Comprising more than 1400 species, bats possess adaptations unique among mammals including powered flight, unexpected longevity given small body size, and extraordinary immunity. Some of the molecular mechanisms underlying these unique adaptations includes DNA repair, metabolism and immunity. However, analyses have been limited to a few divergent lineages, reducing the scope of inferences on gene family evolution across the Order Chiroptera. We conducted an exhaustive comparative genomic study of 37 bat species encompassing a large number of lineages, with a particular emphasis on multi-gene family evolution across immune system and metabolic genes. In agreement with previous analyses, we found lineage-specific expansions of the APOBEC3 and MHC-I gene families, and loss of the proinflammatory PYHIN gene family. We inferred more than 1,000 gene losses unique to bats, including genes involved in the regulation of inflammasome pathways such as epithelial defense receptors, the natural killer gene complex and the interferon-gamma induced pathway. Gene set enrichment analyses revealed genes lost in bats are involved in defense response against pathogen-associated molecular patterns and damage-associated molecular patterns. Gene family evolution and selection analyses indicate bats have evolved fundamental functional differences compared to other mammals in both innate and adaptive immune system, with the potential to enhance anti-viral immune response while dampening inflammatory signaling. In addition, metabolic genes have experienced repeated expansions related to convergent shifts to plant-based diets. Our analyses support the hypothesis that, in tandem with flight, ancestral bats had evolved a unique set of immune adaptations whose functional implications remain to be explored.

Anthropogenic activities are leading to changes in the environment at global scales, and understanding these changes requires rapid, high-throughput methods of assessment. Pollen DNA metabarcoding and related methods provide advantages in throughput and efficiency over traditional methods, such as microscopic identification of pollen and visual observation of plant-pollinator interactions. Pollen DNA metabarcoding is currently being applied to assessments of plant-pollinator interactions and their responses to land-use change such as increased agricultural intensity and urbanisation, surveillance of ecosystem change, and monitoring of spatiotemporal distribution of allergenic pollen. In combination with historical specimens, pollen DNA metabarcoding can compare contemporary and past ecosystems. Current technical challenges with pollen DNA metabarcoding include the need to understand the relationship between sequence read and species abundance, develop methods for determining confidence limits for detection and taxonomic classification, increase method standardisation, and improve of gaps in reference databases. Future research expanding the method to intraspecific identification, analysis of DNA in ancient pollen samples, and increased use of museum and herbarium specimens could open further avenues for research. Ongoing developments in sequencing technologies can accelerate progress towards these goals. Global ecological change is happening rapidly, and we anticipate that high-throughput methods such as pollen DNA metabarcoding are critical for assessing these changes and providing timely management recommendations to preserve biodiversity and the evolutionary and ecological processes that support it.

The development of high-throughput sequencing (HTS) technologies has greatly improved our capacity to identify fungi and unveil their ecological roles across a variety of ecosystems. Here we provide an overview about current best practices in metabarcoding analysis of fungal communities, from experimental design through molecular and computational analyses. By re-analysing published datasets, we find that operational taxonomic units (OTUs) outperform amplified sequence variants (ASVs) in recovering fungal diversity, which is particularly evident for long markers. Additionally, analysis of the full-length ITS region allows more accurate taxonomic placement of fungi and other eukaryotes compared with the ITS2 subregion. We conclude that metabarcoding analyses of fungi are especially promising for co-analyses with the functional metagenomic or transcriptomic data, integrating fungi in the entire microbiome, recovery of novel fungal lineages and ancient organisms as well as barcoding of old specimens including type material.

The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean Sea and the Gulf of Mexico, with mixing occurring throughout the Atlantic. However, recent studies have emerged challenging this assumption by revealing weak genetic differentiation and identifying a previously unknown spawning ground in the Slope Sea used by Atlantic bluefin tuna of uncertain origin. To further understand the current and past population structure and connectivity of Atlantic bluefin tuna, we have assembled a unique dataset including thousands of genome-wide Single Nucleotide Polymorphisms (SNPs) from five hundred larvae, young of the year and spawning adult samples covering the three spawning grounds and including individuals of other Thunnus species. Our analyses support two weakly differentiated but demographically connected ancestral populations that interbreed in the Slope Sea. Moreover, we also identified signatures of introgression from albacore into the Atlantic bluefin tuna genome, exhibiting varied frequencies across spawning areas, indicating strong gene flow from the Mediterranean Sea towards the Slope Sea. We hypothesize that the observed genetic differentiation may be attributed to increased gene flow caused by a recent intensification of westward migration by the eastern population, which could have implications for the genetic diversity and conservation of western populations. Future conservation efforts should consider these findings to address potential genetic homogenization in the species.

