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Pond physical characteristics (connectivity, hydroperiod) have shown to be highly relevant in explaining species presence, reproductive success, and survival in breeding-pond amphibians. However, few studies have addressed the influence that these factors may have on the genetic variability of pond populations. We examined genetic variation at 11 microsatellite loci in Iberian endemic, the pygmy newt (Triturus pygmaeus), from 58 breeding ponds in the Doñana National Park (Andalusia), including both temporary ponds and artificially deepened ponds that remain wet during the whole year. Temporary ponds are located in the North part of the region where the surrounding habitat-wet meadows-facilitates the connectivity among populations, whereas the deepest ponds (‘zacallones’) are located in the southern edge embedded in a matrix of unsuitable habitat (thickets and dry underbrush). We investigated genetic diversity and structure within and among ponds. Our results show that both regions (Doñana-North and Doñana-South) are well-differentiated and form two main clusters. We found higher genetic diversity within ponds from the North region, which also exhibited a higher degree of genetic admixture in comparison with populations from the southern edge. Although we found an isolation-by-distance pattern within each cluster, it arose due to the effect of a few isolated ponds located on the edge of each zone, suggesting the existence of substantial gene flow between ponds in the core area. According to our findings, landscape’s permeability to movement (pond connectivity) may constitute a more important factor than hydroperiod length in determining the genetic diversity and viability of pygmy newt populations in this area. Although Doñana populations show a good state, more peripheral and isolated populations present a more worrisome condition as a result of fragmentation and thus, require conservation efforts. Our study provides key insights that could help guide management pra

Understanding the relative contribution of different biotic interactions in shaping species assemblages constitutes a major goal in community ecology, and consequently, multiple methods aimed at inferring the nature of these associations have emerged during the last decade. In this framework, the stress-gradient hypothesis (SGH) predicts that prevalent biotic interactions shift from competition to facilitation as abiotic stress increases (and productivity decreases). This hypothesis originally raised by plant ecologists has been barely applied to faunal communities. Here, we take advantage of 20 years of abundance data to investigate pairwise patterns in species co-occurrence in alpine bird communities inhabiting two contrasting habitat types: forests (high productivity) and mountain grasslands (low productivity). We also integrate functional data with presence–absence and quantitative matrices in order to detect the signature of processes driving community assembly and test for limiting similarity. We employ a null model approach, probabilistic pairwise association tests and joint species distribution models; all methods revealed a higher frequency of positive interactions in mountain grasslands in agreement with SGH predictions. Both the frequency of positive and negative interactions remained moderately stable over the study period in both habitat types. There was no significant relationship between the degree of co-occurrence of species pairs and their functional distance in either habitat. However, when we only considered those combinations of species whose co-occurrence patterns deviated from that expected at random, we found that co-existing species are functionally more similar than those pairs that show segregated patterns in the forest assemblages. Such a relationship may arise via selective social information use and other processes, including microhabitat preferences. Overall, our findings suggest that interspecific competition does not constitute a majo

Pond physical characteristics (connectivity, hydroperiod) have shown to be highly relevant in explaining species presence, reproductive success, and survival in breeding-pond amphibians. However, few studies have addressed the influence that these factors may have on the genetic variability of pond populations. We examined genetic variation at 11 microsatellite loci in Iberian endemic, the pygmy newt (Triturus pygmaeus), from 58 breeding ponds in the Doñana National Park (Andalusia), including both temporary ponds and artificially deepened ponds that remain wet during the whole year. Temporary ponds are located in the North part of the region where the surrounding habitat-wet meadows-facilitates the connectivity among populations, whereas the deepest ponds (‘zacallones’) are located in the southern edge embedded in a matrix of unsuitable habitat (thickets and dry underbrush). We investigated genetic diversity and structure within and among ponds. Our results show that both regions (Doñana-North and Doñana-South) are well-differentiated and form two main clusters. We found higher genetic diversity within ponds from the North region, which also exhibited a higher degree of genetic admixture in comparison with populations from the southern edge. Although we found an isolation-by-distance pattern within each cluster, it arose due to the effect of a few isolated ponds located on the edge of each zone, suggesting the existence of substantial gene flow between ponds in the core area. According to our findings, landscape’s permeability to movement (pond connectivity) may constitute a more important factor than hydroperiod length in determining the genetic diversity and viability of pygmy newt populations in this area. Although Doñana populations show a good state, more peripheral and isolated populations present a more worrisome condition as a result of fragmentation and thus, require conservation efforts. Our study provides key insights that could help guide management pra

