Heather Ritchie

Population structure, genetic diversity, and gene flow remain poorly understood for the globally vulnerable Himalayan wolf (Canis lupus chanco). We analyzed genetic data from five study areas across Nepal and one reference area on the Qinghai-Tibet Plateau, China, using Bayesian clustering, DAPC, PCA, heterozygosity metrics, pairwise FST, Mantel test, and chord diagram analysis. We identified two primary genetic clusters: (1) a Transhimalayan cluster comprising Humla, Shey-Phoksundo National Park, and Annapurna Conservation Area in western Nepal alongside the Qinghai-Tibet Plateau and (2) a Himalayan cluster encompassing Gaurishankar Conservation Area and Sagarmatha National Park in eastern Nepal. These findings reveal a complex metapopulation dynamics shaped by topographic barriers and high-altitude corridors, where gene flow proceeds along a stepping-stone network. Although marked differentiation separates eastern and western Nepalese populations, a departure from isolation-by-distance demonstrates that landscape resistance, rather than geographic distance alone, mediates regional genetic structure. Furthermore, despite an absence of localized inbreeding across all sampled populations, the relative isolation of Gaurishankar Conservation Area and reduced genetic diversity in Sagarmatha National Park together highlight recent recolonization dynamics and vulnerability to genetic drift. We recommend protecting core habitats and enhancing landscape connectivity across the range to sustain transboundary dispersal corridors vital for long-term population viability.

Background: The northern rockhopper penguin ( Eudyptes moseleyi ) is a threatened species, listed as Endangered globally by the IUCN owing to rapid population decreases in the past, combined with a limited distributional range. Their breeding is confined to five islands in the central South Atlantic Ocean (Gough, Nightingale, Inaccessible, Alex (= Middle), and Tristan da Cunha) and two islands in the southern Indian Ocean (Amsterdam and Saint Paul). Non-breeding birds forage widely in these oceans and vagrant individuals have been recorded in the Falkland Islands/Malvinas, South Africa, Kerguelen Archipelago, Australia, and New Zealand. The origins of these vagrant birds are largely unknown, and it remains unclear to what extent northern rockhopper penguins move between islands and oceans. Understanding connectivity between populations is essential for developing appropriate conservation strategies, especially as some populations may be at greater extinction risk than others. Results: Northern rockhopper penguins from the two oceanic basins are genetically distinct, with minimal evidence of migration between ocean basins. No substructure was detected within ocean island groups and although low, the level of migration between islands was sufficient to prevent genetic differentiation. Differential signatures of genetic diversity and inbreeding may also suggest some island populations are at higher risk of inbreeding depression. Conclusions: This study provides the first comprehensive genetic population structure analysis of the entire breeding range of the Endangered northern rockhopper penguin. This gives an unparalleled understanding of the connectivity within and between populations breeding in the Atlantic and Indian oceans, and highlights areas for further investigation. Knowledge of genetic structure and population dynamics can inform effective conservation management by predicting a species’ ability to adapt and remain resilient to local or global threats, including the increasing impacts of climate-driven changes in marine environments. Our results suggest that northern rockhopper penguins should be managed as two conservation management units to maximise the conservation of genetic diversity within the species and allow strategies to be developed that consider the different pressures affecting the populations in each ocean basin.

We present a genome assembly from an individual male Blera fallax (the pine hoverfly; Arthropoda; Insecta; Diptera; Syrphidae). The genome sequence is 462 megabases in span. Most of the assembly is scaffolded into 7 chromosomal pseudomolecules, including the assembled X and Y chromosomes. The mitochondrial genome has also been assembled, and is 16.2 kilobases in length.

We present a genome assembly from an individual male Blera fallax (the pine hoverfly; Arthropoda; Insecta; Diptera; Syrphidae). The genome sequence is 462 megabases in span. Most of the assembly is scaffolded into 7 chromosomal pseudomolecules, including the assembled X and Y chromosome. The mitochondrial genome has also been assembled, and is 16.2 kilobases in length.

The deep-sea is considered to be an ultimate sink for marine plastic debris. The abyssal (3500-6500 m) covers the bulk of the deep ocean floor yet little is known about the extent of plastic debris on the abyssal seafloor. We undertook a quantitative assessment of debris presents on the abyssal seafloor (5700-5800 m depth) beneath the Kuroshio Extension current system in the Northwest Pacific, which is one of the major transit points for massive amounts of debris sourced from Asia that are entering the North Pacific Ocean. The dominant type of debris was single-use plastics-mainly bags and food packaging. The density of plastic debris (average 4561 items km ⁻² ) in the abyssal zone was the highest recorded for an abyssal plain, suggesting that the deep-sea basin of the Northwest Pacific is a significant reservoir of plastic debris.

Genome size varies considerably across taxa, and extensive research effort has gone into understanding whether variation can be explained by differences in key ecological and life-history traits among species. The extreme environmental conditions that characterize the deep sea have been hypothesized to promote large genome sizes in eukaryotes. Here we test this supposition by examining genome sizes among 13 species of deep-sea amphipods from the Mariana, Kermadec and New Hebrides trenches. Genome sizes were estimated using flow cytometry and found to vary nine-fold, ranging from 4.06 pg (4.04 Gb) in Paralicella caperesca to 34.79 pg (34.02 Gb) in Alicella gigantea . Phylogenetic independent contrast analysis identified a relationship between genome size and maximum body size, though this was largely driven by those species that display size gigantism. There was a distinct shift in the genome size trait diversification rate in the supergiant amphipod A. gigantea relative to the rest of the group. The variation in genome size observed is striking and argues against genome size being driven by a common evolutionary history, ecological niche and life-history strategy in deep-sea amphipods.

Here, we describe the development of 16 polymorphic microsatellite markers using an Illumina MiSeq sequencing approach in the deep-sea amphipod Paralicella tenuipes. A total of 25 577 844 DNA sequences were filtered for microsatellite motifs of which 197 873 sequences were identified. From these sequences, 64 had sufficient flanking regions for primer design and 16 of these loci were polymorphic. Between 5 and 30 alleles were detected per locus, with an average of 13.63 alleles per locus, across a total of 120 individuals from 5 separate deep sea trenches from the Pacific Ocean. For the 16 loci, observed and expected heterozygosity values ranged from 0.116 to 0.414 and 0.422 to 0.820, respectively, with one locus displaying significant deviation from Hardy–Weinberg equilibrium. The microsatellite loci that have been isolated and described here are the first molecular markers developed for deep sea amphipods and will be invaluable for elucidating the genetic population structure and the extent of connectivity between deep ocean trenches.