Advances in genomic sequencing have magnified our understanding of ecological and evolutionary mechanisms relevant to biodiversity conservation. As a result, the field of conservation genomics has grown rapidly. Genomic data can be effective in guiding conservation decisions by revealing fine-scale patterns of genetic diversity and adaptation. Adaptive potential, sometimes referred to as evolutionary potential, is particularly informative for conservation due to its inverse relationship with extinction risk. Yet, global coldspots in genomic resources impede progress towards conservation goals. We undertook a systematic literature review to characterize the global distribution of genomic resources for amphibians and reptiles relative to species richness, IUCN status, and predicted global change. We classify the scope of available genomic resources by their applicability to global change. Finally, we examine global patterns of collaborations in genomics studies. Our findings underscore the urgent need for expanded genomic resources, especially those that directly inform about adaptive potential. Our results also highlight the need for improved global collaborations in genomic research, resource sharing, and capacity building in the Global South.

In a recent paper, “Environmental DNA: What’s behind the term? Clarifying the terminology and recommendations for its future use in biomonitoring”, Pawlowski et al. argue that the term eDNA should be used to refer to the pool of DNA isolated from environmental samples, as opposed to only extra-organismal DNA from macro-organisms. We agree with this view. However, we are concerned that their proposed two-level terminology specifying sampling environment and targeted taxa is overly simplistic and might hinder rather than improve clear communication about environmental DNA and its use in biomonitoring. Not only is this terminology based on categories that are often difficult to assign and uninformative, but it ignores what is in our opinion the most important distinction within eDNA: the type of DNA (organismal or extra-organismal) from which ecological interpretations are derived.

Biodiversity is under threat worldwide. Over the past decade, the field of population genomics has developed across non-model organisms, and the results of this research have begun to be applied in conservation and management of wildlife species. Genomics tools can provide precise estimates of basic features of wildlife populations, such as effective population size, inbreeding, demographic history, and population structure, that are critical for conservation efforts. Moreover, population genomics studies can identify particular genetic loci and variants responsible for inbreeding depression or adaptation to changing environments, allowing for conservation efforts to estimate the capacity of populations to evolve and adapt in response to environmental change and to manage for adaptive variation. While connections from basic research to applied wildlife conservation have been slow to develop, these connections are increasingly strengthening. Here we review the primary areas in which population genomics approaches can be applied to wildlife conservation and management, highlight examples of how they have been used, and provide recommendations for building on the progress that has been made in this field.

Over the past 50 years conservation genetics has developed a substantive toolbox to inform species management. One of the most long-standing tools available to manage genetics - the pedigree - has been widely used to characterize diversity and maximize evolutionary potential in threatened populations. Now, with the ability to use high throughput sequencing (HTS) to estimate relatedness, inbreeding, and genome-wide functional diversity, some have asked whether it is warranted for conservation biologists to continue collecting and collating pedigrees for species management. In this perspective, we argue that pedigrees remain a relevant tool, and when combined with genomic data, create an invaluable resource for conservation genomic management. Genomic data can address pedigree pitfalls (e.g., founder relatedness, missing data, uncertainty), and in return robust pedigrees allow for more nuanced research design, including well-informed sampling strategies and quantitative analyses (e.g., heritability, linkage) to better inform genomic inquiry. We further contend that building and maintaining pedigrees provides an opportunity to strengthen trusted relationships among conservation researchers, practitioners, Indigenous Peoples, and local communities. Keywords: conservation genomics, quantitative genetics, pedigree, kinship,ex situ , in situ

