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The distribution of fitness effects varies phylogenetically across animals.

The distribution of fitness effects (DFE) describes the selection coefficients () of newly arising mutations and fundamentally influences population genetic processes. However, the extent and mechanisms of DFE variation have not been systematically investigated across species with divergent phylogenetic histories and ecological functions. Here, we inferred the DFE in natural populations of eleven animal (sub)species, including humans, mice, fin whales, vaquitas, wolves, collared flycatchers, pied flycatchers, halictid bees, Drosophila, and mosquitoes. We find that the DFE co-varies with phylogeny, where the expected mutation effects are more similar in closely related species (). Additionally, mammals have a higher proportion of strongly deleterious mutations (22% to 47% in mammals; 0.0% to 5.4% in insects and birds) and a lower proportion of weakly deleterious mutations than insects and birds. Population size is significantly negatively correlated with the expected impact of new deleterious mutations (), and the proportion of new beneficial mutations (). These findings align with Fisher's Geometric Model (FGM), which defines organismal complexity as the number of phenotypes under selection. Consistent with the FGM's predictions, we observe that mutations are more deleterious in complex organisms, while beneficial mutations occur more frequently in smaller populations to compensate for the drift load. Our study demonstrates strong phylogenetic constraints in the evolution of a fundamental population genetics parameter, and proposes that, through mechanisms of global epistasis, long-term population size and organismal complexity drive variation in the DFE across animals.

Fisher’s geometric model

Genomic analysis of breed composition and population structure in Montana composite cattle.

The Montana composite was developed in Brazil from crosses between Bos indicus and Bos taurus and structured into four biological types: Zebu (N), adapted taurine (A), British taurine (B), and continental taurine (C). This study aimed to characterize the genetic diversity and population structure of the Montana composite using genomic data through principal component analysis (PCA), admixture analysis, and Wright's FST statistic. The PCA revealed a clear separation between Bos indicus and Bos taurus groups, with Montana animals distributed in an intermediate position. The first two principal components explained 69.48% and 3.45% of the total variation, respectively. Supervised admixture estimates indicated a predominance of taurine contribution, with type A accounting for 34.47%, 52.64%, and 51.71% at K&#x2009;=&#x2009;4, 9, and 11, respectively. Increasing the ancestry resolution refined the contribution of individual founder breeds without changing the overall predominance of taurine ancestry. Comparisons between breed proportions obtained from pedigree and genomic data revealed significant differences, for most biological types and ancestry models (P&#x2009;<&#x2009;0.001), indicating that realized breed composition deviates from theoretical expectations. Estimates of genetic differentiation confirmed greater divergence between Zebu and taurine groups, as well as reduced distances among populations sharing common ancestry. Specific relationships were identified between the composite and some of its founder breeds, particularly Belmont Red, Senepol, and Tuli. Overall, the results demonstrate that the Montana composite has a complex genomic structure, with genomic ancestry varying according to the resolution adopted and differing from pedigree-based expectations.

Animals

Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies.

Range expansions can result in founder effects, increasing genetic differentiation between expanding populations and reducing genetic diversity along the expansion front. However, few studies have addressed these effects in long-distance migratory species, for which high dispersal ability might counter the effects of genetic drift. Monarchs (Danaus plexippus) are best known for undertaking a long-distance annual migration in North America, but have also dispersed around the world to form populations that do not migrate or travel only short distances. Here, we used microsatellite markers to assess genetic differentiation among 18 monarch populations and to determine worldwide colonization routes. Our results indicate that North American monarch populations connected by land show limited differentiation, probably because of the monarch's ability to migrate long distances. Conversely, we found high genetic differentiation between populations separated by large bodies of water. Moreover, we show evidence for serial founder effects across the Pacific, suggesting stepwise dispersal from a North American origin. These findings demonstrate that genetic drift played a major role in shaping allele frequencies and created genetic differentiation among newly formed populations. Thus, range expansion can give rise to genetic differentiation and declines in genetic diversity, even in highly mobile species.

