Meeting Abstract
Elaborate displays are pervasive across the animal kingdom and although much work has explored their ultimate explanations, less attention has been given to the mechanisms underlying them. How does morphological adaptation enable display elaboration? We examine this question using Alston’s singing mouse, Scotinomys teguina, a murid rodent that produces a highly elaborate, sexually dimorphic song used in mate attraction and male-male competition. Notes are more rapidly repeated, have a lower frequency, and span a greater frequency range than other rodents’ vocalizations. For example, the Northern pygmy mouse, Baiomys taylori, belongs to a sister genus and their songs include slower, less dramatic, and entirely ultrasonic frequency modulation. Laboratory mice, Mus musculus, make highly frequency modulated notes but in a narrower frequency band and entirely ultrasonic. To examine whether changes in larynx morphology underlie these behavioral differences, we characterize species differences in collagen, elastin, and glycosaminoglycan abundance in the vocal folds using Masson’s Trichrome, Verhoeff-Van Gieson, and Alcian Blue stains of laryngeal sections. Initial results show all three species have dense bands of elastin and collagen in deep layers and glycosaminoglycans in superficial layers of the vocal folds. Compared to pygmy mice, S. teguina vocal folds seem to exhibit hypertrophy and have a vocal membrane, a structure not present in many rodents, but that has evolved independently in at least four mammalian orders. We are now performing more exhaustive morphometric studies of species differences in larynx structure, along with μCT imaging to relate larynx morphology to other aspects of the vocal and respiratory tracts. This work lays the foundation for understanding what morphological innovations contribute to S. teguina song elaboration.
