Biodiversity of Microbial Eukaryotes in Alpine Pink Snow Across Geographically Diverse Mountain Ranges

Snowy and glaciated alpine environments are among the most threatened on our warming planet, and the organisms that live in and on glaciers are experiencing dramatic changes in their physical environment and rapid loss of habitat. These environments are host to complex microbial eukaryotic communities driven by algal primary production. Snow algae can produce intense blooms in spring and summer months that turn snow and ice pink, orange, or bright red. The colored biomass visibly darkens the snow surface, reducing albedo and accelerating snowmelt. Blooms of snow algae are intricately tied to this process of melting, because they need liquid water to reproduce, while at the same time increased blooms reduce available habitat. Despite the impact of snow algae on glacial melt, there are outstanding questions about their lifecycle, dispersal, and biodiversity across mountain ranges that are critical to understanding how these communities will respond to these impending changes in habitat. Recent DNA surveys from snow algae from snowy and glaciated environments globally have produced conflicting results. Some studies, primarily from polar regions, suggest snow algae communities are species-poor and consistent across all snowy environments, while others suggest more diversity and variability. This study presents data on biodiversity and community structure of snow algae and associated microbial eukaryotes from pink snow from meta-amplicon sequencing of the V4 18S SSU rDNA gene from over 200 samples collected from 5 geographically diverse mountain ranges: the Cascade Range in the Pacific Northwest of the USA, the Rocky Mountains of the USA and Canada, the Cordillera Blanca in Peru, the European Alps and the New Zealand Southern Alps. We use novel phylogenetic-based ecological methods to assess phylogenetic diversity and compare community structure. Our data show there are multiple types of snow algae communities that geographic similarity did not predict biologically similarities. Our results also show there can be as much biological variability within a single mountain range as there is across continents, and there is far more variability within the algal species within a community as there is within the heterotrophic members. Taken together, data suggest complex dispersal mechanisms for these communities.