A comprehensive framework for functional diversity patterns of marine chromophytic phytoplankton using rbcL phylogeny.

Brajogopal Samanta,Punyasloke Bhadury

doi:10.1038/srep20783

Brajogopal Samanta, Punyasloke Bhadury

Open Access

https://doi.org/10.1038/srep20783

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Abstract

Marine chromophytes are taxonomically diverse group of algae and contribute approximately half of the total oceanic primary production. To understand the global patterns of functional diversity of chromophytic phytoplankton, robust bioinformatics and statistical analyses including deep phylogeny based on 2476 form ID rbcL gene sequences representing seven ecologically significant oceanographic ecoregions were undertaken. In addition, 12 form ID rbcL clone libraries were generated and analyzed (148 sequences) from Sundarbans Biosphere Reserve representing the world’s largest mangrove ecosystem as part of this study. Global phylogenetic analyses recovered 11 major clades of chromophytic phytoplankton in varying proportions with several novel rbcL sequences in each of the seven targeted ecoregions. Majority of OTUs was found to be exclusive to each ecoregion, whereas some were shared by two or more ecoregions based on beta-diversity analysis. Present phylogenetic and bioinformatics analyses provide a strong statistical support for the hypothesis that different oceanographic regimes harbor distinct and coherent groups of chromophytic phytoplankton. It has been also shown as part of this study that varying natural selection pressure on form ID rbcL gene under different environmental conditions could lead to functional differences and overall fitness of chromophytic phytoplankton populations.

Highlights

Marine chromophytes are taxonomically diverse group of algae and contribute approximately half of the total oceanic primary production
Majority of the rbcL sequences were generated from East China Sea (27%), Sundarbans mangrove ecosystem (25%), and South China Sea (20%)
Sequences from Sundarbans mangrove ecosystem (SB) has the highest number of observed unique operational taxonomic units (OTUs) as well as 99% amino acid level identity; whereas East China Sea (EC) has highest number of OTUs at 98%, 97%, 95% and 85% amino acid identity grouping was not undertaken before phylogenetic tree construction

Summary

Introduction

Marine chromophytes are taxonomically diverse group of algae and contribute approximately half of the total oceanic primary production. To understand the global patterns of functional diversity of chromophytic phytoplankton, robust bioinformatics and statistical analyses including deep phylogeny based on 2476 form ID rbcL gene sequences representing seven ecologically significant oceanographic ecoregions were undertaken. Present phylogenetic and bioinformatics analyses provide a strong statistical support for the hypothesis that different oceanographic regimes harbor distinct and coherent groups of chromophytic phytoplankton. It has been shown as part of this study that varying natural selection pressure on form ID rbcL gene under different environmental conditions could lead to functional differences and overall fitness of chromophytic phytoplankton populations. World’s ocean surface chlorophyll data derived from satellites show that micro-phytoplankton (mostly diatoms) www.nature.com/scientificreports/

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