Strong Gene Flow Undermines Local Adaptations in a Host Parasite System.

The co-evolutionary pathways followed by hosts and parasites strongly depend on the adaptive potential of antagonists and its underlying genetic architecture. Geographically structured populations of interacting species often experience local differences in the strength of reciprocal selection pressures, which can result in a geographic mosaic of co-evolution. One example of such a system is the boreo-montane social wasp Polistes biglumis and its social parasite Polistes atrimandibularis, which have evolved local defense and counter-defense mechanisms to match their antagonist. In this work, we study spatial genetic structure of P. biglumis and P. atrimandibularis populations at local and regional scales in the Alps, by using nuclear markers (DNA microsatellites, AFLP) and mitochondrial sequences. Both the host and the parasite populations harbored similar amounts of genetic variation. Host populations were not genetically structured at the local scale, but geographic regions were significantly differentiated from each other in both the host and the parasite in all markers. The net dispersal inferred from genetic differentiation was similar in the host and the parasite, which may be due to the annual migration pattern of the parasites between alpine and lowland populations. Thus, the apparent dispersal barriers (i.e., high mountains) do not restrict gene flow as expected and there are no important gene flow differences between the species, which contradict the hypothesis that restricted gene flow is required for local adaptations to evolve.

Waste prevention impacts on small municipalities: Three experiences from northern Italy.

Waste management is an important issue all over the world and it will become even more urgent in the near future due to the increase of global volumes of waste. Waste prevention is at the top of the European waste hierarchy, followed by reuse, recycling, other recovery (including energy recovery), and safe disposal. In Italy, municipalities are the authorities that concretely choose the prevention actions to be applied in their territory and therefore they are crucial in promoting a decrease in waste amounts. In our research we investigated costs and benefits of prevention actions in three small municipalities in the north of Italy. We found that the "Pay as You Throw" (PAYT) scheme is an effective action in preventing waste production, with many instances, on analyzing the collection data. The specific effect of the other actions (such as the awareness raising campaigns) is difficult to isolate, even if we found positive impacts. We analyzed some external drivers, such as the migration effect, in order to understand the real effectiveness of the implemented actions. One of the objectives of the study was to comprehend the consequences of political choices at a bigger scale than the individual municipality. Analyzing the results obtained in three typical small Italian municipalities, this study suggests that local authorities, with their choices, can greatly affect the efficacy of selected waste collection and waste prevention.

Population diversity in cuticular hydrocarbons and mtDNA in a mountain social wasp.

Nestmate recognition is a common phenomenon in social insects that typically is mediated by cuticular hydrocarbons. Geographical variation in cuticular hydrocarbons has been observed, although the pattern of variation is not consistent across species and is usually related to the biology and ecology of the different species. Polistes biglumis (Hymenoptera: Vespidae) is a social wasp that lives in high mountains where populations are separated by significant geographical barriers. Here we investigated the level of chemical variation among populations of P. biglumis in the Alps, and shed light on the phylogeography of this species. Populations could be discriminated by means of their cuticular hydrocarbon profiles, which showed a pattern consistent with the isolation-by-distance hypothesis. Molecular data highlighted two areas with different levels of haplotype diversity, although all wasps belonged to the same species. These results suggest that the populations of P. biglumis in the Alps are geographically isolated from one another, favoring their genetic and chemical differentiation.