ABSTRACT
The Amblyopsid cavefi shes, family Amblyopsidae, have been viewed as a model system for studying the ecological and evolutionary processes of cave adaptation because the four cave-restricted species in the family represent a range of troglomorphy that refl ect variable durations of isolation in caves (Poulson 1963, Poulson and White 1969). This group has both intrigued and excited biologists since the discovery and description of Amblyopsis spelaea, the fi rst troglobitic fi sh ever described, in the early 1840s. Other than the Mexican cavefi sh (Astyanax fasciatus), cave Amblyopsids are the most comprehensively studied troglobitic fi shes (Poulson, this volume). The Amblyopsidae (Fig. 1) includes species with some unique features for all cavefi sh. Typhlichthys subterraneus is the most widely distributed of any cavefi sh species. Its distribution spans more than 5° of latitude and 1 million km2 (Proudlove 2006). Amblyopsis spelaea is the only cavefi sh known to incubate eggs in its gill chamber. In fact, this species is the only one of the approximately 1100 species in North America with this behavior. The Amblyopsidae is the most specious family of subterranean fi shes in the United States containing four of the eight species recognized. Two other
families have species adapted to subterranean habitats, the Ictaluridae and Cottidae. Two species of ictalurids are endemic to the Edwards Aquifer of Texas, the widemouth blindcat (Satan eurystomus) and the toothless blindcat (Trogloglanis pattersoni); and troglomorphic populations of sculpins (Cottus sp.) are known from Missouri and Pennsylvania. Our primary aims of this chapter are to provide an up-to-date, comprehensive review of the pertinent literature and unpublished research (Niemiller on phylogenetics and phylogeography and Poulson on pigment, foraging patterns, metabolic effi ciencies, and metabolic acclimation to temperature) regarding Amblyopsid cavefi shes, including their surface and troglophilic relatives in the family. We begin with a synopsis of the history of Amblyopsid research from the early 1840s to the present day. Here we discuss the signifi cant studies and researchers that have shaped the knowledge base. Next, we review the systematic relationships and taxonomy of the family. The Amblyopsidae have only recently been the subject of phylogenetic examination using molecular markers and we include preliminary data here. We then discuss the biogeography, habitat, and distribution of the family. In the next section, we review morphology of the family in general and morphology of cave adaptation in particular. We include some new data on pigment systems. Subsequently, we summarize aspects of ecology, life history, and behavior including topics such as reproduction, diet, parasites and disease, longevity, metabolism, and demography. Here we also include some new data. Finally, we end with a discussion of the conservation status and threats to members of the family. In each section, we suggest avenues of future research that are needed. Our review is intended to be as detailed and comprehensive as possible and to include the majority of relevant references. With this in mind, we hope that this chapter will serve as both a stimulus for future research and an exhaustive bibliographic reference regarding Amblyopsid biology.
