The allelic diversity of exon 2 (DQB gene) and exon 3 (DRB gene) of major histocompatibility complex class II was studied for the first time in two species of the landlocked pinnipeds, Baikal (N = 79) and Caspian (N = 32) seals, and these were in compared with the widespread Arctic species, the ringed seal (N = 13). The analysis of the second exon comprising the antigen-binding region revealed high allelic diversity in all three species but the pattern of the diversity was the most specific for the Baikal seal. This species differs from the other two by the smallest number of alleles in the population, yet they have the largest number of alleles per individual and by the maximum similarity of individual genotypes. Presumably, this specificity is a consequence of the spatial and temporal homogeneity of the Lake Baikal environment. Analysis of the third exon encoding the conserved β2-domain showed that the Baikal seal differs by the greatest number of amino acid sequences per individual, while the Caspian seal has the lowest number of variants. A single variant of the β2-domain, the same as in the ringed seal, predominates in the Caspian seal, whereas in the Baikal seal the two other variants predominate. At the same time, three species-specific amino acid sequences were observed among minor variants in the Caspian seal, while only one was found in the Baikal seal. This fact may suggest a longer period of independent evolution in the Caspian seal compared to the Baikal seal.

Melanin-based plumage polymorphisms in birds are often associated with mutations in the melanogenesis genes, notably the melanocortin-1 receptor (MC1R), but may also arise through changes in the expression of these genes. Here we investigate the molecular basis of plumage polymorphism in both adult and juvenile black sparrowhawks (Accipiter melanoleucus), an African raptor that occurs in two adult colour morphs, light and dark, and also exhibits variation in juvenile plumage colouration. Our results confirmed that plumage differences in adult morphs were a result of differential deposition of eumelanin in their ventral contour feathers. No polymorphisms in the coding regions of the MC1R or the agouti signalling protein (ASIP) genes associated with adult colour morph were identified. However, lack of pigmentation in the developing breast feathers of light morph birds was strongly associated with elevated ASIP expression, and concomitant down-regulation of the downstream melanogenesis genes microphthalmia-associated transcription factor (MITF), tyrosinase (TYR) and tyrosinase-related protein 1 (TYRP1). Variation in the rufous coloured plumage of juveniles was found to be due to covariation in eumelanin and pheomelanin levels in dorsal and ventral contour feathers. As in adult birds, an inverse relationship between melanin pigmentation and ASIP expression was observed. This covariation between eumelanin and pheomelanin levels is not consistent with the pigment type-switching model of melanogenesis, where increased ASIP expression results in a switch from eumelanin to pheomelanin production. This highlights the need for caution when extrapolating results from model systems to other animals and the value of conducting research in wild species.

Calasterella californica belongs to a monotypic genus of liverworts endemic to the west coast of North America, primarily distributed in California. This dioicous species occurs in a variety of ecosystems from deserts to redwood forest; little is known about how this species is adapted to live in those seemingly contrasting environments. In this paper, we report the assembly of the nuclear genome of Calasterella californica. As part of the California Conservation Genomics Project (CCGP), we used Pacific Biosciences HiFi long-read sequencing data to produce a de novo assembly that consists of 772 contigs, with a total length of 517 Mbp and a BUSCO complete score of 95%. C. californica is only the sixth species of liverworts - a group with more than 7200 described species - to have a nuclear reference genome. The availability of this reference genome will facilitate the study of the unique features of C. californica and other liverworts, pave the road towards a comparative understanding of liverwort genomes, and add an important starting point for studies of the geographic variation of this species within the CCGP project.

Mountain lions, Puma concolor, are widespread and adaptable carnivores. However, due to their large home ranges and long distance dispersals, they are strongly impacted by habitat fragmentation, which results in small and isolated populations. Genomic analyses play an important role in understanding and predicting the impacts of increased isolation of populations, such as decreased genetic diversity and increased levels of inbreeding. Here we report a high-quality, chromosome-level reference genome of P. concolor that was generated as part of the California Conservation Genomics Project. The primary assembly has a total length of 2.5 Gb contained in 258 scaffolds, a contig N50 of 42.3 Mb, a scaffold N50 of 149.8 Mb, and a BUSCO completeness score of 95%. This P. concolor genome assembly will provide an important resource for genomic analyses that aid decision makers in managing the species in fragmented landscapes.

