Why the delay in recognizing terrestrial obligate cave species in the tropics?

Abstract

“Nothing could possibly live there!” They believed. Indeed, until recently, few specialized cave- adapted animals were known from volcanic, tropical, or oceanic island caves, and plausible theories had been put forward to explain their absence. But assume nothing in science! One must illuminate, explore, and survey habitats before declaring them barren. Our understanding of cave biology changed dramatically about 50 years ago following the serendipitous discovery of cave-adapted terrestrial arthropods in Brazil and on the young oceanic islands of the Galápagos and Hawai‘i. These discoveries and subsequent studies on the evolutionary ecology of cave animals have revealed a remarkable hidden fauna and created new sub- disciplines within biospeleology. Biological surveys of caves in other regions have continued to expand our understanding of the evolution, adaptation, and ecology of the subterranean biome. We now predict that, rather than being relicts trapped in caves by changing climate, many animals actively colonized caves and adapted to exploit food resources wherever there were suitable subterranean voids. The physical environment in caves can be determined with great precision because the habitat is buffered by rock. Furthermore, the bizarre adaptations displayed by obligatory cave animals are similar across many taxonomic groups. These two characteristics make caves nearly ideal natural laboratories for studying evolution and ecology. However, to the untrained researcher, caves can appear hostile and dangerous, and in fact, fieldwork in caves requires a unique marriage of athletic ability and science. In other words, cave research is exciting! In this contribution, I describe the exploration, discovery, and research in tropical caves and describe the factors that delayed the recognition of a significant tropical cave fauna.