Molecular Ecology最新文献

Environmental adaptation and speciation are key processes shaping biodiversity, especially in extreme environments. This study investigates the Yarkand hare (Lepus yarkandensis), inhabiting the arid Tarim Basin, and the Desert hare (Lepus tibetanus), residing in the cold and hypoxic Pamir Plateau. These species, facing distinct environmental pressures, provide an ideal model for understanding how organisms adapt to extreme conditions. Using whole-genome resequencing, we identified genomic regions associated with environmental adaptation in both species, and employed selective sweep and functional enrichment analyses to pinpoint important candidate genes. Additionally, we examined morphological adaptations, measuring body size, nasal bone structure and tympanic bulla, to explore how these traits facilitate survival in their respective environments. The results reveal common adaptive strategies, such as selection for genes related to energy metabolism and immune function. However, due to their distinct environments, the species exhibit different evolutionary paths. The Yarkand hare has larger tympanic bullae but a smaller body size, aiding heat dissipation and predator avoidance. In contrast, the Desert hare has a larger body size and longer nasal bones, reducing heat loss and warming the cold air at high altitudes. These findings highlight the crucial role of divergent selection in shaping adaptive traits, contributing to ecological isolation and supporting speciation in response to environmental challenges. This research enhances our understanding of adaptive evolution and has implications for conservation strategies aimed at addressing climate change impacts.

Environmental stressors and sex-specific life-history strategies synergistically shape senescence patterns in ectotherms, yet their interactive effects on telomere dynamics remain poorly understood. This study investigates how altitude-related environmental factors and sexual dimorphism drive telomere length variation in the montane salamander Pachytriton cheni across an elevational gradient (850–1350 m) in Qingliangfeng Nature Reserve, China. Using qPCR, skeletochronology and physiological assays, we analysed telomere length, age, oxidative damage markers and environmental parameters in 100 individuals. Results revealed a significant positive correlation between altitude and relative telomere length (RTL), with males exhibiting stronger elevational dependence than females. Multivariate models identified divergent environmental effects: higher flow velocity promoted telomere maintenance, whereas elevated water temperature, dissolved oxygen and dietary diversity accelerated attrition. Despite lower mobility, females maintained longer telomeres than males, suggesting sex-specific trade-offs favouring somatic maintenance over reproductive investment. Oxidative damage markers (malondialdehyde and protein carbonyls) were elevated at lower altitudes, aligning with free radical theory predictions. These findings highlight the interplay of environmental stressors (e.g., thermal and oxidative pressures) and sex-driven energy allocation in shaping telomere dynamics. Our work underscores the importance of integrating climate resilience into conservation strategies for high-altitude amphibians, particularly as habitat degradation and climate change threaten montane ecosystems. Our findings on the genotype-environment-sex interactions in P. cheni provide a conceptual framework for predicting how ectotherms may senesce in rapidly changing environments.

Ecological differences among species, particularly dispersal capacity and life history strategies, influence population response to environmental changes. Genetic simulations now allow us to directly incorporate this variation into models of past demographic changes. However, the impact of life history strategies in demographic inference has been far less explored relative to that of dispersal capacity. Here, we utilise individual-based simulations of a non-Wright-Fisher population to ask whether differences in life history traits (the average age of first reproduction of individuals, the average adult mortality and the average number of mates per reproductive season) lead to consistent and predictable differences in the summary statistics of genetic diversity commonly used for simulation-based parameter estimation and demographic inference. Using a Random Forest model, we also estimate three population parameters (variance in reproductive success, generation time and effective population size) from genome-wide SNP variation for two bird species known to have distinct life history strategies. The results demonstrate that life history variation leads to predictable differences in patterns of genetic diversity: higher values of life history traits, representing extreme polygamy, long adult longevity and later onset of reproduction, are associated with higher variance in reproductive success, longer generation times, smaller effective population sizes and overall lower genetic diversity. Parameter estimates from empirical datasets also agree with the general expectation that polygamic species with later onset of reproduction and long adult longevity exhibit higher variance in reproductive success, longer generation times and smaller effective population sizes. Since the signal of life history differences is observed in the genetic summary statistics, we argue that simulation- and model-based multi-species demographic inference will gain from the incorporation of life history information.

Hybridisation is a powerful evolutionary force that can lead to diverse reproductive outcomes, including the emergence of asexual lineages such as hybridogenesis. During hybridogenesis, found in water frog hybrids Pelophylax esculentus, one parental genome is eliminated during gametogenesis while the other is clonally propagated to the gametes. Although this reproductive mode allowed hybrids to spread across Europe, the ability to undergo hybridogenesis varies in hybrids throughout their range. To explain this gametogenic variability, we investigated the role of genomic introgression. Using cytogenetic analysis, we examined gametogenesis in diploid and triploid hybrid males from four eastern Ukrainian population systems, known for high hybrid abundance and diverse gametogenic pathways. Most hybrids from the studied localities showed canonical hybridogenetic reproduction, characterised by the expected hybrid genome composition and no detectable intergenomic rearrangements or introgressions. We also identified hybrids with disrupted or absent genome elimination, which were incapable of hybridogenetic reproduction and exhibited reduced fertility and aneuploid gamete formation. These individuals exhibited intergenomic rearrangements, with chromosomal regions showing interchanges of parental chromosomes. Additionally, some chromosomal fragments did not match either parental genome, suggesting introgression from an unidentified lineage. Notably, half of the triploid hybrids had rearranged chromosomes, likely originating from diploid hybrids that failed parental genome elimination and transmitted diploid gametes. Our study reveals that hybridogenesis in P. esculentus is not a conserved mechanism but rather significantly relies on the genomic background. These findings highlight the role of genomic introgression in shaping reproductive diversity and influencing the evolution and persistence of asexual vertebrates.

Alpaca (Vicugna pacos) is a large camelid that originated in South America. However, its evolutionary origin is debated, with hypotheses suggesting domestication from vicuña (V. vicugna) or guanaco (Lama guanicoe) or descent from extinct wild species with introgression from these two camelids. We show by means of phylogenetic, population and demographic genomic analyses, that the alpaca is a homoploid hybrid species that originated following hybridization between vicuña and the ancestor of wild guanaco and domesticated llama (L. glama). This event occurred during the mid-Holocene (~6.3 thousand years ago [Ka]) and shortly before the two Lama species diverged from each other (~5.9 Ka). Following its origin, the alpaca occasionally interbred with both llama and vicuña with recent gene flow and introgression. In addition, we identify alleles of many genes in alpaca that are derived alternately from its two parents. In combination, these alleles may have contributed to the reproductive isolation of the alpaca from its parents due to their effects on body size and sperm development, respectively. While attempting to domesticate camelids in South America, it is likely that humans may have retained hybrid offspring that exhibited preferred traits from both parents. This selective retention, along with the alternately inheriting highly diverged genes, may have led to the establishment of a new homoploid hybrid species in the case of alpaca, as sexual reproduction was restored through iterative evolution.