Cladogenesis and niche evolution in Madagascan forests

Madagascan palms as a model for tropical forest plant evolution

Tropical rain forests are the world’s most biodiverse terrestrial ecosystems, but the evolutionary history underpinning this diversity is still poorly understood. Madgascar is a biodiversity hotspot combining high plant diversity with high endemism, thus lending itself to addressing this question. The project MADCLADES uses palms (Arecaceae) as a model group for studying the evolutionary assembly of the island’s forests. Madagascan palms (more than 200 native species, almost all endemic) are present in all forest types of the island and play an integral role in forest ecology.

We have conducted extensive fieldwork to sample Madagascar's palm diversity, and we are now reconstructing the phylogenetic history of the island's entire palm flora using RNA hybrid baiting, and Next-Generation Sequencing. We will analyse the phylogenetic trees together with information on species distributions, traits, and niches to study the dynamics of cladogenesis and niche evolution. Firstly, we will address the question as to why some clades have diversified excessively (e.g. Dypsidinae with 165 species), while others have not? Secondly, we will study the diversification of two larger clades in detail and test hypotheses regarding the roles of traits, niches, and environmental change. Finally, we will integrate the phylogenetic information with distribution data and IUCN Red List assessments to derive new conservation priorities for species and regions. The results will add to the fundamental knowledge about biodiversity dynamics required to tackle the societally important biodiversity crisis.

Kew's role in the project

Kew scientists have driven the exploration of the Madagascan palm flora since the 1980s, leading to a range of resources (herbarium and DNA specimens, taxonomic accounts including trait data, distributional information, conservation assessments, etc.) that are pivotal for establishing Madagascan palms as an evolutionary model. No other Madagascan plant lineage is served with a comparable amount of data. Now, within the framework of Kew's Plant and Fungal Trees of Life strategic output, we are taking this resource to the next level by providing a phylogenetic framework that can link all available datasets allowing us to analyse them in an evolutionary context. Thereby, this research directly contributes towards Kew's aim to answer the fundamental question 'what drivers and processes underpin global plant and fungal diversity?'.

Objectives

• Comprehensively sample the Madagascan palm flora.
• Use a next-generation HybSeq approach to obtain genomic data for all available Madagascan palm species, and reconstruct robust phylogenetic trees for all Madagascan palm lineages.
• Assemble datasets on the niches and traits, building on Kew's long-standing work on Madagascan palms.
• Jointly analyse the phylogenomic, geographic, ecological and morphological trait datasets to test selected evolutionary hypotheses regarding the origin and diversification of Madagascan palm diversity, with implications for Madagascan forests in general.

Team

Félix Forest
Robyn S. Cowan
Dion S. Devey
Prof William J. Baker

• Comprehensive DNA collection of Madagascan palms.
• Develop a robust phylogenetic framework for the Madagascan palm flora.
• Several high-impact scientific publications shedding light on the drivers of palm diversification in Madagascar, with implications for tropical forest plant diversification in general, establishing Madagascan palms as a model for evolutionary studies.

International

• The University of Georgia, Athens, GA, USA
• University of Antananarivo, Madagascar

• European Union FP7-PEOPLE programme (Marie Curie actions, grant # 327259)
• National Geographic Society – Global Exploration Fund Northern Europe
• International Palm Society
• Royal Horticultural Society