Animal Distribution

The distribution of fitness effects of nonsynonymous mutations varies phylogenetically across animals.

The distribution of fitness effects (DFE) describes the selection coefficients of newly arising mutations and fundamentally influences population genetic processes. However, the extent and mechanisms of differences in the DFE for non-synonymous mutations have not been systematically investigated across species with divergent phylogenetic histories and ecologies. Here, we inferred the DFE in natural populations of 11 animal (sub)species, including humans, mice, fin whales, vaquitas, wolves, collared flycatchers, pied flycatchers, halictid bees, Drosophila, and mosquitoes. We found that mammals have a higher proportion of strongly deleterious mutations (defined as s&#x2264;-0.01; 22% to 47% in mammals; 0.0% to 5.4% in insects and birds) and a lower proportion of weakly deleterious mutations than insects and birds. Further, the DFE co-varies with phylogeny, such that the mean mutation effects are more similar in closely related species (Pagel's &#x3bb; = 0.84, P&#x2009;=&#x2009;0.01). Next, we investigated whether various summary statistics of the DFE were related to variation in life-history traits across these organisms. We found some support for genome size, body mass, and long-term effective population size being correlated with the DFE. Overall, our findings are consistent with predictions derived independently from the Fisher's Geometric Model (FGM), which defines organismal complexity as the number of phenotypes under selection. FGM predicts that mutations are more deleterious in complex organisms, while strongly deleterious mutations occur more frequently in smaller populations. Our study demonstrates strong phylogenetic signal in the evolution of a fundamental population genetics parameter, and proposes that, through mechanisms of epistasis, long-term population size and organismal complexity could be underlying variation in the DFE across animals.

Journal Article

Ancient dog mitogenomes support the dual dispersal of dogs and agriculture into South America.

Archaeological and palaeogenomic data show that dogs were the only domestic animals introduced during the early peopling of the Americas. Hunter-gatherer groups spread quickly towards the south of the continent, but it is unclear when dogs reached Central and South America. To address this issue, we generated and analysed 70 complete mitochondrial genomes from archaeological and modern dogs ranging from Central Mexico to Central Chile and Argentina, revealing the dynamics of dog populations. Our results demonstrate that pre-contact Central and South American dogs are all assigned to a specific clade that diverged after dogs entered North America. Specifically, the divergence time between North, Central and South American dog clades is consistent with the spread of agriculture and the adoption of maize in South America between 7000 and 5000 years ago. An isolation-by-distance best characterizes how dogs expanded into South America. We identify the arrival of new lineages of dogs in post-contact South America, likely of European origin, and their legacy in modern village dogs. Interestingly, the pre-contact Mesoamerican maternal origin of the Chihuahua has persisted in some modern individuals.

Animals

Uncovering new lineages in the Sunda pangolin (Manis javanica) with museum mitogenomics.

Accurately identifying evolutionarily significant units (ESUs) is crucial for conservation planning, especially for species like pangolins threatened by overhunting and habitat loss. ESUs help categorize different pangolin populations, aiding in understanding their genetic diversity and distribution, which is vital for targeted conservation efforts. This research generated mitochondrial genomes from historical museum specimens of Sunda pangolins (Manis javanica) from underrepresented locations, uncovering a new evolutionary lineage from the Mentawai Islands that diverged from Indochina and west Sundaland populations around 760 000 years ago. This population thereby represents a divergent ESU with a small distribution, important for conservation planning. The novel sequences provide resources for forensic labs tracing the origin of confiscated scales and shed light into the potential distribution of the 'mysterious pangolin'. Additionally, this research confirmed the presence of the two major M. javanica lineages in Java and extended the known distribution of the eastern clade to Bali and East Kalimantan. Our findings potentially suggest a recent bottleneck and postglacial expansion of pangolins across Indochina and west Sundaland. Further investigation with genomic and morphological evidence, contact area sampling and type sequencing will be required to evaluate the taxonomic status of different M. javanica lineages and M. culionensis.

