Alexander Sergeyevich Mikheyev

Inbreeding depression can have major negative effects on both individual fitness and population performance. The impact of inbreeding depression in wild populations remains poorly understood, and our knowledge is primarily based on estimations in insular populations with limited dispersal, which has been predicted to enhance the capacity for outcrossing. Limited migration and small population sizes, which make insular and endangered populations tractable models for fieldwork, often experience low genetic variation and may be subject to stronger inbreeding effects. Estimating inbreeding effects is difficult in many populations because pedigrees of migrants are unknown. Genomic data offer methods to estimate realised inbreeding even in migrants. Here, we apply genomic methods to a superb fairy‐wren ( Malurus cyaneus ) population that has been subject to detailed study of fitness variation over three decades. The population has sex‐biased dispersal, resulting in many immigrant females. We use genomic inbreeding estimates to explicitly test for inbreeding depression across several key components of individual fitness, including nestling condition, juvenile survival and adult traits. Genomic methods were able to recover previous pedigree‐based findings of inbreeding depression in early nestling condition and additionally identified some evidence for inbreeding depression in fledgling but not juvenile mortality. The only adult fitness trait affected, male extra‐pair paternity, is highly variable and under strong sexual selection. Our findings suggest that natural populations experiencing high effective population sizes and regular dispersal might be less affected by inbreeding depression than previously assumed based on studies of often insular and smaller populations.

BACKGROUND: Insecticide resistance management (IRM) strategies, such as rotation and mixture, rely on fitness tradeoffs and susceptible population dilution to slow resistance. While IRM is widely recommended, its robustness when a target pest's biology violates these foundational assumptions remains poorly tested. The honey bee parasite, Varroa destructor, provides a test case to evaluate these limits. For instance, V. destructor's obligate sibling mating prevents genetic dilution, resistance mutations appear to carry low fitness costs, and acaricide‐absorbing beeswax exerts continuous sub‐lethal selection even after treatment ceases. Using this system to validate IRM principles, we asked: (1) Does treatment cessation successfully restore acaricide susceptibility? and (2) Do rotation and mixture strategies effectively maintain high mite mortality when standard IRM conditions are compromised? RESULTS: We conducted the first meta‐analysis of IRM outcomes in V. destructor synthesizing treatment history and efficacy data from 15 studies (nine on rotation, seven on mixtures). Modelling revealed acaricide effectiveness declined by 5.5% per year of active treatment, while sensitivity rebounded by 10.7% per year following treatment cessation. Despite this partial recovery, neither rotation nor mixture strategies were associated with improved mite mortality. Susceptibility rebounds were likely insufficient to restore the near‐complete kill rates rotation requires, while progressive efficacy declines undermined the baseline conditions necessary for mixtures. CONCLUSION: Ultimately, although IRM is the standard recommendation for V. destructor , our findings demonstrate that real‐world implementation is unlikely to succeed without treatment‐history tracking and prescriptive intervention before widespread resistance is established. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Genetic diversity is essential for populations adapting to environmental-changes. Following genetic bottlenecks, invasive species often have reduced diversity, yet must rapidly adapt to novel environments. This paradox is especially pronounced in parasites, which face repeated transmission bottlenecks and anthropogenic countermeasures. The challenge of maintaining diversity in the short-term intensifies in haplodiploid species, where males inherit and transmit only half of their mother’s genome, limiting effective population size. To examine how such species may maintain adaptability, we study inheritance in Varroa mites (Varroa destructor), the globally invasive honey bee parasite. Using three-generation pedigrees, we find that Varroa is not haplodiploid, as previously thought. Rather, females produce diploid clone sons who transmit either copy of their mother’s genome to daughters. This system slows reduced heterozygosity loss under sib-mating, compared to ancestral haplodiploidy, increasing effective population size and adaptability. Our findings reveal a rare reversion from haplodiploidy, long considered an evolutionary end state, and suggest reproductive plasticity underlies the resilience of invasive parasites like Varroa.