Transcriptome analysis has become a central tool in evolutionary and functional genomics. However, variation among biological samples and analysis techniques can greatly influence results, potentially compromising insights into the phenomenon under study. Here, we evaluate differences in the brain transcriptome between female and male Gulf pipefish (Syngnathus scovelli). We perform comparisons between results from entire pipelines for brain transcriptome assembly, quantification, and analysis. We also offer a unique biological comparison between two sampling instances (Redfish Bay: n = 15, Port Lavaca: n = 7). Our results demonstrate crucial shortcomings with current experimental approaches. We found high variation within our results that was driven by both technical differences between pipelines and biological differences between pipefish samples. In our analysis of highly expressed genes, we found that the choice of methods influenced the degree of contamination or noise included in the identified genes. Notably, genes identified within the same pipeline were more similar than any other comparison. Our differential expression analysis revealed that both methodology and sampling location influenced the quantity and consistency of statistically significant transcripts. In the context of these results, we offer modifications to current practices that may increase the robustness of transcriptome-based conclusions. In particular, the use of a reference-guided assembly and an increase in sample sizes are likely to improve resistance to noise or error.

We present the first nuclear genome assembly and a complete mitogenome for Hylesia metabus (Arthropoda; Insecta; Lepidoptera; Saturniidae). The assembled nuclear genome sequence is 1,271 Mb long, which is among the 10 largest lepidopteran genome assemblies published to date. It is scaffolded in 31 pseudo chromosomes, has a BUSCO score of 99.5%, and has a highly conserved synteny compared to phylogenetically close species. Repetitive elements make up 67% of the nuclear genome and are mainly located in intergenic regions, among which LINEs were predominant, with CR1-Zenon being the most abundant. Phylogenetic and comparative analyses of H. metabus assembly and 17 additional Saturniidae and Sphingidae assemblies suggested that an accumulation of repetitive elements likely led to the increased size of H. metabus' genome. Gene annotation using Helixer identified 26,122 transcripts. The Z scaffold was identified using both a synteny analysis and variations of coverage for two resequenced male and female H. metabus. The H. metabus nuclear genome and mitogenome assemblies can be found and browsed on the BIPAA website and constitute useful resources for future population and comparative genomics studies.

The federally endangered sister species, Eucyclogobius newberryi (northern tidewater goby) and E. kristinae (southern tidewater goby) comprise the California endemic genus Eucyclogobius, which historically occurred in all coastal California counties. Isolated lagoons that only intermittently connect to the sea are their primary habitat. Reproduction occurs during lagoon closure, minimizing marine dispersal and generating the most genetically subdivided vertebrate genus on the California coast. We present a new genome assembly for E. newberryi using HiFi long reads and Hi-C chromatin-proximity sequencing. The 980Mb E. newberryi reference genome has an N50 of 34Mb with 22 well-described scaffolds comprising 88% of the genome and a complete BUSCO score of 96.7%. This genome will facilitate studies addressing selection, drift, and metapopulation genetics in subdivided populations, as well as the persistence of the critically endangered E. kristinae, where reintroduction will be an essential element of conservation actions for recovery. It also provides tools critical to the recovery of the genetically distinct management units in the northern tidewater goby, as well as broader ecological and evolutionary studies of gobies, the most speciose family of fishes in the world.

