2012), there are notable examples of parallel morphological evolution in the elongate, worm-like body forms of fossorial taxa (Wake 1966 Parra-Olea and Wake 2001), and in the extensive convergent modification to foot size and inter-digit webbing in climbing species (Adams and Nistri 2010). Although plethodontid salamanders demonstrate strong phylogenetic conservatism in body morphology across diverse microhabitats (Blankers et al. Plethodontids are a speciose and widespread group of salamanders that have undergone remarkable adaptive radiation to a wide range of habitats from arboreal bromeliads in the tropics to perpetually dark caves in temperate regions. Salamanders of the family Plethodontidae present an excellent model system for investigating the role of ecology in the generation of morphological variation.

These expectations predict that ecological niche-specific selective pressures drive phenotypic variation such that phylogenetically independent lineages within similar niches will share behavioral and morphological traits. Variation in morphological traits can mediate shifts in behavior and life history that permit colonization of new ecological niches conversely, biotic and abiotic conditions within habitats can shape adaptive modifications to functional morphology to support an organism's survival within their niche (Wainwright and Reilly 1994 Schluter 2000 Losos 2011). One tool used to address this goal is ecomorphology, or the study of the relationship between the ecology of organisms and the morphology of phenotypic traits to infer potential adaptive qualities of structural differences (Wainwright and Reilly 1994). The morphological correlates of ecology among diverse species reveal underlying evidence of habitat specialization in the inner ear and suggest that there exists physiological variation in the function of the salamander ear even in the apparent absence of selective pressures on the auditory system to support acoustic behavior.Īmphibian, auditory, ecomorphology, geometric morphometrics, vestibularĪ primary goal of evolutionary biology is to identify the factors driving morphological diversification.

Cave specialists show parallel enlargement of auditory-associated structures. Species that dwell in spatially complex microhabitats exhibit robust, highly curved semicircular canals suggesting enhanced vestibular sense, whereas species with reduced visual systems demonstrate reduced canal curvature indicative of relaxed selection on the vestibulo-ocular reflex. Phylogenetic comparative analyses demonstrate structural convergence in the inner ear across ecologically similar species. We collected traditional and 3D geometric morphometric measurements to characterize variation in size and shape of the otic endocast and peripheral structures of the salamander ear. We examined the influence of habitat, development, and vision on inner ear morphology in 52 plethodontid species. Substantial morphological variation in the otic region coupled with great ecological diversity within this clade make plethodontids an excellent model for exploring the ecomorphology of the amphibian ear.

Lungless salamanders (Family Plethodontidae) form a highly speciose group that has undergone spectacular adaptive radiation to colonize a multitude of habitats.

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