European honey bees, Apis mellifera, are essential pollinators for cultivated plants and native vegetation. The endemic and exported populations' existence is at risk due to numerous abiotic and biotic factors. Significantly, among the latter, the ectoparasitic mite Varroa destructor is the primary single driver of colony death. The choice to select for mite resistance in honey bee colonies is deemed a more sustainable alternative to treating varroa infestations with varroacidal products. Recent research has underscored the efficiency of applying natural selection principles observed in surviving European and African honey bee populations against Varroa destructor infestations, compared to conventional approaches emphasizing resistance traits. Still, the difficulties and limitations of employing natural selection as a solution to the varroa infestation have been given minimal attention. Our assertion is that overlooking these elements may produce adverse effects, such as enhanced mite virulence, a reduction in genetic diversity thus weakening host resilience, population collapses, or poor acceptance from the beekeeping community. For this reason, it is fitting to evaluate the possibilities of success for these programs and the characteristics of the individuals. Having examined the literature's proposals and their consequences, we analyze the merits and demerits, and then formulate perspectives for overcoming the obstacles they pose. Our analysis of host-parasite dynamics extends beyond theory to include the underappreciated, yet critical, practical constraints in beekeeping, conservation, and rewilding. To optimize the performance of programs utilizing natural selection for these purposes, we suggest designs that combine naturally occurring phenotypic variations with human-directed selections of characteristics. A dual strategy facilitates the use of field-grounded evolutionary methodologies to ensure the survival of V. destructor infestations and to promote improved honey bee health.
Heterogeneous pathogenic stressors affect the immune response's functional plasticity, a factor that subsequently affects the diversity of major histocompatibility complex (MHC). Therefore, the variety in MHC molecules could correspond with environmental stressors, underscoring its significance in uncovering the pathways of adaptive genetic differences. In this study of the greater horseshoe bat (Rhinolophus ferrumequinum), a species with three distinct genetic lineages in China, we analyzed the interplay of neutral microsatellite loci, an immune-related MHC II-DRB locus, and climatic conditions to understand the mechanisms determining MHC gene diversity and genetic differentiation. Microsatellite-based analysis of population differences highlighted increased genetic differentiation at the MHC locus, a sign of diversifying selection. Significantly, the genetic differentiation of MHC and microsatellite markers was found to be strongly correlated, suggesting the influence of demographic factors. MHC genetic differentiation exhibited a noteworthy relationship with geographical distance among populations, a correlation that remained significant even after controlling for the influence of neutral genetic markers, suggesting a crucial selective effect. Finally, the MHC genetic variance, while surpassing that of microsatellites, exhibited no discernible difference in genetic divergence between the two markers across diverse genetic lineages, thus, supporting the action of balancing selection. Considering MHC diversity and supertypes alongside climatic factors, there were significant correlations with temperature and precipitation; however, no such correlations were observed with the phylogeographic structure of R. ferrumequinum, indicating a local adaptation effect on MHC diversity driven by climate. Subsequently, the MHC supertype count differed across populations and lineages, hinting at regional traits and potentially bolstering the case for local adaptation. Our study's findings, when analyzed in conjunction, offer a compelling view of the diverse adaptive evolutionary pressures affecting R. ferrumequinum across varying geographic scales. Climate factors, in addition, could have been critically important in the adaptive evolution of this species.
