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Biomechanics of ant (Hymenoptera: Formicidae) bite Effects of mandible and head morphology

Klunk, Cristian Luan (2023)
Biomechanics of ant (Hymenoptera: Formicidae) bite Effects of mandible and head morphology.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00024722
Dissertation, Erstveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

The necessity to capture and process food represents a relevant evolutionary pressure. Insects are incredibly diverse, showing several feeding modes and their associated morphological adaptations. Many insect lineages evolved a chewing feeding mode, where the mandibles are essential appendices to cut, crush, and tear food items that are further processed by other mouthparts. Mandibles can also be employed to perform additional behaviors. In ants, workers use their mandibles to execute most of the colony's non-reproductive tasks, like carry brood and objects, excavate, cut, crush, and punch. Not surprisingly, this heavy reliance on mandibles leads to a significant development of the mandibular muscles in ant workers, especially the mandibular closing muscles, the largest of an ant worker. Those muscles originate in the head capsule, whose shape has relevant consequences for muscle packing. Ants show an astounding head and mandible morphological diversity, whose functional implications have been investigated through distinct approaches, but usually regarding closely related species. Some ant species have further morphological variation among the workers, characterizing a worker polymorphism with profound implications for the colony division of labor. Biomechanical simulations can be effectively used to test a structure's functional performance under external loading. Concerning ant worker heads and mandibles, the functional relevance of the morphological variation observed in different lineages, or even among distinct worker types of the same species, could be investigated through simulations that resemble bite-loading conditions. Finite Element Analysis (FEA) is a numerical method used to approximate the mechanical responses of a structure to an external load. With digital reconstructions of the target structure, it is possible to perform an FEA, providing the relevant mechanical aspects of the behavior intended to simulate, like an ant bite. The main aim of this thesis is to explore the morphological variation observed in ant worker heads and mandibles under a functional perspective at two levels: intra and interspecifically. We employed FEA to test the mechanical responses of ant worker heads and mandibles under bite loading conditions, comparing the functional performance of major and minor workers of the dimorphic ant genus Pheidole at the intraspecific level, and of several ant lineages that span many of the currently recognized ant subfamilies at the interspecific level. Our results suggest that in the genus Pheidole, the major worker subcaste have heads and mandibles better suited to deal with the mechanical demands of bite, agreeing with its duties in the colony as workers responsible for defense and food processing. At the interspecific level, head and mandible morphology variation were also relevant in the mechanical responses of those structures to bite-loading demands, although with unclear relationships with ecological aspects. We demonstrated that FEA is a valuable tool to explore functional aspects of ant morphological variation and to provide insights into ant morphological evolution.

Typ des Eintrags: Dissertation
Erschienen: 2023
Autor(en): Klunk, Cristian Luan
Art des Eintrags: Erstveröffentlichung
Titel: Biomechanics of ant (Hymenoptera: Formicidae) bite Effects of mandible and head morphology
Sprache: Englisch
Referenten: Heethoff, Dr. Michael ; Pie, Dr. Marcio Roberto ; Blanke, Dr. Alexander ; Lattke B., Dr. John Edwin
Publikationsjahr: 7 November 2023
Ort: Darmstadt
Kollation: 159 Seiten
Datum der mündlichen Prüfung: 14 August 2023
DOI: 10.26083/tuprints-00024722
URL / URN: https://tuprints.ulb.tu-darmstadt.de/24722
Kurzbeschreibung (Abstract):

The necessity to capture and process food represents a relevant evolutionary pressure. Insects are incredibly diverse, showing several feeding modes and their associated morphological adaptations. Many insect lineages evolved a chewing feeding mode, where the mandibles are essential appendices to cut, crush, and tear food items that are further processed by other mouthparts. Mandibles can also be employed to perform additional behaviors. In ants, workers use their mandibles to execute most of the colony's non-reproductive tasks, like carry brood and objects, excavate, cut, crush, and punch. Not surprisingly, this heavy reliance on mandibles leads to a significant development of the mandibular muscles in ant workers, especially the mandibular closing muscles, the largest of an ant worker. Those muscles originate in the head capsule, whose shape has relevant consequences for muscle packing. Ants show an astounding head and mandible morphological diversity, whose functional implications have been investigated through distinct approaches, but usually regarding closely related species. Some ant species have further morphological variation among the workers, characterizing a worker polymorphism with profound implications for the colony division of labor. Biomechanical simulations can be effectively used to test a structure's functional performance under external loading. Concerning ant worker heads and mandibles, the functional relevance of the morphological variation observed in different lineages, or even among distinct worker types of the same species, could be investigated through simulations that resemble bite-loading conditions. Finite Element Analysis (FEA) is a numerical method used to approximate the mechanical responses of a structure to an external load. With digital reconstructions of the target structure, it is possible to perform an FEA, providing the relevant mechanical aspects of the behavior intended to simulate, like an ant bite. The main aim of this thesis is to explore the morphological variation observed in ant worker heads and mandibles under a functional perspective at two levels: intra and interspecifically. We employed FEA to test the mechanical responses of ant worker heads and mandibles under bite loading conditions, comparing the functional performance of major and minor workers of the dimorphic ant genus Pheidole at the intraspecific level, and of several ant lineages that span many of the currently recognized ant subfamilies at the interspecific level. Our results suggest that in the genus Pheidole, the major worker subcaste have heads and mandibles better suited to deal with the mechanical demands of bite, agreeing with its duties in the colony as workers responsible for defense and food processing. At the interspecific level, head and mandible morphology variation were also relevant in the mechanical responses of those structures to bite-loading demands, although with unclear relationships with ecological aspects. We demonstrated that FEA is a valuable tool to explore functional aspects of ant morphological variation and to provide insights into ant morphological evolution.

