Phalanx morphology in salamanders: A reflection of microhabitat use, life cycle or evolutionary constraints?

Morphological patterns are modeled by the interaction of functional, phylogenetic, ecological, and/or developmental constraints. In addition, the evolution of life cycle complexity can favor phenotypic diversity; however, the correlation between stages of development may constrain the evolution of some organs. Salamanders present microhabitat and life cycle diversity, providing an excellent framework for testing how these factors constrain phenotypic evolution. We reconstructed the morphological evolution of the terminal phalanx using a sample of 60 extinct and living species of salamanders. Using a geometric morphometric approach combined with comparative analyses, we further investigated the impact of phylogenetic, ecological, and/or life cycle factors on the shape of the terminal phalanx. We find that the phylogeny has some influence in determining the dorsal shape of the phalanges; whereas a relationship between microhabitat or life cycle and the dorsal and lateral shapes of the phalanx was not observed in the analyzed species. The allometric pattern found in the phalanx shape implies that small phalanges are more curved and with more truncated end than bigger phalanges. The evolutionary rate of phalanx shape was higher in the semiaquatic species, and the morphological disparity was significantly higher on biphasic groups. These results contradict the hypothesis that a complex life cycle constrains body shape. Finally, the phalanx shape of the salamander remains quite conserved from the Mesozoic. This configuration would allow them to occur in the different microhabitats occupied by the salamander lineages.Fil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Barrionuevo, J. Sebastián. Fundación Miguel Lillo; Argentin

Phylogenetic patterns and correlation of key structures for jumping: Bone crests and cross-sectional areas of muscles in Leptodactylus (Anura, Leptodactylidae)

Anurans are characterized by their saltatory mode of locomotion, which is associated with a specific morphology. The coordinated action of the muscles and bones of the pelvic girdle is key to the transmission of the force of the hindlimbs to the axial skeleton during jumping. Two features are critical for optimal locomotory performance: the cross-sectional area of muscle and the bone crest attachment sites. The first character is a proxy of the force exerted by the muscle, whereas the crests are muscle attachments sites related to muscle force. The provisory relationship between these features has previously been identified and bone crest size can be used to infer the magnitude and, therefore, muscle force in fossils records. In this work, we explore the correlation between the cross-sectional area of essential muscles to the jumping mechanism (longissimus dorsi, extensor iliotibialis B, tenuissimus, puboischiofemoralis internus B, coccygeo-sacralis and coccygeo-iliacus) and the bone crests where these muscles are inserted (dorsal tubercle, dorsal crest and urostylar crest) in species of the genus Leptodactylus. This genus, along with other leptodactylids, exhibits a diversity of locomotor modes, including jumping, hopping, swimming and burrowing. We therefore analyzed the morphometric variation in the two features, cross-sectional area and bone crest area, expecting a correlation with different locomotor types. Our results showed: (i) a correlation between the urostylar crest and the cross-sectional area of the related muscles; (ii) that the bone crest surface area of urostyle and ilium and the cross-sectional area of the corresponding muscles can be utilized to infer locomotor faculties in leptodactylid frogs; and (iii) that the evolution of both characters demonstrates a general tendency from lower values in leptodactylid ancestors to higher values in the Leptodactylus genus. The results attest to the importance of the comparison of current ecological and phylogenetic analogues as they allow us to infer functionality and behavior in fossil and extant groups based on skeletal evidence. Phylogenetic patterns in character evolution and their correlation with locomotory types could imply that functional restrictions are also inherited in leptodactylid.Fil: Ponssa, María Laura. Unidad Ejecutora Lillo Uel Conicet-fml San Miguel de Tucumán; ArgentinaFil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: 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; Argentin

The influence of locomotion and habitat use on tendo-muscular units of an anuran clade (Anura, Diphyabatrachia)

