Comparative analysis of the shape and size of the middle ear cavity of turtles reveals no correlation with habitat ecology.

Comparative analysis of the shape and size of the middle ear cavity of turtles reveals no correlation with habitat ecology.
J Anat. 2019 Aug 02;:
Authors: Foth C, Evers SW, Joyce WG, Volpato VS, Benson RBJ
Abstract
The middle ear of turtles differs from other reptiles in being separated into two distinct compartments. Several ideas have been proposed as to why the middle ear is compartmentalized in turtles, most suggesting a relationship with underwater hearing. Extant turtle species span fully marine to strictly terrestrial habitats, and ecomorphological hypotheses of turtle hearing predict that this should correlate with variation in the structure of the middle ear due to differences in the fluid properties of water and air. We investigate the shape and size of the air-filled middle ear cavity of 56 extant turtles using 3D data and phylogenetic comparative analysis to test for correlations between habitat preferences and the shape and size of the middle ear cavity. Only weak correlations are found between middle ear cavity size and ecology, with aquatic taxa having proportionally smaller cavity volumes. The middle ear cavity of turtles exhibits high shape diversity among species, but we found no relationship between this shape variation and ecology. Surprisingly, the estimated acoustic transformer ratio, a key functional parameter of impedance-matching ears in vertebrates, also shows no relation to habitat preferences (aquatic/terr...

Source: Journal of Anatomy - August 1, 2019 Category: Anatomy Authors: Foth C, Evers SW, Joyce WG, Volpato VS, Benson RBJ Tags: J Anat Source Type: research