Project B2

Defining the hyperarid core of the Atacama Desert

Research areas: Biological evolution, Biodiversity, Biogeography, Geobiology, Sedimentology

Principal investigator: Prof. Dr. Reinhard Predel, Prof. Dr. Christine Heim, Dr. Alvaro Zúñiga Reinoso, Dr. Benedikt Ritter

Project Info: Phase 3

Hyperarid areas of the Atacama Desert are regarded as largely free of animals. However, results with extensive trap systems within B02 of CRC 1211 indicate that there is virtually no “death zone” without animals. Instead, we found a gradual transition from complex food webs via very simple food webs to extremely hyperarid habitats solely inhabited by Maindronia (Insecta: Zygentoma). We plan to use this information for defining the hyperarid core of the Atacama Desert from a biological perspective as a region characterized by the exclusive presence of Maindronia (no other animals). Abiotic variables within and outside the boundaries of this hyperarid core will be studied to determine the key factors responsible for the collapse of more complex food webs and, in turn, the disappearance of desert specialists such as tenebrionid beetles. Habitat characterization will be based on meteorological observations using the CRC implemented weather station network in northern Chile (A01, Z03), and existing paleoclimate data. Surface and subsurface sediment composition (mineralogy, salt content, grain-size, sediment structure) will be analysed in close collaboration with C04 and C09 for representative transects using standard techniques such as XRD, grain‑size determination, and ICP-OES. Analysis of sediment samples also includes the identification of layers containing microorganisms or dead organic remnants. These may serve as food and water source for the Maindronia, but are often difficult or impossible to detect in salt crusts by gene sequencing methods. Therefore, we plan to use SEM and molecular analyses such as GC-MS and NMR as primary detection tools. Our planned extensive grid sampling (25 x 25 km) across the Atacama Desert using trap systems, developed and deployed for such purposes in Phase 2, will not only provide sufficient information regarding the hyperarid core of the Atacama Desert, but will also be used to reconstruct spatially the different “layers of biodiversity” surrounding the hyperarid core. Based on the distribution and molecular analysis of desert arthropod communities, particularly tenebrionid beetles and Maindronia spp., we will further add temporal information on the evolution and migration history of selected taxa to track environmental changes in the past. This detailed information will then be used to postulate key determinants for the evolution of the desert specialists among insects and thus consolidate the knowledge we have accumulated over the entire duration of the CRC. The definition of the hyperarid core of the Atacama Desert based on biological data will be compared to definitions of it on a geological/geomorphic and meteorological perspective, using existing information and gained knowledge from the other CRC subprojects. Our interdisciplinary approach (biological vs geological perspectives) enables a better understanding of what hyperaridity means and what boundary conditions are crucial for biological life and/or geological and geomorphological processes.