A paper on the morphological evolution of amblyopsid cavefishes was recently published in the journal Copeia. The full citation and abstract are below.
Armbruster JW, Niemiller ML, & Hart PB. 2016. Morphological evolution of the cave-, spring- and swampfishes of the family Amblyopsidae (Percopsiformes). Copeia 104: 763–777.
The Amblyopsidae is a small family of fishes from North America in which most of the species occur in caves. Despite considerable interest and study by biologists, a comprehensive morphological phylogenetic analysis of the family has not been conducted to date. We examined the skeletal morphology of all six genera and recognized species, which included 66 characters. The resulting phylogeny was compared to morphological- and molecular-based phylogenies of previous studies. Results showed a progression of cave adaptation that was significantly different from previous phylogenetic studies. Amblyopsidae was supported by 34 synapomorphies of the skeleton, but relationships within the Amblyopsidae were comparatively weak. The relationships of amblyopsids are likely influenced by morphological convergence as well as changes in the timing of development of some characters. Heterochrony is most visible in the unfused bones of the dorsal portion of the skull. The sister group to Amblyopsidae is Aphredoderidae (pirate perches), and the main character that supports this relationship is the presence of a unique set of upper jaw bones termed here lateromaxillae. This relationship is also supported by an anterior position of the vent, which is used for expelling gametes in Aphredoderus and for moving eggs to the gill chamber in Amblyopsis. It is more likely that Amblyopsis is the only branchial brooding amblyopsid and all other species likely exhibit transbranchioral spawning.
My coauthors Daphne Soares, Dennis Higgs and I have a chapter titled “Hearing in cavefishes” in the recently published book “Fish Hearing and Bioacoustics – An Anthology in Honor of Arthur N. Popper and Richard R. Fay.” The volume is edited by Joe Sisneros and honors the scientific contributions of Art Popper and Richard Fay.
The full citation and abstract of the chapter are included below. The chapter and book can be downloaded from the Springer website here.
Soares D, Niemiller ML, & Higgs DM. Hearing in cavefishes. Pp. 187–195 in: Fish Hearing and Bioacoustics – An Anthology in Honor of Arthur N. Popper and Richard R. Fay (Sisneros JA, ed). Springer.
Caves and associated subterranean habitats represent some of the harshest environments on Earth, yet many organisms, including fishes, have colonized and thrive in these habitats despite the complete absence of light, and other abiotic and biotic constraints. Over 170 species of fishes are considered obligate subterranean inhabitants (stygobionts) that exhibit some degree of troglomorphy, including degeneration of eyes and reduction in pigmentation. To compensate for lack of vision, many species have evolved constructive changes to non-visual sensory modalities. In this chapter we review hearing in cavefishes, with particular emphasize on our own studies on amblyopsid cavefishes. Hearing in cavefishes has not been well studied to date, as hearing ability has only been examined in four species. Two species show no differences in hearing ability relative to their surface relatives, while the other two species (family Amblyopsidae) exhibit regression in the form of reduced hearing range and reduction in hair cell densities on sensory epithelia. In addition to reviewing our current knowledge on cavefish hearing, we offer suggestions for future avenues of research on cavefish hearing and discuss the influence of Popper and Fay on the field of cavefish bioacoustics.