Tendons have unique mechanical properties, contributing to the transmission, amplification, and recycling of muscle energy. In this light, anuran tendons are especially interesting due to their highly mechanically demanding locomotor modes. Herein we aim to investigate the relation between tendons and muscles from two perspectives: (1) the tendinous area in relation to the potential force produced by associated muscles, and how this relation varies for different tendons of the anuran body; (2) the tendinous proportion of a tendo-muscle unit in relation to different locomotor modes and habitat uses in a monophyletic unranked anuran clade (Diphyabatrachia) which includes Leptodactylidae and Centrolenidae, two highly diverse frog family groups of the Neotropics. Our data suggest a significant and positive relation between tendon dimensions and potential muscle force for most of the analyzed elements. We also found that species of different locomotion and habitat use show a divergence of tendinous proportions for tendo-muscle units of the pectoral girdle and hindlimb. Notably, jumper-arboreal species differentiate from all others in all tendo-muscle units tested. Finally, the optimization of tendinous proportions showed great phylogenetic correspondence. These results are in agreement with the hypothesis that morphological variation is related to a combination of phylogenetic, functional, and ecological factors.Fil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Rada, Marco. Museu de Zoologia Da Usp; BrasilFil: Abdala, Virginia Sara Luz. Universidad Nacional de Tucumán; Argentina. 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; Argentin

The role of hand, feet, and digits during landing in anurans

Jumping consists of a series of complex movements with more variability in landing than in take-off. Different modes have been described concerning the landing phase, which seems to be linked to the general phylogenetic relationships of anuran groups. For example, the belly hit has been recorded in the basal-most living frog family Leiopelmatidae. Here we used high-speed videography to observe the role of hand and foot digits in landing behavior in ten species of neotropical anurans exhibiting different locomotor modes. We also calculated the time-lapse of each jump. We hypothesize that the role of digits can be pivotal to many anuran species during terrestrial landing. We also present data on the comparative anatomy of digits and those parts of the hands and feet involved in landing. Our video records show that landing through hand hit among anurans is performed with the distal curved phalanges of the hand digits. The morphological results show that all species surveyed, even the walker ones, exhibit distally curved phalanges, in lateral view. Movements of the distal phalanges of the hand are a key to understanding landing in anurans. All digits must be resistant to compression, since all the weight of the body falls on them. Digit hit seems to be action-driven by an elastic mechanism, which could indicate the activation, for example, of the flexor digitorum communis muscle. Landing in terrestrial frogs like Rhinella arenarum and Leptodactylus chaquensis follows a highly coordinated and synchronic pattern, with a longer time-lapse to complete each jump. Arboreal jumping frogs like Scinax fuscovarius and Boana riojana and semiaquatic hoppers like Pleurodema borellii and Physalaemus biligonigerus tend to be asynchronic and uncoordinated, but with a shorter time-lapse to complete each jump.Fil: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucuman. Facultad de Cs.naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Cátedra de Biología General; ArgentinaFil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: 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; Argentin

Male homophily in South American herpetology: one of the major processes underlying the gender gap in publications

The growing number of gender studies encourages more refined analyzes and greater conceptualization of the underlying processes of gender gap in science. In Herpetology, previous studies have described gender disparities and a scrutiny of individual interactions may help revealing the mechanisms modelling the global pattern. In this contribution we modeled a co-authorship network, a previously unexplored methodology for gender studies in this discipline, in addition to a broad and classic bibliometric analysis of the discipline. Co-authorship networks were modelled for two South American journals, because this geo-political location is considered to present the best gender balance within general scientific communities. However, we found a pattern of male preferential connections (male homophily) that marginalizes women and maintains the gender gap, at both regional and global scales. This interpretation arises from results coming from multiple analyses, such as high homophily index in collaboration networks, lower female representation in articles than expected in a non-gender biased environment, the decrease of female co-authors when the article leader is a man, and the extreme masculinization of the editorial boards. The homophilic dynamics of the publication process reveals that academic activity is pervasive to unbalanced power relationships. Personal interactions shape the collective experience, tracing back to the Feminist Theory´s axiom: "the personal is political".Fil: Grosso, Jimena Renee. Universidad Austral de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Humedales Río Cruces (uach); ChileFil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; ArgentinaFil: Fontanarrosa, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Bio y Geociencias del Noroeste Argentino; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical; ArgentinaFil: Chuliver Pereyra, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Bio y Geociencias del Noroeste Argentino; ArgentinaFil: Duport Bru, Ana Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schneider, Rosio Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Casagranda, Maria Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Ferraro, Daiana Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Vicente, Natalin Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Salica, María José. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pereyra, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; ArgentinaFil: Medina, Regina Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán; Argentina. Universidad Católica de Chile; Chile. Pontificia Universidad Católica de Chile; ChileFil: Bessa, Carla Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Semhan, Romina Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vera, Miriam Corina. Universidad Nacional de Misiones. Facultad de Humanidades y Ciencias Sociales. Departamento de Genética. Laboratorio de Genética Evolutiva y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Carta a los Editores