Genomics

A new southern limit for the distribution of African great apes: sympatric western lowland gorilla (Gorilla gorilla gorilla) and central chimpanzee (Pan troglodytes troglodytes) confirmed in Mayombe National Park, Angola.

The distribution of African great apes has remained unconfirmed regarding their southern limit, particularly on the western side of the continent. IUCN maps include the Mayombe forest of Angola as part of the estimated distribution of western lowland gorillas (Gorilla gorilla gorilla) and central chimpanzees (Pan troglodytes troglodytes). However, until now no published evidence-based records had confirmed the continued presence of both species. The Mayombe forest is a key biodiversity hotspot and a potentially important stronghold for the conservation of great ape populations in Africa. Here, we report the first systematic evidence of both species in the Mayombe National Park, Cabinda, Angola. In 2023, a grid of camera traps was systematically deployed, producing the first visual records of gorillas and chimpanzees. Building on these findings, in 2024, a pilot survey including ad libitum field observations was carried out along exploratory trails to maximise data collection. The combination of these records identified a hotspot of great ape activity where six transects were established, and systematic direct and indirect evidence was documented. Chimpanzees were recorded more times across a broader range of evidence categories, while gorillas appeared less and seemed more spatially restricted. Notably, both species were detected at overlapping sites but never simultaneously, indicating sympatric coexistence with spatio-temporal partitioning. These findings confirm the southernmost predicted distribution of both species for this part of Africa, filling critical gaps in the understanding of great ape evolution and biogeography, and providing a baseline for the first demographic and ecological census of great apes in Angola.

Animals

Comparative phylogeographic patterns in three pan-Amazonian antwren lineages (Aves: Passeriformes: Thamnophilidae: Myrmotherula and Isleria).

We examined DNA sequences of 328 individuals of three lineages (species or species complexes) of Amazonian antwrens to evaluate their degree of geographical and historical concordance. All lineages (Myrmotherula longipennis, M. menetriesii, and the Isleria guttata-hauxwelli species complex) consist of small insectivorous birds that occupy understory or midstory of terra firme forest and are widely distributed across the Amazon Basin. Individuals of each of the three lineages grouped into genetic clades mainly separated by the Amazon and some major tributaries, although members of different clades of both M. menetriesii and I. hauxwelli were documented in the Madeira-Tapaj&#xf3;s interfluvium. Branching patterns differed among taxa, but all taxa were highly differentiated across the lower or upper Amazon. Despite the morphological, ecological, and phylogenetic similarities among lineages, and despite the fact that nearly all taxa are bounded by rivers, the effect of the other major rivers as biogeographic barriers was highly variable. The Mara&#xf1;&#xf3;n, Ucayali, Madeira, Tapaj&#xf3;s, Xingu, Napo, Negro, and Branco all separated main clades in one or two lineages but not in the others. Levels of genetic differentiation along the Teles Pires were substantially higher than those across the Tapaj&#xf3;s in M. menetriesii and I. hauxwelli, consistent with a proposed historical change of river course for the Tapaj&#xf3;s. Genetic units in this study were comparable for the most part to taxonomic units delineated by analyses of vocal and morphological variation, and identical, with one exception, to units defined solely by vocal variation in a companion paper (Isler et al. 2025). These results, in conjunction with those of Isler et al. (2025), provide additional instances of the variability of responses to the historical dynamism of Amazonia, in this case in closely related and ecologically similar species; highlight the consistency of genetic differentiation with vocal differentiation in additional species of Neotropical suboscine birds; support the importance of Amazonian rivers in creating conditions that result in the differentiation of independent evolutionary lineages; and demonstrate that species richness in two of the lineages studied (M. longipennis and M. menetriesii) was previously underestimated.

Passeriformes

The hidden threat from food-derived carbon dots: Formation, biodistribution, and potential health risks.

