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Species and nestmate recognition in social insects occurs mostly through cuticular hydrocarbons acting as chemical cues. These compounds generate a colony‐specific odor profile depending on genetic and environmental factors. Species and nestmate recognition results in specific behavioral responses, regulating the level of aggression toward other individuals during an interaction. Although species discrimination and recognition cues have been poorly studied in the context of interspecific hybridization, such systems offer an opportunity to further investigate the influence of heritable and environmental factors on recognition. We explored the strength of discrimination in a hybrid zone between two ant species—Tetramorium immigrans and T. caespitum—by comparing cuticular hydrocarbon profiles and measuring intra‐ and interspecific worker aggression in both areas of sympatry and areas of allopatry among species. Species cuticular hydrocarbon profiles were well‐differentiated and interspecific aggression was high, revealing highly discriminating species recognition cues. Hybrids' cuticular hydrocarbon profiles consisted of a mixture of the parental bouquets, but also exhibited hybrid‐specific patterns. Behavioral assays showed that T. immigrans is as aggressive toward hybrids as toward heterospecifics. Finally, aggression between heterospecific workers was lower when interacting individuals came from areas of sympatry among species than from areas of allopatry. Taken as a whole, these findings paint a particularly complex picture of the recognition system in T. immigrans, T. caespitum, and their hybrids, and highlight that hybrid zones afford a still underexplored opportunity for investigating recognition mechanisms and discrimination between species. [ABSTRACT FROM AUTHOR]

Human trade and movements are central to biological invasions worldwide. Human activities not only transport species across biogeographical barriers, but also accelerate their post‐introduction spread in the landscape. Thus, by constraining human movements, the spatial structure of road networks might greatly affect the regional spread of invasive species. However, few invasion models have accounted for the topology of road networks so far, and its importance for explaining the regional distribution of invasive species remains mostly unexplored. To address this issue, we developed a spatially explicit and mechanistic human‐mediated dispersal model that accounts and tests for the influence of transport networks on the regional spread of invasive species. Using as a model the spread of the invasive ant Lasius neglectus in the middle Rhône valley (France), we show that accounting for the topology of road networks improves our ability to explain the current distribution of the invasive ant. In contrast, we found that using human population density as a proxy for the frequency of transport events decreases models' performance and might thus not be as appropriate as previously thought. Finally, by differentiating road networks into sub‐networks, we show that national and regional roads are more important than smaller roads for explaining spread patterns. Overall, our results demonstrate that the topology of transport networks can strongly bias regional invasion patterns and highlight the importance of better incorporating it into future invasion models. The mechanistic modelling approach developed in this study should help invasion scientists explore how human‐mediated dispersal and topography shape invasion dynamics in landscapes. Ultimately, our approach could be combined with demographic, natural dispersal and environmental suitability models to refine spread scenarios and improve invasive species monitoring and management at regional to national scales. Keywords: biological invasions, human‐mediated dispersal, road network, secondary spread, spatially explicit model, stochastic jump model [ABSTRACT FROM AUTHOR]

Limestone areas across the world develop karstic caves, which are populated by a wide range of macro‐ and microorganisms. Many of these caves display Paleolithic art or outstanding speleothems, and in the last century they have been subjected to anthropization due to touristic management and intense human frequentation. Despite their cultural importance and associated conservation issues, the impact of anthropization on cave biodiversity is not known. Here, we show that anthropization is associated with specific cave biota modifications. We compared diversity in four pristine caves, four anthropized show caves, and the iconic Lascaux Cave with even stronger anthropization. The predominant microbial higher taxa were the same in all caves, but the most anthropized cave (Lascaux) was unique as it differed from the eight others by a higher proportion of Bacteroidetes bacteria and the absence of Euryarchaeota and Woesearchaeota archaea. Anthropization resulted in lower diversity and altered community structure for bacteria and archaea on cave walls, especially in Lascaux, but with a more limited effect on microeukaryotes and arthropods. Our findings fill a key gap in our understanding of the response of karstic communities to anthropization, by revealing that tourism‐related anthropization impacts on the prokaryotic microbiome rather than on eukaryotic residents, and that it shapes cave biota irrespective of cave natural features. [ABSTRACT FROM AUTHOR]