Las actividades profesionales son afectadas por las construcciones socioculturales que configuran los roles, las percepciones, y el estatus de las mujeres y los hombres en una sociedad. El ámbito científico no es ajeno a esta situación y las desigualdades de género en ciencia son ampliamente conocidas. Es por eso que en los últimos tiempos en la comunidad científica, en consonancia con el movimiento global por los derechos de las mujeres, se ha suscitado un proceso de autoevaluación bajo una perspectiva de género (Scott et al., 2010; Shen, 2013; Greshake Tzovaras, 2017; Berenbaum, 2019). En Argentina, pese a que las mujeres representan el 53% del conjunto de investigadores del Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, 2020), su participación en cargos superiores—académicos y administrativos—es minoritaria, alcanzando por ejemplo en 2018 sólo el 23% de representación en la categoría superior de CONICET (Baringoltz y Posadas, 2009; CONICET, 2020). Este marcado sesgo de género en puestos jerárquicos es un patrón conocido como techo de cristal, que da cuenta de las limitaciones del ascenso laboral de las mujeres en una organización (Lühe, 2014).Asociación Herpetológica Argentin

Carta a los Editores

Las actividades profesionales son afectadas por las construcciones socioculturales que configuran los roles, las percepciones, y el estatus de las mujeres y los hombres en una sociedad. El ámbito científico no es ajeno a esta situación y las desigualdades de género en ciencia son ampliamente conocidas. Es por eso que en los últimos tiempos en la comunidad científica, en consonancia con el movimiento global por los derechos de las mujeres, se ha suscitado un proceso de autoevaluación bajo una perspectiva de género (Scott et al., 2010; Shen, 2013; Greshake Tzovaras, 2017; Berenbaum, 2019). En Argentina, pese a que las mujeres representan el 53% del conjunto de investigadores del Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, 2020), su participación en cargos superiores—académicos y administrativos—es minoritaria, alcanzando por ejemplo en 2018 sólo el 23% de representación en la categoría superior de CONICET (Baringoltz y Posadas, 2009; CONICET, 2020). Este marcado sesgo de género en puestos jerárquicos es un patrón conocido como techo de cristal, que da cuenta de las limitaciones del ascenso laboral de las mujeres en una organización (Lühe, 2014).Asociación Herpetológica Argentin

Tendinous system in Anura: morphological diversity in Diphyabatrachia (Amphibia, Anura)

