The impact of climate on biodiversity is indisputable. Climate changes over geological time must have significantly influenced the evolution of biodiversity, ultimately leading to its present pattern. Here we consider the paleoclimate data record, inferring that present-day hot and cold environments should contain, respectively, the largest and the smallest diversity of ancestral lineages of microbial eukaryotes.

Methodology/Principal Findings

We investigate this hypothesis by analyzing an original dataset of 18S rRNA gene sequences from Western Greenland in the Arctic, and data from the existing literature on 18S rRNA gene diversity in hydrothermal vent, temperate sediments, and anoxic water column communities. Unexpectedly, the community from the cold environment emerged as one of the richest observed to date in protistan species, and most diverse in ancestral lineages.


This pattern is consistent with natural selection sweeps on aerobic non-psychrophilic microbial eukaryotes repeatedly caused by low temperatures and global anoxia of snowball Earth conditions. It implies that cold refuges persisted through the periods of greenhouse conditions, which agrees with some, although not all, current views on the extent of the past global cooling and warming events. We therefore identify cold environments as promising targets for microbial discovery.


Originally published in PLoS ONE 2(8): e728. doi:10.1371/journal.pone.0000728

This research was supported by the US NSF grant OPP-0214231 to SSE and Deutsche Forschungsgemeinschaft grants STO414/2-2 and STO 414/2-3 to TS.


climate, biodiversity, Arctic, rRNA, paleoclimate, microbial eukaryotes

Subject Categories

Biodiversity - Climatic factors, Protista - Arctic Ocean


Biodiversity | Microbiology


Public Library of Science

Publication Date


Rights Information

Copyright 2007


This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Rights Holder

Thorsten Stoeck, et al.

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