Paul Zaharias

  • Advisor:
      • Nicolas Puillandre
  • Departments:
  • Areas of Expertise:
      • bioinformatics
      • computational biology
  • Thesis Title:
      • Integrative taxonomy, phylogeny and diversification of Turridae (Gastropoda, Conoidea)
  • Thesis abstract:
      • The Turridae are a group of predatory venomous marine gastropods, found in almost all the pantropical zone, from shallow-water to more than 3000m deep. Considering their low diversity (about 200 described species), relatively to their sister taxa within the Conoidea, and the apparent absence of specific key innovation, the question of this PhD is: what is the diversification dynamic and the drivers of diversification within the Turridae? However, it is possible to answer to this question only with a robust systematic framework. Traditional approaches of systematics, based on morpho-anatomical considerations only, are confronted to problems of shell and organ plasticity, whether it is on a short or long evolutionary timeframe. Hence, molecular tools were privileged to answer this question. In the first part, a taxonomic pipeline was defined and used to delimit species hypotheses within the Turridae. This pipeline resulted in about 200 species hypotheses, for which it is not always easy to know if they have been previously described or not. I explore this problematic with an analysis of Cryptogemma. The semi-automatized acquisition of morphometric data allowed attributing 23 name-bearing specimens to the 8 delimited species with more confidence, illustrating the great taxonomic confusion in the Turridae. In the second part, I constructed a phylogeny of Turridae using a “reduced-genome” approach. These approaches allowed me to sequence about 4000 loci for 110 species hypotheses. The retrieved topologies showed robust evidence for the paraphyly of Gemmula, for which 13 new genera can potentially be described. Finally, I combined the results from integrative taxonomy and phylogeny, as well as recent methods to study diversification dynamics. The Turridae family appears as a group with higher past diversification rates than present ones. Furthermore, links have been found between diversification rates and some traits like protoconch, shell shape and size and bathymetry. The systematic strategy applied in this PhD show great efficiency and allowed answering key evolutionary questions linked to diversification in marine gastropods, with unprecedented results.
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    Contact information:
    zaharias@illinois.edu