Abstract:

Forms, size and time in ontogeny of Amphibians and Reptiles. In the life of an organism (ontogeny), phenotypic changes happen throughout the time. This contribution is a review of: a)terms and definitions used in studies of the ontogeny, b) the importance to distinguish between shape variation (development) and size variation (growth); and c) the need to consider the real time (age) in which the ontogeny takes place. Based on available information about the ontogeny among tetrapods with emphasis in anurans and nonavian sauropsids, it is outlined the need to increase the information about the ontogeny for comparative studies. We denote the relevancy to get tables of development to identify ontogenetic variation, the study of three fundamental components of ontogenies (it forms - size-time), and the processes that the age organizes (development and growth) to contribute the paradigm of the Evolution of the Development

En la vida de un organismo (ontogenia) suceden cambios fenotípicos a lo largo del tiempo. Esta contribución es una revisión de: a) términos y definiciones usados en estudios de la ontogenia, b) la importancia de distinguir entre la variación de la forma (desarrollo) y del tamaño (crecimiento); y c) la necesidad de considerar el tiempo real (edad) en el que se organiza la ontogenia. Sobre la base de información disponible de la ontogenia en tetrápodos con énfasis en anuros y saurópsidos no avianos, se destaca la necesidad de incrementar la información sobre la ontogenia para estudios comparados. Enfatizamos en la relevancia y pertinencia de contar con tablas de desarrollo donde se describa la variación en trayectorias ontogenéticas y el estudio de los tres componentes fundamentales de las ontogenias (forma-tamaño-tiempo) y los procesos que la edad organiza (desarrollo y crecimiento) para avanzar en el paradigma de la Evolución del Desarrollo.

Author affiliation: Fabrezi, Marissa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina

Author affiliation: Quinzio, Silvia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina

Author affiliation: Cruz, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina

Author affiliation: Chuliver Pereyra, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina

Author affiliation: Manzano, Adriana Silvina. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina

Author affiliation: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina

Author affiliation: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina

Author affiliation: Prieto, Yanina. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina

Author affiliation: Goldberg, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina

Abstract:

Bats possess a series of patagial tracts that together act as an aerofoil for powered flight. Here we discuss the homology of a small portion of the patagium, the brevis section, traditionally assigned as a part of the handwing (dactilopatagium). Using dissected specimens and literature references we show that the muscle occipitopollicalis, a morphological marker of the propatagium, extends into the brevis section in a variety of bats. This led us to conclude that the brevis section is in fact a part of the propatagium, which is also supported by developmental evidence.

Author affiliation: Amador, Lucila Inés. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Abdala, Virginia Sara Luz. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina

Author affiliation: Giannini, Norberto Pedro. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. American Museum Of Natural History; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

Movement plays a main role in the correct development of joint tissues. In tetrapods, changes in normal movements produce alterations of such tissues during the ontogeny and in adult stages. The knee-joint is ideal for observing the influence of movement disorders, due to biomechanical properties of its components, which are involved in load transmission. We analyze the reaction of knee tissues under extreme exercise in juveniles and adults of five species of anurans with different locomotor modes. We use anurans as the case study because they undergo great mechanical stress during locomotion. We predicted that (a) knee tissues subjected to overuse will suffer a structural disorganization process; (b) adults will experience deeper morphological changes than juveniles; and (c) morphological changes will be higher in jumpers compared to walkers. To address these questions, we stimulated specimens on a treadmill belt during 2 months. We performed histological analyses of the knee of both treated and control specimens. As we expected, overuse caused structural changes in knee tissues. These alterations were gradual and higher in adults, and similar between jumpers and walkers species. This study represents a first approach to the understanding of the dynamics of anuran knee tissues during the ontogeny, and in relation to locomotion. Interestingly, the alterations found were similar to those observed in anurans subjected to reduced mobility and also to those described in joint diseases (i.e., osteoarthritis and tendinosis) in mammals, suggesting that among tetrapods, changes in movement generate similar responses in the tissues involved.

Author affiliation: Vera, Miriam Corina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina

Author affiliation: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina

Author affiliation: Aráoz, Ezequiel. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina

Author affiliation: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina

Abstract:

Most textbooks and research reports state that the structures of the tetrapod forelimbs and hindlimbs are serial homologues. From this view, the main challenge of evolutionary biologists is not to explain the similarity between tetrapod limbs, but instead to explain why and how they have diverged. However, these statements seem to be related to a confusion between the serial homology of the vertebrate pelvic and pectoral appendages as a whole, and the serial homology of the specific soft- and hard-tissue structures of the tetrapod forelimbs and hindlimbs, leading to an even more crucial and puzzling question being overlooked: why are the skeletal and particularly the muscle structures of the forelimb and hindlimb actually so strikingly similar to each other? Herein we provide an updated discussion of these questions and test two main hypotheses: (i) that the similarity of the limb muscles is due to serial homology; and (ii) that tetrapods that use hindlimbs for a largely exclusive function (e.g. bipedalism in humans) exhibit fewer cases of similarity between forelimbs and hindlimbs than do quadrupedal species. Our review shows that of the 23 arm, forearm and hand muscles/muscle groups of salamanders, 18 (78%) have clear ‘topological equivalents' in the hindlimb; in lizards, 14/24 (58%); in rats, 14/35 (40%); and in modern humans, 19/37 (51%). These numbers seem to support the idea that there is a plesiomorphic similarity and subsequent evolutionary divergence, but this tendency actually only applies to the three former quadrupedal taxa. Moreover, if one takes into account the total number of ‘correspondences’, one comes to a surprising and puzzling conclusion: in modern humans the number of forelimb muscles/muscle groups with clear ‘equivalents’ in the hindlimb (19) is substantially higher than in quadrupedal mammals such as rats (14), lizards (14) and even salamanders (18). These data contradict the hypothesis that divergent functions lead to divergent morphological structures. Furthermore, as we show that at least five of the 19 modern human adult forelimb elements that have a clear hindlimb ‘equivalent’ derive from embryonic anlages that are very different from the ones giving rise to their adult hindlimb ‘equivalents’, they also contradict the hypothesis that the similarity in muscle structures between the forelimb and hindlimb of tetrapods such as modern humans are due to their origin as serial homologues. This similarity is instead the result of phylogenetically independent evolutionary changes leading to a parallelism/convergence due to: (i) developmental constraints, i.e. similar molecular mechanisms are involved (particularly in the formation of the neomorphic hand), but this does not necessarily mean that similar anlages are used to form the similar adult structures; (ii) functional constraints, related to similar adaptations; (iii) topological constraints, i.e. limited physical possibilities; and even (iv) phylogenetic constraints, which tend to prevent/decrease the occurrence of new homoplasic similarities, but also help to keep older, ancestral homoplasic resemblances.

