Raina Maier, a professor in the Department of Soil, Water and Environmental Science at the College of Agriculture and Life Sciences the study's principal investigator said the team expected to find the overall microbial diversity in the cave to be only a fraction of that found in the soil on the surface.
"We expected the surface community many times more diverse than the cave," said Maier, who is also a member of the UA's BIO5 Institute. "Instead, we found the cave is about half as diverse as the terrestrial environment where there is sunlight and soil and vegetation. At the same time, the two ecosystems share only 16 percent of the microbial species. In other words, there is a difference of 84 percent between the two, which is amazing."
Previous studies had shown that, to the cave microbes, the stalactite they live on is like an island: Restricted to the stalactite they happen to be on, there appears to be little mixing between populations, resulting in different assemblages from one cave formation to another.
To analyze the DNA swabbed from the cave formations, Neilson and her team enlisted the help of the lab of Rod Wing, a professor in the UA's Department of Plant Sciences and director of the Arizona Genomics Institute at BIO5.
"When you work in extreme starving environments, you barely get enough DNA," Neilson explained. "In some of our samples we got about half of what is considered the minimum amount for DNA sequence analysis. But, we said, let's just try it. And the wonderful technicians in Rod Wing's lab tried all those new techniques and they managed to get us a data set even from the dry rock, where there is no drip water and where there are very few microbes living to begin with."
In addition to encountering all the major players that make up a complex food web in the cave, the scientists discovered what likely are microbes yet unknown to science.
"Twenty percent of the bacteria whose presenc
|Contact: Daniel Stolte|
University of Arizona