Nitrogen and carbon stable isotope analysis sheds light on trophic competition between two syntopic land iguana species from Galápagos.

Coexistence between closely related species can lead to intense competition for resources. Stable isotope analysis (SIA) is a reliable tool to estimate the extent of species competition. We employed SIA to evaluate niche partitioning among two syntopic species of Galápagos land iguanas: Conolophus subcristatus and C. marthae. Samples were collected on Wolf Volcano, Isabela Island, where C. marthae is endemic and syntopic with C. subcristatus. We determined δ13C and δ15N ratios and described the isotopic niche of each species using corrected standard ellipse area (SEAc). We tested for differentiation between the isotopic niches, while controlling for sex, body size, spatial location of samples and mean annual primary productivity at capture points, using bivariate linear models. Despite the extensive overlap of the isotopic niches, we found species and sex to be a significant, interacting predictor of a sample's location in the δ13C, δ15N space, indicating the existence of niche partitioning mechanisms acting between species and sexes. We also found that body size and productivity at the capture points, compounded with yet undetermined spatial effects, explain ca. 75% of the differences observed between species and sexes, providing evidence for differential microhabitat and food-items usage. Our study provides essential baselines for evaluating conservation actions for C. marthae, such as the potential translocation to a sanctuary area free of competition from C. subcristatus.

Exploring mobility in Italian Neolithic and Copper Age communities.

As a means for investigating human mobility during late the Neolithic to the Copper Age in central and southern Italy, this study presents a novel dataset of enamel oxygen and carbon isotope values (δ18Oca and δ13Cca) from the carbonate fraction of biogenic apatite for one hundred and twenty-six individual teeth coming from two Neolithic and eight Copper Age communities. The measured δ18Oca values suggest a significant role of local sources in the water inputs to the body water, whereas δ13Cca values indicate food resources, principally based on C3 plants. Both δ13Cca and δ18Oca ranges vary substantially when samples are broken down into local populations. Statistically defined thresholds, accounting for intra-site variability, allow the identification of only a few outliers in the eight Copper Age communities, suggesting that sedentary lifestyle rather than extensive mobility characterized the investigated populations. This seems to be also typical of the two studied Neolithic communities. Overall, this research shows that the investigated periods in peninsular Italy differed in mobility pattern from the following Bronze Age communities from more northern areas.

Palaeodiet reconstruction in a woman with probable celiac disease: a stable isotope analysis of bone remains from the archaeological site of Cosa (Italy).

Stable isotope analysis in the reconstruction of human palaeodiets can yield clues to early human subsistence strategies, origins and history of farming and pastoralist societies, and intra- and intergroup social differentiation. In the last 10 years, the method has been extended to the pathological investigation. Stable isotope analysis to better understand a diet-related disease: celiac disease in ancient human bones was carried out. To do this, we analyzed the nitrogen and carbon isotopic composition of human (n = 37) and faunal (n = 8) bone remains from the archaeological site of Cosa at Ansedonia, on the Tyrrhenian coast near Orbetello (Tuscany), including the skeletal remains of a young woman (late 1st century-early 2nd century Common Era [CE]) with morphological and genetic features suggestive of celiac disease. We compared the young woman's isotopic data with those of other individuals recovered at the same site but from two later time periods (6th century CE; 11-12th century CE) and with literature data from other Italian archaeological sites dating to the same period. Her collagen δ(13) C and δ(15) N values differed from those of the samples at the same site, and from most but not all of the contemporary sites. Although the woman's diet appears distinct, chronic malnutrition resulting from severe malabsorption of essential nutrients due to celiac disease may have affected the isotopic composition of her bone collagen.

A unique midgut-associated bacterial community hosted by the cave beetle Cansiliella servadeii (Coleoptera: Leptodirini) reveals parallel phylogenetic divergences from universal gut-specific ancestors.

BACKGROUND: Cansiliella servadeii (Coleoptera) is an endemic troglobite living in deep carbonate caves in North-Eastern Italy. The beetle constantly moves and browses in its preferred habitat (consisting in flowing water and moonmilk, a soft speleothem colonized by microorganisms) self-preens to convey material from elytra, legs, and antennae towards the mouth. We investigated its inner and outer microbiota using microscopy and DNA-based approaches. RESULTS: Abundant microbial cell masses were observed on the external appendages. Cansiliella's midgut is fully colonized by live microbes and culture-independent analyses yielded nearly 30 different 16S phylotypes that have no overlap with the community composition of the moonmilk. Many of the lineages, dominated by Gram positive groups, share very low similarity to database sequences. However for most cases, notwithstanding their very limited relatedness with existing records, phylotypes could be assigned to bacterial clades that had been retrieved from insect or other animals' digestive traits. CONCLUSIONS: Results suggest a history of remote separation from a common ancestor that harboured a set of gut-specific bacteria whose functions are supposedly critical for host physiology. The phylogenetic and coevolutionary implications of the parallel occurrences of these prokaryotic guilds appear to apply throughout a broad spectrum of animal diversity. Their persistence and conservation underlies a possibly critical role of precise bacterial assemblages in animal-bacteria interactions.