Author affiliation: Diogo, Rui. Howard University College of Medicine; Estados Unidos

Author affiliation: Linde Medina, Marta. University of Manchester; Reino Unido

Author affiliation: Abdala, Virginia Sara Luz. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Author affiliation: Ashley Ross, Miriam A.. University Wake Forest; Estados Unidos

Abstract:

We present the ontogeny of the integrated musculoskeletal complex that comprises the pelvic girdle and hind limbs of anurans. Our histological data show that the pelvic girdle originates from a single mesenchymatic condensation. The tissue differentiation sequence is cartilage, muscle and tendon. The intrusion of the ischiadic nerve into the limb bud is produced very early in ontogeny. The pre-cartilage appears in the pre-motile stage. Therefore, the nerve produces a movement analogous to the ?embryonic motility? that would induce the emergence of the pre-cartilage. The acetabulum is the first of all cavitation processes to form, the second one being the knee. The acetabulum appears before the muscles are mature, although it has been stressed that the muscle contraction maintains joint progenitors committed to their fate. Our data indicate an explosive differentiation of all 11 muscular masses together. We provide three new characters that support the monophyly of Hyloides, Acosmanura and Neobatrachia.

Author affiliation: Manzano, Adriana Silvina. Universidad Autónoma de Entre Ríos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina

Author affiliation: Abdala, Virginia Sara Luz. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina

Author affiliation: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina. Universidad Nacional de Tucumán; Argentina

Author affiliation: Soliz, Monica Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; Argentina. Universidad Nacional de Tucumán; Argentina

Abstract:

Movement is one of the most important epigenetic factors for normal development of the musculoskeletal system, particularly during genesis and joint development. Studies regarding alterations to embryonic mobility, performed on anurans, chickens and mammals, report important phenotypical similarities as a result of the reduction or absence of this stimulus. The precise stage of development at which the stimulus modification generates phenotypic modifications however, is yet to be determined. In this work we explore whether the developmental effects of abnormal mobility can appear at any time during development or whether they begin to express themselves in particular phases of tadpole ontogeny. We conducted five experiments that showed that morphological abnormalities are not visible until Stages 40-42. Morphology in earlier stages remains normal, probably due to the fact that the bones/muscles/tendons have not yet developed and therefore are not affected by immobilization. These results suggest the existence of a specific period of phenotypical expression in which normal limb movement is necessary for the correct development of the joint tissue framework.

Author affiliation: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina

Author affiliation: Abdala, Virginia Sara Luz. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales E Instituto Miguel Lillo. Cátedra de Biología General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Abstract:

Signaling for limb bone development usually precedes that for muscle development, such that cartilage is generally present before muscle formation. It remains obscure, however, if: (i) tetrapods share a general, predictable spatial correlation between bones and muscles; and, if that is the case, if (ii) such a correlation would reflect an obligatory association between the signaling involved in skeletal and muscle morphogenesis. We address these issues here by using the results of a multidisciplinary analysis of the appendicular muscles of all major tetrapod groups integrating dissections, muscle antibody stainings, regenerative and ontogenetic analyses of fluorescently-labeled (GFP) animals, and studies of non-pentadactyl human limbs related to birth defects. Our synthesis suggests that there is a consistent, surprising anatomical pattern in both normal and abnormal phenotypes, in which the identity and attachments of distal limb muscles are mainly related to the topological position, and not to the developmental primordium (anlage) or even the homeotic identity, of the digits to which they are attached. This synthesis is therefore a starting point towards the resolution of a centuries-old question raised by authors such as Owen about the specific associations between limb bones and muscles. This question has crucial implications for evolutionary and developmental biology, and for human medicine because non-pentadactyly is the most common birth defect in human limbs. In particular, this synthesis paves the way for future developmental experimental and mechanistic studies, which are needed to clarify the processes that may be involved in the elaboration of the anatomical patterns described here, and to specifically test the hypothesis that distal limb muscle identity/attachment is mainly related to digit topology.

Author affiliation: Diogo, Rui. Howard University. College of Medicine; Estados Unidos

Author affiliation: Walsh, Sean. Howard University. College of Medicine; Estados Unidos

Author affiliation: Smith, Christopher. University Johns Hopkins; Estados Unidos

Author affiliation: Ziermann, Janine M.. Howard University. College of Medicine; Estados Unidos

Author affiliation: Abdala, Virginia Sara Luz. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina