Seeing a subterranean animal any naturalist finds it difficult not to wonder about evolutionary processes that shaped it. However, the value of these animals reaches far beyond pure naturalist curiosity. Many of them are excellent models for studying evolutionary processes, as they are replicated across different karst regions and live in an environment with strong directional selection pressures. Neutral mutations, selection-driven adaptations to extreme subterranean environment, pleiotropy, dispersal through the network of human-inaccessible voids and speciation following colonization of the subterranean environment, are some of the topics that have enriched our understanding of evolution in general. We exploit these processes at three partially overlapping levels.
Crossing the Styx: adaptation and speciation
Species entering the subterranean realm are subdued to a dramatic environmental change. Who were the early colonizers? A random subsample of surface populations? Individuals with behavioral and/or morphological advantages? What evolutionary processes drive loss of pigment and eyes – neutral mutations, selection, or both? Have similar phenotypes evolved through same or different evolutionary processes? How has the evolution of behavioral traits interacted with evolution of morphology? Has ecological adaptation to the subterranean environment caused the cessation of gene flow between surface and subterranean populations? We study these and other questions on Asellus aquaticus, a freshwater isopod crustacean with independently replicated surface and subterranean populations by combining comparative methods with experimental work.