The practice of sequentially infecting hosts with parasites has a long history of use in manipulating the virulence of pathogens. Despite the application of passage methods to numerous invertebrate pathogens, a clear theoretical understanding of virulence enhancement strategies has been lacking, resulting in inconsistent experimental results. Explaining virulence evolution is a complex problem because parasite selection occurs across multiple spatial scales, and this may result in differing selective pressures on parasites with differing life-history characteristics. Replication rate selection, particularly intense within host environments of social microbes, can select for cheating behaviors and a weakening of virulence, because investments in public-good virulence functions detract from individual replication. This study investigated the impact of varying mutation rates and selective pressures for infectivity or pathogen yield (population size in hosts) on virulence evolution against resistant hosts in the specialist insect pathogen Bacillus thuringiensis, with the goal of optimizing strain improvement strategies for enhanced efficacy against a challenging insect target. Metapopulation competition for infectivity among subpopulations results in the prevention of social cheating, the preservation of key virulence plasmids, and an increase in virulence. Virulence's enhancement was associated with reduced efficiency in sporulation, and the potential loss of function within regulatory genes, contrasting with no alterations in expression of the chief virulence factors. The effectiveness of biocontrol agents can be broadly improved via the strategic application of metapopulation selection. Besides this, a structured host population can promote the artificial selection of infectivity, and selection for life history traits like accelerated replication or increased population sizes might decrease virulence in microbial societies.
Effective population size (Ne) assessment is vital for both theoretical advancements and practical applications in evolutionary biology and conservation. In spite of this, determining N e in organisms possessing sophisticated life cycles is challenging, arising from the difficulties of the estimation methods. Plants that reproduce both clonally and sexually frequently show a pronounced difference between the number of visible individuals and the number of genetic lineages. How this disparity connects to the effective population size (Ne) remains an open question. Phenformin AMPK activator This investigation into two Cypripedium calceolus populations aimed to analyze the correlation between clonal and sexual reproduction rates and the resulting N e. We genotyped more than 1000 ramets at microsatellite and SNP loci, and calculated contemporary effective population size (N e) using the linkage disequilibrium method, anticipating that variance in reproductive success, stemming from clonal reproduction and limitations on sexual reproduction, would decrease N e. Considering variables possibly influencing our estimations, we included distinct marker types, diverse sampling strategies, and the impact of pseudoreplication on N e confidence intervals in genomic datasets. The N e/N ramets and N e/N genets ratios we have presented can serve as a guide when studying other species with similar life history traits. The observed patterns in our study suggest that effective population size (Ne) in partially clonal plants cannot be estimated by the number of sexual genets produced; instead, population dynamics play a critical role in shaping Ne. Phenformin AMPK activator Conservation concern species may experience undiagnosed population declines if relying only on the measure of genets.
In Eurasia, the spongy moth, Lymantria dispar, a forest pest exhibiting irruptive behavior, has a range extending from the coasts inland, across the entire continent, and even spilling over into northern Africa. Following its unintentional introduction from Europe to Massachusetts between 1868 and 1869, this species has now established itself across North America, where it is recognized as a highly destructive invasive pest. A comprehensive analysis of its population's genetic structure would aid in pinpointing the origin of specimens seized in North America during ship inspections, and this knowledge would facilitate mapping introduction routes to prevent further invasions into new territories. Besides that, a comprehensive analysis of L. dispar's global population distribution would offer new insights into the accuracy of its current subspecies classification system and its phylogeographic past. Phenformin AMPK activator By generating over 2000 genotyping-by-sequencing-derived single nucleotide polymorphisms (SNPs) from a diverse set of 1445 contemporary specimens sampled across 65 locations in 25 countries/3 continents, we sought to address these issues. Multiple analytical approaches allowed us to identify eight subpopulations, which subsequently broke down into 28 distinct subgroups, enabling an unprecedented level of resolution for the population structure of this species. While the task of aligning these clusters with the three established subspecies proved complex, our genetic findings unequivocally demarcated the japonica subspecies' range as Japan. Although a genetic cline exists across Eurasia, from L. dispar asiatica in Eastern Asia to L. d. dispar in Western Europe, this reveals no distinct geographical boundary, such as the Ural Mountains, as previously hypothesized. Indeed, the genetic distances between North American and Caucasus/Middle Eastern L. dispar moths were high enough to establish the need for their classification as distinct subspecies. While previous mtDNA studies highlighted the Caucasus as the origin point for L. dispar, our research points to East Asia as its cradle of evolution, followed by its expansion into Central Asia, Europe, and ultimately, Japan via Korea.