Thirty years of invasion: the distribution of the invasive crayfish Procambarus clarkii in Italy

The presence of the red swamp crayfish Procambarus clarkii in Italy is documented since 1989, but no comprehensive data are available on its spread through time at the national scale. New confirmed records for Procambarus clarkii are continuously arising in recent years across the country. By reviewing the scientific and grey literature, we obtained an up-to-date map of the species invasion in Italy. This information can help to monitor and understand the spread of this highly invasive crayfish and to implement more effective management measures.

Amphibian Biology. Volume 11, Part 4: Status of Conservation and Decline of Amphibians: Eastern Hemisphere. Southern Europe and Turkey

Heatwole, H. and J. W. Wilkinson (eds.). 2015. Amphibian Biology. Volume 11, Part 4: Status of Conservation and Decline of Am­phibians: Eastern Hemisphere. Southern Europe and Turkey. 158 pp. Pelagic Publishing, Exeter, UK

Numerical methods for sedimentary‐ancient‐DNA‐based study on past biodiversity and ecosystem functioning

Abstract Sedimentary ancient DNA (SedaDNA) is an emerging tool to reconstruct past biodiversity with high taxonomic resolution. Its growing popularity has stimulated an increasing complexity of SedaDNA data production (e.g., DNA extraction, amplification, and sequencing; authentication of molecules; bioinformatics). Conversely, less attention has been devoted to how appropriate statistical analyses can help to extract ecological information from SedaDNA. Until now, ecological studies based on SedaDNA have taken limited advantage of the multiple statistical and numerical methods available for analysis. Here, we present a range of numerical approaches that can be particularly useful to multispecies ecological analysis on SedaDNA, with a special focus on biodiversity studies on macroorganisms. We discuss the advantages and complexity of such methods and describe how some of them can be optimized for ecological analyses of SedaDNA‐based metabarcoding data, with a special focus on SedaDNA studies. First, site occupancy‐detection models can help to better ascertain the variation through time of the occurrence of target species and to identify the factors determining their detection through time. Second, several approaches can be used to estimate variation of relative abundance. Even though methods for abundance estimation have major limitations, they can provide useful information on temporal variation of ecosystem functions. Third, approaches exist to obtain better measures of species diversity, while taking into account the uncertainties of species abundance and identification. Fourth, techniques of clustering, ordination, and constrained ordination allow identification of temporal trends and testing of candidate drivers of community variation. Finally, structural equation models can be used to assess complex causal relationships among biodiversity, human activities, and environment. SedaDNA studies can make use of a broad panel of analytical approaches, which can improve our understanding of long‐term biodiversity changes, maximizing the information we can obtain from past ecosystems

Switching from mesopredator to apex predator: how do responses vary in amphibians adapted to cave living?

AbstractThe effective detection of both prey and predators is pivotal for the survival of mesopredators. However, the condition of being a mesopredator is strongly context dependent. Here we focus on two aquatic caudate species that have colonised caves: the Pyrenean newt (Calotriton asper) and the olm (Proteus anguinus). The former maintains both surface and subterranean populations, while only cave-adapted populations of the latter exist. Both species are apex predators in underground waterbodies, while the Pyrenean newt is a mesopredator in surface waterbodies. Shifting to a higher level of the trophic web through colonising caves may promote the loss of anti-predator response against surface apex predators, and an increase in the ability to detect prey. To test these two non-exclusive hypotheses, we integrated classical behavioural characterisations with a novel approach: the assessment of lateralisation (i.e. preference for one body side exposure). Behavioural experiments were performed using laboratory-reared individuals. We performed 684 trials on 39 Pyrenean newts and eight olms. Under darkness and light conditions, we tested how exposure to different chemical cues (predatory fish, prey and unknown scent) affected individuals' activity and lateralisation. Both cave and surface Pyrenean newts responded to predator cues, while olms did not. In Pyrenean newts, predator cues reduced the time spent in movement and time spent in lateralisation associated with hunting. Our results show that predator recognition is maintained in a species where recently separated populations inhabit environments lacking of higher predators, while such behaviour tends to be lost in populations with longer history of adaptation.Significance statementPredator recognition can be maintained in animals adapted to predator free habitats, but varies with their history of adaptation. Species that are not at the apex of the food web can become top predators if they colonise subterranean environments. We compared the behavioural responses of the olm, a strictly cave species with a long underground evolutionary history, and of the Pyrenean newt, a facultative cave species that also has stream-dwelling populations. Moreover, we integrated a classical behavioural characterisation, such as movement detection, with a novel approach: the assessment of lateralisation. While olms do not respond to external predators scent, cave-dwelling newts still recognise it. This clearly indicates that predator recognition is still maintained in species that have colonised predator-free environments more recently