Food-derived carbon dots (CDs) are a new class of carbon-based nanoparticles generated during the thermal processing of food matrices. These nanomaterials have been extensively studied for their unique fluorescence, good biocompatibility, and tunable surface chemistry in food detection, intelligent packaging, and biomedical applications. However, their nanoscale size and high surface activity have raised safety concerns regarding biological interactions, in vivo biodistribution, and potential long-term health hazards. Although CDs have traditionally been regarded as low-toxicity materials due to their favorable biocompatibility, the potential hidden risks of CDs have not received sufficient attention. CDs exhibit dose-dependent toxicity, not only accumulating in various tissues and organs but also potentially inducing oxidative stress and interfering with cellular metabolic functions. Therefore, this review summarizes the advances in sources, synthetic strategies, and core properties of CDs, with a special focus on in vivo biological interactions, fates, and potential safety challenges. In addition, it is proposed that the standardized detection and risk assessment system should be established to further explore the long-term health effects of CDs under real dietary exposure, thereby ensuring their safety and sustainable application.

Carbon Quantum Dots

Pleistocene island connectivity did not enhance dispersal or impact population size change in Gal&#xe1;pagos geckos.

Patterns of biodiversity on remote archipelagos are largely shaped by intra-archipelago colonization followed by in situ diversification. Pleistocene sea-level fluctuations purportedly enhanced gene flow among terrestrial organisms by increasing connectivity during periods of lower sea level. Furthermore, changes in sea-level are hypothesized to impact population sizes as a result of fluctuations in island sizes. Here, we used genomic data to test the role of Pleistocene island connectivity on the diversification and demographics of leaf-toed geckos (Phyllodactylus) endemic to the Gal&#xe1;pagos. Consistent with previous studies, we found that present diversity of Gal&#xe1;pagos Phyllodactylus stems from three independent dispersal events. Contrary to the hypothesis of Pleistocene-driven diversification, we found no correspondence between lineage divergence and island connectivity. Furthermore, we found no evidence of introgression; demographic modelling indicated that all species increased rapidly in effective population size in the period 20-150 ka, and these inferred demographic expansions were largely asynchronous and apparently unassociated with species or island age. Collectively, these results indicate that more complex abiotic and/or biotic factors may better explain the recent demographic history of Phyllodactylus and underscore the need for additional population genomic studies of terrestrial taxa to understand the impact of past climate cycles on Gal&#xe1;pagos island communities.

Animals

Combined Evidence Reveals the Origin of a Rapid Range Expansion Despite Retained Genetic Diversity and a Weak Founder Effect.

Many species are currently experiencing range shifts in response to changing environmental conditions with potentially serious genetic consequences. Repeated founder events and strong genetic drift are expected to erode genetic variation at the range front, reducing adaptive potential and slowing or even halting the expansion. However, the severity of these consequences for common and highly mobile species undergoing environment-driven range shifts (c.f. invasions) is less clear. Here, we combined historical observations and contemporary movement data of the common reed warbler (Acrocephalus scirpaceus) with genomic evidence from across its European breeding range to (1) infer the origin and (2) quantify the genetic consequences of a recent and rapid northward range expansion. Although there were no reductions in levels of nucleotide diversity or allelic richness, nor a signal of founder effect in the directionality index (&#x3c8;), our combined dataset approach was able to infer an expansion origin from the southwest. Furthermore, we found that private allelic richness retained a slight but significant linear decline along the colonisation route. These results suggest that high dispersal capabilities can allow even philopatric species to avoid the loss of genetic diversity during rapid range expansions. Nevertheless, if multiple lines of evidence enable identification of an expansion pathway, we may still detect genetic signals of expansion.

Founder Effect

Climatic data sources and limitations of ecological niche models impact the estimations of historical ranges and niche overlaps in distantly related Korean salamanders.