This review asks how variation in genome architecture impacts speciation across the plant and animal kingdoms. First, we briefly summarize what is known about speciation in these groups; importantly, the diversification rate of plants is about twice that of animals, and species barriers in plants appear to arise at an earlier stage of divergence. Next, we discuss several of the major differences in how plant and animal genomes evolve, and how they may impact the evolution of reproductive barriers and potentially speciation rates. Key differences include (1) the higher frequency of whole genome duplications and more rapid loss of synteny in plants; (2) the higher incidence and greater divergence of sex chromosomes in animals; (3) higher rates of sequence change, but slower rates of structural evolution, in animal relative to plant mitochondrial genomes; and (4) the higher abundance of transposable elements in plant genomes. Overall, we find the genomes of plants typically diverge much more rapidly in structure than those of animals (although there are many exceptions), which likely contributes to the more rapid emergence reproductive barriers in plants. However, we also found that comparisons of genome evolution between the kingdoms are hampered by inconsistency in the methods employed, and in the metrics used to report on rates of structural evolution. Another theme from our review is the huge variation in genome architecture within each kingdom. While this variation complicates broad generalizations, it also enables powerful comparative analyses that link differences in genome architecture to patterns and processes of speciation.

Skin is the largest mammalian organ and the first defensive barrier against the external environment. The skin and fur of mammals can host a wide variety of ectoparasites, many of which are phylogenetically diverse, specialized, and specifically adapted to their hosts. Among hematophagous dipteran parasites, volatile organic compounds (VOCs) are known to serve as important attractants, leading parasites to compatible sources of blood meals. VOCs have been hypothesized to be mediated by host-associated bacteria, which may thereby indirectly influence parasitism. Host-associated bacteria may also influence parasitism directly, as has been observed in interactions between animal gut microbiota and malarial parasites. Hypotheses relating bacterial symbionts and eukaryotic parasitism have rarely been tested among humans and domestic animals, and have to our knowledge never been tested in wild vertebrates. In this study, we use Afrotropical bats, hematophagous ectoparasitic bat flies, and haemosporidian (malarial) parasites vectored by bat flies as a model to test the hypothesis that the vertebrate host microbiome is linked to parasitism in a wild system. We identify significant correlations between bacterial community composition of the skin and dipteran ectoparasite prevalence across four major bat lineages, as well as striking differences in skin microbial network characteristics between ectoparasitized and non-ectoparasitized bats. We also identify links between the oral microbiome and presence of malarial parasites among miniopterid bats. Our results support the hypothesis that microbial symbionts may serve as indirect mediators of parasitism among eukaryotic hosts and parasites.

Disentangling the relative role of environmental filtering and dispersal limitation in driving metacommunity structure across mountainous regions remains challenging, as the way we quantify spatial connectivity in topographically and environmentally heterogeneous landscapes can influence our perception of which process predominates. More empirical datasets are required to account for taxon- and context-dependency but relevant research is often compromised by coarse taxonomic resolution. We here employed haplotype-level community DNA metabarcoding, enabled by stringent filtering of Amplicon Sequence Variants (ASVs), to characterize metacommunity structure of soil microarthropod assemblages across a mosaic of five forest habitats on the Troodos mountain range in Cyprus. We found similar β diversity patterns at ASV and species (OTU, Operational Taxonomic Unit) levels, which pointed to a primary role of habitat filtering resulting in the existence of largely distinct metacommunities linked to different forest types. Within-habitat turnover was correlated to topoclimatic heterogeneity, again emphasizing the role of environmental filtering. However, when integrating landscape matrix information for the highly fragmented Golden Oak habitat, we also detected a major role of dispersal limitation imposed by patch connectivity, indicating that stochastic and niche-based processes synergistically govern community assembly. Alpha diversity patterns varied between ASV and OTU levels, with OTU richness decreasing with elevation and ASV richness following a longitudinal gradient, potentially reflecting a decline of genetic diversity eastwards due to historical pressures. Our study demonstrates the utility of haplotype-level community metabarcoding for characterising metacommunity structure of complex assemblages and improving our understanding of biodiversity dynamics across mountainous landscapes worldwide.

