Genomics Reveals Complex Population History and Unexpected Diversity of Eurasian Otters (Lutra lutra) in Britain Relative to Genetic Methods

Epidemiological and genotypic assessment of cystic echinococcosis in ruminant populations of Northern Punjab, Pakistan: a neglected zoonotic disease

Echinococcus granulosus is a zoonotic dog parasite, which causes cystic echinococcosis in humans and animals, adversely affecting health and food production. The resultant socio-economic impacts in lower-middle-income countries and the paucity of epidemiology data prompted the World Health Organization to classify cystic echinococcosis as a neglected tropical disease. Between November 2019 and December 2020, the prevalence of cystic echinococcosis was assessed from 3600 post-slaughter livestock (1142 sheep, 1258 goats and 1200 buffalo) from three districts, Narowal, Sheikhupura and Sialkot, in Northern Punjab, Pakistan. The collected hydatid cysts were subjected to microscopy and PCR followed by Sanger sequencing and phylogenetic analysis. A questionnaire targeted 3600 animal owners to assess disease risk factors. Of the 28 cyst samples sequenced for mtDNA COI, the species was confirmed as Echinococcus granulosus and phylogenetic analysis revealed the presence of both G1 and G3 lineages. Overall, we noted a regional difference in prevalence, where infections were significantly higher in Sheikhupura (9.8%) than Sialkot (6.1%) or Narowal (5.9%) districts. Prevalence was higher in buffalo (9.3%) than sheep (7%) or goats (5.5%), significantly higher (9.3%) in older (> 4 years) compared to younger (< 4 years) animals (5.7%) and higher in females (9.1%) compared to males (3.8%). In sheep and buffalo, more cysts were found in the liver (77.7% and 68.7%, respectively), whereas the lungs were more commonly infected in goats (67.1%). Epidemiological data revealed that combining dog deworming with effective disposal of viscera is needed for a significant reduction in infection prevalence. Similarly, animal deworming was only associated with significantly reduced infections when the animals were not kept near an abattoir, where dogs would normally be present and feeding on discarded viscera. This study adds to growing evidence that simple public health measures and awareness are needed to reduce the prevalence of cystic echinococcosis infection.

Spatio-Temporal Changes in Effective Population Size in an Expanding Metapopulation of Eurasian Otters

Conservation efforts are leading to demographic growth and spatial expansion of some previously endangered species. However, past population bottlenecks or population size fluctuations can have lasting effects on effective population size (N e), even when census size (N c) appears large or recovered. The UK metapopulation of Eurasian otters (Lutra lutra) has a well-documented history of population recovery over recent decades, with indicators of presence (faeces and footprints) increasing in distribution and number over successive national surveys. To determine whether this increase in N c is reflected in increased N e, we analysed a large-scale microsatellite dataset (21 years: 1993-2014; 407 individuals) for signals of recent N e change using BOTTLENECK and LDNe, and evaluated potential biases associated with unaccounted spatial genetic structuring and inclusion of admixed genotypes. We obtained clear bottleneck signals in East England, and signals of recent population expansion in Wales and South West England in some analyses, consistent with national otter surveys and recent findings from whole-genome sequencing. Analyses that did not account for spatial genetic structuring yielded strong spurious signals of United Kingdom-wide population expansion, and N e estimates from these analyses were suppressed by a factor of 3-4. Inclusion of admixed individuals had weaker impacts on N e estimates, with overlapping 95% confidence intervals from different analyses. Notably, total N e summed across regions was small and well below the N e = 500 size deemed necessary for long-term population viability (sum of river basin district groups: 170.6, 95% C.I.: 102.1-348.3). Conclusions drawn from UK otter surveys, which had suggested a robust population close to panmixia, are therefore not supported by our genetic evidence. Our study highlights the value of including genetic monitoring of endangered or recovering species in monitoring plans, while also providing methodologically important information about N e estimation from real-world datasets.

