Call variation and correlated vocal production mechanisms: Intraspecific and interspecific comparisons from the Physalaemus pustulosus species group
2003
Thesis
University of Texas at Austin
Austin, USA
Reserva Nacional Tambopata animals amphibians frogs animal behavior intermediate spatial scales vocal communication communication Madre de Dios Bibliography
Surveys have shown that Physalaemus pustulosus and its sister species, P. petersi, are the only species within the P. pustulosus species group that produce complex calls, or calls with two components. This thesis reveals substantial call variation both within and between populations of P. petersi along a north-south transect. Not only do some populations lack complex calls, but also the variation in the majority of call variables corresponds to a north-south difference, consistent with the species separation of P. petersi and P. freibergi. The details of the variation of the advertisement call and the implications for evolution are discussed within the second chapter. Understanding the evolution of advertisement calls can be aided through understanding the mechanisms associated with call production. Studies have shown that a structure in the larynx, the fibrous mass (FM1), is correlated with complex call production. With the hypothesis that the advertisement call variation mirrors laryngeal variation, the third chapter examines calls and larynges of P. petersi in the western extent of its range and the evolutionary pathways that might have occurred. Additionally, the results of P. petersi were compared with P. pustulosus and a closely related congeneric, P. coloradorum, a species that does not produce complex calls. The FM1 is significantly larger in populations of P. petersi that produce complex calls than those that do not. Even more interesting is the finding that the FM1 sizes of populations of P. petersi were more similar to other species with the same call type than they were to populations of their own species with a different call type. Evolutionary pathways of call complexity and potential mechanisms of how the FM1 may contribute to call complexity are discussed.