Dataset Information

Delimiting the boundaries of sesamoid identities under the network theory framework.

ABSTRACT: 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.

SUBMITTER: Fontanarrosa G

PROVIDER: S-EPMC7439958 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Delimiting the boundaries of sesamoid identities under the network theory framework.

Fontanarrosa Gabriela G Fratani Jessica J Vera Miriam C MC

PeerJ 20200817

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 <i>Leptodactylus latinasus</i> (Anura: Leptodactylidae). Through the dissection of <i>L. latinasus</i>' skeleton, we modeled its anatomical network where sk ...[more]

PMID: 32874781

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Project description:BACKGROUND: Delimiting genetic units is useful to enhance taxonomic discovery and is often the first step toward understanding evolutionary mechanisms generating diversification. The six species within the Rhinella crucifer group of toads were defined under morphological criteria alone. Previous data suggest limited correspondence of these species to mitochondrial lineages, and morphological intergradation at transitions between forms suggests hybridization. Here we extensively sampled populations throughout the geographic distribution of the group and analyzed mitochondrial and nuclear sequence data to delimit genetic units using tree-based and allele frequency-based approaches. RESULTS: These approaches yielded complementary results, with allele frequency-based methods performing unexpectedly well given the limited number of loci examined. Both mitochondrial and nuclear markers supported a genetic structure of five units within the group, with three of the inferred units distributed within its main range, while two other units occur in separate isolates. The inferred units are mostly discordant with currently described forms: unequivocal association exists for only two of the six species in the group. Genetic evidence for hybridization exists for two pairs of units, with clear cyto-nuclear allele mixing observed in one case. CONCLUSIONS: Our results confirmed that current taxonomy does not represent evolutionary units in the Rhinella crucifer group. Correspondence between genetically distinguishable units and the currently recognized species is only possible for Rhinella henseli and R. inopina. The recognition of other species relies on the reassessment of the geographic range of R. crucifer, the examination of the type series of R. ornata for hybrids, and on the use of additional markers to verify the genetic distinctiveness of R. abei. We state that R. pombali should not remain a valid species since its description appears to be based on hybrids, and that the name R. pombali should be considered a synonym of both R. crucifer and R. ornata. The fifth inferred but undescribed genetic unit may represent a new species. Our results underscore the potential of the R. crucifer species group to contribute to a better understanding of diversification processes and hybridization patterns in the Neotropics, and provide the basis for future evolutionary and taxonomic studies.

Project description:How are evaluative reactions pertaining post-national citizenship identities interrelated and what are the potential mechanisms how post-national identities evolve? Previous efforts to operationalize and measure post-national citizenship identities leave it open how people's stances on different issues are related and suffer from a variety of theoretical and methodological shortcomings regarding the nature of political attitudes and ideologies. A recently proposed approach conceptualizes ideologies as networks of causally connected evaluative reactions to individual issues. Individual evaluative reactions form the nodes in a network model, and these nodes can influence each other via linked edges, thereby giving rise to a dynamic thoughts system of networked political and identity-related views. To examine this system at large, we apply network analysis to data from the European Values Study. Specifically, we investigate 33 evaluative reactions regarding national and supra-national identity, diversity, global empathy, global environmentalism, immigration, and supra-national politics. The results reveal a strongly connected network of citizenship identity-related attitudes. A community analysis reveals larger clusters of strongly related evaluative reactions, which are connected via bridges and hub nodes. Centrality analysis identifies evaluative reactions that are strategically positioned in the network, and network simulations indicate that persuasion attempts targeted at such nodes have greater potential to influence the larger citizenship identity than changes of more peripheral attitude nodes. We lastly show that socio-demographic characteristics are not only associated with the overall level of post-national citizenship, but also with the network structure, suggesting that these structural differences can affect the network function as people develop national or post-national citizenship identities, or respond to external events. These results provide new insights into the structure of post-national identities and the mechanism how post-national identities might evolve. We end with a discussion of future opportunities to study networked attitudes in the context of civic and citizenship education.

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Delimiting the boundaries of sesamoid identities under the network theory framework.

Publications

Delimiting the boundaries of sesamoid identities under the network theory framework.

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