COS 211-5 - Priority effects structure microbial communities of Antarctic cryoconite holes

Wednesday, August 9, 2023

4:30 PM – 4:45 PM PDT

Location: B118

Presenting Author(s)

DP

Dorota L. Porazinska

Assistant Professor
Univeristy of Florida
Gainesville, Florida, United States

Coauthor(s)

PS

Pacifica Sommers

Metagenomics Data Scientist
Bayer Crop Sciences
Boulder, Colorado, United States
FZ

Felix Zamora

Portland State University
Portland, Oregon, United States
JC

Julian Cross

PhD Student
Portland State University
Portland, Oregon, United States
AF

Andrew G. Fountain

Professor
Portland State University
Portland, Oregon, United States
AS

Adam J. Solon

PhD student
University of Colorado Boulder
Boulder, Colorado, United States
LV

Lara Vimercati

Post Doc
University of Colorado Boulder
Boulder, Colorado, United States
KC

Kaelin Cawley

Ecologist III
National Ecological Observatory Network
Boulder, Colorado, United States
SS

Steven K. Schmidt

Professor
University of Colorado Boulder
Boulder, United States

Abstract: Microbial communities play critical roles in animal and plant health and drive ecosystem functions including the cycling of carbon, nitrogen, and other elements. Understanding how communities assemble is of great importance for predicting their responses to global change scenarios. Although priority effects (how the order of arrival of species alters eventual community composition) have been increasingly recognized as drivers of microbial community assembly, their relevance under natural conditions has been difficult to study largely due to inability to control dispersal.

Ice-lidded Antarctic cryoconite holes represent a model of naturally isolated microbial ecosystems with limited dispersal. To test the strength of priority effects at the whole community level, we used a robustly replicated in situ manipulative experiment with artificially created cryoconite holes on the surface of Canada Glacier in Taylor Valley, Antarctica. Cryoconite holes were seeded with either one or a mixture of two very distinct types of microbial mats (“black” and “orange”) and after two weeks seeded again with the second round of microbial mat inoculum, either of the same, the opposite, or both mats. Cryoconite holes were destructively sampled twice (after 1^st and 2^nd growing seasons) and the composition and structure of their communities was determined based on16S rRNA metabarcoding.

Here we show that significant community-level priority effects were observed. The effects were particularly evident after the 1^st growing season when the experimental communities strongly reflected the first mat type added. By the 2^nd season, although still present, these effects were somewhat diminished likely due to strong selection by the harsh environment. The results demonstrate that biotic interactions, not just the physical environment, are important in shaping how microbial communities assemble in this extreme environment of cryosphere. These findings broaden our understanding of factors driving the biodiversity of the cryobiosphere at a time when it is severely threatened by global change.