Effective population size (Ne) is one of the most important parameters in, ecology, evolutionary and conservation biology; however, few studies of Ne in surface freshwater organisms have been published to date. Even fewer studies have been carried out in groundwater organisms, although their evolution has long been considered to be particularly constrained by small Ne. In this study, we estimated the contemporary effective population size of the obligate groundwater isopod: Proasellus walteri (Chappuis, 1948). To this end, a genomic library was enriched for microsatellite motifs and sequenced using 454 GS-FLX technology. A total of 54,593 reads were assembled in 10,346 contigs or singlets, of which 245 contained candidate microsatellite sequences with suitable priming sites. Ninety-six loci were tested for amplification, polymorphism and multiplexing properties, of which seven were finally selected for Ne estimation. Linkage disequilibrium and approximate Bayesian computation methods revealed that Ne in this small interstitial groundwater isopod could reach large sizes (> 585 individuals). Our results suggest that environmental conditions in groundwater, while often referred to as extreme, are not necessarily associated with small Ne. [ABSTRACT FROM AUTHOR]

Mate preference was long assumed to be static and open-ended. However, a growing body of evidence actually suggests that the predominant factor in mate choice fluctuates due to the context dependence of the factors involved in sexual selection. In particular, fluctuation in the local environment, the density of individuals, and the presence of heterospecifics can all alter the strength, form, or direction of sexual selection by shaping the fitness costs and benefits of the traits that mediate male-female interactions. Amphibians constitute useful biological models to examine context dependence in sexual selection as the availability of suitable breeding resources may significantly impact the cost-benefit trade-off between mating strategies. Using an experimental approach, we examined how the risk of larval competition in breeding ponds affects pond occupancy, male-male spacing behavior, and spawning decisions in an anuran, the yellow-bellied toad (Bombina variegata). Then, we examined how female mate choice is affected by male body condition and how the risk of larval competition might influence females when choosing a mate. Our results indicate that male pond preference is strongly affected by the presence of conspecific tadpoles. Males preferentially selected ponds free of tadpoles, and spawning mainly occurred in these same ponds. This preference influenced male spacing behavior by enhancing the proximity of competing males when the availability of good-quality sites was experimentally manipulated, which had further significant consequences on females' choice of mate. The article also discusses the evolutionary causes and consequences of such contextdependent mate choice in amphibians and beyond. [ABSTRACT FROM AUTHOR]

Aim: Cities are thought to promote biological invasions because invasive species are more often introduced in urban areas and because they are more successful in disturbed environments. However, the association is not as strongly supported by the literature as is generally assumed and might depend on how urbanization and invasion are measured. In this study, we test if the type of data used to assess the link between urbanization and invasion can affect a study's conclusions. Location: Europe and middle Rhône valley (~5000 km2 in south‐eastern France). Method: We studied the spatial distribution of the invasive garden ant Lasius neglectus in its current introduced range in Europe and tested its association with urbanization using three measures of invasion (presence‐only, presence–absence and population area) and two measures of urbanization (urban/nonurban land cover classification and proportion of impervious surfaces (buildings, road) per spatial unit). Results: Based on presence‐only data across Europe, L. neglectus occurred in urban areas 10 times more often than expected from a random geographical distribution. However, when controlling for spatial bias in sampling effort with presence–absence data (1870 sampling locations in the middle Rhône valley, France), the occurrence of the species was independent of urbanization. Moreover, the surface occupied by L. neglectus populations was negatively correlated with urbanization. Main conclusions: These findings show that the type of occurrence data used to test the link between urbanization and invasion can strongly affect the conclusion of a study. This is particularly concerning because invasion studies often use presence‐only data that are likely biased towards cities. Future urban invasions studies must be carefully designed to avoid this pitfall. [ABSTRACT FROM AUTHOR]

Interspecific hybridization is becoming more frequent worldwide due to increasing global changes and translocations of organisms. For individual organisms, the most significant negative consequences are sterility or inviability of hybrid offspring. However, hybridization sometimes leads to fertile offspring, promoting introgression from one species into another. In such situations, hybridization can play a key role in evolution and speciation. Combining hypervariable DNA (microsatellites) and mitochondrial DNA markers with the use of several modeling methods allow an efficient detection of hybridization processes. The present study therefore investigates hybridization between two ant species, Tetramorium immigrans and T. caespitum, using multiple methods, and systematically comparing results with simulated data to ensure accurate identification of hybrids. Introgression was revealed both by backcross detection based on 14 nuclear microsatellite loci and by mitochondrial‐nuclear discordance based on comparison with mitochondrial DNA (cytochrome c oxidase subunit I). Results were spatially consistent, with hybrids located at latitudes where parental species are sympatric. The causes and consequences of hybridization and introgression between T. caespitum and T. immigrans remain to be further investigated, especially because T. immigrans could be an invasive species in France. [ABSTRACT FROM AUTHOR]