Early‐life telomere length can be an integrated and accessible biomarker of lifetime fitness. Telomere length can result from complex interactions between heritable genetic variation, inherited gametic variation and accumulated environmental effects acting on individuals and parents. Consequently, to understand early‐life telomere length and its fitness consequences, both offspring traits and intergenerational effects resulting from parental traits need to be studied simultaneously. This is, particularly, true for inbreeding as poor performance or impaired telomere maintenance in offspring as well as poor parental reproductive effort or changes in gametic telomeres can reduce telomere length of offspring. Here, we explore the effects of individual inbreeding, parental inbreeding and parental age in a large dataset ( n = 679) of nestling telomere length in a long‐term studied wild population of purple‐crowned fairy‐wrens ( Malurus coronatus coronatus ) with multigenerational ecological and environmental data. We find no effect of nestling inbreeding on telomere length, even in adverse (hot and dry) climatic conditions. Offspring telomere length was not associated with paternal inbreeding or age (neither within‐ nor between‐fathers). However, nestling telomere length declined with maternal inbreeding and with increasing maternal age. Combined, these results do not support inherited gametic effects but rather suggest that effects of inbreeding and ageing on the mother's phenotypic state may affect pre‐ and/or post‐natal reproductive investment. Offspring from older and more inbred mothers, with shorter telomeres, will suffer reduced lifetime fitness. Moreover, inheritance of shorter telomeres could lead to population‐level changes in performance.

Venoms are powerful weapons that shape ecological interactions across the animal kingdom. They also have high medical importance, causing thousands of human fatalities annually, while offering a rich resource for drug discovery. Despite this, considerable logistical, safety and ethical challenges mean only a fraction of the world’s venoms have been profiled quantitatively. Natural history collections offer opportunities to greatly expand our knowledge of venom systems. We used quantitative proteomic mass spectrometry on preserved venom glands, spanning 0–57 years in age, from 37 venomous snake species (32 elapids and 5 viperids), alongside fresh venom samples from most of the same taxa. Preserved glands and fresh venoms from the same species showed strong concordance in venom composition across multiple metrics. Critically, specimen age did not degrade data quality, indicating that decades-old material yields reliable quantitative profiles, opening the possibility for vast quantities of existing museum specimens to be used. When we integrate our data with published profiles, we confirm known elapid vs viper broad diversity patterns while revealing substantial Australasian elapid venom diversity. Our findings demonstrate the potential of natural history collections as a vast, largely untapped biochemical archive for high-throughput “museum venomics,” enabling evolutionary and temporal analyses of venom diversity at unprecedented scale.

Animals frequently display aggressive behaviour, for example, when competing for food. Aggression is influenced by various extrinsic and intrinsic factors such as temperature, the microbiome, and genetics. However, we currently lack understanding what factors cause an animal to start aggression. Here, we use an ant species to test if chemical, microbiome, genomic, and/or transcriptomic traits correlate with the start of aggression and the reactions to it, that is, reacting aggressively or peacefully. We found nine bacterial operational taxonomic units, mutations in two genes, and eight differentially expressed genes, which were positively or negatively associated with the start of aggression or reactions to it. These traits are mainly linked to hormone signalling and neurological and synaptic functions. The results indicate that multiple traits, possibly acting in concert, affect the start of aggression and reactions to it. We speculate that such traits could promote aggression and could thus play important evolutionary roles.

Insect populations have declined worldwide, but the extent and drivers of these declines are debated. Most studies rely on field surveys performed in the past century, leaving gaps in our understanding of longer-term trends. Using a “community genomics” approach, we estimated community assembly over millions of years and more recent demographic trends of ant species in the Fijian archipelago. We found that 79% of endemic species are in decline, starting after the arrival of humans approximately 3000 years ago and accelerating in the past 300 years, whereas recent arrivals are expanding. The primary correlate of population decline among endemic species was found to be sensitivity to habitat disturbance. This study demonstrates the value of contemporary collections for estimating long-term community trends and highlights the vulnerability of endemic island species to anthropogenic change.

