Porcupines in Italian islands: update on the distribution of Hystrix cristata in Sardinia

In the last few decades, the crested porcupine (Hystrix cristata L., 1758) showed a remarkable range expansion in Italy, due to legal protection, climatic change and antropochorous releases. Particularly, porcupines have been released also in Sardinia, with first records of this large rodent in the wild dating back to 2005. Historical and social factors related to the progressive urbanization and the consequent abandonment of the traditional land use in mountain landscapes probably helped the re-expansion of forest, uncultivated fields and of animal’s species associated with these habitats. In Sardinia, a population establishment and a subsequent expansion of the area of distribution can be predicted as large portions of the island are highly suitable for the crested porcupine. Therefore, this recently introduced population should be removed to limit potential ecological and social conflicts.

Evaluation of skull and mandible morphometric measurements and three-dimensional modelling of computed tomographic images of porcupine (Hystrix cristata)

Although there have been morphological and morphometric studies on the porcupine skull, three-dimensional modelling of the skull is performed for the first time with the present study. In this study, it was aimed to model the skull and mandible of Hystrix cristata in 3D to reveal its morphometric values and the differences between the sexes. Morphometric analyses were performed on a total of eight (four male and four female) adult porcupine skulls and mandibles. Skulls and mandibles of porcupines were scanned usinf a 64-detector MDCT (General Electric Revolution) device at 80 kV, 200 MA, 639 mGY and 0.625 mm slice thickness. Skull and mandible reconstructions were made with the help of MIMICS 20.1 (Materialize) software program and the surface area and volume values of the skull and mandible were calculated. Statistical analyses were carried out using SPSS 22.0 software. The longest measurement in the skulls, based on the metric measurement points, was the total length (TL), and it was measured as 135.4750 ± 0.54976 mm in males and 134.4725 ± 0.86681 mm in females (p < 0.5). The highest value was the foramen magnum index (p < 0.5), and the lowest value the was skull index (p < 0.1). While the total volume ratio of the mandibles was 29901.64 mm3 in males, it was 27296.20 mm3 in females (p > 0.5). Statistical differences in the morphometric values of skulls and mandibles of male and female porcupines were demonstrated for the first time using CT and three-dimensional modelling software.

Occipital condyle width (OCW) is a highly accurate predictor of body mass in therian mammals

BACKGROUND

Body mass estimation is of paramount importance for paleobiological studies, as body size influences numerous other biological parameters. In mammals, body mass has been traditionally estimated using regression equations based on measurements of the dentition or limb bones, but for many species teeth are unreliable estimators of body mass and postcranial elements are unknown. This issue is exemplified in several groups of extinct mammals that have disproportionately large heads relative to their body size and for which postcranial remains are rare. In these taxa, previous authors have noted that the occiput is unusually small relative to the skull, suggesting that occiput dimensions may be a more accurate predictor of body mass.

RESULTS

The relationship between occipital condyle width (OCW) and body mass was tested using a large dataset (2127 specimens and 404 species) of mammals with associated in vivo body mass. OCW was found to be a strong predictor of body mass across therian mammals, with regression models of Mammalia as a whole producing error values (~ 31.1% error) comparable to within-order regression equations of other skeletal variables in previous studies. Some clades (e.g., monotremes, lagomorphs) exhibited specialized occiput morphology but followed the same allometric relationship as the majority of mammals. Compared to two traditional metrics of body mass estimation, skull length, and head-body length, OCW outperformed both in terms of model accuracy.

CONCLUSIONS

OCW-based regression models provide an alternative method of estimating body mass to traditional craniodental and postcranial metrics and are highly accurate despite the broad taxonomic scope of the dataset. Because OCW accurately predicts body mass in most therian mammals, it can be used to estimate body mass in taxa with no close living analogues without concerns of insufficient phylogenetic bracketing or extrapolating beyond the bounds of the data. This, in turn, provides a robust method for estimating body mass in groups for which body mass estimation has previously been problematic (e.g., "creodonts" and other extinct Paleogene mammals).

