Cyanidiales diversity in Yellowstone National Park

Abstract The Cyanidiales are unicellular red algae that are unique among phototrophs. They thrive in acidic, moderately high‐temperature habitats typically associated with geothermally active regions, although much remains to be learned about their distribution and diversity within such extreme environments. We focused on Yellowstone National Park (YNP), using culture‐dependent efforts in combination with a park‐wide environmental polymerase chain reaction ( PCR ) survey to examine C yanidiales diversity and distribution in aqueous (i.e. submerged), soil and endolithic environments. Phylogenetic reconstruction of C yanidiales biodiversity demonstrated the presence of C yanidioschyzon and G aldieria lineages exhibiting distinct habitat preferences. C yanidioschyzon was the only phylotype detected in aqueous environments, but was also prominent in moist soil and endolithic habitats, environments where this genus was thought to be scarce. G aldieria was found in soil and endolithic samples, but absent in aqueous habitats. Interestingly, C yanidium could not be found in the surveys, suggesting this genus may be absent or rare in YNP . Direct microscopic counts and viable counts from soil samples collected along a moisture gradient were positively correlated with moisture content, providing the first in situ evidence that gravimetric moisture is an important environmental parameter controlling distribution of these algae. Significance and Impact of the Study The C yanidiales are an order of unicellular eukaryotic algae that thrive in acidic geothermal environments. In this study, we report several novel observations relative to C yanidiales ecology in Y ellowstone N ational Park, including the following: (i) the identification of two phylogenetic lineages of C yanidiales: C yanidioschyzon and G aldieria ; (ii) the absence of G aldieria in aquatic environments; (iii) the absence of C yanidium and G aldieria phlegrea in prime C yanidiales habitats; (iv) the cohabitation of C yanidioschyzon and G aldieria in nonaqueous environments; and (v) the first in situ evidence regarding the relationship between soil moisture and C yanidiales habitat preference and viability