Alternatives oder übersetztes Abstract:
Alternatives AbstractSprache

Die Notwendigkeit, Nahrung zu verarbeiten, stellt einen relevanten evolutionären Druck dar. Insekten sind sehr vielfältig und weisen verschiedene Ernährungsweisen und die damit verbundenen morphologischen Anpassungen auf. Viele Insekten haben eine kauende Ernährungsweise entwickelt, bei der die Mandibeln wesentliche Anhängsel zum Schneiden, Zerkleinern und Zerreißen der Nahrung sind, die dann von anderen Mundwerkzeugen weiterverarbeitet werden. Die Mandibeln können auch für zusätzliche Verhaltensweisen eingesetzt werden. Bei Ameisen verwenden die Arbeiterinnen ihre Mandibeln, um die meisten nicht-reproduktiven Aufgaben der Kolonie auszuführen, wie das Tragen von Brut und Gegenständen, Ausgraben, Schneiden und Zerkleinern. Es überrascht nicht, dass diese starke Abhängigkeit von den Mandibeln bei den Ameisenarbeiterinnen zu einer verstärkten Entwicklung der Mandibelmuskulatur führt, die größten Muskeln einer Ameisenarbeiterin. Diese Muskeln haben ihren Ursprung in der Kopfkapsel, deren Form erhebliche Auswirkungen auf die Muskelmasse hat. Ameisen weisen eine erstaunliche morphologische Vielfalt von Kopf- und Mandibelformen auf, deren funktionelle Auswirkungen mit unterschiedlichen Ansätzen untersucht wurden. Bei einigen Ameisenarten gibt es weitere morphologische Unterscheidungen zwischen den Arbeiterinnen, die auf einen Arbeiterinnen-Polymorphismus mit tiefgreifenden Auswirkungen auf die Arbeitsteilung in der Kolonie zurückzuführen sind. Biomechanische Simulationen können effektiv eingesetzt werden, um die funktionelle Leistung einer Struktur unter externer Belastung zu testen. Bei den Köpfen und Mandibeln von Ameisenarbeiterinnen könnte die funktionelle Relevanz der morphologischen Variationen, die in verschiedenen Abstammungslinien oder sogar zwischen verschiedenen Arbeiterinnenarten derselben Spezies beobachtet wurden, durch Simulationen untersucht werden, die den Bedingungen einer Bissbelastung entsprechen. Die Finite-Elemente-Analyse (FEA) ist eine numerische Methode, mit der die mechanischen Reaktionen einer Struktur auf eine äußere Krafteinwirkung angenähert werden können. Mit digitalen Rekonstruktionen der Zielstruktur ist es möglich, eine FEA durchzuführen, die die relevanten mechanischen Aspekte des zu simulierenden Verhaltens, z. B. eines Ameisenbisses, liefert. Das Hauptziel dieser Arbeit besteht darin, die morphologische Variation der Köpfe und Mandibeln von Ameisenarbeiterinnen unter funktionalen Gesichtspunkten auf zwei Ebenen zu untersuchen: intra- und interspezifisch. Daher haben wir FEA eingesetzt, um die mechanischen Reaktionen von Ameisenarbeiterinnenköpfen und -mandibeln unter Bissbelastungsbedingungen zu testen und die funktionelle Leistung der dimorphen Ameisengattung Pheidole auf intraspezifischer Ebene und von mehreren Ameisenarten, die viele der derzeit anerkannten Ameisenunterfamilien umfassen, auf interspezifischer Ebene zu vergleichen. Unsere Ergebnisse deuten darauf hin, dass in der Gattung Pheidole die wichtigsten Arbeiterinnen-Unterkaste Köpfe und Mandibeln haben, die besser geeignet sind, um mit den mechanischen Anforderungen des Bisses umzugehen, was mit ihren Aufgaben in der Kolonie als Arbeiterinnen, die für die Verteidigung und die Nahrungsverarbeitung verantwortlich sind, übereinstimmt. Auf interspezifischer Ebene waren die Unterschiede in der Morphologie von Kopf und Mandibeln ebenfalls relevant für die mechanischen Reaktionen dieser Strukturen auf die Beißanforderungen, wenn auch mit unklaren Beziehungen zu ökologischen Aspekten. FEA ist demnach eine sehr gute geeignete Methode, um funktionelle Aspekte der morphologischen Variation von Ameisen zu untersuchen und Einblicke in die morphologische Evolution von Ameisen zu gewinnen.