In the context of climate changes, factors that determine the distribution patterns of European species of the ubiquitous ant genus Tetramorium were investigated.The study took place along a steep North‐South climatic gradient across the boundary between the European Continental and Mediterranean biogeographical regions spanning 460 km along the Rhône valley, France.Ants from 1690 Tetramorium colonies were collected in 19 sampling zones. Species were identified using an integrative approach based on a two‐step process combining nuclear DNA (14 microsatellite markers), morphological examination and mitochondrial DNA cytochrome oxidase I sequencing. The impact of climate on species distribution patterns was tested using bioclimatic variables.Species discrimination was successful, despite a complex situation with cryptic species, inter‐specific hybridisation and uneven sampling across species. Our results showed a strong effect of latitude, temperature and rainfall on the distribution of three of four species. Tetramorium semilaeve was found only south of the boundary, in warmer and dryer sites; Tetramorium caespitum extended north and 70 km south of the boundary and favoured colder sites with strong seasonal variation. Tetramorium immigrans was absent from the northernmost sampling zones and favoured warmer and wetter sites. Tetramorium moravicum was mostly found close to the boundary, but without significant climatic preferences.The fundamental role of climate as a factor limiting the ranges of these species at a major biogeographical boundary is confirmed. Monitoring range limits of these strongly climate‐dependant species may offer exciting insights on the impact of climate changes on species distributions. [ABSTRACT FROM AUTHOR]

The hyporheic zone of rivers potentially acts as a dispersal corridor for groundwater organisms because it provides a spatially continuous interstitial habitat between isolated aquifers. Yet, the degree to which it can facilitate the movement of organisms has been hypothesized to vary in response to change in sediment regime, which determines channel morphology., In this study, we used microsatellite markers to test for a relationship between the genetic structure and diversity of the minute interstitial isopod Proasellus walteri and channel morphology along three nearby hyporheic corridors differing widely in their sediment regime. We predicted that genetic diversity would decrease and genetic structuring would increase as sediment supply-limited channels would become prominent features in the river corridor. The reason is that such channels have fewer and less suitable sedimentary habitats for migration because they lack large depositional bedforms such as gravel bars., Using genotypic data from seven microsatellite loci for a total of 713 individuals distributed among 25 demes, we found that demes had on average more alleles and were less differentiated in the river showing the most extensive alluvial deposits and shortest length of sediment supply-limited channels. Population clusters were also of greater size, reaching up to 30 km in length. The longitudinal pattern of genetic differentiation in this sediment-rich river was best explained by hydrologic distance and the longitudinal pattern of allelic richness was bell-shaped, as expected under a stepping-stone model with symmetrical migration., The length of sediment supply-channels was more important than hydrologic distance in explaining the longitudinal distribution of genetic differentiation in the two other corridors facing a sediment shortage. Allelic richness decreased monotonically upstream in the most sediment-poor river. This correlates with the expansion further downstream of sediment supply-limited channels in this river, which is likely to decrease animal movement and hence gene flow among demes., This study provides the first evidence that the degree to which the hyporheic zone facilitates the movement of groundwater organisms varies greatly among rivers of contrasted geomorphology. Extending the application of riverscape genetics across a range of interstitial taxa and geomorphic settings holds much promise for assessing the contribution of the hyporheic zone to the dispersal of groundwater organisms. [ABSTRACT FROM AUTHOR]

When deciding to mate, it is assumed that females choose males bearing genes that will improve the genetic quality of their offspring, which is affected by both additive and nonadditive genetic variation. In this context, a ‘compatible genes’ model has been put forward to explain female mating decisions. According to this model, females are assumed to increase the genetic quality of their offspring by choosing mates on the basis of interactions between maternal and paternal genomes. Yet, this model is mainly supported by empirical data in endotherm vertebrates. Few studies have investigated this issue in terrestrial ectotherms like amphibians. These organisms often live in spatially structured populations characterized by small subpopulations and a high degree of philopatry, leading to striking reduction in gene flow, high genetic drift and relatively high inbreeding levels. In such a situation, one might expect that natural selection should favour mating tactics limiting the risk of inbreeding depression. In this paper, using an experimental approach controlling for the reproductive state of males, we examined how genetic compatibility may affect mating behaviour in an anuran, the yellow-bellied toad, Bombina variegata . First, our analyses confirmed a high degree of inbreeding in the studied population. Yet, we did not find any mating tactic that reduced the risk of inbreeding depression. Contrary to our expectations, males more closely related to the female had the higher mating success. We discuss the ecological and evolutionary implications of these results. [ABSTRACT FROM AUTHOR]