When confronted with a predator, many mammalian species emit vocalizations known as alarm calls. Vocal structure variation results from the interactive effects of different selective pressures and constraints affecting their production, transmission, and detection. Body size is an important morphological constraint influencing the lowest frequencies that an organism can produce. The acoustic environment influences signal degradation; low frequencies should be favoured in dense forests compared to more open habitats (i.e. the ‘acoustic adaptation hypothesis'). Such hypotheses have been mainly examined in birds, whereas the proximate and ultimate factors affecting vocalizations in nonprimate mammals have received less attention. In the present study, we investigated the relationships between the frequency of alarm calls, body mass, and habitat in 65 species of rodents. Although we found the expected negative relationship between call frequency and body mass, we found no significant differences in acoustic characteristics between closed and open-habitat species. The results of the present study show that the acoustic frequencies of alarm calls can provide reliable information about the size of a sender in this taxonomic group, although they generally do not support the acoustic adaptation hypothesis.

We investigated taxonomic and functional beta diversity of bird communities inhabiting Mediterranean olive groves subject to either intensive or low-intensity management of the ground cover and located in landscapes with different degrees of complexity. Location: Andalusia, southern Spain. Methods: We partitioned taxonomic and functional beta diversity into its two additive components, turnover and nestedness. We also explored the contributions of single sites to overall beta diversity (LCBD) and separated the effects of species replacement (turnover) and richness difference (nestedness) in order to identify ecologically unique sites—keystone communities—within the metacommunity. In a further step, we employed abundance-and functional-based indicator species analyses to characterize bird assemblages. Results: Taxonomic beta diversity increased with landscape complexity. Although both taxonomic and functional differences among assemblages were driven mainly by species replacement (regardless of management or landscape type), the contribution of trait replacement to the total functional beta diversity was much lower, suggesting that species performing similar functions replace each other between sites. There were no differences in LCBD between management types or categories of landscape complexity, but the contributions of sites to beta diversity decreased as the percentage cover of olive groves increased. Species richness was also important in explaining variation in LCBD as species-poor sites tended to contribute the most to the local-to- regional beta diversity. However, some farms displayed high values of LCBD due to the existence of a high replacement component, indicating that some species recorded in these sites were scarce elsewhere. The indicator species analyses of biodiversity in this agro-forestry system. Main conclusions: Our results show that agricultural expansion promotes biotic homogenization and exemplify how the identification of both keystone speci

Background: Trophic shifts from one dietary niche to another have played major roles in reshaping the evolutionary trajectories of a wide range of vertebrate groups, yet their consequences for morphological disparity and species diversity differ among groups. Methods: Here, we use phylogenetic comparative methods to examine whether the evolution of nectarivory and other trophic shifts have driven predictable evolutionary pathways in Australasian psittaculid parrots in terms of ecological traits such as body size, beak shape, and dispersal capacity. Results: We found no evidence for an ‘early-burst’ scenario of lineage or morphological diversification. The bestfitting models indicate that trait evolution in this group is characterized by abrupt phenotypic shifts (evolutionary jumps), with no sign of multiple phenotypic optima correlating with different trophic strategies. Thus, our results point to the existence of weak directional selection and suggest that lineages may be evolving randomly or slowly toward adaptive peaks they have not yet reached. Conclusions: This study adds to a growing body of evidence indicating that the relationship between avian morphology and feeding ecology may be more complex than usually assumed and highlights the importance of adding more flexible models to the macroevolutionary toolbox

Understanding the relative contribution of different biotic interactions in shaping species assemblages constitutes a major goal in community ecology, and consequently, multiple methods aimed at inferring the nature of these associations have emerged during the last decade. In this framework, the stress-gradient hypothesis (SGH) pre-dicts that prevalent biotic interactions shift from competition to facilitation as abiotic stress increases (and productivity decreases). This hypothesis originally raised by plant ecologists has been barely applied to faunal communities. Here, we take advantage of 20 years of abundance data to investigate pairwise patterns in species co-occurrence in alpine bird communities inhabiting two contrasting habitat types: forests (high productivity) and mountain grasslands (low productivity). We also integrate functional data with presence–absence and quantitative matrices in order to detect the signature of processes driving community assembly and test for limiting similarity. We employ a null model approach, probabilistic pairwise association tests and joint species distribution models; all methods revealed a higher frequency of positive interactions in mountain grasslands in agreement with SGH predictions. Both the frequency of positive and negative interactions remained moderately stable over the study period in both habitat types. There was no significant relationship between the degree of co-occurrence of species pairs and their functional distance in either habitat. However, when we only considered those combinations of species whose co-occurrence patterns deviated from that expected at random, we found that co-existing species are functionally more similar than those pairs that show segregated patterns in the forest assemblages. Such a relationship may arise via selective social information use and other processes, including microhabitat preferences. Overall, our findings suggest that interspecific competition does not constitute a maj

