Divergence and diversification of the genus Piper and the order Piperales (Columbia)

Piper is one of the most species rich genera within the basal lineages of angiosperms and also in the wet tropical forests. Phylogenetic studies directed to explore evolutionary questions of clade divergence and diversification in Piper and the order Piperales were conducted. Within the order Piperales I studied how flowers have evolved using a combination of developmental and phylogenetic data. To infer evolutionary changes in the piperalean flower, ancestral character states were reconstructed for both mature floral structures and ontogenies using a robust molecular phylogeny framework. The evolutionary developmental changes in the flowers of Piperales are: paedomorphosis, peramorphosis and convergence of mature structures by identical or dissimilar developmental sequences (Chapter 1). Most of the variation in flower structure is expressed within Piper, defining subclades within the genus. An exemplar sampling of Piper species from the tropics of America and Asia was used to reconstruct the relationships of the putative subgenera (Chapter 2). Three major clades of distinct geographic distributions were obtained: Neotropics, Paleotropics, and the South Pacific Islands. While many of the previously recognized infrageneric groupings were supported by the molecular phylogeny, a few subgenera were shown to be polyphyletic, as seems to be the case for the miniature taxa classified within Trianaeopiper. An intensive sampling of species within Trianaeopiper was conducted to determine the relationships among them and their close relatives (Chapter 3). Trianaeopiper species formed three well-supported clades of species related to different sets of Neotropical taxa. The diagnostic character for the group was found to be convergent and most probably associated with the low light environment prevalent in the very wet forests of the Choco Region, the only area where these plants occur. To address the necessity of biodiversity conservation relative to all knowledge acquired about diversification forests an effort was made to assess conservation priorities in the Choco Region using phylogenetic diversity measures (Chapter 4). Using distribution and phylogenetic data, diversity was scored for species richness, endemism and phylogenetic diversity. Conservation priorities were assessed by hotspots and complementarity analysis. Four areas were selected as the regions with highest priority for conservation using the different diversity indices and analytical procedures. The diversity of Piper in the Choco Region seems to be the result of recent diversification of several clades, originating very localized endemisms.