ß-Diversity partitioning of moth communities within and between different forest types.

The partitioning of ß-diversity is a recurrent practice in biogeographic and ecological studies that can provide key insights for land management, such as identification of biodiversity hot-spots. In this study, we used Baselga's metrics to measure the contribution of spatial turnover (ßsim) and nestedness-resultant dissimilarity (ßnes) to overall ß-diversity (ßsor) within- and between-forest types. We analyzed a presence/absence dataset concerning 593 species of nocturnal Lepidoptera sampled within chestnut, silver fir, beech, and black pine forests of southern Italy. Ordination methods and analysis of similarities were used to assess the relative contribution of ßsim and ßnes to ßsor, and to assess their relationships with variables linked to the experimental design and known to be determinant for insect diversity and abundance. We found that ßsor was mostly due to turnover, around 98.5% in ß-diversity assessment of the whole sample, and around 91% in ß-diversity assessment of individual forests. Using ordination analyses based on ßsim, stands were grouped according to forest type, while ßnes alone was used to ordinate stands coherently with their species richness. Nevertheless, the addition of ßnes to ßsim produced a more ecologically coherent grouping of stands within individual forest types, and ßnes alone was able to recognize patterns determined by human disturbance. In conclusion, we demonstrate that ß-diversity partitioning can help to detect differences in magnitude and role of processes determining the composition of forest moth communities as in different forests the same pattern can be due to opposite processes, providing strong ecological insights into managing forest biodiversity.

Reproductive isolation and patterns of genetic differentiation in a cryptic butterfly species complex.

Molecular studies of natural populations are often designed to detect and categorize hidden layers of cryptic diversity, and an emerging pattern suggests that cryptic species are more common and more widely distributed than previously thought. However, these studies are often decoupled from ecological and behavioural studies of species divergence. Thus, the mechanisms by which the cryptic diversity is distributed and maintained across large spatial scales are often unknown. In 1988, it was discovered that the common Eurasian Wood White butterfly consisted of two species (Leptidea sinapis and Leptidea reali), and the pair became an emerging model for the study of speciation and chromosomal evolution. In 2011, the existence of a third cryptic species (Leptidea juvernica) was proposed. This unexpected discovery raises questions about the mechanisms preventing gene flow and about the potential existence of additional species hidden in the complex. Here, we compare patterns of genetic divergence across western Eurasia in an extensive data set of mitochondrial and nuclear DNA sequences with behavioural data on inter- and intraspecific reproductive isolation in courtship experiments. We show that three species exist in accordance with both the phylogenetic and biological species concepts and that additional hidden diversity is unlikely to occur in Europe. The Leptidea species are now the best studied cryptic complex of butterflies in Europe and a promising model system for understanding the formation of cryptic species and the roles of local processes, colonization patterns and heterospecific interactions for ecological and evolutionary divergence.

Hydrocarbon rank signatures correlate with differential oophagy and dominance behaviour in Polistes dominulus foundresses.

Social life offers animals increased fitness opportunities. However, the advantages are not evenly distributed and some individuals benefit more than others. The ultimate advantage of reaching the highest rank in a dominance hierarchy is the achievement of reproduction monopoly. In social insects, dominant individuals and queens keep their reproductive control through differential oophagy of unwanted eggs (egg policing). Egg recognition is the main proximate mechanism for maintaining reproductive dominance. In the social wasp Polistes dominulus, subordinate queens often lay eggs in the presence of the dominant individual. Combining gas chromatography-mass spectrometry (GC-MS) analysis and laboratory bioassays, we found that chemical differences between eggs of subordinate and dominant foundresses can explain the differential success in oophagy enjoyed by dominant individuals. We propose that dominance behaviour is an investigative behaviour as well as a ritualized agonistic behaviour. In fact, the frequency of dominance acts increases with the chemical similarity of the surfaces of dominant- and subordinate-laid eggs. Therefore, dominant individuals probably perform dominance behaviour to test the cuticular signatures of subordinates and so better assess the chemical profiles of subordinate eggs. Finally, we provide evidence that in particular social contexts, subordinate Polistes foundresses can develop ovaries as large as those of dominant individuals but nevertheless lay very few eggs. The subordinates probably lay a limited number of eggs to avoid unnecessary energy loss, as a result of efficient queen policing, but will start laying eggs as soon as the queen fails.

On status badges and quality signals in the paper wasp Polistes dominulus: body size, facial colour patterns and hierarchical rank.

To establish a dominance order, social animals often rely on indicators of fighting to avoid costly aggressive encounters. In some species, individuals use colour patterns to signal their social status. Recent studies claimed that facial markings in the eusocial paper wasp Polistes dominulus are status badges that allow co-foundresses to form a linear hierarchy based on individual quality. Here, we evaluated facial patterns in natural populations of P. dominulus, in its native range, to observe whether the marks reflect overall wasp quality in different contexts. We used the same measures of clypeus patterns used by earlier studies, but did not find that they functioned as status badges. Our analyses showed no evidence that visual markers are related to: (i) size, (ii) probability of surviving winter, (iii) social rank in spring associations, or (iv) health status (assessed by the presence of strepsipteran endoparasites). Size, however, is important. Larger wasps are more likely to survive the winter and to acquire the dominant position in spring associations. Larvae infected with endoparasites become smaller adult wasps. These findings suggest that body size is a reliable quality indicator on which wasps build their social networks, and that clypeus patterning is not involved.

