significant management units. Using a complete sun bear mitochondrial genome, we developed a set of mitochondrial markers to assess haplotype variation and the evolutionary history of sun bears from Peninsular (West) Malaysia and Sabah (East Malaysia). Genetic samples from 28 sun bears from Peninsular Malaysia, 36 from Sabah, and 18 from Thailand were amplified with primers targeting a 1800 bp region of the mitochondrial genome including the complete mitochondrial control region and adjacent genes. Sequences were analyzed using phylogenetic methods. We identified 51 mitochondrial haplotypes among 82 sun bears. Phylogenetic and network analyses provided strong support for a deep split between Malaysian sun bears and sun bears in East Thailand and Yunnan province in China. The Malaysian lineage was further subdivided into two clades: Peninsular Malaysian and Malaysian Borneo (Sabah). Sun bears from Thailand occurred in both Sabah and Peninsular Malaysian clades. Our study supports recent findings that sun bears from Sundaland form a distinct clade from those in China and Indochina with Thailand possessing lineages from the three clades. Importantly, we demonstrate a more recent and clear genetic delineation between sun bears from the Malay Peninsula and Sabah indicating historical barriers to gene flow within the Sundaic region.

Closely related species show species-specific environmental responses and different spatial conservation needs: Prionailurus cats in the Indian subcontinent

Phylogenetically closely related species are often assumed to have similar responses to environmental conditions, but species-specific responses have also been described. These two scenarios may have different conservation implications. We tested these two hypotheses for Prionailurus cats (P. rubiginosus, P. bengalensis, P. viverrinus) in the Indian subcontinent and show its implications on species current protected area coverage and climatic suitability trends through time. We fitted ecological niche models with current environmental conditions and calculated niche overlap. In addition, we developed a model for the Jungle Cat Felis chaus to compare species responses and niche overlap estimates within Prionailurus with those for a related sympatric small cat species. Then we estimated the proportion of current suitable environment covered by protected area and projected climatic models from past (last interglacial) to future (2070; RCP4.5 and RCP8.5) conditions to show implications on population management and conservation. The hypothesis of a similar response and niche overlap among closely related species is not supported. Protected area coverage was lowest for P. viverrinus (mean = 0.071, SD = 0.012) and highest for P. bengalensis (mean = 0.088, SD = 0.006). In addition, the proportion of the subcontinent with suitable climate varied through time and was species-specific. For P. bengalensis, climatic suitability shrunk since at least the mid-Holocene, a trend that can be intensified by human-induced climate warming. Concerning P. viverrinus, most predictions show stable future climatic suitability, but a few indicated potential loss. Climatic suitability for P. rubiginous was predicted to remain stable but the species exhibited a negative association with intensive agriculture. Similar responses to environmental change by phylogenetically closely related species should not be assumed and have implications on protected area coverage and natural trends of species climatic suitability over time. This should be taken into account during conservation and management actions.

Genetic Diversity and Genetic Structure of the Wild Tsushima Leopard Cat from Genome-Wide Analysis

Simple Summary

The Tsushima leopard cat, Prionailurus bengalensis euptilurus, is a small regional population of the Amur leopard cat and is only found on Tsushima Island in Japan. A breeding program will require adequate information on parentage, kinship, and inbreeding for this population. Hence, there is an urgent need to develop this information in order to conserve the population and its genetic diversity. We performed GRAS-Di analysis to investigate the genetic diversity and genetic structure of the Tsushima leopard cat. We identified between 133 and 158 single-nucleotide polymorphism (SNP) markers in three different genotyping methods. These SNP markers can be used in identification of individuals and parentage. In addition, structure analysis using these markers demonstrated the similar genetic composition of the samples from 48 Tsushima leopard cats, and indicated Tsushima leopard cats have no subpopulations. We have provided genetic markers that are useful for conservation of the Tsushima leopard cat, such as individual identification and parentage. Moreover, we have also clarified units for conservation of the Tsushima leopard cat population from structure analysis.