Global determinants of zoogeographical boundaries

The distribution of living organisms on Earth is spatially structured. Early biogeographers identified the existence of multiple zoogeographical regions, characterized by faunas with homogeneous composition that are separated by biogeographical boundaries. Yet, no study has deciphered the factors shaping the distributions of terrestrial biogeographical boundaries at the global scale. Here, using spatial regression analyses, we show that tectonic movements, sharp changes in climatic conditions and orographic barriers determine extant biogeographical boundaries. These factors lead to abrupt zoogeographical transitions when they act in concert, but their prominence varies across the globe. Clear differences exist among boundaries representing profound or shallow dissimilarities between faunas. Boundaries separating zoogeographical regions with limited divergence occur in areas with abrupt climatic transitions. In contrast, plate tectonics determine the separation between deeply divergent biogeographical realms, particularly in the Old World. Our study reveals the multiple drivers that have shaped the biogeographical regions of the world

Applications and limitations of measuring environmental DNA as indicators of the presence of aquatic animals

1. In Rees et al. (2014b), we reviewed the current status of environmental DNA (eDN A) tomonitor aquatic populations. Our aim was to focus on discus sion of methodologies used,application of eDNA analysis as a survey tool in ecology, and to include some innovativeideas for using eDNA in conservation and management. 2. Roussel et al. (2015) claim that analysis of Rees et al. (2014b) and other publicationshighlights the downsides of the method, and they suggest that some conclusions should betoned down. Many of their arguments were covered in our original paper (Rees et al. ,2014b); however, they make the point that modelling approaches should be encouraged, andwe fully agree with this suggestion. 3. Roussel et al. (2015) also claim that we neglected to recognize that there are two sourcesof imperfect detection (at the field level and at the laboratory level). We feel that our reviewpaper implies this point. 4. Synthesis and applications. Roussel et al. (2015) reiterate many of the points made in theoriginal paper but do cover some additional areas that improve the debate on the use of envi-ronmental DNA (eDNA). Both the comment (Roussel et al., 2015) and our rebuttal clearlyhighlight that detailed laboratory protocols and rigorous field sampling design are crucial fac-tors which require sufficient reporting in the literature to allow for experimenta l comparisonand replication. Any development of a new method for eDNA detection should be compareddirectly with established ‘gold standard’ methods for the detection of the species or habitatunder investigation. None of the issues raised in Roussel et al. (2015) would alter our mainconclusions

Microhabitat analyses support relationships between niche breadth and range size when spatial autocorrelation is strong

Multiple evidence of positive relationships between nice breadth and range size (NB\u2013RS) suggested that this can be a general ecological pattern. However, correlations between niche breadth and range size can emerge as a by-product of strong spatial structure of environmental variables. This can be problematic because niche breadth is often assessed using broad-scale macroclimatic variables, which suffer heavy spatial autocorrelation. Microhabitat measurements provide accurate information on species tolerance, and show limited autocorrelation. The aim of this study was to combine macroclimate and microhabitat data to assess NB\u2013RS relationships in European plethodontid salamanders (Hydromantes), and to test whether microhabitat variables with weak autocorrelation can provide less biased NB\u2013RS estimates across species. To measure macroclimatic niche, we gathered comprehensive information on the distribution of all Hydromantes species, and combined them with broad-scale climatic layers. To measure microhabitat, we recorded salamander occurrence across > 350 caves and measured microhabitat features influencing their distribution: humidity, temperature and light. We assessed NB\u2013RS relationships through phylogenetic regression; spatial null-models were used to test whether the observed relationships are a by-product of autocorrelation. We observed positive relationships between niche breadth and range size at both the macro- and microhabitat scale. At the macroclimatic scale, strong autocorrelation heavily inflated the possibility to observe positive NB\u2013RS. Spatial autocorrelation was weaker for microhabitat variables. At the microhabitat level, the observed NB\u2013RS was not a by-product of spatial structure of variables. Our study shows that heavy autocorrelation of variables artificially increases the possibility to detect positive relationships between bioclimatic niche and range size, while fine-scale data of microhabitat provide more direct measure of conditions selected by ectotherms, and enable less biased measures of niche breadth. Combining analyses performed at multiple scales and datasets with different spatial structure provides more complete niche information and effectively tests the generality of niche breadth\u2013range size relationships

The Racovitzan impediment and the hidden biodiversity of unexplored environments

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Rapid adaptation to invasive predators overwhelms natural gradients of intraspecific variation

Invasive predators can exert strong selection on native populations. If selection is strong enough, populations could lose the phenotypic variation caused by adaptation to heterogeneous environments. We compare frog tadpoles prior to and 14 years following invasion by crayfish. Prior to the invasion, populations differed in their intrinsic developmental rate, with tadpoles from cold areas reaching metamorphosis sooner than those from warm areas. Following the invasion, tadpoles from invaded populations develop faster than those from non-invaded populations. This ontogenetic shift overwhelmed the intraspecific variation between populations in a few generations, to the point where invaded populations develop at a similar rate regardless of climate. Rapid development can have costs, as fast-developing froglets have a smaller body size and poorer jumping performance, but compensatory growth counteracts some costs of development acceleration. Strong selection by invasive species can disrupt local adaptations by dampening intraspecific phenotypic variation, with complex consequences on lifetime fitness