Systematics/Phytogeography / Taxonomie/ Section
McDade, Lucinda , Daniel, Thomas F. , Kiel, Carrie .
Evolutionary processes and the phylogeny of ‘justicioids’ (Acanthaceae: Justicieae): Biogeography, molecular and morphological evolution, and species richness.
The phylogenetic hypothesis for ‘justicioids’ (Acanthaceae: Justicieae) presented by Kiel et al. at this conference adds three cp loci (i.e., trnTL, trnSG, trnL[uga]-ndhF) that evolve more rapidly than those used previously to study Justicieae, thus tripling the data assembled to examine relationships within this large (>1000 species) lineage. It also represents a three-fold increase in taxon sampling, with taxa selected to permit tests of taxonomic concepts including monophyly of recognized genera and infrageneric taxa. Here, we use this phylogeny to examine biogeographic patterns, including area of origin and pattern of dispersal events among the New World (NW), Africa and Madagascar. Our data support an African origin for ‘justicioids’ with at least two dispersal events to the NW and three to Madagascar. Previous studies using nrITS and trnLF sequences have shown NW ‘justicioids’ to be species-rich and mutation-poor, with the group showing little molecular divergence compared to their sister group, Diclipterinae. We reexamine this pattern with the present character-rich and more densely sampled data set; notably the present study gives us a better understanding of the likely full taxonomic range of Diclipterinae. The pattern holds for the data set as a whole and for four of five genic regions used here. The fifth, trnL(uga)-ndhF, is the exception that proves the rule in that Diclipterinae share a deletion in this genic region that is nearly 450 bp long: with 1/3 of the sequence missing, Diclipterinae have branch lengths comparable to those among NW ‘justicioids.’ We test the hypothesis that species diversity in the NW is associated with the evolution of hummingbird pollination and examine preliminary evidence as to why this might be the case. Lastly, with improved sampling and resolution, we can begin to examine patterns of character evolution in this remarkably heterogeneous group of plants.
Log in to add this item to your schedule
1 - Rancho Santa Ana Botanic Garden, Research, 1500 North College Avenue, Claremont, CA, 91711, USA
2 - California Academy of Sciences, Department of Botany, 875 Howard Street, San Francisco, California, 94103-3009, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 11:45 AM