Many species are currently experiencing range shifts in response to changing environmental conditions, but 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 the more common and highly mobile species undergoing environment-driven range shifts (c.f. invasions) is less clear. Here we combined historical observations of the common reed warbler (Acrocephalus scirpaceus) with contemporary movement data from ringing re-encounters and genomic (RAD-seq) data 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. While there were no reductions in levels of nucleotide diversity or allelic richness, nor a signal of founder effect in the directionality index (ψ), 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.

Sex chromosomes of teleost fishes undergo frequent turnovers. Annual Nothobranchius killifishes provide a suitable system to study sex chromosome turnover as they comprise the XY sex chromosome system in the model turquoise killifish, N. furzeri, and X1X2Y multiple sex chromosomes in six other representatives scattered across the Nothobranchius phylogeny, nested within species without cytologically detectable sex chromosomes. We combined molecular cytogenetics and genomic analyses to examine the X1X2Y systems in four Nothobranchius spp. and their outgroup Fundulosoma thierryi. Fluorescence in situ hybridization with painting probes specific for three sex chromosome systems and N. furzeri bacterial artificial chromosomes (BAC) bearing orthologues of eight genes repeatedly co-opted as master sex determining (MSD) genes in fishes suggests at least four independent origins of sex chromosomes in the genus Nothobranchius. The synteny block carrying the amhr2 gene was shared by X1X2Y systems of N. brieni, N. guentheri, and N. lourensi, which, however, differ by their fused autosomes. The gdf6 gene is sex-linked in F. thierryi. None of the mapped MSD gene candidates was sex-linked in N. ditte. We further sequenced F. thierryi and N. guentheri genomes and performed analyses of male and female Pool-seq and coverage data to determine their non-recombining regions and their differentiation. Level of sex chromosome differentiation was low in F. thierryi, but we identified two distinct sex-linked evolutionary strata in N. guentheri. While the amhr2 gene represents a candidate for MSD in N. guentheri, its localization in the younger stratum and low allelic variation questions its role in sex determination in a common ancestor of N. brieni, N. guentheri, and N. lourensi. Recombination cold spots such as fusion breakpoints could have contributed to formation of sex chromosome evolutionary strata.

Large-scale evolutionary radiations often take place through marked climatic gradients that could promote morphological variation. However, opposite trends to the well-known ecogeographical rules can be observed in closely related clades across different geographic regions. Here, we compared macroscale patterns of morphological diversification between two geographically separated evolutionary radiations of widespread frogs to assess how morphological diversity has arisen and tested whether distinct ecogeographical rules operate at broad spatial scales. We combined phylogenetic, morphological, climatic, and microhabitat data for 65 species of Rana and Lithobates and used phylogenetic comparative methods to identify which factors have played a major role in the phenotypic diversification of the two radiations. Morphological evolution in Eurasian subclades closely followed phylogenetic relatedness, with slow and constant rates of body size diversification through time. By contrast, American species showed accelerated rates of body size evolution in one subclade. Adaptive models (OU) best explained the morphological evolution of this radiation despite the lack of significant correlations with climatic variables, suggesting that selective pressures might have driven adaptation. Discordant ecogeographical trends were also found between radiations: Eurasian species followed Bergmann’s rule and the water conservation hypothesis, while no clear trend was observed among American species. Overall, different evolutionary trajectories between the two radiations lead to contrasting ecogeographical patterns, highlighting that distinct selective pressures and adaptive mechanisms can play very different roles in the evolution of phylogenetically related clades. Our research demonstrates that ecogeographical rules should not be considered universally applicable but rather context-dependent, and that widespread radiations are valuable systems to uncover mechanisms regulating these general patterns and potential constraints hindering their emergence.

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While biodiversity loss is undeniably a global phenomenon, an increase in taxonomic richness has recently been reported from some ecosystems and spatial scales. A striking increase in abundance and/or species richness has been documented from temperate rivers over the last 25 years, with many of the expanding species (i.e. winners) being native species. However, the lack of repeatedly collected local environmental data prevents the exploration of their niche dynamics and also makes it difficult to distinguish between possible causes. We fill this gap by using species occurrence data from 65 pristine Czech rivers sampled in 1997-2000 and 2015. The same methods were used for sampling macroinvertebrates and measuring environmental parameters in both periods. We selected 43 winners, defined as taxonomically validated and originally non-rare native macroinvertebrate species whose occupancy increased by at least six sites between the time periods. We searched for consistent patterns of niche dynamics (i.e. (stability, expansion, and restriction) among species that might contribute most to the overall increase in species richness. Using several biological traits, we also compared the winners with the other 253 taxa collected to look for differences. Analysis of the occurrence data showed that niche stability was by far the predominant pattern of the niche dynamics. This clearly indicates that the winners fill their original niche, with a limited contribution of niche shift or expansion, depending on the species. As no significant differences in either temperature preferences or the other biological traits were found between the winners and the other taxa, there is no unique set of functional traits that explain the success of the winners. The observed mechanism of filling the original niche space by the spreading native species not only explains the increase in local species richness, but also contributes to support the hypothesis of a climate-driven increase in ecosystem energy flow from a new perspective. The increased metabolism of the system may relax interspecific competition allowing to carry more individuals and species, even without the need for an increase in nutrients and ecosystem recovery.