Snake genomes attract significant attention from multiple disciplines, including medicine, drug bioprospection, and evolutionary biology. However, genomic research within the Viperidae family has mostly focused on the subfamily Crotalinae, while the true vipers (Viperinae) have largely been overlooked. European vipers ( Vipera ) have been the subject of extensive research due to their phylogeographic and ecological diversification, as well as their venoms. Nevertheless, phylogeography and systematics in this genus have primarily relied on biased information from mitochondrial genes, which fail to capture the likely effects of introgression and are prone to biases. On the other hand, venom research in this group has been conducted predominantly through proteomics alone. In this study, we generated chromosome‐level genome assemblies for three Vipera species and whole‐genome sequencing data for 94 samples representing 15 Vipera lineages. This comprehensive dataset allowed us to disentangle the phylogenomic relationships of this genus, affected by mito‐nuclear discordance and pervaded by ancestral introgression. Population‐level analyses in the Iberian Peninsula, where the three oldest lineages within Vipera meet, revealed signals of recent adaptive introgression between old‐diverged and ecologically dissimilar species, whereas chromosomal rearrangements isolate species occupying similar niches. Finally, using transcriptomic and proteomic data, we characterised the Vipera toxin‐encoding genes, in which opposing selective forces were unveiled as common drivers of the evolution of venom as an integrated phenotype.

The mountain-dwelling lizards of the genus Iberolacerta inhabit several isolated massifs across central and southwestern Europe. Their restricted and fragmented ranges, coupled with high altitude specialization in most species, entail a significant threat in the context of climate change for this group of lizards that has attracted interest from different fields. On the one hand, the alpine confinement of these relict species precedes the Pleistocene glacial cycles, and a few hypotheses have been proposed to explain it: from competitive exclusion by the wall lizards of the genus Podarcis , to adaptations to either cold or hypoxia, that would prevent them from expanding into lowlands. On the other hand, extensive research on chromosome evolution has shown Iberolacerta karyotypes to fairly differ from other lacertid lizards, exhibiting reductions in chromosome numbers and multiple sex chromosome determination systems. Here we present a chromosome-level genome assembly for Iberolacerta aurelioi , an Endangered rock lizard endemic to the Pyrenees. This genome has shed light on a genome architecture shaped by chromosome fusions, whose adaptive potential we discuss, as well as on expression shifts towards a hemoglobin isoform of enhanced oxygen affinity, as an adaptation to altitudinal hypoxia. In addition, medium coverage whole-genome sequencing data from 12 representatives encompassing all species and subspecies within the genus allowed us to address phylogenomic relationships, unveiling introgression events, gathering evidence in support of the competitive exclusion hypothesis through past demographic inference, and providing insights into homozygosity burdens, which offer valuable information for conservation efforts.

Transitions to captivity often produce population bottlenecks. On the one hand, bottlenecks increase inbreeding and decrease effective population size, thus increasing extinction risk. On the other hand, elevated homozygosity associated with inbreeding may purge deleterious mutations. Previous empirical studies of purging in captive breeding programs have focused on phenotypic measurements. We test natural selection's ability to purge deleterious mutations following an extreme population bottleneck by analyzing patterns of genetic diversity in wild and captive-bred individuals of the Lord Howe Island stick insect, Dryococelus australis. Dryococelus australis has been bred in captivity for two decades, having passed through an extreme bottleneck—only two mating pairs with few new additions since then. The magnitude of the bottleneck together with high female fecundity but low offspring recruitment set up nearly ideal conditions for the purging of deleterious mutations. As expected, captive-bred individuals had a greater number of long runs of homozygosity compared with wild individuals, implying strong inbreeding in captivity which would facilitate purging in homozygous regions. Stop-codon mutations were preferentially depleted in captivity compared with other mutations in coding and noncoding regions. The more deleterious a mutation was predicted to be, the more likely it was found outside of runs of homozygosity, implying that inbreeding facilitates the expression and thus removal of deleterious mutations, even after such an extreme bottleneck and under the benign conditions of captivity. These data implicate inbreeding and recessive deleterious mutation load in fitness variation among captive and wild D. australis.