BACKGROUND: Ecological niche models (ENMs) and analyses of niche overlap/divergence have become popular methods in ecology and evolutionary biology. These analyses rely on environmental data available from several databases. However, the influence of data sources on these analyses is rarely tested. Here, we test the impact of climatic data choice on the prediction of current and Plio-Pleistocene suitable habitats for two distantly related, but broadly sympatric, salamanders endemic to the Korean Peninsula. We ran MaxEnt separately on WorldClim and CHELSA climate data. We then hindcasted ENMs to five time periods of the Plio-Pleistocene, bracketing the estimated intraspecific divergence times for these species. We then quantified the differences in predictions between WorldClim- and CHELSA-based models. Also, given the sympatry and similar habitat requirements of the two species, we tested for niche overlaps using niche identity and background tests and tested the sensitivity of the results to climatic data choice. RESULTS: The ENMs successfully predicted contemporary suitable habitats for the two species. However, the predictions were highly sensitive to climatic data choice as well as variable combinations. The hindcasted ENMs produced contrasting predictions depending on the choice of climatic dataset and failed to predict suitable habitats for some Pleistocene time periods regardless of the climatic data choice. The niche analyses were also sensitive to climatic data choice, with results suggesting either niche overlaps or divergence depending on the climatic dataset used for the analyses. CONCLUSIONS: Our study highlights the influence of climatic data choice on the outcomes of ENMs and niche analyses. Our results also underscore the limitations of macroclimate-based ENMs, especially when the species is likely buffered from macroclimatic changes by microhabitat. We argue for the need for additional ecological, ecophysiological, and population genomic studies to better understand the range formation of these enigmatic species.

Animals

Generating correlated data for omics simulation.

Simulation of realistic omics data is a key input for benchmarking studies that help users obtain optimal computational pipelines. Omics data involves large numbers of measured features on each sample and these measures are generally correlated with each other. However, simulation too often ignores these correlations, perhaps due to computational and statistical hurdles of doing so. To alleviate this, we describe three approaches for generating omics-scale data with correlated measures which mimic real datasets. These approaches are all based on a Gaussian copula approach with a covariance matrix that decomposes into a diagonal part and a low-rank part. This decomposition allows for extremely efficient simulation, overcoming a hurdle for adoption of past methods. We use these approaches to demonstrate the importance of including correlation in two benchmarking applications. First, we show that variance of results from the popular DESeq2 method increases when dependence is included. Second, we demonstrate that CYCLOPS, a method for inferring circadian time of collection from transcriptomics, improves in performance when given gene-gene dependencies in some circumstances. We provide an R package, dependentsimr, that has efficient implementations of these methods and can generate dependent data with arbitrary marginal distributions, including discrete (binary, ordered categorical, Poisson, negative binomial), continuous (normal), or with an empirical distribution.

Computer Simulation

Elements on the move: How ungulate migration expands Alpine biogeochemical footprints.

Through depositing waste products, animals influence the spatial distribution of elements across landscapes. Yet the relationship between animal movement and element distribution remains poorly characterized. We developed a spatially explicit agent-based model to test how migratory versus resident red deer (Cervus elaphus) influence nitrogen redistribution across an alpine landscape in the Central-Eastern Italian Alps. Specifically, we asked how both local-scale and landscape-scale movement alter the spatial extent and magnitude of nitrogen deposition. We parameterized our model with GPS telemetry from 2021 to 2024 and remotely sensed vegetation data. We simulated four different scenarios which allowed us to disentangle the relative effects of large-scale (migration persisting) and fine-scale (resident behaviour) movement: (i) mixed migratory-resident (300 deer), (ii) fully resident (300 deer), (iii) reduced resident (150 deer) and (iv) reduced migratory (150 deer). The potential for nitrogen intake, assimilation, and excretion occurred hourly across a seasonally dynamic landscape. Across all scenarios, tree cover density and slope consistently emerged as positive predictors of nitrogen transport. Thus, regardless of resident or migratory status, red deer act as mediators of local element transport. Similarly, proximity to roads/trails reduced nitrogen inputs and created closed systems, indicating that barriers constrain both local and landscape-scale element transport. Migration substantially expanded the spatial extent of nitrogen redistribution and enabled the upward movement of elements, both locally upslope and into higher elevation habitats, effectively transporting elements against gravitational forces. Consequently, the loss of migration is likely to weaken these large-scale element linkages and reduce associated ecosystem functions. Our results demonstrate that different animal movement patterns play distinct and complementary roles in connecting element pools across landscapes. While both resident and migrant foraging redistribute elements locally, migratory movements link lowland and alpine habitats, expanding the spatial reach of element redistribution. Thus, loss of migration not only reduces the spatial extent of element distribution but also alters the topographic pathways through which elements are cycled. These findings highlight the broader ecosystem consequences of declining animal movement extent, and migration in particular, and underscore the importance of conserving behavioural diversity to maintain element heterogeneity and ecosystem functioning in mountain systems.

animal ecology

Wildlife as a reservoir of OXA-48-like carbapenemase-producing Enterobacterales.

