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Lungless salamanders (Family Plethodontidae) form a highly speciose group
that has undergone spectacular adaptive radiation to colonize a multitude
of habitats. 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
inner ear. We examined the influence of habitat, development, and vision
on inner ear morphology in 53 plethodontid 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. Phylogenetic comparative analyses demonstrate
structural convergence in the inner ear across ecologically similar
species. 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. Cave specialists show parallel enlargement of auditory-associated
structures. 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.
148 views reported since publication in 2019.