Different facets of the same niche: Integrating citizen science and scientific survey data to predict biological invasion risk under multiple global change drivers.

Citizen science initiatives have been increasingly used by researchers as a source of occurrence data to model the distribution of alien species. Since citizen science presence-only data suffer from some fundamental issues, efforts have been made to combine these data with those provided by scientifically structured surveys. Surprisingly, only a few studies proposing data integration evaluated the contribution of this process to the effective sampling of species' environmental niches and, consequently, its effect on model predictions on new time intervals. We relied on niche overlap analyses, machine learning classification algorithms and ecological niche models to compare the ability of data from citizen science and scientific surveys, along with their integration, in capturing the realized niche of 13 invasive alien species in Italy. Moreover, we assessed differences in current and future invasion risk predicted by each data set under multiple global change scenarios. We showed that data from citizen science and scientific surveys captured similar species niches though highlighting exclusive portions associated with clearly identifiable environmental conditions. In terrestrial species, citizen science data granted the highest gain in environmental space to the pooled niches, determining an increased future biological invasion risk. A few aquatic species modelled at the regional scale reported a net loss in the pooled niches compared to their scientific survey niches, suggesting that citizen science data may also lead to contraction in pooled niches. For these species, models predicted a lower future biological invasion risk. These findings indicate that citizen science data may represent a valuable contribution to predicting future spread of invasive alien species, especially within national-scale programmes. At the same time, citizen science data collected on species poorly known to citizen scientists, or in strictly local contexts, may strongly affect the niche quantification of these taxa and the prediction of their future biological invasion risk.

The Eurasian otter (Lutra lutra) as a potential host for rickettsial pathogens in southern Italy.

Canine monocytic ehrlichiosis and rickettsiosis are zoonotic tick-borne diseases of canids caused by the intracellular obligate bacteria Ehrlichia canis and Rickettsia species respectively. In this study, we investigated using standard and real-time PCR and sequencing, the occurrence and molecular characterization of E. canis and Rickettsia species in the Eurasian otter (Lutra lutra) from the southern Italian population. Samples were screened by using molecular assays also for Neospora caninum, Toxoplasma gondii, Clamydophyla spp., Coxiella burnetii, Leishmania spp., Cryptosporidium spp., and Giardia spp. detection, and helminths were studied by traditional methods. Out of six carcasses tested, three were positive for E. canis and co-infection with Rickettsia sp. occurred in one of those. Sequences of the 16S rRNA E. canis gene were identical to each other but differed from most of those previously found in red foxes (Vulpes vulpes) and wolves (Canis lupus) from southern Italy. Helminths included just cystacanths of Sphaerirostris spp. from the intestine of two Eurasian otters and the nematode Angiostrongylus vasorum from the lungs of a single Eurasian otter. None of the samples was positive for the other investigated selected pathogens. This study is the first report on the evidence of infection by rickettsial pathogens in the Eurasian otter. The present result prompts some inquiries into the pathogenic role of those bacteria for the isolated sub-populations of the endangered Eurasian otter in southern Italy.

A combination of long term fragmentation and glacial persistence drove the evolutionary history of the Italian wall lizard Podarcis siculus.

BACKGROUND: The current distribution of genetic diversity is the result of a vast array of microevolutionary processes, including short-term demographic and ecological mechanisms and long-term allopatric isolation in response to Quaternary climatic fluctuations. We investigated past processes that drove the population differentiation and spatial genetic distribution of the Italian wall lizard Podarcis siculus by means of sequences of mitochondrial cytb (n = 277 from 115 localities) and nuclear mc1r and ß-fibint7genes (n = 262 and n = 91, respectively) from all its distribution range. The pattern emerging from the genetic data was compared with current and past (last glacial maximum) species distribution modeling (SDM). RESULTS: We identified seven deeply divergent parapatric clades which presumably remained isolated in different refugia scattered mainly throughout the Tyrrhenian coast. Conversely, the Adriatic coast showed only two haplogroups with low genetic variability. These results appear to agree with the SDM prediction at the last glacial maximum (LGM) indicating a narrow area of habitat suitability along the Tyrrhenian coast and much lower suitability along the Adriatic one. However, the considerable land exposure of the Adriatic coastline favored a glacial colonization of the Balkan Peninsula. CONCLUSIONS: Our population-level historical demography showed a common trend consistent with glacial expansions and regional persistence during the last glacial maximum. This complex genetic signature appears to be inconsistent with the expectation of the expansion-contraction model and post-LGM (re)colonizations from southern refugia. Hence it is one of an increasing number of cases in which these assumptions are not met, indicating that long-term fragmentation and pre-LGM events such as glacial persistence were more prominent in shaping genetic variation in this temperate species.