Los tendones son estructuras viscoelásticas con propiedadesmecánicas únicas relacionadas al movimiento, que funcionanprincipalmente como transmisores, amplificadores y recicladores deenergía. El salto es el más importante desafío locomotor deanuros, con una demanda mecánica ligada a un plan corporal altamenteespecializado. Sin embargo, la locomoción en el grupo incluyetambién especializaciones a distintos ambientes, por lo que lamorfología de cinturas y miembros está relacionada a la diversidadde estos modos locomotores y usos de hábitat. Con esta tesis sepretende contribuir al conocimiento del sistema tendinoso del cladoDiphyabatrachia, analizando su variación en relación a factoresfilogenéticos, funcionales y ecológicos. Se analizaron 99 especiesy diez unidades tendinosas-musculares de 188 ejemplares del grupo deestudio, incluyendo una parte significativa de la diversidadtaxonómica, modos locomotores y hábitos ecológicos. El grupo enestudio incluye, en términos generales, especiestrepadoras/saltadoras y de uso de hábitat arborícola(Centrolenidae) y saltadoras/caminadoras de uso de hábitat terrestrey acuático (Leptodactylidae), además de exhibir habilidadesespeciales relacionadas con los hábitos reproductivos, como laexcavación. Se describió el sistema tendinoso como una red continuae interconectada, cuya variación fue comparada utilizandomorfometría geométrica con el objeto de descubrir patrones de formay su covariación con los elementos musculares asociados. Como lavariación de las especies no es independiente, debido a suancestralidad común, también se incluyó la filogenia del grupo deestudio em los análisis. Los resultados muestran una gran diversidadestructural de forma y tamaño entre los tendones de los principalesgrupos estudiados y en relación a variados aspectos ecológicos.Desde la morfometría geométrica encontramos que la forma de lostendones se relaciona a una combinación de factores alométricos,funcionales y filogenéticos. Hay diferencias significativas entre laforma de los tendones y los distintos modos locomotores,principalmente en relación al tendón patelar que diferencia lasespecies saltadoraarborícolas de las demás. En cuanto a lavariación del tamaño, todos los elementos tendinosos analizadospresentan variación relacionada a locomoción, con distintaspendientes de cambio de forma según cada categoría combinada demodo locomotor/uso de hábitat. A través de la optimización de lasformas de los tendones se encontraron sinapomorfías putativas parala subfamilia Leptodactylinae en la forma del tendón del longissimusdorsi y para la familia Centrolenidae en la forma del tendónpatelar. También se encontró significativa la covariaciónanatómica entre los tendones de la rodilla y del talón,considerando la analogía funcional entre esas estructuras en Anura.Existe una relación directa y positiva en la variación entretendones y músculos, reflejando la gran influencia del movimiento enel desarrollo y estructura del sistema tendinoso. También se puedepostular un grado de correspondencia entre estructura y función enla relación tendón/músculo, ya que se pudo diferenciar a lasespecies saltadoras-arborícolas de las demás en todos los elementosanalizados y entre todas las categorías de modo locomotor/uso dehábitat para elementos de la cintura pectoral y miembro posterior.Asimismo, se encontró gran congruencia filogenética en ladistribución de los caracteres optimizados en la filogenia. Estatesis representa un primer acercamiento al sistema tendinoso como unmodelo independiente de otros sistemas anatómicos tales como elmuscular u óseo. Las evidencias encontradas permiten inferir lainfluencia de una combinación de factores alométricos, funcionalesy filogenéticos en la evolución del sistema tendinoso enDyphiabatrachia.p { margin-bottom: 0.25cm; line-height: 120%; }Tendons are viscoelastic elements with unique mechanical properties. With a close relation to movement, tendons function is mainly related to the transmission, amplification and recycling of energy. In Anura, jumping is the principal locomotor challenge, and most related anatomical specializations have been observed in pelvic girdle and hindlimbs. Despite of a greatly specialized body plan, locomotor variation in anurans goes beyond jumping, including specializations for swimming, burrowing, and climbing. The main goal of this thesis is to present a novel perspective on tendons, proposing its consideration as an interconnected and independent system. The variation of ten tendinous elements of 99 species of Diphyabatrachia clade was analyzed as a study case, taking in consideration functional and ecological aspects of species, the associated muscles, and also the phylogenetic context. Diphyabatrachia includes jumping and climbing species of arboreal habitats (Centrolenidae) and jumping species of long and short distances with terrestrial and aquatic habitats (Leptodactylidae). The group also includes species with special abilities related to their reproductive modes, such as digging for nest construction. The tendinous system was described as an interconnected network and the variation of the most conspicuous tendons identified were analyzed. First using geometric morphometrics for understanding shape patterns, and also the comparative method for analyzing morphometric variables considering the associated muscles. As data for species are not independent because of shared history, a phylogenetic framework was included for all statistical analyses. The results show a great anatomic diversity of shape and size among tendons and a significant relation to locomotor mode and habitat use. A relationship between tendon shape and size, function and phylogeny could be detected. There are significant differences between locomotor modes and habitat use regarding tendon shape, especially in the patellar tendon of jumping-arboreal species when compared to others. In all analyzed tendons, locomotor modes and habitat use showed interaction with size. Optimization and reconstruction of tendon shape revealed two putative synapomophies, a broad tendon of the longissimus dorsi for Leptodactylinae and an elongated patellar tendon for Centrolenidae. In addition, considering the functional analogy between the knee and the heel in Anura, there was a significant covariation of shape between the two structures. Regarding the covariation between tendons and the associated muscles, there was a direct 7 and positive relation, which reflects the influence of movement on the development and structure of the tendinous system. There is also a structure-function correspondence when analyzing the tendo-muscle index, since jumping-arboreal species could be differentiated form others in all studies elements, and all locomotor mode/habitat use categories could be differentiated for pectoral girdle and hindlimb elements. This study represents a first approach to the tendinous system as an independent model. All evidence points to an adaptive significance of tendon variation, yet the results also showed a great influence of phylogeny. Therefore, it is possible to conclude that a combination of factors, rather than one determinant variable, is influencing tendon evolution in Dyphiabatrachia.Fil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin

Delimiting the boundaries of sesamoid identities under the network theory framework

Sesamoid identity has long been the focus of debate, and how they are linked to other elements of the skeleton has often been considered relevant to their definition. A driving hypothesis of our work was that sesamoids' nature relies deeply on their connections, and thus we propose an explicit network framework to investigate this subject in Leptodactylus latinasus (Anura: Leptodactylidae). Through the dissection of L. latinasus' skeleton, we modeled its anatomical network where skeletal elements were considered nodes while joints, muscles, tendons, and aponeurosis were considered links. The skeletal elements were categorized into canonical skeletal pieces, embedded sesamoids, and glide sesamoids. We inquired about the general network characterization and we have explored further into sesamoid connectivity behavior. We found that the network is structured in a modular hierarchical organization, with five modules on the first level and two modules on the second one. The modules reflect a functional, rather than a topological proximity clustering of the skeleton. The 25 sesamoid pieces are members of four of the first-level modules. Node parameters (centrality indicators) showed that: (i) sesamoids are, in general terms, peripheral elements of the skeleton, loosely connected to the canonical bone structures; (ii) embedded sesamoids are not significantly distinguishable from canonical skeletal elements; and (iii) glide sesamoids exhibit the lowest centrality values and strongly differ from both canonical skeletal elements and embedded sesamoids. The loose connectivity pattern of sesamoids, especially glides, could be related to their evolvability, which in turn seems to be reflected in their morphological variation and facultative expression. Based on the connectivity differences among skeletal categories found in our study, an open question remains: can embedded and glide sesamoids be defined under the same criteria? This study presents a new approach to the study of sesamoid identity and to the knowledge of their morphological evolution.Fil: Fontanarrosa, Gabriela. 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; ArgentinaFil: Fratani Da Silva, Jéssica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Vera, Miriam Corina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentin

Network architecture associated with the highly specialized hindlimb of frogs.

Network analyses have been increasingly used in the context of comparative vertebrate morphology. The structural units of the vertebrate body are treated as discrete elements (nodes) of a network, whose interactions at their physical contacts (links) determine the phenotypic modules. Here, we use the network approach to study the organization of the locomotor system underlying the hindlimb of frogs. Nodes correspond to fibrous knots, skeletal and muscular units. Edges encode the ligamentous and monoaxial tendinous connections in addition to joints. Our main hypotheses are that: (1) the higher centrality scores (measured as betweenness) are recorded for fibrous elements belonging to the connective system, (2) the organization of the musculoskeletal network belongs to a non-trivial modular architecture and (3) the modules in the hindlimb reflect functional and/or developmental constraints. We confirm all our hypotheses except for the first one, since bones overpass the fibrous knots in terms of centrality. Functionally, there is a correlation between the proximal-to-distal succession of modules and the progressive recruitment of elements involved with the motion of joints during jumping. From a developmental perspective, there is a correspondence between the order of the betweenness scores and the ontogenetic chronology of hindlimbs in tetrapods. Modular architecture seems to be a successful organization, providing of the building blocks on which evolution forges the many different functional specializations that organisms exploit