Chapter 19 - Life histories in groundwater organisms

Abstract

In this chapter, we explore the current state of life history research in groundwater fauna, including a brief review of life history evolution, life history traits, and life table variables. While a large body of research exists on life history traits, life tables, and evolution of life histories in general, including trade-offs and life history plasticity, the study of life histories in groundwater organisms is exceptionally limited. The current view of life history evolution in groundwater species is consistent with a “habitat template” model whereby strong selective forces associated with the groundwater habitat template (particularly environmental stability and energy limitation) have resulted in convergence of similar characteristics, including life history traits, among disparate groups of organisms. While theory and data appear to align generally, our perspective on life histories of groundwater species has advanced little beyond the generalization that “groundwater species exhibit k-selected life history strategies.” Life history traits are poorly described in most groundwater species, with much of our inferences derived from a few model taxa. In addition, few comparative studies of life history traits have been conducted between related groundwater and surface species and even fewer comparative studies among groundwater ecosystems. Consequently, the “habitat template” conceptual model warrants intensive continued study in groundwater species. We offer recommendations on how to improve our understanding of life history traits and evolution in groundwater fauna, including life history plasticity, trade-offs, and the influence of population demography and molecular evolution.