Diversity and evolutionary history of mygalomorph spiders in the Western Mediterranean and the Canary Islands = La diversidad e historia evolutiva de las arañas migalomorfas en el Mediterráneo Occidental y las Islas Canarias

• Autores: Vera Opatova
• Directores de la Tesis: Miquel Àngel Arnedo Lombarte (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2014
• Idioma: inglés
• Tribunal Calificador de la Tesis: Salvador Carranza Gil-Dolz del Castellar (presid.), Diego San Mauro Martín (secret.), Stuart J. Longhorn (voc.)
• Materias:
  • Ciencias de la vida
    • Biología animal (zoología)
      • Genética animal
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB 
• Resumen

  • The spider infraorder Mygalomorphae, comprising tarantulas, funnel-web spiders and the trap-door spiders, is one of the three main evolutionary lineages recognized within spiders. Its family level phylogenetic relationships are with a few exceptions relatively well solved, but its actual diversity in the Mediterranean region is probably underestimated. Because of the extremely low dispersal capacity, mygalomorph spiders usually show high levels of local endemism and deep population genetic structure, however, closely related species tend to be morphologically conservative. The low vagility and high habitat fidelity of mygalomorphs makes them a perfect model system for biogeographic studies as their distribution ranges are more likely to reflect geological processes such as continental break ups or tectonic plates rearrangements, while their conservative morphology makes them a good system to test species delimiting methods. The present Ph.D. thesis provides insights into the cryptic diversity, distribution patterns and phylogenetic relationships of the species of the families Ctenizidae, Hexathelidae and Idiopidae that inhabit the Western Mediterranean and the Canary Islands. By using a multi-locus approach and state of the art phylogenetic inference methods, the pattern and time frame of the diversification of these groups is inferred. The phylogenetic and temporal information sheds light on the biogeographic scenario and the diversification drivers of the selected families. Molecular based species delimitation approaches are further used to identify species boundaries in morphologically conservative groups. The results of the present study have greatly contributed to improve our current understanding of the diversity, biogeography and phylogeny of the mygalomorph spiders inhabiting the Mediterranean region and the Canary Islands. The existence of the independent evolutionary lineages that may correspond to undescribed species was detected in all studied groups, so far neglected by taxonomists due to their secluded habits and uniform morphology. The study also reveals that the past geological events had a great impact on the present day distribution of Mediterranean mygalomorphs. In the family Ctenizidae, the amphi-Atlantic distribution of Ummidia, traces back to a former Laurasian distribution and the rearrangement of the microplates following the Hercynian Belt break up, drove the diversification of both Cteniza and Ummidia in the Western Mediterranean. Our findings support that the genus Macrothele colonised the Mediterranean region during the Eocene in two independent waves, presumably from Asia, which in turn may have been colonised from Africa by rifting on the Indian subcontinent, following the Gondwana break up. On the other hand, the Canary Islands were colonised once by the genus Titanidiops presumably by passive rafting from the nearby mainland. Finally, the study sheds additional light on the high level phylogeny of mygalomorph spiders. The first ever-molecular phylogeny of the family Ctenizidae that includes representatives of all genera was conducted, revealing that their current higher taxonomic groupings are polyphyletic and failing to retrieve the monophyly of the family as whole, mostly due to the position of Cteniza and Cyrtocarenum. Unfortunately, topology tests could not reject the single origin of the family. Similarly, the results further confirmed the polyphyly of the family Hexathelidae, mostly due to the inclusion of the Atracinae subfamily. Our findings emphasize the need for redefining the limits of the families Ctenizidae and Hexathelidae and re-evaluating the morphological characters used in the current taxonomy of both groups.