Undergraduate Honors Theses

Thesis Defended

Spring 2016

Document Type


Type of Thesis

Departmental Honors


Ecology and Evolutionary Biology

First Advisor

Steven Schmidt

Second Advisor

Pieter Johnson

Third Advisor

Brian Hynek


Investigating Earth for life in extreme environments provides insight into what life might exist elsewhere in the universe. Many celestial bodies have dry and cold landscapes. On Earth the Andes Mountains that form the eastern border of the Atacama Desert in South America are marked by a very dry and cold environment. A previous study in the region, of a volcanic mountain with a summit above 6000 meters above sea level (m.a.s.l.), discovered a fumarole (geothermal vent) that supports an oasis of life in an otherwise barren landscape. This study re-sampled the same fumarole located at 5825 m.a.s.l. and a second fumarole near the summit at 6050 m.a.s.l., which is now the highest elevation fumarole ever investigated for biota. Additionally, three non-fumarole sites were sampled; two at 5825 m.a.s.l. and one at 6050 m.a.s.l. Biogeochemical parameters (enzyme activity, percent water, and percent carbon and nitrogen) were measured in addition to the creation of high-throughput DNA sequencing libraries of 16S and 18S rRNA operational taxonomic unit (OTU) identifiers. Sequence analysis and statistical tests were done to determine the effects of fumarolic activity, elevation, and biogeochemical parameters on community alpha and beta diversity. Fumarole samples had much higher alpha diversity than all non-fumarole samples, with over three times more bacterial and eukaryotic OTUs observed. Furthermore, beta diversity analyses revealed fumarolic soils closely clustered together, to the exclusion of non-fumarolic soils for all three domains of life. This pattern was shown to be statistically significant using Adonis, while elevation and biogeochemical properties were not a significant driver of community composition. These findings indicate that fumarolic activity allows the proliferation of complex microbial communities, even in environments that are seemingly devoid of life due to dry and cold conditions.