The island rule explains consistent patterns of body size evolution in terrestrial vertebrates

Island faunas can be characterized by gigantism in small animals and dwarfism in large animals, but the extent to which this so-called 'island rule' provides a general explanation for evolutionary trajectories on islands remains contentious. Here we use a phylogenetic meta-analysis to assess patterns and drivers of body size evolution across a global sample of paired island-mainland populations of terrestrial vertebrates. We show that 'island rule' effects are widespread in mammals, birds and reptiles, but less evident in amphibians, which mostly tend towards gigantism. We also found that the magnitude of insular dwarfism and gigantism is mediated by climate as well as island size and isolation, with more pronounced effects in smaller, more remote islands for mammals and reptiles. We conclude that the island rule is pervasive across vertebrates, but that the implications for body size evolution are nuanced and depend on an array of context-dependent ecological pressures and environmental conditions.

Interspecific Aggressions between Crested Porcupines and Roe Deer

Despite being common amongst carnivore mammals, behavioral interference between wild herbivore species is poorly documented. Particularly, in temperate areas, where the ungulate guild is composed of a few species, and large-sized rodents are scarce, most cases of interspecific interactions involve at least one alien species. In this work, we report the first data on behavioral interactions between roe deer, Capreolus capreolus, and crested porcupine, Hystrix cristata. Aggressions by crested porcupines toward roe deer were observed in 34 out of 202 observations of both species feeding at the same site. In the other 168 observations, roe deer and porcupines shared the same feeding area, without any interaction. In 58% cases of interaction, porcupines chased and pushed roe deer away from feeding areas, and in several other cases, roe deer were bitten, or injured with quills. Aggressions by porcupines occurred mostly during warm months, when roe deer are mostly solitary and when competition for food between these species is suggested to be the highest, and against single female individuals.

Long live the alien: is high genetic diversity a pivotal aspect of crested porcupine (Hystrix cristata) long-lasting and successful invasion?

Studying the evolutionary dynamics of an alien species surviving and continuing to expand after several generations can provide fundamental information on the relevant features of clearly successful invasions. Here, we tackle this task by investigating the dynamics of the genetic diversity in invasive crested porcupine (Hystrix cristata) populations, introduced to Italy about 1500 years ago, which are still growing in size, distribution range and ecological niche. Using genome-wide RAD markers, we describe the structure of the genetic diversity and the demographic dynamics of the H. cristata invasive populations and compare their genetic diversity with that of native African populations of both H. cristata and its sister species, H. africaeaustralis. First, we demonstrate that genetic diversity is lower in both the invasive Italian and the North Africa source range relative to other native populations from sub-Saharan and South Africa. Second, we find evidence of multiple introduction events in the invasive range followed by very limited gene flow. Through coalescence-based demographic reconstructions, we also show that the bottleneck at introduction was mild and did not affect the introduced genetic diversity. Finally, we reveal that the current spatial expansion at the northern boundary of the range is following a leading-edge model characterized by a general reduction of genetic diversity towards the edge of the expanding range. We conclude that the level of genome-wide diversity of H. cristata invasive populations is less important in explaining its successful invasion than species-specific life-history traits or the phylogeographic history in the native source range.

Development of primers to amplify mitochondrial DNA control region of Old World porcupines (subgenus Hystrix)

Eight primers were developed for the amplification of mitochondrial DNA control region of Old world porcupines (subgenus Hystrix). Successful amplifications of low-quality DNA extracted from old (12 years old) and recent quills were performed, thus facilitating field sampling. Successful cross-species amplifications were obtained for Hystrix africaeaustralis, H. cristata and H. indica. Length and structure of mitochondrial DNA control region were analysed and its usefulness as genetic marker for interspecific and population investigation was discussed.

On the Indian crested porcupine, Hystrix indica (Kerr, 1792) in Turkey (Mammalia: Rodentia)

This study presents some data about ecological, biological and taxonomical characteristics of Hystrix indica (Kerr, 1792) from Turkey. For this purpose characteristics of burrow, skull, tooth and measurements of external and cranial characters of two female H. indica from Turkey were investigated. It was concluded that our specimens are between the Middle East and Indian sub-region specimens in terms of morphometrical. It was also determined that there were roots in stomach contents of specimens.