Keyword: modularity

Pattern of bat-ectoparasite interaction in the state of Sergipe, Brazil: an ecological networks approach

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Interaction networks can help understand how species are connected and the implications of these interactions for the ecosystem. This study aimed to identify the pattern of interaction between bats and ectoparasites in Sergipe and calculate the metrics of connectance, specialization, nesting, modularity, and centrality. This study was conducted based on host-parasite relationship data recorded in Sergipe and reported in previous studies. Connectance and specialization (H2′) were calculated using the “networklevel” and “specieslevel” functions, respectively. The NODF and QuanBiMo (Q) metrics were used to determine nesting and modularity, respectively. For centrality, relative degree (Kr), closeness centrality (CC), and betweenness centrality (BC) were determined. The connectance value (0.11) was considered high. H2′ was 0, and the complementary specialization (d’) values ranged from 0 to 1. The nesting and modularity values were 15.95 and 0.58, respectively. The highest Kr value was observed for Platyrrhinus lineatus. The highest CC value was observed for Artibeus planirostris. The highest BC values were recorded for A. planirostris and P. lineatus. High modularity, low nesting, and low connectivity have been frequently reported for antagonistic interactions, which may be due to the high specificity indices of these interactions. In this study, although the modularity value was significant, specialization was low, suggesting that the studied network has a composite topology. Thus, this study provides relevant information on the subject, highlighting the need for more studies to help understand the topology of networks.

Padrão de interação morcego-ectoparasito em áreas do nordeste do Brasil: uma abordagem de redes ecológicas. Redes de interação podem auxiliar na compreensão de como as espécies estão conectadas e as implicações dessas interações para o ecossistema. Esse estudo teve como objetivos identificar o padrão de interação entre morcegos e ectoparasitos em Sergipe e calcular as métricas de conectância, especialização, aninhamento, modularidade e centralidade. Esse estudo foi realizado a partir de dados da relação hospedeiro-parasito relatados em artigos científicos para Sergipe. A conectância e especialização (H2′) foram calculadas utilizando a função “networklevel” e “specieslevel”. Para o aninhamento, foi utilizada a métrica NODF. Para a modularidade foi utilizado o QuanBiMo (Q). Para a centralidade foi utilizado o relative degree (Kr), closeness centrality (CC) e betweenness centrality (BC). A conectância (0,11) foi considerada alta. O H2′ foi 0 e os valores de especialização complementar (d’) variaram de 0 a 1. O aninhamento foi 15,95 e a modularidade 0,58. Para a centralidade, o maior valor de Kr correspondeu a Platyrrhinus lineatus. Para a CC, o maior valor foi para Artibeus planirostris. Para a BC os maiores valores foram registrados para A. planirostris e P. lineatus. Alta modularidade, baixo aninhamento e baixa conectância são frequentemente relatadas para interações antagonistas, podendo ocorrer devido ao alto índice de especificidade das interações. Nesse estudo, apesar do valor de modularidade ter sido significativo, a especialização foi baixa. Isso pode sugerir que a rede estudada possua uma topologia composta. Assim, esse trabalho traz informações relevantes a cerca do tema, evidenciando a necessidade da realização de mais estudos que auxiliem na compreensão sobre topologia de redes.

Graphical abstract for the article “Pattern of bat-ectoparasite interaction in the state of Sergipe, Brazil: an ecological networks approach” (Bezerra & Bocchiglieri, 2024)

Efecto de la fragmentación sobre la diversidad de murciélagos (Chiroptera) y estréblidos (Diptera: Streblidae) y redes de interacción en Puebla, México

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En el presente estudio se comparó la riqueza, diversidad y especialización de las redes de interacción hospedador-ectoparásito en dos ambientes contrastantes de Puebla, México. Se colocaron redes de niebla para la captura de murciélagos, y los ectoparásitos fueron colectados manualmente con pinzas entomológicas. Se registraron 188 murciélagos de 20 especies, de las cuales se colectaron 263 estréblidos de 11 especies. La riqueza y abundancia de murciélagos y estréblidos fue mayor en el bosque continuo, aunque el análisis de diversidad verdadera mostró que no existían diferencias significativas entre el sitio fragmentado y el bosque continuo. En el caso de los estréblidos, aunque la diversidad fue significativamente mayor en el bosque continuo, los valores de la carga parasitaria fueron similares en ambos sitios. Las redes de interacciones de los dos sitios fueron altamente especializadas y presentaron valores similares; no obstante, se observó un mayor número de enlaces en el bosque continuo. Estos resultados sugieren que la fragmentación aparentemente puede influir más sobre la diversidad de estréblidos que en la de sus hospedadores; esto puede deberse a que en ambos sitios los murciélagos Phyllostomidae tuvieron una mayor presencia. En los estréblidos, aunque no hay un efecto sobre la especialización producto de la especificidad de las interacciones murciélago-estréblido, sí existe una disminución en la riqueza de especies que da como resultado una disminución en el número de interacciones.

