Meeting Abstract
Tongue projection in plethodontid salamanders ranges from relatively low performance, muscle-powered projection to extremely high performance, elastically powered, ballistic tongue projection. During ballistic projection, the tongue skeleton completely leaves the mouth and can achieve accelerations over 600 G. This impressive performance increase is largely accomplished via shifts in morphology as opposed to significant changes in muscle activation or physiology. For example, species exhibiting ballistic tongue projection tend to have increased collagen present in projector muscle compared to species exhibiting muscle-powered projection. However, tongue projection is a complex movement which involves both a tongue skeleton and projector muscles. Thus, we may expect that shifts in multiple morphological traits are required to produce the observed improvement in projection performance. To better understand the morphological underpinnings of ballistic tongue projection, we closely examine the evolution of both tongue skeleton and muscle morphology within Plethodontid salamanders. We find that several functionally important morphological traits show correlated evolution. For example, a lack of muscle fiber attachment to the tongue skeleton is correlated with a more circular epibranchial cross section. This correlated evolution of several traits has resulted in a suite of characters that clearly distinguish species exhibiting ballistic tongue projection from those using muscle powered projection.
