The peripheral innervation in anuran tadpoles, new insights into its classical approach

QUINZIO, SILVIA INÉS

Simposio; I Symposium in tadpole Evolution; 2020

Universidade Federal do Paraná, Departamento de Zoologia Curitiba, Paraná

Based onlimited knowledge, the peripheral nervous system of anuran larvae has beenassumed to be largely invariant. During the ontogeny of biphasic anurans, itconstitutes an anatomical system, with continuity between the larval and adultbody plan that undergoes transformations during metamorphosis. Functionally, itintegrates all the organism's reactions to the physics and chemistry of thesurrounding environment, coordinating vital functions like locomotion andfeeding in which not only the nervous but the sensory, locomotor and digestivesystems are also involved. Thus, a question that has been recurring to meis whether the nervous system is really invariable in terms of the number,organization and arrangement of its components, taking into account the differentarrays of spatial and temporal modifications in development that have resultedin different larval morphotypes, including from omnivorous to megalophagouslarvae. The characterization of the nervous system as invariable was due inpart to the few comparative studies that have been carried out on this topicand that have led to certain generalizations. However, some of my studies inrecent years analyzing cranial, spinal and lateral line nerves at differentlarval stages and in different species allowed me to found variation in theorganization of many of the traits considered such as theloss or reduction of some exclusively larval elements, the retention of blindmotor ramules (without effector organ); changes in the spatial arrangement ofbranches, the asymmetry of certain lines, and temporal changes in themetamorphic reorganization of cranial nerves or metamorphic disappearance oflateral line nerves. Here, I present some of the aspects considered inthese comparative studies on the peripheral nervous system in anuran tadpoles,the variation found, and how a comprehensive approach to its organization andintegration with those components of other anatomical systems allow a betterinterpretation of the variation and, ultimately, of the evolution of larvalmorphology.