Investigating processes and timing of differentiation of organisms is critical in the understanding of the evolutionary mechanisms involved in microevolution, speciation, and macroevolution that generated the extant biodiversity. From this perspective, the Telestes genus is of special interest: the Telestes species have a wide distribution range across Europe (from the Danubian district to Mediterranean districts) and have not been prone to translocation. Molecular data (mtDNA: 1,232 bp including the entire Cyt b gene; nuclear genome: 11 microsatellites) were gathered from 34 populations of the Telestes genus, almost encompassing the entire geographic range. Using several phylogenetic and molecular dating methods interpreted in conjunction with paleoclimatic and geomorphologic evidence, we investigated the processes and timing of differentiation of the Telestes lineages. The observed genetic structure and diversity were largely congruent between mtDNA and microsatellites. The Messinian Salinity Crisis (Late Miocene) seems to have played a major role in the speciation processes of the genus. Focusing on T. souffia, a species occurring in the Danube and Rhone drainages, we were able to point out several specific events from the Pleistocene to the Holocene that have likely driven the differentiation and the historical demography of this taxon. This study provides support for an evolutionary history of dispersal and vicariance with unprecedented resolution for any freshwater fish in this region.
Chappaz, R. (2010). Speciation pattern of Telestes souffia complex (Teleostei, Cyprinidae) in Europe using morphological and molecular markers. 39,[225][226][227][228][229][230][231][232][233][234][235][236][237][238][239][240][241][242] It is notorious that many species boundaries are erroneously defined. When molecular markers are used, misleading evidence can notably be due to the characteristics inherent to mitochondrial DNA and quantity of markers used but also because of a limited range distribution sampling. European cyprinids biodiversity inventory is still an ongoing task and surprising phylogeographic patterns and phylogenetic relationships are still recovered on account of methodological evolution. This is particularly obvious for the Telestes souffia complex. This species occurs in a fragmented range and species boundaries is greatly debated. In this study, we provide an updated delimitation of the different evolutionary entities constituting this T. souffia complex and propose a taxonomic revision. Morphological and molecular analyses were carried out on 520 specimens coming from 19 localities representing the complete geographical range of this species complex and six related sister species that could potentially interact with it (outgroup 'sensu lato'). Phylogenetic reconstructions and multivariate analyses demonstrated that the T. souffia complex is constituted of at least three species (T. souffia, Telestes muticellus and Telestes montenigrinus). Data also suggested that T. souffia comprises three subspecies (T. s. souffia, T. s. agassii; T. s. rysela). We also confirm the splitting of the T. souffia sister species Telestes pleurobipunctatus into two distinct species. The Peloponnesian lineage will be referred as Telestes alfiensis and the continental lineage as T. pleurobipunctatus. Morphological and molecular markers displayed some degree of incongruence within T. souffia suggesting that introgressive hybridization has played a role in the evolution of the Telestes genus. However, discordance among data sets could also result from heterogeneous rate of morphological evolution. Finally, we demonstrated that T. muticellus was implicated in two categories of hybridization: an inter-species hybridization (between T. muticellus and T. souffia) and an inter-generic hybridization (between T. muticellus and Squalius lucumonis), a phenomenon rarely observed for a same species.
Shock filter represents an important family in the field of nonlinear Partial Differential Equations (PDEs) models for image restoration and enhancement. Commonly, the smoothed second order derivative of the image assists this type of method in the deblurring mechanism. This paper presents the advantages to insert information issued of oriented half Gaussian kernels in a shock filter process. Edge directions assist to preserve contours whereas the gradient direction allow to enhance and deblur images. For this purpose, the two edge directions are extracted by the oriented half kernels, preserving and enhancing well corner points and object contours as well as small objects. The proposed approach is compared to 7 other PDE techniques, presenting its robustness and reliability, without creating a grainy effect around edges.
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