Abstract

The Tsushima leopard cat (Prionailurus bengalensis euptilurus) lives on Tsushima Island in Japan and is a regional population of the Amur leopard cat; it is threatened with extinction. Its genetic management is important because of the small population. We used genotyping by random amplicon sequencing-direct (GRAS-Di) to develop a draft genome and explore single-nucleotide polymorphism (SNP) markers. The SNPs were analyzed using three genotyping methods (mapping de novo, to the Tsushima leopard cat draft genome, and to the domestic cat genome). We examined the genetic diversity and genetic structure of the Tsushima leopard cat. The genome size was approximately 2.435 Gb. The number of SNPs identified was 133–158. The power of these markers was sufficient for individual and parentage identifications. These SNPs can provide useful information about the life of the Tsushima leopard cat and the pairings and for the introduction of founders to conserve genetic diversity with ex situ conservation. We identified that there are no subpopulations of the Tsushima leopard cat. The identifying units will allow for a concentration of efforts for conservation. SNPs can be applied to the analysis of the leopard cat in other regions, making them useful for comparisons among populations and conservation in other small populations.

The Tsushima leopard cat exhibits extremely low genetic diversity compared with the Korean Amur leopard cat: Implications for conservation

We examined genetic diversity of the wild Tsushima leopard cat-a regional population of the Amur leopard cat-using microsatellite markers. In addition, we compared genetic diversity of the Tsushima leopard cat with that of the Korean population of Amur leopard cat. Although bias should be considered when applying cross-species amplification, the Tsushima leopard cat showed a lower index of molecular genetic diversity than did the Korean population. These results were consistent with those obtained using other genetic markers, such as mitochondrial DNA and Y chromosome sequences. This low genetic diversity of the wild Tsushima leopard cat may be derived from the founding population. Furthermore, our results suggest that the captive populations held in Japanese zoos may show extremely low genetic diversity, leading to difficulties in genetic management of the Tsushima leopard cat. Moreover, the two regional populations were clearly separated using these marker sets. In the present study, we demonstrated that the genetic diversity of the Tsushima leopard cat is extremely low compared with that of the continental regional population. Importantly, the Japanese captive population for ex situ conservation was derived from a founding population with extremely low genetic diversity; hence, we assume that both the captive and wild populations showed extremely low genetic diversities. Our findings emphasize the need to develop carefully considered management strategies for genetic conservation.

Historical biogeography of the leopard (Panthera pardus) and its extinct Eurasian populations

Background

Resolving the historical biogeography of the leopard (Panthera pardus) is a complex issue, because patterns inferred from fossils and from molecular data lack congruence. Fossil evidence supports an African origin, and suggests that leopards were already present in Eurasia during the Early Pleistocene. Analysis of DNA sequences however, suggests a more recent, Middle Pleistocene shared ancestry of Asian and African leopards. These contrasting patterns led researchers to propose a two-stage hypothesis of leopard dispersal out of Africa: an initial Early Pleistocene colonisation of Asia and a subsequent replacement by a second colonisation wave during the Middle Pleistocene. The status of Late Pleistocene European leopards within this scenario is unclear: were these populations remnants of the first dispersal, or do the last surviving European leopards share more recent ancestry with their African counterparts?

Results

In this study, we generate and analyse mitogenome sequences from historical samples that span the entire modern leopard distribution, as well as from Late Pleistocene remains. We find a deep bifurcation between African and Eurasian mitochondrial lineages (~ 710 Ka), with the European ancient samples as sister to all Asian lineages (~ 483 Ka). The modern and historical mainland Asian lineages share a relatively recent common ancestor (~ 122 Ka), and we find one Javan sample nested within these.

Conclusions

The phylogenetic placement of the ancient European leopard as sister group to Asian leopards suggests that these populations originate from the same out-of-Africa dispersal which founded the Asian lineages. The coalescence time found for the mitochondrial lineages aligns well with the earliest undisputed fossils in Eurasia, and thus encourages a re-evaluation of the identification of the much older putative leopard fossils from the region. The relatively recent ancestry of all mainland Asian leopard lineages suggests that these populations underwent a severe population bottleneck during the Pleistocene. Finally, although only based on a single sample, the unexpected phylogenetic placement of the Javan leopard could be interpreted as evidence for exchange of mitochondrial lineages between Java and mainland Asia, calling for further investigation into the evolutionary history of this subspecies.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1268-0) contains supplementary material, which is available to authorized users.