RESEARCH

Origin and diversification of Neotropical orchids

Orchids are one of the most prominent components of the Neotropical Flora, but their origin and diversification in the different biodiversity hotspots and ecosystems in the American Tropics remain poorly understood. In particular, the Andes, a premier biodiversity hotspot containing ca 15% of the world's plant species in just 1% of the earth's surface, is unclear how different biotic and abiotic variables have affected the pace at which Andean orchids diversified. This is mainly due to the lack of densely sampled, solid phylogenetic frameworks that have precluded research on these issues. To answer these questions, I am currently compiling phylogenies of assorted orchid lineages distributed mainly in the Andes and Central America using Sanger and next-generation sequencing methods. Using as a model group speciose Andean orchid lineages, we aim to trace in time and space their diversification, and to disentangle the contribution of main biotic (e.g. pollination syndromes, plant habits) and abiotic (e.g. Andean orogeny) diversification drivers. We are also interested in understanding how main geological events have affected migrations through time in the Neotropical region. Currently, we are building a phylogeny of the species-richest neotropical subtribe Pleurothallidinae using a target enrichment approach combined with genome skimming to resolve deep polytomies and provide support to nodes leading to rapid diversifications. An exciting paper derived from this project is available here, and was featured in the Kew Science blog (also available here). This project is supported by Prof. Alexandre Antonelli via a grant from the European Research Council. 

Changes in climatic niches and pollinators, and their corresponding morphological adaptations are recurrent across the evolutionary history of flowering plants. However, the genomic bases of those morpho-ecological transitions and their contribution to lineage diversifications are still poorly studied. To better understand the evolution of morphological novelty in plants and its link with lineage diversification, we are investigating changes in climatic envelopes and morphology through time in the orchid genus Dendrobium. This hyper-diverse clade of approximately 1500 species inhabits in a rich array of ecosystems in tropical Asia and Australasia, ranging from sea-level xerophytic forests to subalpine vegetation (>3000 m). The lineage is characterized by a remarkable diversity of vegetative and reproductive morphology, driven by repeated transitions contrasting morphological states. This system provides a unique opportunity to elucidate the role that duplication and loss of genes associated to plant development play in the evolution of morphological diversity and diversifications in plants. We are generating a well-resolved phylogenomic framework for Dendrobium, by combining newly sequenced skimmed-genomic data with GenBank sequences. Using a novel target enrichment approach optimized for complex gene families, we are sequencing genomic regions containing MADS-domain transcription factors for selected Dendrobium species spanning the entire morphological and climatic diversity of the lineage. 

Building a family-wide orchid phylogeny using target enrichment and genome skimming

Using a combination of target enrichment and genome skimming approaches, this project aims to provide the first solid, genus-level phylogeny of one of the most speciose clades and spectacular diversifications among flowering plants: the orchid family. Perhaps equally important, it will also provide genomic data of several lineages for which DNA data is not available to date in public databases (i.e. ~40% of the genera). We aim to sample genome-wise ca. 50% of all current generic lineages, but will expand sampling in hyper-diverse clades (e.g. Bulbophyllum, Dendrobium, Epidendrum, Lepanthes). Orchid sampling makes part of the "Plant and Fungal Trees of Life" initiative developed at Kew gardens. This project is supported by the PAFTOL steering group, but additional funds top keep expanding the taxon sampling are always welcome!

Genome evolution of date palms and watermelon through archaeogenomics

In an effort to gain a better understanding of Gene Transcription Enhancers, I have recently begun to use a new technique to investigate the organization and functionality of the diverse parts of my experimental model. I am currently looking to expand this work by collaborating with other labs who have the facilities and prior experience to investigate this project further.

 

Royal Botanic Gardens Kew 

Richmond, Surrey

TW9 3AB

UK

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©2017 by Oscar Alejandro Pérez-Escobar