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Titre : Análisis de la Diversidad Genética DE Pardosa sierra Banks, 1898 (ARANEAE : LYCOSIDAE) en la Península de Baja California, México.

Auteur : Correa Ramirez, Miguel Mauricio

Etablissement de soutenance : Centro de Investigaciones Biológicas del Noroeste (CIBNOR)

Grade : Doctorado en Ciencias en el Uso, Manejo y Preservación de los Recursos Naturales 2010

Résumé
The two biogeographical theories that have attempted to explain the current distribution of species are dispersionism and vicariance, one explains how the species expands to different distribution areas (dispersion), while the other explains species fragmentation in space and time (vicariance). In this sense, molecular markers such as cytochrome c oxidase subunit 1 (COI) of mitochondrial DNA, which generally have moderate mutation rates are used as sources of taxonomic information providing information that help delineatespecies and in studying their phylogeny. Whereas markers with fast rates of mutation like nuclear DNA microsatellites allow for analyzing the processes occurring in inland species, such as isolation between populations, dispersal mechanisms, among others. Pardosa sierra is a species that in the literature is reported as having a wide geographical range (Utah, USA to Veracruz, Mexico) and also shows a controversial taxonomic history. Population genetic studies of the species the claim that different morphological types are observed along the geographical distribution of the species has led to the following questions : Do different morphs represent a balanced polymorphism in P. sierra, therefore, belong to the same species ? Is lapidicina group to which belongs P. sierra, a monophyletic group ? By knowing the taxonomic boundaries of Pardosa sierra is there genetic differentiation among populations and gene flow levels that can indirectly provide information about the species dispersal capabilities that is presently not well known in this species ? Using biological material collected from museums and from other various localities of Mexico as well as electron micrographs of the genitalia of males and females, and variation of a gene fragment information from mitochondrial DNA COI it can be concluded that P. sierra is composed of three distinct species consisting of P. sierra, P. atromedia and P. sura, possibly by convergence, males have a high degree of similarity. The analyzed data also allowed to provide new information on the geographical distribution of species, being two of them endemic, one on the peninsula of Baja California (P. sierra), one in California (P. atromedia) and the third with a broad distribution (P. sura). The latter, likewise represents a complex of cryptic species difficult to separate morphologically, where COI sequences could help define its cohesion as a taxonomic unit. The variation of COI sequences also established that the lapidicina and milvina groups are monophyletic. After resolving the geographicallimits of Pardosa sierra, genetic variability was estimated using five species-specific microsatellite loci, which were analyzed from seven collection sites along the peninsula, the results indicate that P. sierra in Baja California Peninsula shows a small but significant genetic differentiation with a high degree of gene flow. These results reject the hypothesis that P. sierra have reduced dispersal capabilities and indicates that they are strongly associated to oasis. These results are confirmed by the analysis of individual’s assignament, the phylogenetic reconstruction and analysis of molecular variance. There was no isolation by distance, so the ecological landscape (geomorphology, winds, rains, and hurricans) may be influencing the process of migration among the populations of P. sierra analyzed with other factors such as sinantropy and the incidence of seasonal hurricanes.

Mots Clés : Marcadores ; Moleculares ; Taxonomía ; Genética ; Poblaciones ; Filogenia ; Pardosa ; Sierra

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