Earlier events :: 2014 :: STUDENT Talks

A Phylogenetic Approach to Measuring Biodiversity in Dry Forest Tree Communities

Presented by
Divya B
Indian Institute Of Science
Authors
Divya B, Dr. Praveen Karanth

Introduction: What conservation problem or question does your study address?

Measuring biodiversity is pivotal to conservation. Phylogenetic diversity (PD) quantifies morphological, behavioral and physiological diversity. This study aims to analyze PD of tree communities of dry forest around Bangalore and its implication in conservation. The study will also test the efficacy of using proxies for PD such as richness at higher taxonomic levels and node-based measures and their impact on conservation decisions.

Methods: What were the main research methods you used?

The intensive quadratic entropy (J) is a measure of PD that is independent of taxon richness, thus suitable to analyze communities where there could be low richness but high diversity. Data of tree species present in 3 locations (Nandi, Devrayanadurga, and Savandurga) were collected. A master phylogeny of all 129 genera was generated; tree topology was built from known phylogenies and branch lengths were generated from matK sequence alignment. Distance matrices were generated, which were used to calculate PD. For each community, J and J-non-unique were calculated. J-non-unique is the PD calculated after excluding the taxa unique to that community from the data. This index gives insight into how these taxa contribute to that community’s PD. Family- and order-level richness, and node-based measure (J-node) were calculated for each community to test for their use as proxies for PD.

Results: What are your most important results?

The dry forests showed decoupling of richness and PD. Nandi has high PD but relatively low richness, while Devrayanadurga showed the opposite pattern. J-non-unique revealed phylogenetically distinct and clustered relationships of the taxa unique to each community. Neither family- and order-level richness nor J-node showed correlation to PD; and in some cases showed opposite patterns – community with high PD having low proxy-index values and vice versa.

Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?

Elucidating Nandi’s high PD-low richness, and the distinct nature of its unique taxa makes it possible to design targeted methods to conserve this diversity. Although easier, using the proposed proxies could lead to disastrous planning due to inflated (higher level richness) and/or underrepresented (node-based) values. This preliminary analysis paves way for expanding this study to include more plots and phylogeny randomization to obtain robust results.