Carbapenemase-producing Enterobacterales (CPEs) have globally emerged and spread beyond human compartments. However, data in wild animals, especially from low- and middle-income countries, such as Algeria, are still very scarce. Here, we investigated CPEs recovered from feces samples collected between October 2021 and June 2023 from wild terrestrial and aquatic mammals, wild migratory/nesters/sedentary birds, and zoo animals, including their environment (water, food, and fecal samples of animal care workers) distributed over six Algerian provinces. Carbapenem-resistant Enterobacterales were characterized using MALDI-TOF-MS, Carba NP, immunochromatographic assay NG-Test CARBA 5, antimicrobial susceptibility testing, and whole-genome sequencing. Thirty CPEs were identified out of the 1,899 samples collected (1.6%). The carriage rate was higher in captive animals (3.2%) than in wild animals (1.2%). Twenty-six produced OXA-48, three OXA-244, and one OXA-181, along with CTX-M-15 ESBL. Clonal expansion of Enterobacter hormaechei hoffmannii ST145 and Klebsiella pneumoniae ST13 was evidenced. Plasmid analysis confirmed that 24/30 isolates harbored a transferable 62 kb IncL pOXA-48 plasmid. Five/six E. coli isolates belonged to high-risk clones with chromosome-mediated blaOXA-244 gene in three isolates, blaOXA-48 in two isolates, and blaOXA-181 gene encoded on an IncFII-ColKP3 hybrid plasmid in one isolate. This study showed widespread dissemination of OXA-48-like producing Enterobacterales in free and captive wild animals, largely driven by epidemic plasmids and clones. It underscores the role of wild animals as a reservoir of CPEs, particularly species living close to humans, such as gulls and pigeons, and occasionally food-producing animals, increasing the risk of bidirectional dissemination between animal, environmental, and human sectors.IMPORTANCEThe global rise of carbapenemase-producing Enterobacterales (CPEs) harboring blaOXA-48-like has been increasingly documented in clinical settings. However, their emergence and transmission in wild and captive animals are less documented. This study provides a high-resolution genomic characterization of CPEs isolated from the feces of wild animals, especially migratory birds, and from captive wild animals, to evaluate the potential risk of dissemination through these animals. Whole-genome sequencing data, genetic investigations, and antimicrobial susceptibility results highlighted the spread of multidrug-resistant CPEs in both animals and humans. The widespread detection of blaOXA-48 across multiple niches suggests sustained circulation beyond hospital settings in Algeria. Human-associated lineages, such as E. coli ST131, ST38, and ST540, were identified with a clear link with humans. This study demonstrates carriage of CPEs in multiple bird species living in areas commonly inhabited by humans and provides further evidence for an effective dissemination of resistance in wildlife, facilitated by feeding habits.

Animals

Phylogenomics of Manticorini tiger beetles supports ancient Gondwanan vicariance and recent American amphitropical disjunction.