Environmental DNA and metabarcoding have great potential for the biomonitoring of freshwater environments. However, successful application of metabarcoding to biodiversity monitoring requires universal primers with high taxonomic coverage that amplify highly-variable, short metabarcodes with high taxonomic resolution. Moreover, reliable and extensive reference databases are essential to match the outcome of metabarcoding analyses with the available taxonomy and biomonitoring indices. Benthic invertebrates, particularly insects, are key taxa for freshwater biomonitoring. Nevertheless, so far, no formal comparison has assessed primers for metabarcoding of freshwater macrobenthos. Here we combined in vitro and in silico analyses to test the performance of metabarcoding primers amplifying regions in the 18S rDNA (Euka02 metabarcode), 16S rDNA (Inse01), and COI (BF1_BR2-COI) genes, and developed an extensive database of benthic invertebrates of France and Europe, with a special focus on three key insect orders (Ephemeroptera, Plecoptera and Trichoptera). In vitro analyses on 1514 individuals, belonging to 578 different taxonomic units showed very different amplification rates across primer combinations. The Euka02 marker showed the highest universality, while the Inse01 marker showed excellent performance for the amplification of insects. The BF1_BR2-COI metabarcode showed the highest resolution, while the resolution of Euka02 was often limited. By combining in vitro data with GenBank information, we developed a curated database including sequences representing 822 genera. The heterogeneous performance of the different metabarcodes highlights the complexity of the identification of the best markers, and advocates for the integration of multiple metabarcodes for a more comprehensive and accurate understanding of ecological impacts on freshwater biodiversity.

The gut microbiota of bees affect nutrition, immunity, and host fitness, yet the role of diet, sociality, and geographic variation in determining microbiome structure, including strain-level diversity and relatedness, remain poorly understood. Here, we use full-length 16S amplicon sequencing to compare the crop and gut microbiomes of two incipiently social carpenter bee species, Xylocopa sonorina and Xylocopa tabaniformis, from multiple geographic sites within each species’ range. We found that Xylocopa species share a set of core taxa consisting of Bombilactobacillus, Bombiscardovia, and Lactobacillus apis, found in >95% of all individual bees sampled, and Gilliamella and Apibacter were also detected in the gut of both species with high frequency. The crop bacterial community of both species was comprised nearly entirely of Apilactobacillus with occasionally abundant nectar bacteria. Despite sharing core taxa, Xylocopa species’ microbiomes were distinguished by multiple bacterial lineages, including species-specific strains of core taxa. In both bee species, bacterial species exhibited geographic patterns in the presence of specific sequence variants. The use of long-read amplicons revealed otherwise cryptic species and population-level differentiation in core microbiome members which was masked when a shorter fragment of the 16S (V4) was considered. We conclude that these Xylocopa species host a distinctive microbiome, similar to that of previously characterized social apids, which suggests that further investigation to understand the evolution of bee microbiome and its drivers is warranted.

By their paternal transmission, Y-chromosomal haplotypes are sensitive markers of population history and male-mediated introgression. Previous studies identified biallelic single-nucleotide variants in the SRY, ZFY, DDX3Y genes, which in domestic goats identified four major Y-chromosomal haplotypes Y1A, Y1B, Y2A and Y2B with a marked geographic partitioning. Here, we analyze whole-genome sequences of 386 domestic goats from 75 modern breeds and 7 wild goat species that were generated by the VarGoats goat genome project. Phylogenetic analyses indicated domestic haplogroups corresponding to Y1B, Y2A and Y2B, respectively, whereas Y1A is split into Y1AA and Y1AB. All five haplogroups were detected in 26 ancient DNA samples from southeast Europe or Asia. Haplotypes from present-day bezoars are not shared with domestic goats and are attached to deep nodes of the trees and networks. Haplogroup distributions for 180 domestic breeds indicate ancient paternal population bottlenecks and expansions during the migrations into northern Europe, eastern and southern Asia and Africa south of the Sahara. In addition, sharing of haplogroups indicates male-mediated introgressions, most notably an early gene flow from Asian goats into Madagascar and the crossbreeding that in the 19th century resulted in the popular Boer and Anglo-Nubian breeds. More recent introgressions are those from European goats into the native Korean goat population and from Boer goat into Uganda, Kenya, Tanzania, Malawi and Zimbabwe. This study illustrates the power of the Y-chromosomal variants for reconstructing the history of domestic species with a wide geographic range.