Preventing species invasion: A role for integrative taxonomy?

Integrative taxonomy, a multi-disciplinary approach adding modern techniques to traditional morphology-based methods (e.g. molecular and morphological criteria), can play an important role in bioinvasion research to identify introduced taxa, discover pathways of introduction and inform authorities to control and prevent future introductions. The present study is the first on introduced populations of Callosciurus, Asiatic tree squirrels, known as potentially invasive species in Europe (Italy, Belgium and France). We combined molecular (mitochondrial DNA markers: CoxI, D-loop) and morphometric analysis on skulls, comparing them to the widest morphological and molecular datasets ever assembled for Callosciurus. Squirrels collected in Italy and Belgium share the same haplotypes and skull characteristics, but are conspicuously different from the French population in Antibes. Genetic data revealed close similarity between French squirrels and Pallas's squirrels, Callosciurus erythraeus, from Taiwan, China. Italian and Belgian squirrels formed an independent taxonomic lineage in genetic analyses, whose taxonomic rank needs further investigation. The morphological and morphometric characteristics of these 2 populations are, however, similar to known specimens assigned to Callosciurus erythraeus. These results may indicate a common origin for the populations found in Belgium and Italy. In contrast, French specimens suggest an independent introduction event of squirrels originating from Asia.

Modern analyses on an historical data set: skull morphology of Italian red squirrel populations.

Recent molecular evidence suggests that Sciurus vulgaris populations from Calabria (southern Italy) are distinct from those occurring in northern and central Italy. Here, we re-analyzed using multivariate and univariate techniques an historical dataset provided by Cavazza (1913), who documented measurements for the now extinct squirrel population from Campania. Both univariate and multivariate analyses confirmed that the sample from Calabria was homogenous and relatively distinct compared to the rest of the squirrel samples.

Birth of a hotspot of intraspecific genetic diversity: notes from the underground.

Hotspots of intraspecific diversity have been observed in most species, often within areas of putative Pleistocene refugia. They have thus mostly been viewed as the outcome of prolonged stability of large populations within the refugia. However, recent evidence has suggested that several other microevolutionary processes could also be involved in their formation. Here, we investigate the contribution of these processes to current range-wide patterns of genetic diversity in the Italian endemic mole Talpa romana, using both nuclear (30 allozyme loci) and mitochondrial markers (cytochrome b sequences). Southern populations of this species showed an allozyme variation that is amongst the highest observed in small mammals (most populations had an expected heterozygosity of 0.10 or above), which was particularly unexpected for a subterranean species. Population genetic, phylogeographic and historical demographic analyses indicated that T. romana populations repeatedly underwent allopatric differentiations followed by secondary admixture within the refugial range in southern Italy. A prolonged demographic stability was reliably inferred from the mitochondrial DNA data only for a population group located north and east of the Calabrian peninsula, showing comparatively lower levels of allozyme variability, and lacking evidence of secondary admixture with other groups. Thus, our results point to the admixture between differentiated lineages as the main cause of the higher levels of diversity of refugial populations. When compared with the Pleistocene evolutionary history recently inferred for species from both the same and other geographic regions, these results suggest the need for a reappraisal of the role of gene exchange in the formation of intraspecific hotspots of genetic diversity.

Molecular phylogeography of European Sciurus vulgaris: refuge within refugia?

The red squirrel (Sciurus vulgaris) is a well-known forest animal distributed all over Europe. Still, we are far from having a firm knowledge of the species' phylogeography. This study investigates the genetic differentiation of S. vulgaris across the species' Eurasian range, using sequence data from the mitochondrial DNA gene (D-loop, 252 base pairs, cytochrome b, 359 base pairs), and eight variable autosomal microsatellite loci genotyped for 236 individuals. The results reveal the presence of two main mitochondrial phylogroups. The first clade comprises the individuals from the region of Calabria in southern Italy, belonging to the subspecies S. v. meridionalis, while the second clade contains the remainder of the studied individuals. Bayesian analysis of microsatellite genotypes resulted in three main clusterings corresponding to the three S. vulgaris subspecies: infuscatus, meridionalis and fuscoater. Geographical distribution of mtDNA haplotypes and mismatch analysis suggest a common refugium for the red squirrel across most of its present range from which expansion happened rather rapidly. The genotype mixing of italicus with northern populations could be a residual of postglacial expansion. The lack of mixing between the Calabrian lineage and the rest of European red squirrel haplotypes can be seen as evidence for distinct histories throughout the Pleistocene. Calabrian mtDNA probably diverged in an ice age contraction and remained isolated from the neighbouring squirrel populations until very recent times.