Phylogeny of Trochetia species based on morphological and molecular markers

Abstract

Trochetia is a genus of six species out of which five are endemic to Mauritius. Its taxonomic classification has been  hanged from the Sterculiaceae family to the Malvaceae recently. Molecular and morphological  characterization was carried out for the five Trochetia species as a means to conserve endangered Trochetia  species and to understand their genetic diversity. Hibiscus genevii and Dombeya mauritiana were also included in  the study as outgroups to infer the phylogeny of Trochetia. A modified protocol was used for DNA extraction using  CTAB. Morphological characterization was based on both quantitative and qualitative traits. Random Amplified   Polymorphic DNA (RAPD) technique was used for assessing genetic diversity of Trochetia species. High levels of  polymorphism were noted among the Trochetia species using RAPD markers. Both molecular and morphological  data were cladistically analyzed using the unweighted pair group method with arithmetic average (UPGMA) based  on Jaccard’s coefficient. Cluster analysis revealed two different phylogenies of Trochetia for the two different markers used. T. triflora was found to have more similar features to D. mauritiana as compared to its congeneric  species, as evident from the dendogram based on morphological characters. Out of the twenty nine morphological  haracters used, T. triflora bears four characters similar to D. mauritiana as compared to the other Trochetia species. Moreover, both T. triflora and D. mauritiana are best adapted to similar climatic conditions and  have similar geographical distribution, suggesting that their close similarity may possibly be due to convergence.  Sterculiaceae family has been reported to be polyphyletic and hence similar characters might have been derived  from same or different ancestors for both T. triflora and D. mauritiana. However, the molecular characters  separated the genus Trochetia as a different clade from the outgroups. The use of other techniques such as DNA  sequencing may elucidate further the phylogenetic relationships of Trochetia species.

Keywords: Trochetia, morphological data, molecular markers.