Deutsch

A necessidade de capturar e processar alimentos representa uma importante pressão evolutiva. Insetos são incrivelmente diversos, apresentando inúmeros hábitos alimentares e adaptações morfológicas relacionadas. Muitas linhagens de insetos evoluíram um hábito alimentar mastigador, onde as mandíbulas são apêndices essenciais para cortar, moer e rasgar itens alimentares que são adicionalmente processados pelas demais partes bucais. Mandíbulas também podem ser utilizadas para desempenhar outros comportamentos. Em formigas, as operárias utilizam as mandíbulas para executar a maior parte das atividades não reprodutivas da colônia, como carregar objetos e juvenis, escavar, cortar, moer e perfurar. Não surpreende, portanto, que essa dependência nas mandíbulas tenha gerado um significativo desenvolvimento dos músculos mandibulares das operárias de formigas, especialmente dos músculos adutores das mandíbulas, os maiores de uma operária de formiga. Esses músculos originam-se na cápsula da cabeça, cuja forma tem consequências relevantes para o armazenamento dos músculos. Formigas apresentam uma impressionante diversidade morfológica quanto à cabeça e mandíbulas, cujas implicações funcionais vem sendo investigadas sob distintas abordagens, porém usualmente restritas à espécies proximamente relacionadas. Algumas espécies de formigas apresentam diferenciações morfológicas entre as operárias, caracterizando um polimorfismo da casta operária com profundas implicações na divisão de trabalho da colônia. Simulações biomecânicas podem ser ferramentas efetivas para testar o desempenho funcional de uma estrutura sujeita à cargas externas. Em se tratando da cabeça e mandíbulas de operárias de formigas, a relevância funcional da variação morfológica observada nas diferentes linhagens, ou mesmo entre operárias da mesma espécie, pode ser investigada através de simulações que aproximem a mecânica da mordida. A Análise de Elementos Finitos (AEF) consiste num método numérico utilizado para aproximar as respostas mecânicas de uma estrutura submetida à cargas externas. Através de reconstruções digitais da estrutura de interesse é possível aplicar a AEF, considerando os aspectos mecânicos relevantes para o comportamento que se pretende simular, como uma mordida de formiga. O principal objetivo da presente tese é explorar a variação morfológica observada na cabeça e mandíbulas de formigas sob uma perspectiva funcional em dois níveis: intra e interespecificamente. Utilizamos a AEF para testar as respostas mecânicas dessas estruturas às demandas da mordida, comparando o desempenho funcional de operárias maiores e menores do gênero Pheidole no nível intraespecífico, e de diversas linhagens de formigas que compõem distintas subfamílias de formigas atualmente reconhecidas ao nível interespecífico. Nossos resultados sugerem que no gênero Pheidole, as operárias maiores possuem cabeças e mandíbulas melhor adaptadas para lidar com as demandas mecânicas da mordida, o que concorda com suas responsabilidades na colônia, já que são recrutadas para a defesa e processamento de alimento. Ao nível interespecífico, a variação morfológica também se mostrou relevante na resposta mecânica da cabeça e mandíbulas de formigas às demandas da mordida, embora apresentando relações incertas com características ecológicas das espécies. Nós demonstramos que a AEF é uma ferramenta valiosa para explorar aspectos funcionais da variação morfológica de formigas, e para gerar novas perspectivas sobre a evolução morfológica desses insetos.

Portugiesisch
Status: Verlagsversion
URN: urn:nbn:de:tuda-tuprints-247221
Sachgruppe der Dewey Dezimalklassifikatin (DDC): 500 Naturwissenschaften und Mathematik > 590 Tiere (Zoologie)
Fachbereich(e)/-gebiet(e): 10 Fachbereich Biologie
10 Fachbereich Biologie > Animal evolutionary ecology
Hinterlegungsdatum: 07 Nov 2023 15:44
Letzte Änderung: 08 Nov 2023 06:13
PPN:
Referenten: Heethoff, Dr. Michael ; Pie, Dr. Marcio Roberto ; Blanke, Dr. Alexander ; Lattke B., Dr. John Edwin
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: 14 August 2023
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