Disjunct distributions have long fascinated biologists, particularly those found in the Southern Hemisphere. Gondwanan vicariance has been invoked to explain these patterns, with relatively limited studies having phylogenetically tested this hypothesis. Another intriguing pattern of disjunction involving South America is the American amphitropical distribution, where Western Hemisphere taxa have close relatives either north or south of the tropics. While better known in plants, this pattern is rarely proposed for animals and only phylogenetically tested in a handful of studies on hymenopteran insects. The Manticorini is a tribe of large-bodied, flightless tiger beetles whose members possess a complex distribution pattern attributable to both Gondwanan vicariance and American amphitropical disjunction. Using genomic-scale data we perform phylogenetic analyses to produce a time-calibrated evolutionary history of the Manticorini. With the resultant time tree we perform ancestral range reconstruction in order to recover the historical biogeography of this group. Our results show deep divergence between most manticorine genera, contrasted with young crown ages indicative of recent diversification. Our analyses support Gondwanan vicariance and amphitropical disjunction resulting from recent dispersal as part of the historical biogeography of the tribe. These findings highlight the role of both vicariance and dispersal in shaping diversification and complex modern distributions.

Animals

Whole-Genome Sequencing of Feline Uropathogens Reveals Multidrug Resistance and Zoonotic Potential in Domestic Cats in Tunisia.

BACKGROUND: Urinary tract infections (UTIs) in cats are increasingly recognized as clinically relevant conditions frequently associated with multidrug-resistant (MDR) bacteria of potential zoonotic origin, yet genomic data on feline uropathogens remain scarce in Tunisia. METHODS: We used whole-genome sequencing to characterize seven bacterial isolates recovered from six cats with clinical signs of UTI: Mammaliicoccus lentus (n = 2), Staphylococcus schleiferi (n = 1), Mammaliicoccus sciuri (n = 1), Enterococcus faecalis (n = 1), Enterococcus casseliflavus (n = 1), and Klebsiella aerogenes (n = 1). RESULTS: Resistome analysis revealed determinants conferring resistance to &#x3b2;-lactams (blaZ, blaCMY-132), methicillin (mecC-type), macrolides (erm(43), ermB), tetracyclines (tet(M), tet(45), tetB), fosfomycins (fosI, fosB, fosA5), and aminoglycosides (aac(6'), aph(3')-IIIa, aph(6)-Id), alongside efflux pump genes (efrA, sepA, sdrM, oqxA, KpnE/F/G), vancomycin-operon genes (vanT, vanY, vanC, vanG), and biofilm/biocide-tolerance genes (salB, qacG). Notably, M. lentus S104 carried mecC-type elements, the first such report in Tunisia, while K. aerogenes displayed an extensive MDR profile, including blaCMY-132 and fosA5. Multilocus sequence typing/ribosomal multilocus sequence typing (MLST/rMLST) identified diverse lineages, including the internationally distributed E. faecalis ST19 and the rarely reported K. aerogenes ST242. Plasmids were absent in all isolates; a Tn916/1545-type transposon occurred in E. casseliflavus, and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems were unevenly distributed. CONCLUSIONS: These findings highlight companion animals as reservoirs of clinically important resistance genes, reinforcing the need for One Health AMR surveillance.

Animals

Emerging trends in the study of spiralian larvae.

Many animals undergo indirect development, where their embryogenesis produces an intermediate life stage, or larva, that is often free-living and later metamorphoses into an adult. As their adult counterparts, larvae can have unique and diverse morphologies and occupy various ecological niches. Given their broad phylogenetic distribution, larvae have been central to hypotheses about animal evolution. However, the evolution of these intermediate forms and the developmental mechanisms diversifying animal life cycles are still debated. This review focuses on Spiralia, a large and diverse clade of bilaterally symmetrical animals with a fascinating array of larval forms, most notably the archetypical trochophore larva. We explore how classic research and modern advances have improved our understanding of spiralian larvae, their development, and evolution. Specifically, we examine three morphological features of spiralian larvae: the anterior neural system, the ciliary bands, and the posterior hyposphere. The combination of molecular and developmental evidence with modern high-throughput techniques, such as comparative genomics, single-cell transcriptomics, and epigenomics, is a promising strategy that will lead to new testable hypotheses about the mechanisms behind the evolution of larvae and life cycles in Spiralia and animals in general. We predict that the increasing number of available genomes for Spiralia and the optimization of genome-wide and single-cell approaches will unlock the study of many emerging spiralian taxa, transforming our views of the evolution of this animal group and their larvae.

Animals