Anthropogenically fragmented populations may have reduced fitness due to loss of genetic diversity and inbreeding. The extent of such fitness losses due to fragmentation and potential gains from conservation actions are infrequently assessed together empirically. Controlled crosses within and among populations can identify whether populations are at risk of inbreeding depression and whether interpopulation crossing alleviates fitness loss. Because fitness depends on environment and life stage, studies quantifying cumulative fitness over a large portion of the lifecycle in conditions that mimic natural environments are most informative. To assess fitness consequences of habitat fragmentation, we leveraged controlled within-family, within-population, and between-population crosses to quantify inbreeding depression and heterosis in seven populations of Echinacea angustifolia within a 6400-hectare area. We then assessed cumulative offspring fitness after 14 years of growth in a natural experimental plot (N = 1136). Mean fitness of progeny from within-population crosses varied considerably, indicating genetic differentiation among source populations, even though these sites are all less than 9 km apart. The fitness consequences of within-family and between-population crosses varied in magnitude and direction. Only one of the seven populations showed inbreeding depression of high effect, while four populations showed substantial heterosis. Outbreeding depression was rare and slight. Our findings indicate that local crossings between isolated populations yield unpredictable fitness consequences ranging from slight decreases to substantial increases. Interestingly, inbreeding depression and heterosis did not relate closely to population size, suggesting that all fragmented populations could contribute to conservation goals as either pollen recipients or donors.

This study evaluated the effectiveness of genetic introgression of the SLICK1 allele derived from Senepol cattle into the Holstein breed to enhance thermotolerance. The SLICK1 allele, located in PRLR gene, confers a short and sleek coat that is inherited as a simple dominant phenotype. Approximately 40 years ago, the University of Florida initiated efforts to introgress this allele into the Holstein population. Here we tracked the introgression of the SLICK1 allele using a medium-density genotyping array and a reference population of both breeds (50 Holstein, 46 Senepol). Among the 31 SLICK1+ Holsteins, there was 15.25% ± 11.11% (mean ± SD) Senepol ancestry on BTA20. Holsteins at the University of Florida descended from slick matings that did not inherit the SLICK1 allele (n=9) exhibited no Senepol ancestry. A secondary introgression of Senepol genetics in SLICK1+ animals was found on BTA4, spanning 54 markers and 15 genes, with 26.67% Senepol ancestry. This region, previously linked to heat stress adaptation, suggests that the introgression extends beyond the SLICK1 allele to incorporate additional beneficial genetics for thermal stress adaptation. These findings indicate that deliberate introgression of the SLICK1 allele enhances specific traits and potentially introduces other adaptive genetic variations. The study demonstrates the successful use of genetic interventions to improve livestock resilience against environmental challenges without significantly disrupting the recipient breed's genetic structure. The introgression of the SLICK1 allele serves as a model for breeding programs aimed at optimizing animal welfare and productivity in the face of global climate change while maintaining breed integrity.

Scorpions are an ancient and charismatic group of arthropods with medical importance, but a high-quality reference genome for this group is still lacking. Here we perform whole-genome sequencing of Mesobuthus przewalskii, a desert scorpion endemic to the Taklimakan Desert. We combine PacBio HiFi sequencing and Hi-C chromosome conformation capturing to generate chromosomal-level, haplotype-resolved, and fully annotated genome assembly for this medically important scorpion. The assembly consists of two haplotypes (1052.01 Mbp and 1055.19 Mbp, respectively) reaching chromosome-level contiguity and >98% BUSCO completeness. Sequences were anchored in 13 chromosomes with a contig N50 of 34.44 Mbp and scaffold N50 of 81.43 Mbp. Several key genome features and the mitochondrial genome assembly were also provided. This genome represents the fifth but the most complete assembly for the order Scorpiones.