Large carnivores have made a remarkable comeback in Europe during the last half century, and recovery is still ongoing in large parts of the continent (Andrén 2018; Boitani 2018; Boitani et al. 2022; Chapron et al. 2014; Huber 2018; Ranc 2018; von Arx 2020). While this expansion can be celebrated as a huge conservation success, it also creates considerable challenges for coexistence in the multi-use landscapes of Europe (Linnell 2013). Having a common understanding of the distribution, size and trends of large carnivore populations in Europe is one prerequisite for a knowledge-based dialogue in the often heated and highly politicized discussions about future scenarios of large carnivore conservation and management in Europe. Because of the scale at which large carnivores utilize the landscape it is essential to conduct periodic continental scale assessments of their status transcending sub-national and national borders. Assessments at this scale require harmonising diverse datasets that arise from different jurisdictions using different monitoring approaches. These shapefiles provides the best available overview of brown bear (Ursus arctos), Eurasian lynx (Lynx lynx), wolf (Canis lupus), golden jackal (Canis aureus), and wolverine (Gulo gulo) distributions a continental scale.

The estimation of foraging parameters is fundamental for understanding predator ecology. Predation and feeding can vary with multiple factors, such as prey availability, presence of kleptoparasites, and human disturbance. However, our knowledge is mostly limited to local scales, which prevents studying effects of environmental factors across larger ecological gradients. Here, we compared inter-kill intervals and handling times of Eurasian lynx (Lynx lynx) across a large latitudinal gradient from subarctic to the Mediterranean ecosystems using a standardised dataset of predicted adult ungulate kills from 107 GPS-collared lynx from nine distinct populations in Europe. We analysed variations in these two foraging parameters in relation to proxies reflecting prey availability, scavengers’ presence, and human disturbance, to improve our understanding of lynx predation at a continental scale. We found that inter-kill intervals and handling times varied between populations, social status and in different seasons within the year. We observed marked differences in inter-kill intervals between populations, which do not appear to be driven by variation in handling time. Increases in habitat productivity (expressed by NDVI, used as a proxy for prey availability) resulted in reduced inter-kill intervals (i.e. higher kill rates). We observed less variation in handling (i.e. feeding) times, although presence of dominant scavengers (wild boars and brown bears) and higher human impact led to significantly shorter handling times. This suggests that kleptoparasitism and human disturbance may limit the energetic input that lynx can obtain from their prey. We also observed that the human impact on foraging parameters can be consistent between some populations but context-dependent for others, suggesting local adaptations by lynx. Our study highlights the value of large-scale studies based on standardised datasets, which can aid the implementation of effective management measures, as patterns observed in one area might not be necessarily transferable to other regions. Our results also indicate the high degree of adaptability of these solitary felids, which enables them to meet their energy requirements and persist across a wide range of environmental conditions despite the constraints imposed by humans, dominant scavengers and variable prey availability.

Batesian mimicry in brood parasites is often viewed as an evolutionary strategy to mitigate host aggression. Female common cuckoos (Cuculus canorus) exhibit two morphs: the hawk-like grey and the rufous one, potentially maintained by apostatic selection. It was hypothesized that the grey morph's predator-like appearance deters host defences, while the rufous morph benefits from its rarity by evading host attention. Previous research predominantly utilized static cuckoo dummies, lacking insights into real-world interactions. We investigated the effectiveness of the cuckoo morphs in accessing great reed warbler (Acrocephalus arundinaceus) nests under natural conditions. Analysing video-recorded cuckoo attempts, we found no significant difference in nest-access success between the morphs. Both experienced a similar probability of physical attacks when hosts were present, and the rufous morph did not increase success in the nest-access attempts in the absence of hosts. These results fail to support the assumptions of (1) Batesian mimicry that hawk-like mimicry enhances nest access or reduces host aggression, and (2) apostatic selection that the rarity of the rufous morph confers an advantage in the successfully accessing the host nest. Future research should aim to identify stages in the cuckoo's life cycle or host interactions where colour polymorphism provides an evolutionary benefit.

Elevational gradients offer valuable opportunities to investigate biodiversity patterns and the ecological and evolutionary processes that shape them. Although tropical mountains are recognized as biodiversity hotspots, the various dimensions of biodiversity in these systems, particularly in equatorial Africa, remain poorly understood. In this study, we examined the functional (FD) and phylogenetic diversity (PD) of bird assemblages along a primary forest elevational gradient in Cameroon, West-Central Africa, spanning from lowland forests to the treeline (~2300 m a.s.l.). We analyzed how FD and PD vary with elevation and tested the roles of abiotic filtering and biotic interactions, such as competition, in community assembly. Additionally, we assessed whether taxonomic diversity (TD) increases through niche packing or expansion, based on morphological and resource-use traits. Using null models and bird occurrence data, we inferred the drivers of FD and PD patterns and evaluated whether species in more diverse assemblages occupied novel functional space compared to less diverse assemblages. Our results showed that both functional richness and TD declined with elevation, whereas functional nearest neighbor distance, functional evenness, and mean nearest taxon distance increased. Traits related to resource use suggested that bird species at higher elevations were functionally less similar than expected by chance, partially supporting the influence of competition consistent with the guild assembly rule. Phylogenetic clustering observed at both low and high elevations pointed to independent species radiations, likely shaped by historical forest dynamics. In species-rich lowland assemblages, we found evidence of niche packing, suggesting increased specialization or niche overlap. In contrast, niche expansion appeared to contribute to higher TD at elevated sites. Overall, our findings indicate that while abiotic filters along forested elevational gradients and competition in lowland forests play roles in shaping avian diversity, they are not the sole or dominant mechanisms. Nonetheless, partial support for competition aligns with theoretical expectations under the guild assembly framework.