DOI: 10.5061/dryad.ksn02v746
title: DNA metabarcoding data: Altitudinal zonation of green algae biodiversity in the French Alps

description: Mountain environments are marked by an altitudinal zonation of habitat
 types. They are home to a multitude of terrestrial green algae, who have
 to cope with abiotic conditions specific to high elevation, e.g., high UV
 irradiance, alternating desiccation, rain and snow precipitations, extreme
 diurnal variations in temperature and chronic scarceness of nutrients.
 Even though photosynthetic green algae are key primary producers
 colonizing open areas and potential markers of climate change, their
 overall biodiversity in the Alps has been poorly studied so far, in
 particular in soil, where alga have been shown to be major components of
 microbial communities. Here, we investigated whether the spatial
 distribution of green algae followed the altitudinal zonation of the Alps,
 based on the assumption that algae can spread via airborne spores and
 settle in their preferred habitats under the pressure of parameters
 correlated with elevation. We did so by focusing on selected
 representative elevational gradients at distant locations in the French
 Alps, where soil samples were collected at different depths. Soil was
 considered as either a potential natural habitat or temporary reservoir of
 algae. We showed that algal DNA represented a relatively low proportion of
 the overall eukaryotic diversity as measured by a universal Eukaryote
 marker. We designed two novel green algae metabarcoding markers to amplify
 the Chlorophyta phylum and its Chlorophyceae class, respectively. Using
 our newly developed markers, we showed that elevation was a strong
 correlate of species and genus level distribution. Altitudinal zonation
 was thus determined for about fifty species, with proposed accessions in
 reference databases. In particular, Planophila laetevirens and
 Bracteococcus ruber related species as well as the snow alga Sanguina
 genus were only found in soil starting at 2,000 m above sea level.
 Analysis of the vertical distribution in soils further highlighted the
 importance of pH and nitrogen/carbon ratios. This metabolic trait may also
 determine the Trebouxiophyceae over Chlorophyceae ratio. Guidelines are
 discussed for future, more robust and precise analyses of environmental
 algal DNA in soil in mountain ecosystems, to comprehend the distribution
 of green algae species and dynamics in response to environmental changes.
description: The datasets correspond to DNA metabarcoding data produced
 following the protocol described in  article:
 Altitudinal zonation of green algae biodiversity in the French
 Alps, 2021, Frontiers in Plant
 science (<b>DOI:</b> 10.3389/fpls.2021.679428).
 The published data correspond to the alignment of forward and
 reverse reads using <em>illumiinapairedends</em>,
 demultiplexed by samples using <em>ngsfiler</em>, dereplicated
 using <em>obiuniq</em> and expunged of singleton sequences
 (sequences appearing only once in the complete data set) using
 <em>obigrep</em>. The process of analysis
 is detailed at: https://alpalga.github.io/Zonation/ All
 scripts are available at: https://github.com/Alpalga/Zonation
description: Data are FASTA formatted sequence files using the OBITools header
 convention for annotations. <br> The analysis of the data can be
 facilitated using the  OBITools package
 http://mertabarcoding.org/obitools