Facultative parthenogenesis (FP), or asexual reproduction by sexually-reproducing female animals, has been reported across several clades of vertebrates and is increasingly being recognized as a reproductive mechanism with significant implications for the genetic variation of captive and wild populations. The definitive identification of parthenogens requires molecular confirmation, with large genomic data sets necessary to accurately parse the parthenogenetic mechanism (i.e., endoduplication, gametic duplication, terminal fusion automixis, or central fusion automixis). Current methods for inferring FP from large genomic data sets are statistically intensive, require competency in R scripting for their execution, and are not designed for detection of facultative parthenogenesis or screening of large numbers of mother/offspring pairs, whereas small data sets (i.e., microsatellites) that can be evaluated visually lack the power to discriminate among FP mechanisms. Here, we present the user-friendly software program, ParthenoGenius, that uses intuitive logic to infer presence and mechanism of FP from even large genomic data sets comprising many mothers and offspring. ParthenoGenius runs relatively quickly and does not require the researcher to have knowledge of R scripting or statistics. ParthenoGenius was tested on eight empirical data sets, and in each case identified parthenogens (and parthenogenic mechanism when present) consistent with results of previous studies or corroborating evidence. ParthenoGenius will facilitate the rapid screening of large genomic data sets comprising many mothers and offspring for the presence and mechanism of parthenogenesis, improving our understanding of the frequency and phylogenetic distribution of FP across the animal kingdom.

The penstemons are ornamental annual flowering plants native to the Intermountain West and Rocky Mountains and commonly used for urban landscaping. Elite commercial penstemons are generally susceptible to abiotic stresses, including drought, root rot, cold, and high salinity. Firecracker penstemon (Penstemon eatonii), however, is much more tolerant to these stresses than most elite cultivars. Importantly, firecracker penstemon has been reported to hybridize with many other penstemons and therefore provides the opportunity to develop more tolerant elite cultivars through strategic crossing. To facilitate the study and utilization of firecracker penstemon, we sequenced and annotated the genome of a P. eatonii accession collected from Utah, USA. We also performed low-coverage, whole-genome sequencing of 26 additional accessions from three different varieties of P. eatonii. This chromosome-scale genome assembly is the most contiguous and complete Penstemon genome sequenced to date.

Hybridization produces a range of outcomes from advantageous to disadvantageous, and a goal of genetic research is to understand the gene interactions that generate these outcomes. Interactions between cytoplasmic elements, such as mitochondria, and the nucleus may be particularly vulnerable to accruing disadvantageous combinations as a result of their different rates of evolution. However, mitonuclear incompatibilities often do not have an observable effect until the F2 and later generations. We used Tigriopus californicus, a model system for mitonuclear incompatibilities that is also known for exhibiting heterosis in the F1 generation, to test whether hypoxia was more stressful for mitonuclear interactions than other environmental stressors. We generated 284 parental and 436 F1 hybrids from four population crosses (720 total) and compared parental and F1 populations for hypoxia tolerance. We observed that, on average, F1 hybrids were less likely to survive a hypoxia stress test than parental populations (Parental:F1 coefficients ranged from -0.04 to 0.14 with none significantly different from 0). This suggests that hypoxia may be a particularly intense stressor for mitonuclear coordination, and that hybridization outcomes vary by trait.

Squamate reptiles are a highly diverse and intriguing group of tetrapods, offering valuable insights into the evolution of amniotes. The Australian water dragon (Intellagama lesueurii) is a member of the Agamidae, and sister to the core mesic Australian endemic radiation (Amphibolurinae). The species is renowned for its urban adaptability and complex social systems. We report a 1.8 Gb chromosome-length genome assembly together with the annotation of 23,675 protein-coding genes. Comparative analysis with other squamate genomes highlights gene family expansions associated with immune function, energetic homeostasis, and wound healing. This reference genome will serve as a valuable resource for studies of evolution and environmental resilience in lizards.

Sex-ratio meiotic drivers are selfish genes or gene complexes that bias the transmission of sex chromosomes resulting in skewed sex ratios. Existing theoretical models have suggested the maintenance of a four-chromosome equilibrium (with driving and standard X and suppressing and susceptible Y) in a cyclic dynamic, but studies of natural populations have failed to capture this pattern. Although there are several plausible explanations for this lack of cycling, interference from autosomal suppressors has not been studied using a theoretical population genetic framework even though autosomal suppressors and Y-linked suppressors coexist in natural populations of some species. In this study, we use a simulation-based approach to investigate the influence of autosomal suppressors on the cycling of sex chromosomes. Our findings demonstrate that the presence of an autosomal suppressor can hinder the invasion of a Y-linked suppressor under some parameter space, thereby impeding the cyclic dynamics, or even the invasion of Y-linked suppression. Even when a Y-linked suppressor invades, the presence of an autosomal suppressor can prevent cycling. Our study demonstrates the potential role of autosomal suppressors in preventing sex chromosome cycling and provides insights into the conditions and consequences of maintaining both Y-linked and autosomal suppressors.

