M Simonato

Publications of M Simonato

• Phylogeography of the pine processionary moth Thaumetopoea wilkinsoni in the Near East.

  Authors: M Simonato, Z Mendel, C Kerdelhué, J Rousselet, E Magnoux, P Salvato, A Roques, A. Battisti, L Zane

  Molecular ecology. 07/2007; 16(11):2273-83.

  Phylogeographic structure of the eastern pine processionary moth Thaumetopoea wilkinsoni was explored in this study by means of nested clade phylogeographic analyses of COI and COII sequences ofPhylogeographic structure of the eastern pine processionary moth Thaumetopoea wilkinsoni was explored in this study by means of nested clade phylogeographic analyses of COI and COII sequences of mitochondrial DNA and Bayesian estimates of divergence times. Intraspecific relationships were inferred and hypotheses tested to understand historical spread patterns and spatial distribution of genetic variation. Analyses revealed that all T. wilkinsoni sequences were structured in three clades, which were associated with two major biogeographic events, the colonization of the island of Cyprus and the separation of southwestern and southeastern Anatolia during the Pleistocene. Genetic variation in populations of T. wilkinsoni was also investigated using amplified fragment length polymorphisms and four microsatellite loci. Contrasting nuclear with mitochondrial data revealed recurrent gene flow between Cyprus and the mainland, related to the long-distance male dispersal. In addition, a reduction in genetic variability was observed at both mitochondrial and nuclear markers at the expanding boundary of the range, consistent with a recent origin of these populations, founded by few individuals expanding from nearby localities. In contrast, several populations fixed for one single mitochondrial haplotype showed no reduction in nuclear variability, a pattern that can be explained by recurrent male gene flow or selective sweeps at the mitochondrial level. The use of both mitochondrial and nuclear markers was essential in understanding the spread patterns and the population genetic structure of T. wilkinsoni, and is recommended to study colonizing species characterized by sex-biased dispersal.

• Demographic history and population structure of the Antarctic silverfish Pleuragramma antarcticum.

  Authors: L Zane, S Marcato, L Bargelloni, E Bortolotto, C Papetti, M Simonato, V Varotto, T Patarnello

  Molecular ecology. 01/2007; 15(14):4499-511.

  The Antarctic silverfish Pleuragramma antarcticum (Nototheniidae) is the most abundant pelagic fish inhabiting Antarctic waters. In this study we investigated, through partial sequencing of theThe Antarctic silverfish Pleuragramma antarcticum (Nototheniidae) is the most abundant pelagic fish inhabiting Antarctic waters. In this study we investigated, through partial sequencing of the D-loop mitochondrial region, samples collected at four different locations in the Southern Ocean, three in the Atlantic and one in the Pacific sector. Sampling was replicated in two different years at two locations. Sequence analysis showed a remarkably high polymorphism, with 110 haplotypes over the 256 investigated specimens, and about 80% of haplotypes occurring only once. Neutrality tests indicated that all samples were not at mutation-drift equilibrium, and suggested a past population expansion. This result was supported by the presence of a star-like topology in the D-loop gene tree, and by results of mismatch distribution. The start of the expansion was dated, using a specifically calibrated clock, between 111 and 126 thousand years ago. This value corresponds to the start of the cooling period that led to the last glaciation peak, and is in close agreement with a recently suggested range expansion for pelagic Antarctic ecosystems. Analysis of molecular variation indicated a small, though highly significant, value of differentiation between samples. This result, together with the lack of association between clades and geographical locations, indicates a weak population structure for the species.