Systematics of the Subaerial Green Algal Order Trentepohliales (Chlorophyta, Ulvophyceae) Based on Morphological and Molecular Evidence

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The taxonomic order Trentepohliales is a unique group of green algae. They are abundant and diverse in tropical and subtropical regions but at the same time one of the least studied algal groups. All the representatives of the trentepohlialean group are non-aquatic. They are found in terrestrial habitats (sometimes referred to as subaerial) such as rocks, on bark of trees, and on leaves of land plants. Long-neglected by scientists, this group includes economically and ecologically important species. Some of them are agents of biodeterioration to human constructions while others are affecting citrus cultivars and Magnolia trees. Some species are being used as biomonitors of air quality and as sources of chemicals with biotechnological applications. Unfortunately, basic information on their systematics, phylogeny, distribution, life cycles, and ecology is lacking or outdated. Morphological characters at microscopic scale have been traditionally used to define genera and species in this order. However, preliminary gene analyses challenge the current taxonomy of this order, and reveal that morphological criteria alone are not correlated with phylogenetic patterns, urging major systematic rearrangements. The goal of this research is to investigate the phylogenetic relationships of the Trentepohliales and to develop a modern systematic treatment of the order. This research will integrate two independent data sets: morphological data and gene sequences (both nuclear and chloroplast genes). The use of several genes with dissimilar levels of variability will help to understand the systematics of the Trentepohliales at several levels. The use of a phragmoplastin gene will further help to evaluate the usefulness of this marker in clarifying the evolutionary history of the cell division process in the Trentepohliales. This investigation will build a modern revisionary taxonomic treatment and will prepare keys to identify genera based on morphological characters that are phylogenetically relevant.This work will provide training (one postdoctoral associate, one Ph. D. graduate student, and several undergraduates) in all activities during the production of a modern systematic treatment of the green algal order Trentepohliales. Besides peer-reviewed publications and dissemination of results at scientific meetings, the research team will generate communications for local and regional media, educational videos and museum exhibitions oriented to K-12 students. A website exclusively on Trentepohliales will be developed targeting not only specialists but also to a wider audience; it will provide information on the biology of this algal group, responsive identification keys, GenBank accession numbers, and digital imaging. The Principal Investigator will target underrepresented groups and will prepare (in English and Spanish) talks, printed and digital resources to the growing minorities in the SE USA. The Trentepohliales are a challenging and important group of green algae that should be studied comprehensively, particularly in the tropics and subtropics where they are abundant and diverse, but are disappearing as fast as their habitats are disappearing.