Recognition of social parasites as nest-mates: adoption of colony-specific host cuticular odours by the paper wasp parasite Polistes sulcifer.

Colonies of the polistine wasp Polistes dominulus are parasitized by the permanent worker-less social parasite Polistes sulcifer. After usurpation of the host colony, parasite females are characterized by a change in the relative proportions of their cuticular hydrocarbons to match those of the host species. In this paper we present evidence from field data and laboratory experiments that P. sulcifer females adopt a colony-specific host odour that facilitates their acceptance by host females of the usurped colony. Presentation experiments demonstrate that parasite females are recognized as foreign individuals by workers of other parasitized nests. We show that the modification of parasite cuticular compounds is sufficient for this recognition. This provides evidence that, after invasion, P. sulcifer queens do not require appeasement or propaganda substances for their acceptance by host colonies. Furthermore, multivariate discriminant analysis of the cuticular hydrocarbon proportions of the parasites after usurpation assigns the parasites together with P. dominulus females of their own host colony. To the authors' knowledge, this is the first confirmation that social parasites adopt colony-specific host odours.

Rank integration in dominance hierarchies of host colonies by the paper wasp social parasite Polistes sulcifer (Hymenoptera, Vespidae).

In multiple-foundress nests of the wasp Polistes dominulus, dominance hierarchies are established among foundresses, and only the dominant (=alpha) individual lays eggs. The alpha female can be distinguished from subordinate females and workers on the basis of the proportions of some hydrocarbons present on the cuticle, suggesting that chemical signaling of her reproductive status could occur. P. dominulus is also the host species of the obligate social parasite Polistes sulcifer. After aggressively usurping host colonies and behaviorally replacing the host alpha female, parasites are characterized by a change in the proportions of their cuticular hydrocarbons to match that of the host cuticular profile at both species and colony levels. In the current study, we demonstrate that P. sulcifer queens also modify their cuticular hydrocarbon proportions after usurpation to match that of the host alpha female. Parasite females, therefore, acquire the dominant rank in host colonies both reproductively and chemically by mimicking the typical alpha profile of the host. Parasite females were not able to fully inhibit ovary development in host foundresses, and 10 days after usurpation, parasites, alpha and beta foundresses show similar chemical profiles and ovarian development.

Radioisotope evidence of varying transit of solid food in gastrectomized patients with and without dumping syndrome.

Of 29 Billroth II gastrojejunostomy patients studied by scintigraphy, 11 were dumpers and 18 were non-dumpers; of 20 controls, 11 were patients with different gastric complaints and 9 volunteers with no history of gastrointestinal pathology. The tracer used was human albumin microspheres labelled with 99mTc, mixed thoroughly with a fresh scrambled egg, cooked as an omelet and eaten as a sandwich with white toasted bread. The transit and emptying of the radiolabelled meal in the gastric and derivative loop areas were followed with gamma camera 90-120 min. In the dumpers half-emptying times were significantly shorter than in the controls; in the non-dumpers they were even shorter. Dynamic selective analysis of the radiolabelled food transit through derivative afferent and efferent loops showed, on the other hand, different patterns for the two groups of gastroresected patients: the progression of propulsive waves was very irregular and constantly hyperperistaltic only in the dumpers.

Behaviour and chemical signature of pre-hibernating females of Polistes dominulus infected by the strepsipteran Xenos vesparum.

Polistes dominulus are social wasps which are the host of the strepsipteran endoparasite Xenos vesparum. In the hibernating phase, unparasitized and parasitized wasps leave natal nests and aggregate together in sheltered quarters. In aggregations, wasps are socially active, and some individuals perform helping behaviour. Here we investigated if castrated parasitized wasps perform worker tasks in mixed aggregations. Moreover, by gas chromatography and mass spectrometry, we examined the cuticular hydrocarbons of unparasitized and parasitized wasps to evaluate if the infection alters the composition of cuticular waxes that are recognition cues in social insects. In clusters, infected females do not perform helping behaviour and they are less active than unparasitized wasps. Cuticular hydrocarbons are slightly differentiated between unparasitized and parasitized wasps but, generally, unparasitized wasps are more similar to wasps infected by Xenos females compared to wasps infected by Xenos males. Wasps infected by Xenos males do not usually survive the winter. This chemical similarity is probably a consequence of the similar physiological condition of unparasitized and female-affected Polistes wasps. At this stage, it is difficult to affirm whether these modifications are a true parasite manipulation or a consequence of infection.