Composition and Function of Haemolymphatic Tissues in the European Common Shrew

BACKGROUND: Studies of wild animals responding to their native parasites are essential if we are to understand how the immune system functions in the natural environment. While immune defence may bring increased survival, this may come at a resource cost to other physiological traits, including reproduction. Here, we tested the hypothesis that wild common shrews (Sorex araneus), which produce large numbers of offspring during the one breeding season of their short life span, forgo investment in immunity and immune system maintenance, as increased longevity is unlikely to bring further opportunities for mating. In particular, we predicted that adult shrews, with shorter expected lifespans, would not respond as effectively as young animals to infection. METHODOLOGY/PRINCIPAL FINDINGS: We examined haemolymphatic tissues from wild-caught common shrews using light and transmission electron microscopy, applied in conjunction with immunohistology. We compared composition and function of these tissues in shrews of different ages, and the extent and type of inflammatory reactions observed in response to natural parasitic infections. All ages seemed able to mount systemic, specific immune responses, but adult shrews showed some signs of lymphatic tissue exhaustion: lymphatic follicles in adults (n = 21) were both smaller than those in sub-adults (n = 18; Wald = 11.1, p<0.05) and exhibited greater levels of depletion (Wald = 13.3, p<0.05). CONCLUSIONS/SIGNIFICANCE: Contrary to our expectations, shrews respond effectively to their natural parasites, and show little indication of immunosenescence as adults. The pancreas of Aselli, a unique lymphoid organ, may aid in providing efficient immune responses through the storage of large numbers of plasma cells. This may allow older animals to react effectively to previously encountered parasites, but infection by novel agents, and eventual depletion of plasma cell reserves, could both still be factors in the near-synchronous mortality of adult shrews observed shortly after breeding

Response behaviour of native lizards and invading wall lizard to interspecific scent: implications for invasion success

The human-assisted movement of species beyond their native range facilitates novel interactions between invaders and native species that can determine whether an introduced species becomes invasive and the nature of any consequences for native communities. Avoiding costly interactions through recognition and avoidance can be compromised by the naïvety of native species to novel invaders and vice versa. We tested this hypothesis using the common wall lizard, Podarcis muralis, and the native lizard species with which it may now interact in Britain (common lizard, Zootoca vivipara, sand lizard, Lacerta agilis) and on Vancouver Island (northern alligator lizard, Elgaria coerulea) by exploring species' responses (tongue flicks, avoidance behaviour) to heterospecific scent cues in controlled experiments. The tongue flick response of P. muralis depended on the different species’ scent, with significantly more tongue flicks directed to E. coerulea scent than the other species and the control. This recognition did not result in any other behavioural response in P. muralis (i.e. attraction, aggression, avoidance). Lacerta agilis showed a strong recognition response to P. muralis scent, with more tongue flicks occurring close to the treatment stimuli than the control and aggressive behaviour directed towards the scent source. Conversely, Z. vivipara spent less time near P. muralis scent cues than the control but its tongue flick rate was higher towards this scent in this reduced time, consistent with an avoidance response. There was no evidence of E. coerulea recognition of P. muralis scent in terms of tongue flicks or time spent near the stimuli, although the native species did show a preference for P. muralis-scented refuges. Our results suggest a variable response of native species to the scent of P. muralis, from an avoidance response by Z. vivipara that mirrors patterns of exclusion observed in the field to direct aggression observed in L. agilis and an ambiguous reaction from E. coerulea which may reflect a diminished response to a cue with a low associated cost. These results have significant implications for the invasive success and potential impacts of introduced P. muralis populations on native lizards

Observations of two melanistic smooth snakes (Coronella austriaca) from Dorset, United Kingdom.

We report the capture of two smooth snakes (Coronella austriaca) with melanistic colouration from a site in Dorset. These two individuals constitute the second published report of melanism in smooth snakes from the United Kingdom

Chemoreception and kin discrimination by neonate smooth snakes, Coronella austriaca

The study of chemoreception by squamate reptiles has become integral to understanding many aspects of their behaviour. However, previous studies of snakes have concentrated on its importance in prey choice and few studies have examined its role in kin discrimination. We examined the role of chemoreception not only in prey selection by ingestively naı¨ve neonate smooth snakes, but also as a mechanism for discrimination between kin. We tested the responses of neonate smooth snakes to cotton-tipped applicators labelled with odours of potential prey species and control substances, both before and after their natal shedding events. Neonates tested prior to their natal shedding event were able to discriminate between potential prey species and an odourless control but not between potential prey and a pungent control. In contrast, neonates tested after their natal shedding event showed a significantly increased tongue-flick response towards the scent of nonkin conspecifics, lizard (Anguis fragilis and Zootoca vivipara) and mammalian prey (Mus musculus) compared to that towards both pungent and odourless controls. However, scents of invertebrate prey species and kin, while eliciting more tongue-flicks than the odourless control, did not elicit more than the pungent control. The apparent ability of smooth snake neonates to differentiate between kin and nonkin using chemoreception was confirmed during ‘blind’ trials. The mechanism by which kin discrimination occurs is discussed

Macro-and microhabitat use of Telfair's skink (Leiolopisma telfairii) on Round Island, Mauritius: implications for their translocation.

The successful eradication of introduced rodents from islets off the coast of Mauritius has led to local conservation bodies investigating the possibility of translocation as a measure of safeguarding endemic reptile populations. The present study was the first to determine the habitat and microhabitat requirements of Telfair's skinks (Leiolopisma telfairii) on Round Island, Mauritius, with a view to aiding future translocation projects to islands within their historic range. Contrasting preferences found for Telfair's skink at macro- and micro- habitat levels underline the importance of sampling at multiple ecological scales in such investigations. Significantly fewer sightings of L. telfairii were recorded in bare rock habitats compared to more vegetated habitats. Conversely, at a microhabitat scale principal component analysis indicated structural characteristics were the primary determinant of microhabitat choice. The first dietary analysis of Telfair's skinks confirmed their status as omnivores. Cockroaches (Blattodea spp.) appeared to be a primary food source. Four exotic plant species were also present in faecal samples and the potential for L. telfairii to aid their dispersal is discussed. Implications for the long-term management and proposed translocation of Telfair's skinks are discussed

Sexual size dimorphism and microhabitat use of the orange-tail skink (Gongylomorphus spp.) on Flat Island, Mauritius: conservation implications

The Gongylomorphus skinks are an endemic genus of Mauritius and comprise two described species. Following the recent discovery of a third putative species, endemic to Flat Island, 11 km off the coast ofMauritius, this study was conducted to examine morphometrics and the pattern of microhabitat use by the species in an effort to provide effective conservation recommendations. There was a clear sexual size dimorphism with males significantly larger than females in terms of; snout-vent length, head length, head width, snout-mouth length, snout-ear length, upper and lower fore- and hind-limb lengths and fourth toe length. There was no sexual dimorphism in other measures including pelvic width, width at the base of the tail, head depth or body weight. Microhabitat use was found to be non-random with lizards occurring in areas with high humidity, high numbers of natural refugia, increased leaf litter coverage and plant species diversity, and low grass cover. We found no evidence that microhabitat use varied in relation to sex or age of lizards. The implications of these results for the conservation management of Flat Island for the orange-tail skink are discussed