The merging of community ecology and phylogenetic biology allows us to link broader evolutionary processes to local ecological processes, thereby increasing our understanding of community assembly. A recurrent way to test how species assemblages respond to different abiotic conditions and evaluate the role of evolutionary constraints in community assembly is through using environmental gradients as natural treatments. Here, we combine phylogenetic and trait-based methods to evaluate how the phylogenetic diversity and composition of bird assemblages and their community-weighted traits vary along an elevational gradient in the Swiss Alps. For this purpose, we used four life-history traits considered to be key indicators of individual species response to environmental changes: clutch size, number of breeding attempts, dispersal capacity and lifespan. Controlling for phylogeny, we determined whether environmental filters (elevation, habitat type) act on these traits independently of the level of relatedness among species. We found that phylogenetic dispersion decreases with elevation, but the signature of phylogenetic clustering was weak. Phylogenetic fuzzy weighting showed that the distribution of bird species across plots was related to the two environmental gradients; nonetheless, such influence was not determined by the phylogenetic relationships in either case. That is, there are no specific clades associated with particular elevation or habitat types. We also found that high elevation communities around the treeline were composed of species with lower reproductive rates, reduced lifespan, and lower dispersal capacity, which would make them less resilient to environmental change. Although traits showed moderate phylogenetic signal, only the lifespan was phylogenetically structured. In the remaining cases, the trait-environment association was not mediated by the phylogenetic relationships among taxa. Our study indicates that evolutionary constraints do not represen

Aim Mountains are biodiversity hotspots and are among the most sensitive ecosystems to ongoing global change being thus of conservation concern. Under this scenario, assessing how biological communities vary over time along elevational gradients and the relative effects of niche-based deterministic processes and stochastic events in structuring assemblages is essential. Here, we examined how the temporal trends of bird communities vary with elevation over a 20 year-period (1999–2018). We also tested for differences in temporal dynamics among habitat types (among-community variability) and functional groups (within-community variability). Taxon 97 species of common breeding birds. Location Swiss Alps. Methods We used abundance data from the Swiss breeding bird survey to compute different temporal dynamic metrics (temporal turnover, synchrony, rate of community change and community-level of covariance among species). We also examined the relative contribution of deterministic and stochastic processes in community assembly using the Raup-Crick method and the normalized stochasticity ratio. Results We found that, with greater elevation, temporal species turnover increased while the rate of overall community change over successive years decreased, suggesting that high-elevation communities display more erratic dynamics with no clear trend. Despite this, we found a more deterministic assembly of alpine communities in comparison to those located at lower elevations. Deterministic processes had greater influence than stochastic processes on community assembly along the entire elevational gradient (80% of communities). Forest communities exhibited higher synchrony in comparison to the remaining habitats likely because they consisted of species with greater functional redundancy, whereas alpine communities were the least stable as a result of their low taxonomic richness (‘portfolio’ effect). Main conclusions Community-level synchrony was overall positive supporting the idea

Aim To determine the effects of competition and divergence time on morphological dissimilarity and geographical range overlap between dasyurid species at both regional and local scales. Our hypothesis is that speciation in this group has been largely allopatric at regional scale, but involved morphological divergence at local scale through sympatric character displacement. Location Australia, New Guinea and surrounding islands. Taxon Dasyurid (Dasyuridae) marsupials, 67 species. Methods Geographical range overlap was quantified using polygons representing the outer limits of species distributions. Local‐scale range overlap was quantified as the degree of co‐occurrence of two taxa across a set of ecological survey plots representing 83 sampled communities. Phylogenies were generated using a novel DNA dataset, with divergence times estimated via total‐evidence dating incorporating fossils. Morphological divergence was determined using body mass and lower molar row length as proxy traits for reconstructing niche exploitation. Results Sister species pairs were found to be sympatric in 52% (11/21) of cases. Range overlap tended to increase with node age, which supports the hypothesis that mammalian speciation is routinely allopatric. We detected no evidence of character displacement with increasing range overlap between sister species pairs. However, a negative relationship was observed between morphological divergence in body mass and range overlap across all sampled taxa, suggesting that selection in sympatry is convergent, while divergent selection occurs in allopatry. Local‐scale co‐occurrences revealed no trace of species aversion, indicating that competition has not impacted on the spatial distribution of dasyurids. Main conclusions Despite moderate levels of sympatry through time, our results evince low rates of spatial co‐occurrence between dasyurid species. Although this may be indicative competitive exclusion, the lack of character displacement suggests that bi