The transition from a free-living lifestyle to endosymbiosis represents a large evolutionary shift, impacting various aspects of any organism’s biology, including its molecular basis. So far, it has been impossible to generalise the impact this lifestyle shift has on genomic architecture. This study explores this phenomenon using a new model system: neodalyellid flatworms (Rhabdocoela), a diverse assemblage of free-living and independently evolved endosymbiotic lineages. A uniquely comprehensive mitochondrial genomic dataset, consisting of 50 complete or partial mitogenome sequences (47 of which are new to science), is constructed, increasing the genomic resources available for rhabdocoel flatworms over tenfold. A robust phylogenomic framework is built, enabling an in-depth exploration of the molecular-genetic signatures associated with evolutionary shifts towards endosymbiosis. To understand speciation influenced by host phylogeny, first steps are taken to unravel the host-switching history of the largest endosymbiotic group of neodalyellids. We test several hypotheses regarding the potential consequences of a symbiotic lifestyle, and find heightened AT content, more pronounced AT skew, and relaxed selection on specific protein-coding genes in endosymbionts compared to their free-living counterparts. Numerous substitutions have accumulated in certain endosymbiotic lineages; however, the correlation with lifestyle remains uncertain. A high frequency of genetic rearrangements across all studied lineages is observed. Our findings affirm the variable nature of rhabdocoel mitogenomes and, for the first time, reveal distinct signatures of an endosymbiotic lifestyle in neodalyellid flatworms. This effort lays the groundwork for future research into the evolutionary and genomic consequences of a symbiotic lifestyle in this and other animal systems.

By studying invasive species, evolutionary geneticists have been able to simultaneously inform management strategies and quantify rapid evolution in the wild. The role of genomics in invasion science is increasingly recognised, and the growing availability of reference genomes for invasive species is paving the way for whole-genome resequencing studies in a wide range of systems. Here, we survey the literature to assess the application of whole-genome resequencing data in invasion biology. For some applications, such as the reconstruction of invasion routes in time and space, sequencing the whole genome of many individuals simply increases the accuracy of existing methods. In other cases, population genomic approaches such as haplotype analysis can permit entirely new questions to be addressed and new technologies to be applied. To date whole-genome resequencing has only been applied to a handful of invasive systems, but these studies have highlighted important roles for processes such as balancing selection and hybridization that allow invasive species to reuse existing adaptations and rapidly overcome the challenges of a foreign ecosystem. The use of genomic data does not constitute a paradigm shift per se, but by leveraging new theory, tools, and technologies, population genomics can provide unprecedented insight into basic and applied aspects of invasion science.

Intense research efforts on phylogeography over the last two decades uncovered major biogeographical trends and renewed our understandings of plant domestication in the Mediterranean. We aim to investigate the evolutionary history and the origin of domestication of the carob tree that has been cultivated for millennia for food and fodder. We used >1000 microsatellite genotypes to identify carob evolutionary units (CEUs) based on genetic diversity structure and geography. We investigated genome-wide diversity and evolutionary patterns of the CEUs with 3557 SNPs generated by restriction-site associated DNA sequencing (RADseq). The 56 populations sampled across the Mediterranean basin, classified as natural, semi-natural or cultivated, were examined. Although, RADseq data are consistent with previous studies identifying a strong West-to-East genetic structure and considerable admixture in some geographic parts, we reconstructed a new phylogeographic scenario with two migration routes occurring from a single refugium likely located in South-Western Morocco. Our results do not favour the regionally bound or single origin of domestication. Indeed, our findings support a cultivation model of locally selected wild genotypes, albeit punctuated by long-distance westward dispersals of domesticated varieties by humans, concomitant with major cultural waves by Romans and Arabs in the regions of dispersal. Ex-situ efforts to preserve carob genetic resources should prioritize accessions from both western and eastern populations, with emphasis on the most differentiated CEUs situated in South-Western Morocco, South Spain and Eastern Mediterranean. Our study underscores the relevance of natural and seminatural habitats of Mediterranean forests and their refugia in the conservation efforts of tree crops.

The recent development of ecological studies has been fueled by the introduction of massive information based on chromosome-scale genome sequences, even for species for which genetic linkage is not accessible. This was enabled mainly by the application of Hi-C, a method for genome-wide chromosome conformation capture that was originally developed for investigating the long-range interaction of chromatins. Performing genomic scaffolding using Hi-C data is highly resource-demanding and employs elaborate laboratory steps for sample preparation. It starts with building a primary genome sequence assembly as an input, which is followed by computation for genome scaffolding using Hi-C data, requiring careful validation. This article presents technical considerations for obtaining optimal Hi-C scaffolding results and provides a test case of its application to a reptile species, the Madagascar ground gecko (Paroedura picta). Among the metrics that are frequently used for evaluating scaffolding results, we investigate the validity of the completeness assessment of chromosome-scale genome assemblies using single-copy reference orthologs, and report problems of the widely used program pipeline BUSCO.