The effect of fragmentation on the diversity of bats (Chiroptera) and bat’s flies (Diptera: Streblidae) and interaction networks in Puebla, Mexico. The present study compares the richness, diversity, and specialization of host-ectoparasite interaction networks in two contrasting environments in Puebla, Mexico. Mist nets were placed to capture bats, while ectoparasites were collected manually with entomological tweezers. A total of 188 bats of 20 species were recorded, of which 263 bat Streblidae bat flies of 11 species were collected. The richness and abundance of bats and bat flies were higher in continuous forest, even though the analysis of true bat diversity showed no significant difference between the fragmented site and the continuous forest. Moreover, while there was a significant difference between sites for bat flies, there was no significant difference between sites for their parasitic loads. The interaction networks of both sites were highly specialized with similar values. However, a higher number of links were observed at the continuous forest. These results suggest that fragmentation may have a greater influence on the diversity of Streblidae flies than on the diversity of their hosts. This result may be due to the fact that Phyllostomidae bats were more common at both sites. Although there is no effect on the specialization of the bat flies due to the specificity of the bat-Streblidae interactions formed over evolutionary time, there is a decrease in species richness and, as a result, a decrease in the number of interactions.

Graphical abstract for the article “Efecto de la fragmentación sobre la diversidad de murciélagos (Chiroptera) y estréblidos (Diptera: Streblidae) y redes de interacción en Puebla, México” (Tlapaya-Romero et al., 2024)

Skull morphology in herbivorous mammals: macropodids (Metatheria, Diprotodontia, Macropodidae) and caviids (Eutheria, Rodentia, Hystricomorpha) as a comparative study case

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Quantification of morphological diversity among herbivorous mammals and comparisons between herbivorous marsupials and placentals are scarce. In this report we compared morphological variation of the skull and mandible in three representatives of caviid rodents and three species of macropodid marsupials, whose size is comparable, using three-dimensional geometric morphometrics. We applied two levels of comparison, one pointed to a placental-marsupial dichotomy and another pointed to the intra-variation in each group. We also performed an analysis of modularity based on a likelihood approach in order to evaluate different modularity models and analyzing the intra- and inter-module correlation (i.e., morphological integration). Beyond strong morphological differences that split caviids and macropodids along the first axes of the morphospaces of the cranium and mandible, they shared similar allometric shape changes, including the enlargement of muscular attachment areas and lengthening of the diastema. In both clades, the largest value of inter-module correlation (as a measure of modular integration) was found for the oral-nasal and orbit modules. We reported relatively low values of within-module correlation for the oral-nasal and molar modules in macropodids while the opposite was recorded for caviids. Beyond the great differences in cranial structure, one of the factors that influence the patterns of morphological variation and differential integration was the processing of plant matter which seems to induce strong structural changes in both clades, in which the efficiency of the masticatory apparatus is resolved in a similar way.

Morfología cráneo-mandibular en mamíferos herbívoros: macropódidos (Metatheria, Diprotodontia, Macropodidae) y cávidos (Eutheria, Rodentia, Hystricomorpha) como un caso de estudio. La cuantificación de la diversidad morfológica entre mamíferos herbívoros y las comparaciones entre herbívoros marsupiales y placentarios son escasas. En este reporte comparamos la variación morfológica del cráneo y mandíbula en representantes de roedores cávidos y marsupiales macropódidos mediante técnicas de morfometría geométrica en 3D. Aplicamos dos niveles de comparación: uno apuntando a una dicotomía placentario-marsupial y el otro a la variación interna en cada grupo. También realizamos un análisis de modularidad basado en un enfoque de verosimilitud para evaluar diferentes modelos y analizar la correlación intra- e inter-módulo (integración morfológica). Cávidos y macropódidos se separaron en los espacios de forma del cráneo y mandíbula, particularmente sobre el primer eje, mientras que se distribuyeron a lo largo del segundo eje principalmente de acuerdo con la variación de tamaño. Los cambios de forma vinculados al tamaño estuvieron relacionados con la ampliación de las áreas de fijación muscular y el alargamiento del diastema. Los módulos oral-nasal y orbital mostraron los valores más altos de correlación tanto en macropódidos como en cávidos. Se obtuvieron valores de correlación intra-módulo relativamente bajos para los módulos oral-nasal y molar en macropódidos, mientras que se registró lo contrario para los cávidos. Más allá de las grandes diferencias en la estructura craneana, uno de los factores que influye en los patrones de variación morfológica e integración diferencial es el procesamiento de materia vegetal que parece inducir fuertes cambios estructurales que en ambos clados, en los que la eficiencia del aparato masticatorio se resuelve de manera similar.