Haplotype-resolved genome and population genomics of the threatened garden dormouse in Europe

Genomic resources are important for evaluating genetic diversity and supporting conservation efforts. The garden dormouse (Eliomys quercinus) is a small rodent that has experienced one of the most severe modern population declines in Europe. We present a high-quality haplotype-resolved reference genome for the garden dormouse, and combine comprehensive short and long-read transcriptomics data sets with homology-based methods to generate a highly complete gene annotation. Demographic history analysis of the genome reveal a sharp population decline since the last interglacial, indicating an association between colder climates and population declines before anthropogenic influence. Using our genome and genetic data from 100 individuals, largely sampled in a citizen-science project across the contemporary range, we conduct the first population genomic analysis for this species. We find clear evidence for population structure across the species' core Central European range. Notably, our data show that the Alpine population, characterized by strong differentiation and reduced genetic diversity, is reproductively isolated from other regions and likely represents a differentiated evolutionary significant unit (ESU). The predominantly declining Eastern European populations also show signs of recent isolation, a pattern consistent with a range expansion from Western to Eastern Europe during the Holocene, leaving relict populations now facing local extinction. Overall, our findings suggest that garden dormouse conservation may be enhanced in Europe through the designation of ESUs.

Exploring fluctuating asymmetry in two recovering populations of the Eurasian otter

The Eurasian otter is a wide-ranging semi-aquatic mammal that underwent a significant population decline in the last century, leading to local extinctions, reduction and fragmentation of populations. The individuals of populations exposed to both external and internal stress may present the inability to produce a specific developmental outcome, generating developmental 'noise' (developmental instability (DI)). Factors contributing to DI include inbreeding depression, population bottlenecks, habitat loss and exposure to pollution. We analysed fluctuating asymmetry (FA) as a proxy of DI in two European otter populations that experienced a major decline in the 1990s. Using three-dimensional geometric morphometrics methods on skull samples of otters from the UK and Sweden, we compared the degree of FA both between populations before, during and after the decline. We found a higher FA in the UK populations compared with Sweden. The level of asymmetry differed significantly over time only in the UK population, where it was higher during the decline phase. FA in the UK populations can be attributed to the specific impact of polychlorinated biphenyls pollution that caused a bottleneck. More generally, our study suggests that habitat loss, pollution and limited gene flow may contribute to DI in declining otter populations, highlighting the need for continued investigation to identify and quantify the specific stressors behind this trend in local populations.

Low but highly geographically structured genomic diversity of East Asian Eurasian otters and its conservation implications

Populations of Eurasian otters Lutra lutra, one of the most widely distributed apex predators in Eurasia, have been depleted mainly since the 1950s. However, a lack of information about their genomic diversity and how they are organized geographically in East Asia severely impedes our ability to monitor and conserve them in particular management units. Here, we re-sequenced and analyzed 20 otter genomes spanning continental East Asia, including a population at Kinmen, a small island off the Fujian coast, China. The otters form three genetic clusters (one of L. l. lutra in the north and two of L. l. chinensis in the south), which have diverged in the Holocene. These three clusters should be recognized as three conservation management units to monitor and manage independently. The heterozygosity of the East Asian otters is as low as that of the threatened carnivores sequenced. Historical effective population size trajectories inferred from genomic variations suggest that their low genomic diversity could be partially attributed to changes in the climate since the mid-Pleistocene and anthropogenic intervention since the Holocene. However, no evidence of genetic erosion, mutation load, or high level of inbreeding was detected in the presumably isolated Kinmen Island population. Any future in situ conservation efforts should consider this information for the conservation management units.

Mitogenomic analysis of Rüppell's fox (Vulpes rueppellii) confirms phylogenetic placement within the Palaearctic clade shared with its sister species, the red fox (Vulpes vulpes)

The Rüppell's fox (Vulpes rueppellii) inhabits desert regions across North Africa, the Arabian Peninsula and southwestern Asia. Its phylogenetic relationship with other fox species, especially within the phylogeographic context of its sister species, V. vulpes, remain unclear. We here report the sequencing and de-novo assembly of the first annotated mitogenome of V. rueppellii, analysed with data from other foxes (tribe Vulpini, subfamily Caninae). We used four bioinformatic approaches to reconstruct the V. rueppellii mitogenome, obtaining identical sequences except for the incompletely assembled tandem-repeat region within the D-loop. The mitogenome displayed an identical organization, number and length of genes as V. vulpes. We found high support for clustering of both known subclades of V. rueppellii within the Palearctic clade of V. vulpes, rendering the latter species paraphyletic, consistent with previous analyses of shorter mtDNA fragments. More work is needed for a full understanding of the evolutionary drivers and consequences of hybridization in foxes.