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

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

Tantalising tongues: male carpet pythons use chemoreception to differentiate among females

For animals sparsely distributed across a landscape, finding and identifying a receptive female during a short breeding period can be a challenge for males. Many snakes appear to rely on the production of sex-specific pheromones to synchronise the timing of reproductive behaviour. The rare Australian south-west carpet python (Morelia spilota imbricata) displays non-aggressive mating aggregations of up to six males around a receptive female, suggesting that males are responding to some chemical signal that enables multiple males simultaneously to identify and locate the female. We investigated chemoreceptive response (tongue-flicking) of 10 male pythons under laboratory conditions to 12 (randomly ordered) treatments each presented for three minutes. Cutaneous chemicals (dissolved in hexane solvent) were collected on cotton buds from the skin of six female pythons and male responses to these were compared with six control treatments. Male pythons produced a greater number of tongue flicks during the first minute of each trial, with fewer in minutes 2 and 3. Male chemoreceptive response in the third minute varied significantly between treatments and was only maintained for trials presenting cutaneous chemicals collected from the three relatively largest female pythons. This experiment suggests that male carpet pythons can use chemoreception to obtain information about their social environment, identifying pheromone cues from large, potentially fecund females. This ability would be adaptive for male mate-selection behaviour and is likely to also reduce costs of searching behaviour

Impact of Climatic Change on NW Mediterranean Deltas

Summary report of the MedDelt project. This project has studied the impact of climate change on the deltas in the northwestern Mediterranean sea.Meddel

Land raising as a solution to sea-level rise: an analysis of coastal flooding on an artificial island in the Maldives

The Maldives (land elevation approximately 1m above mean sea-level) is often associated with the threat of rising sea-levels. Land scarcity due to population pressure is also a major issue. In the late 1990s a new 1.9km2 2m high artificial island, Hulhumalé was created for urban expansion, including an allowance for sea-level rise. This paper assesses flood exposure through an extreme water level scenario on Hulhumalé taking into account sea-level rise and analyses potential adaptation options to extend island life. Results indicate that overtopping is likely to occur with 0.6±0.2m of SLR, with more severe, widespread flooding with 0.9±0.2m of sea-level rise. If the Paris Agreement goals are met, flooding is not anticipated this century, but under a non-mitigation scenario, flooding could occur by the 2090s. Building seawalls 0.5m, 1.0m and 1.5m high could delay flooding for 0.2m, 0.4m and 0.6m of sea-level rise, respectively. Land raising has been successful in Hulhumalé in reducing flood risk simultaneous to addressing development needs. Whilst new land claim and raising can be cost-effective, raising developed land provides greater challenges, such as timeliness with respect to infrastructure design lives or financial costs. Thus the transferability and long-term benefits of land raising requires further consideration

Data from: Dietary niche variation and its relationship to lizard population density

(1) Insular species are predicted to broaden their niches, in response to having fewer competitors. They can thus exploit a greater proportion of the resource spectrum. In turn, broader niches are hypothesized to facilitate (or be a consequence of) increased population densities. (2) We tested whether insular lizards have broader dietary niches than mainland species, how it relates to competitor and predator richness, and the nature of the relationship between population density and dietary niche breadth. (3) We collected population density and dietary niche breadth data for 36 insular and 59 mainland lizard species, and estimated competitor and predator richness at the localities where diet data were collected. We estimated dietary niche shift by comparing island species to their mainland relatives. We controlled for phylogenetic relatedness, body mass, and the size of the plots over which densities were estimated. (4) We found that island and mainland species had similar niche breadths. Dietary niche breadth was unrelated to competitor and predator richness, on both islands and the mainland. Population density was unrelated to dietary niche breadth across island and mainland populations. (5) Our results indicate that dietary generalism is not an effective way of increasing population density nor is it result of lower competitive pressure. A lower variety of resources on islands may prevent insular animals from increasing their niche breadths even in the face of few competitors