Population dynamics of amoeboid protists in a tropical desert: Seasonal changes and effects of vegetation and soil conditions

In arid environments, protist diversity is higher in soil covered by vegetation than in bare soil and is also likely to vary in line with the marked seasonal patterns; however, these patterns have not been explored in detail in arid zones. Herein, we used culture – and morphological-based approaches to describe patterns of amoeboid protist diversity in vegetated and bare soil areas from the intertropical desert of Tehuacán, Mexico, during dry and wet seasons. Overall, 27 protist species belonging to Amoebozoa, Discoba and Rhizaria were retrieved using culture-dependent methods. Among the soil protist groups found, Discoba (principally represented by Heterolobosea) was always the most prevalent taxa. Protist diversity was different between soil with vegetation and bare soil, principally during the dry season. Moreover, the electrical conductivity and pH of the soil were correlated with the protist species during the wet season. Our results support the hypothesis that soil protist diversity patterns exhibit a seasonal variation between dry and wet seasons. This seasonal variation likely relies on water availability, although the role of other environmental factors cannot be completely ruled out. In addition, the soils with vegetation could be a refuge for the amoeboid protists during the harsh soil conditions of dry seasons.