Sex chromosomes often differ between closely related species and can even be polymorphic within populations. Species with multifactorial sex determination segregate for multiple different sex determining loci within populations, making them uniquely informative of the selection pressures that drive the evolution of sex chromosomes. The house fly (Musca domestica) is a model species for studying multifactorial sex determination because male determining genes have been identified on all six of the chromosomes, which means that any chromosome can be a "proto-Y". Natural populations of house fly also segregate for a recently derived female-determining locus, meaning house flies also have a proto-W chromosome. The different proto-Y chromosomes are distributed along latitudinal clines on multiple continents, their distributions can be explained by seasonality in temperature, and they have temperature-dependent effects on physiological and behavioral traits. It is not clear, however, how the clinal distributions interact with the effect of seasonality on the frequencies of house fly proto-Y and proto-W chromosomes across populations. To address this question, we measured the frequencies of house fly proto-Y and proto-W chromosomes across nine populations in the United States of America. We confirmed the clinal distribution along the eastern coast of North America, but it is limited to the eastern coast. In contrast, annual mean daily temperature range predicts proto-Y chromosome frequencies across the entire continent. Our results therefore suggest that temperature heterogeneity can explain the distributions of house fly proto-Y chromosomes in a way that does not depend on the cline.

The common eider, Somateria mollissima mollissima (Chordata; Aves; Anseriformes; Anatidae), is a large sea duck with a circumpolar distribution. We here describe a chromosome-level genome assembly from an individual female. The haplotype-resolved assembly contains one pseudo-haplotype spanning 1205 megabases (with both Z and W sex chromosomes) and one pseudo-haplotype spanning 1080 megabases. Most of these two assemblies (91.13% and 93.18%, respectively) are scaffolded into 32 autosomal chromosomal pseudomolecules plus Z and W for pseudo-haplotype one. The BUSCO completeness scores are 94.0% and 89.9%, respectively, and gene annotations of the assemblies identified 17,479 and 16,315 protein coding genes. Annotation of repetitive sequences classify 17.84 % and 14.62 % of pseudo-haplotype one and two, respectively, as repeats. The genome of the common eider will be a useful resource for the widely distributed northern species in light of climate change and anthropogenic threats.

Polyergus kidnapper ants are widely distributed, but relatively uncommon, throughout the Holarctic, spanning an elevational range from sea level to over 3000 m. These species are well known for their obligate social parasitism with various Formica ant species, which they kidnap in dramatic, highly coordinated raids. Kidnapped Formica larvae and pupae become integrated into the Polyergus colony where they develop into adults and perform nearly all of the necessary colony tasks for the benefit of their captors. In California, Polyergus mexicanus is the most widely distributed Polyergus, but recent evidence has identified substantial genetic polymorphism within this species, including genetically divergent lineages associated with the use of different Formica host species. Given its unique behavior and genetic diversity, Polyergus mexicanus plays a critical role in maintaining ecosystem balance by influencing the population dynamics and genetic diversity of its host ant species, Formica, highlighting its conservation value and importance in the context of biodiversity preservation. Here, we present a high-quality genome assembly of P. mexicanus from a sample collected in Plumas County, CA, USA, in the foothills of the central Sierra Nevada. This genome assembly consists of 364 scaffolds spanning 252.31 Mb, with contig N50 of 481,250 kb, scaffold N50 of 10.36 Mb, and BUSCO completeness of 95.4%. We also assembled the genome of the Wolbachia endosymbiont of P. mexicanus - a single, circular contig spanning 1.23 Mb. These genome sequences provide essential resources for future studies of conservation genetics, population genetics, speciation, and behavioral ecology in this charismatic social insect.