Aim Under a global change scenario, research focused on changes in assembly patterns over spatial and temporal axes is paramount. Despite an increasing need to assess whether associations among diversity and community metrics change in relation to environmental heterogeneity, the way in which community assembly rules vary across habitats has been hardly explored. Here, we tested for differences in patterns of functional diversity (FD) and phylogenetic diversity (PD) between farmland and forest bird communities in order to improve our understanding about how biological communities respond to anthropogenic disturbances. Location Continental France. Taxon 107 species of common birds. Methods We used an extensive dataset (13 years; 7,115 bird communities) from the French Breeding Bird survey in conjunction with a matrix of 142 functional traits (including information on habitat, diet, life‐stories, behaviour and morphology) to compute different metrics of FD and PD and examine how these vary between habitat types and across time. Results We found that farmland assemblages showed higher FD and PD than forest assemblages, which were phylogenetically clustered. Both FD and PD of forest assemblages increased with increasing species richness, whereas in farmland assemblages the relationship was asymptotic in both cases. This pattern may be due to the accumulation of generalists, which can end up displacing specialist species when the environment becomes oversaturated triggering a decline in diversity. Contrary to expectations, FD and PD of farmland assemblages increased over the study period, whereas forest assemblages showed a non‐linear pattern. Farmland and forest assemblages also showed divergent trajectories over time in relation to FD metrics. Main conclusions Although farmland intensification led to a sharp decline in populations of farmland birds, agricultural landscapes in southern Europe still harbour diversity‐rich communities probably due to the legacy effects of

Aim Describing the spatio‐temporal dynamics of biotic communities is critical for understanding how environmental change can affect biodiversity. Mountains are especially susceptible to such changes (e.g., climate change) and, consequently, have been identified as ecosystems of conservation concern. With their sharp physical and ecological transitions, altitudinal gradients allow examining the influence of different climatic conditions and land use types on species assemblages across small spatial extents, and thus, they constitute natural laboratories to study diversity–environment relationships. Location Switzerland. Methods We take advantage of long‐term (20 years) monitoring data and an extensive trait dataset (100 traits) to examine spatial patterns, temporal trends, and spatio‐temporal dynamics in functional and beta diversity of bird communities in the Swiss Alps. Results Functional diversity indices showed a congruent pattern over time and across space; most indices decreased over the study period and were strongly correlated with altitude. In agreement with studies from the tropics, we found that communities in the lowlands were functionally over‐dispersed, whereas communities at higher elevations were functionally clustered. High‐altitude communities exhibited high functional originality, low levels of niche differentiation and a high turnover rate. Beta diversity declined over the study period. Conclusions Our findings suggest that pastoral abandonment does not result in an increase in avian functional diversity as most species colonizing woody‐encroached grasslands are functionally redundant, whereas alpine meadows are inhabited by species exhibiting a high degree of habitat specialization and unique functional traits. Hence, the tree line constitutes a boundary between two well‐differentiated functional groups: one representing a functional continuum from lowlands dominated by agricultural landscape to high‐mountain forests, and the other one composed o

There are examples of coexisting species with similar morphology and ecology, in apparent contradiction to competition theory. Shrews (Soricidae) are a paradigmatic example of this because members of this group exhibit a conserved body form, relatively low variability in lifestyle, and, in many cases, a sympatric distribution. Here, we combined geometric morphometrics and ecological niche modeling to test whether diversification of soricid species inhabiting the Iberian Peninsula has been driven by niche divergence or, conversely, whether niche conservatism has played a paramount role in this process. We also examined whether pairwise morphological distances increase as the degree of niche overlap between species becomes greater, as would be expected if interspecific competition promotes morphological differentiation. Our results showed that water shrews (Neomys ), white‐toothed shrews (Crocidurinae), and red‐toothed shrews (Soricinae) are clearly differentiated in terms of both skull shape and mandible shape. However, we found a lack of phylogenetic signal in most morphological traits, indicating that closely related species are not more similar than expected by random chance. Notably, water shrews show a more “triangular” or sharp skull than white‐toothed and red‐toothed shrews, probably as an adaptation to their semiaquatic lifestyle. In agreement with the phenotypic data, climatic traits (mean annual temperature and annual precipitation) were highly labile and sister taxa showed extensive differentiation in their realized niche space. Finally, we found that phenotypic distances between species tend to increase as the degree of niche overlap increases, suggesting that interspecific competition is an important factor in determining the level of morphological resemblance among relatives. Overall, our results indicate that the existence of limited morphological disparity in a given group does not necessarily imply the existence of a niche conservatism signature.