Social selection and the evolution of a female weapon in queens of the antMessor pergandei(Hymenoptera: Formicidae)

Abstract

The evolution of weaponry occurs less frequently in females than in males and is most often important for protecting ecological resources or offspring rather than winning mates. The purpose of female weapons is often confounded by the presence of similar weapons in males, so cases where only females need weapons provide important tests of our understanding of how and why weapons evolve. In some populations of the ant, Messor pergandei (Mayr), newly mated queens initiate new nests in social groups that subsequently break down when queens engage in battles for control. The incipient social environment differs geographically, so that lethal fighting occurs in some populations but not others. Consistent with the hypothesis that queens in populations where lethal fighting occurs should show selection for weaponry (broad heads and strong mandibles), we found that heads of queens from sites where lethal fighting occurs were broader than those at sites with non-fighting queens and a site with solitary queens. Evolution of weaponry is specific to queens, because regression results from workers often did not follow this pattern.

Subcaste-specific evolution of head size in the ant genusPheidole

“…Moreover, examining polymorphism in morphology in castes other than workers [e.g. queens (Bespalova & Helms, ; Fave et al ., ) and males (Heinze & Hölldobler, )] will provide further insight into its origin and function.…”

Body Size and Symmetry Properties of Termite Soldiers Under Two Intraspecific Competition Scenarios

“…Intraspecific competition as a stress factor has been described in literature (Heinrich, 1993;Warren et al, 2006;Amarillo-Suárez et al, 2011;Wills et al, 2014;Korallo-Vinarskaya et al, 2015). In territorial species where interference competition occurs with physical encounters displayed, larger individuals have better chances to win a fight and monopolize resources than smaller individuals (Price et al, 2011;Bespalova and Helms, 2014;Holland et al, 2021). In our study, we demonstrated that soldiers from multicolonial substrates had significantly larger heads than those from unicolonial substrates, strongly suggesting that in a competitive scenario, colonies produce larger soldiers which increase the chance to win fights and monopolize resources.…”

“…In our work, quitinized traits of N. chilensis that showed differences in size between uni-and multicolonial substrates are closely related to defensive tasks. Thus, head traits (head area, head perimeter, head length, and head maximum width) could be related to the blocking of galleries with the head and to more developed muscles to produce stronger bites (Bespalova and Helms, 2014). When the scape used by two or more colonies is depleted and the tunnels dug by members of different colonies finally meet, all of these traits could improve the chance to win a fight in a hypothetical scenario of interference intraspecific competition (Heinrich and Bartholomew, 1979;Otronen, 1988;Heinrich, 1993;Zobel and Paxton, 2007;Bespalova and Helms, 2014).…”

“…When interference competition occurs, body size generally determines who will dominate the resources; thus, larger individuals are frequently more successful than smaller ones (Heinrich and Bartholomew, 1979;Otronen, 1988;Heinrich, 1993;Zobel and Paxton, 2007;Bespalova and Helms, 2014). In termites, significantly higher fluctuating asymmetry has been detected in soldiers of Coptotermes formosanus Shiraki, which develop within incipient colonies (instable and stressful scenario) in comparison with soldiers which develop within mature colonies (more stable environment) (Chouvenc et al, 2014a).…”

Ontogenia da atratividade sexual em rainhas de >i<Scaptotrigona>/i< aff. >i<depilis>/i< (Hymenoptera, Apidae, Meliponini)

“…Porém, uma alta atratividade sexual não garante um bom desempenho reprodutivo, pois podem ter baixo acasalamento efetivo, apesar de serem bem atrativas (FOSTER et al, 1999). Com isso, a interação social é um fator externo chave afetando a história de vida de reprodução de fêmeas em himenópteros eussociais (FEWELL & PAGE, 1999;BESPALOVA & HELMS, 2014), embora os fatores internos também sejam importantes (WILSON, 1971;LIN & MICHENER, 1972). Além disso, a atratividade, bem como a receptividade, é adquirida ao longo da fase adulta, e é indicada por traços fisiológicos (e.g.…”