Date of Award
Doctor of Philosophy
Ecology, Evolution, and Organismal Biology
Ecology and Evolutionary Biology
Lynn G. Clark
The subfamily Bambusoideae (bamboos) is one of 12 subfamilies in Poaceae (grass family) and is primarily associated with forest habitats. Bambusoideae, which include nearly 1,500 species worldwide, is classified into two tribes of woody bamboos (the tropical Bambuseae and the temperate Arundinarieae) and one tribe of herbaceous bamboos (the Olyreae). The Arundinarieae, with ca. 550 species, is well known for its taxonomic and phylogenetic complexity; to date, there are twelve major lineages found in Arundinarieae based on analyses of selected chloroplast DNA (cpDNA) markers, nuclear DNA genes and complete plastomes. The main objectives of this dissertation are to: 1) conduct molecular phylogenetic analysis for the temperate woody bamboo species using chloroplast DNA with particular emphases on testing the monophyly of Sri Lankan temperate woody bamboos, placing them in the correct genus or genera and perform a taxonomic revision for this group; 2) understand the phylogenetic relationships among and within the woody bamboo clades using complete plastome sequences and low-copy nuclear markers and evaluate morphological evolution of some important characters such as rhizomes and pseudospikelets; 3) develop a web-based multi-access interactive key for the Sri Lankan and South Indian temperate woody bamboos; 4) understand the population genetic structure of A. debilis, a highly threatened temperate woody bamboo species.
The twelfth lineage of the Arundinarieae, the Kuruna clade distributed in Sri Lanka and south India, is based on five plastid markers (rps16–trnQ, trnC–rpoB, trnD–trnT, trnT–trnL and ndhF 3’). In addition to the recognition of this clade as a new genus, I generated a monograph for Kuruna, treating the six Sri Lankan Kuruna species: K. debilis, K. densifolia, K. floribunda, K. scandens and K. walkeriana plus the newly described K. serrulata, and the south Indian endemic K. wightiana. The seven species are described and illustrated and a dichotomous identification key is provided; a preliminary conservation status assessment for each species is also included. I also explored the phylogenetic relationships among the twelve major lineages of Arundinarieae based on sequences of both complete plastomes and 3 low-copy nuclear genes. Most of the previously recognized major clades were supported by both data sets, though there were some conflicting phylogenetic signals. Furthermore, I designed a web-based multi-access identification tool (WEBiKEY) and tested for its usability with genus Kuruna as a sample dataset. This simple, easy-to-use interactive key enables users with plant material from an unknown species in Kuruna to visually inspect characteristics of the bamboo and identify it as one of the seven species in the genus.
I also report the results of a preliminary analysis of genetic diversity and population structure in six known Sri Lankan populations of Kuruna debilis in Sri Lanka. Even though the sample size was relatively low, allelic diversity was high at most loci and, given the limited distances separating populations (<65 km apart), they exhibited fairly high genetic differentiation (FST = 0.113) and strong isolation by distance. STRUCTURE, neighbor-joining, and Neighbor-Net analyses agree that the six K. debilis populations group into three genetic clusters consistent with the spatial proximity of populations. As the first population genetics study of Bambusoideae in Sri Lanka, I anticipate that our results will provide a foundation for future comparative population genetics and conservation studies in the country.
Lakshmi Ruwani Attigala
Attigala, Lakshmi Ruwani, "Phylogenetics, systematics and evolution of the temperate woody bamboos with an emphasis on the Kuruna clade" (2015). Graduate Theses and Dissertations. 14764.