Ethnicity and biodemographic structure in the Arbëreshe of the province of Cosenza, southern Italy, in the XIX century

Cultural and environmental factors interact in determining the genetic structure of human populations. Bio-demographic investigations of ethnic minorities are able to disentangle the influences that these two components have on the evolution of the genetic structure of a population. The ethnic minority of the Arb?reshe of the province of Cosenza (Calabria, southern Italy) is analyzed in this paper and its bio-demographic structure in the early 1800s is compared with that of neighboring Italian populations. The data derive from surnames recorded in the birth registers of the 19 Arbdreshe municipalities of the province of Cosenza and in 5 non-Arb?reshe municipalities of the same province. Isonymy and repeated pairs of surnames are used to analyze the bio-demographic structure of these populations, while analysis of isonymic relationships is used to investigate the variability between populations. Higher values of marital isonymy and subdivision into subpopulations characterize the Arb?reshe populations with respect to their non-Arb?reshe neighbors. However, the high range of variability of these parameters suggests a strong influence of geographic location on the marriage pattern of each community. At the same time, cultural differences linked to group identity had a strong impact in limiting marriage exchanges between the different ethnic groups living in the province of Cosenza in the early 1800s. In fact, the analysis of isonymic relationships demonstrates that geographic location shaped kinship patterns among the Arbereshe communities, but it also shows that the non-Arb?reshe neighbors formed a clearly separate reproductive cluster.     

The effects of fire on communities,guilds and species of breeding birds in burnt and control pinewoods in central Italy

Breeding bird communities in burnt and unburnt residual pinewoods were studied over 3 years by line-transect method, following a catastrophic fire event in Castelfusano (Rome, Central Italy; July 2000). We applied bootstrap procedures to evaluate whether the observed data were true or just produced by chance, and then examined the emerging patterns at three levels: community, guild and species levels. At the community level, fire acted on breeding bird communities by altering especially the total abundance patterns: the species abundance decreased in the burnt pinewood compared to the residual one, but other parameters were not significantly affected by fire. As a consequence of fire, the destruction and structural simplification of the canopy and shrubby component, as well as the increase of edge habitat and patchiness at landscape scale, induced a turnover in species between pinewoods. Species turnover was higher at the burnt than at the residual pinewoods, during all the 3 years of study. At the guild level, the forest species decreased strongly in terms of richness and abundance in the burnt pinewoods, contrary to the edge and open habitat species which increased in terms of richness, abundance and evenness. Edge species showed the highest turnover in burnt pinewood during the whole period of study. At species level, after an a priori subdivision (based on bibliographic search) of the various species in two ecological guilds (forest versus edge species), it was found that an a posteriori statistical analysis confirmed the expected trend, i.e. that the species which decreased significantly in burnt pinewood were essentially the forest species, whereas the species which increased were essentially the edge/open habitat ones. Overall, in order to investigate the effects of fire catastrophes on birds, the guild approach seems more exhaustive than the taxonomic community approach, where intrinsic confounding trends are present.     

Microsatellite variation and evolution of human lactase persistence

The levels of haplotype diversity within the lineages defined by two single-nucleotide polymorphisms (SNPs) (–13910 C/T and –22018 G/A) associated with human lactase persistence were assessed with four fast-evolving microsatellite loci in 794 chromosomes from Portugal, Italy, Fulbe from Cameroon, São Tomé and Mozambique. Age estimates based on the intraallelic microsatellite variation indicate that the –13910*T allele, which is more tightly associated with lactase persistence, originated in Eurasia before the Neolithic and after the emergence of modern humans outside Africa. We detected significant departures from neutrality for the –13910*T variant in geographically and evolutionary distant populations from southern Europe (Portuguese and Italians) and Africa (Fulbe) by using a neutrality test based on the congruence between the frequency of the allele and the levels of intraallelic variability measured by the number of mutations in adjacent microsatellites. This result supports the role of selection in the evolution of lactase persistence, ruling out possible confounding effects from recombination suppression and population history. Reevaluation of the available evidence on variation of the –13910 and –22018 loci indicates that lactase persistence probably originated from different mutations in Europe and most of Africa, even if 13910*T is not the causal allele, suggesting that selective pressure could have promoted the convergent evolution of the trait. Our study shows that a limited number of microsatellite loci may provide sufficient resolution to reconstruct key aspects of the evolutionary history of lactase persistence, providing an alternative to approaches based on large numbers of SNPs.Electronic supplementary material Supplementary material is available for this article at     

The ghost of a recent invasion in the reduced feeding rates of spitting cobras during the dry season in a rainforest region of tropical Africa?

Two species of cobras (Naja melanoleuca and Naja nigricollis) are known to occur in south eastern Nigeria, where much of the pristine rainforest surface has been felled in the last thirty years, and where the actual landscape is generally constituted by a mosaic of farmlands, plantations, suburban areas, with a few remnant forest fragments. In this region, Naja nigricollis is currently extending its range, especially by exploiting recently deforested areas. Based on the known general distribution range of this species and on the available literature data, it appears that Naja nigricollis has been colonizing the forested region of south eastern Nigeria, starting from the relatively arid savannas of central Nigeria, where this species aestivates during the driest months. In the forest region, however, snakes do not need to aestivate during the dry season. Nevertheless, whereas Naja melanoleuca has a foraging activity extended all-the-year round, Naja nigricollis reduces feeding rates during the dry months, although it does not suspend above-ground activity in these months. I suggest that rainforest spitting cobras suspend feeding during the dry months because their behaviour is just a ‘ghost’ of their recent past, when they were ‘normal’ spitting cobras of dry savana regions, which were thus constrained to aestivate during the dry season as it is the rule in this species in central and northern Nigeria. The ‘gost-of-the-past hypothesis’ seems to fit well with the ‘invading’ presence of Naja nigricollis in Nigerian areas where they were reported as rare or, even, absent, up to a few decades ago. Other hypotheses are discussed, and rejected.