Phylogeny of Trochetia species based on morphological and molecular markers
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.