Magadino, Switzerland
Magadino, Switzerland

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The Late Holocene evolution of the Ticino delta in the Lake Maggiore was studied thanks to several boreholes realised in the Bolle di Magadino, to the analysis of historical documents, and to the comparison with the pollen stratigraphy determined in two small lakes of the Southern Swiss Alps. These data allowed determining the main steps of the Ticino delta progradation since the Roman Period and the evolution of the fluvial geomorphology and of the morphosedimentary dynamics of the Ticino River in the Piano di Magadino. In particular, thanks to the analysis of the sedimentation rates, it was possible to show an intensification of the hydrosedimentary activity between the Roman Period and the Late Antiquity/Early Middle Ages, followed by a less active period during the High and the Late Middle Ages, characterised by a meandering fluvial morphology. The transition between the Late Middle Ages and the Modern Epoch was characterised by the Buzza di Biasca of AD 1515. This event, which was superimposed at the natural climatic evolution, was at the origin of a fluvial metamorphosis of the Ticino River, which passes from a meandering fluvial morphology to a braided fluvial morphology. This fluvial pattern was maintained just to the Ticino canalisation of the second half of the 19th century.


Scandolara C.,University of Milan | Scandolara C.,Swiss Ornithological Institute | Lardelli R.,Swiss Ornithological Institute | Sgarbi G.,Fondazione Bolle di Magadino | And 4 more authors.
Behavioral Ecology | Year: 2014

Natal dispersal is a major life-history trait, with important consequences for population dynamics and genetic structure. Successful dispersal depends on a complex blend of decisions at all main stages of the dispersal process: emigration, prospection for a site, and settling. Costs and benefits of such decisions are expected to depend on sex and on the ecological context, on individual physiological state, and on concomitant decisions by relatives, which affect competition with kin and inbreeding. We analyzed natal dispersal propensity (i.e., dispersing or not) and dispersal distance in the semicolonial barn swallow (Hirundo rustica) in relation to context-, phenotype-, and kin-dependent factors. Females had larger dispersal propensity and distance than males. Dispersal propensity of both sexes was negatively density dependent and was less likely from colonies (farms) with large number of livestock, which is important to barn swallow distribution. Dispersal propensity was larger among males ranking high in the body mass brood hierarchy and smaller among late-hatched females. Dispersal distance was larger for late-hatched males and for females that ranked high in the body mass brood hierarchy. Finally, both dispersal propensity and distance of males increased with the number of male siblings. We, thus, identified several context-, phenotype-, and kin-dependent components of dispersal decisions. Phenotype-dependent effects suggest that decisions of whether to disperse and of dispersal distance are different processes under control of sex-specific traits. Finally, male dispersal behavior suggests that kin selection favors males that reduce the risk of sib-sib mating competition, in a population with male-biased tertiary sex ratio. © The Author 2013.


Scandolara C.,University of Milan | Scandolara C.,Swiss Ornithological Institute | Caprioli M.,University of Milan | Lardelli R.,Fondazione Bolle di Magadino | And 5 more authors.
Animal Behaviour | Year: 2013

Prenatal and early postnatal conditions can prime developmental trajectories, with short- as well as major long-term effects on phenotype. Variance in perinatal conditions may be caused by many factors, including number of siblings of either sex, which is expected to influence individual phenotype for two complementary reasons. First, male and female offspring can differ in susceptibility to extrinsic conditions. Second, the effect that an individual has on its siblings can differ according to their sex. Yet, few studies of vertebrates and only one of birds have addressed the long-term consequences of family sex composition on offspring of either sex. We analysed the effect of brood sex composition on adult phenotype and breeding performance in the barn swallow, Hirundo rustica. Male offspring growing with more sisters had shorter wing length, an aerodynamically important trait, and tail length, a condition-dependent, sexually selected trait. In addition, tail length of females decreased with increasing brood size but more steeply so when they grew with more female siblings. Body size of females also declined with increasing brood size. Notably, breeding output of females declined with an increasing proportion of male siblings and also with increasing brood size. This study thus suggests that social environment has major consequences for phenotype and breeding performance in adulthood and that variation in brood sex composition has long-term effects which depend on the sex of the individual as well as on the specific trait considered. Hence, optimal parental sex allocation decisions depend not simply on additive fitness costs and benefits of producing males or females, but also on the long-term effects that sons and daughters exert on each other. © 2013 The Association for the Study of Animal Behaviour.

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