Yellowstone National Park is home to the only plains bison population that has continually existed as wildlife, on the same landscape, through the population bottleneck of the late 19th century. Nevertheless, by the early 1900s, only 23 wild bison were known to have survived poaching. Salvation efforts included the addition of 18 females from Montana and 3 bulls from Texas to augment this population. A century later, nuclear microsatellite-based population level assessment revealed two genetically distinct bison sub-populations. However, in 2016 an analysis of mitochondrial haplotypes showed the two founding lineages were distributed throughout the park. This study is designed to delineate any current sub-structure in the Yellowstone bison population by strategically sampling the two major summer breeding herds and the two major winter ranges. Population level metrics were derived using the same microsatellite loci as the original study along with a newly developed set of highly informative bison specific Single Nucleotide Polymorphisms (SNPs). Our analyses reveal that the modern bison in Yellowstone National Park currently consist of one interbreeding population, comprised of two subunits.

We describe a highly contiguous and complete diploid genome assembly for the Chryxus Arctic, Oeneis chryxus (E. Doubleday, [1849]), a butterfly species complex spanning much of northern and western North America. One subspecies, the Ivallda Arctic (O. c. ivallda), is endemic to California's Sierra Nevada and of particular biogeographic interest and conservation concern. Extreme alpine habitats occupied by this subspecies include the summit of Mt. Whitney, California, representing the highest elevation butterfly population in North America. The assembly presented here consists of two haplotypes, 738.92 and 770.85 Mb in length, with contig N50 values of 10.49 and 10.13 Mb, scaffold N50 values of 25.35 and 25.69 Mb, scaffold L50 values of 13 and 14, and BUSCO completeness scores of 96.5 and 98.3%, respectively. More than 97% of the assembly is organized into 29 scaffolds, which likely represent whole chromosomes. This assembly is the first major genomic resource for Oeneis, providing a foundational reference for future genomic studies on the taxonomy, evolutionary history, and conservation of the genus. As part of the California Conservation Genomics Project, we will use this assembly in conjunction with short-read resequencing to resolve patterns of evolutionary differentiation, adaptive genomic variation, and gene flow among remaining O. c. ivallda populations. These data can and will be used to inform the subspecies' conservation as warming climatic conditions continue to lead to the loss and fragmentation of alpine habitats. We also provide genome assemblies for the O. chryxus mitochondrion and a Wolbachia endosymbiont.

The African hunting dog (Lycaon pictus, 2n=78) once ranged over most sub-Saharan ecosystems except its deserts and rainforests. However as a result of (still ongoing) population declines, today they remain only as small fragmented populations. Furthermore, the future of the species remains unclear, due to both anthropogenic pressure as well as interactions with domestic dogs, thus their preservation is a conservation priority. On the tree of life, the hunting dog is basal to Canis and Cuon and forms a crown group with them, making it a useful species for comparative genomic studies. Here, we present a diploid chromosome level assembly of an African hunting dog. Assembled according to VGP guidelines from a combination of PacBio HiFi reads and HiC data, it is phased at the level of individual chromosomes. The maternal (pseudo)haplotype (mat) of our assembly has a length of 2.38 Gbp, and 99.36 % of the sequence is encompassed by 39 chromosomal scaffolds. The rest is included in only 36 unplaced short scaffolds. At the contig level, mat consists of only 166 contigs with an N50 of 39 Mbp. BUSCO analysis showed 95.4 % completeness based on Сarnivora conservative genes (carnivora_odb10). When compared to other available genomes from subtribe Canina, the quality of the assembly is excellent, typically between the 1st and 3rd depending on the parameter used, and a significant improvement on previously published genomes for the species. We hope this assembly will play an important role in future conservation efforts and comparative studies of canid genomes.