Food from Seed-Dispersal Mutualism Shifts Sex Ratios in Colonies of the Ant Aphaenogaster rudis

Morales, Manuel A.; Heithaus, E. Raymond

doi:10.2307/176966

Cited by 67 publications

(103 citation statements)

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“…So far, however, studies of this type have provided contradictory results. Food supplementation has caused an increased female bias among sexuals in some studies (Deslippe and Savolainen 1995;Herbers and Banschbach 1998;Morales and Heithaus 1998), no change in investment in others (Aron et al 2001;DeHeer et al 2001;Bono and Herbers 2003), and an increase in male production (in association with a host of changes in colony social structure and demography) in one study (Herbers and Banschbach 1999). The interactions between resource availability and colony investment are thus not yet well understood, making it difficult to draw conclusions about the relationship between resource abundance and costs of sex ratio manipulation.…”

Section: Discussionmentioning

confidence: 99%

Effects of Brood Manipulation Costs on Optimal Sex Allocation in Social Hymenoptera

Reuter

Helms

Lehmann

et al. 2004

The American Naturalist

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In eusocial Hymenoptera, queens and workers are in conflict over optimal sex allocation. Sex ratio theory, while generating predictions on the extent of this conflict under a wide range of conditions, has largely neglected the fact that worker control of investment almost certainly requires the manipulation of brood sex ratio. This manipulation is likely to incur costs, for example, if workers eliminate male larvae or rear more females as sexuals rather than workers. In this article, we present a model of sex ratio evolution under worker control that incorporates costs of brood manipulation. We assume cost to be a continuous, increasing function of the magnitude of sex ratio manipulation. We demonstrate that costs counterselect sex ratio biasing, which leads to less female-biased population sex ratios than expected on the basis of relatedness asymmetry. Furthermore, differently shaped cost functions lead to different equilibria of manipulation at the colony level. While linear and accelerating cost functions generate monomorphic equilibria, decelerating costs lead to a process of evolutionary branching and hence split sex ratios.Keywords: kin selection, conflict, model, evolutionary branching.Queen-worker conflict over sex allocation has been an important area of research on social insects over the past 25 years. As first outlined by Trivers and Hare (1976) queens and workers in a hymenopteran colony differ in their optimal sex allocation. This difference is caused by relatedness asymmetries arising from haplodiploidy, the hymenopteran system of sex determination. In haplodiploid species, females develop from fertilized (diploid) eggs, whereas males develop from unfertilized (haploid) eggs. As a consequence, in a colony headed by one singly mated queen, workers are three times more related to female sexuals (their sisters; life-for-life relatedness r p ) than to male sexuals (their brothers; life-for-life re-0.75 latedness ). Corresponding to this asymmetry in r p 0.25 relatedness, equilibrium sex allocation under worker control is female biased, with three times more resources invested in females than in males. Queens, in contrast, are equally related to sons and daughters, and their equilibrium sex ratio is therefore an equal investment in the two sexes.Since Trivers and Hare, hymenopteran sex ratio theory has been greatly developed. Predictions of optimal sex allocation under queen and worker control have been generated to include a variety of genetic structures of colonies and populations (for reviews, see Bourke and Franks 1995;Crozier and Pamilo 1996). However, almost all theoretical work has assumed that there are no costs associated with sex ratio manipulation. This assumption is likely to be wrong, especially in the case of workers. In order to alter sex allocation, workers have to manipulate the primary egg sex ratio, which is controlled by the queen. There are two likely mechanisms of sex ratio manipulation. First, workers can eliminate male eggs or larvae to increase the relative investment...

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Section: Discussionmentioning

confidence: 99%

Effects of Brood Manipulation Costs on Optimal Sex Allocation in Social Hymenoptera

Reuter

Helms

Lehmann

et al. 2004

The American Naturalist

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“…O uso de diásporos mirmecocóricos como alimento por formigas, em geral, afeta a produção de indivíduos reprodutivos, incrementando a produção de fêmeas aladas e consequentemente o fi tness das colônias, como em Aphaenogaster rudis Enzmann, 1947 (Myrmicinae) HEITHAUS, 1998;BONO;HEITHAUS, 2002). Além disso, colônias que recebem dieta suplementada com o elaiossomo de sementes mirmecocóricas apresentam larvas maiores, como em Myrmica ruginodis Nylander, 1846 (Myrmicinae) (GAMMANS et al, 2005).…”

Section: Implicações Do Consumo De Diásporos Para As Formigasunclassified

As formigas poneromorfas do Brasil

Delabie¹,

Feitosa²,

Serrão³

et al. 2015

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SciELO Books / SciELO Livros / SciELO Libros DELABIE, JHC., et al., orgs. As formigas poneromorfas do Brasil [online]. Ilhéus, BA: Editus, 2015, 477 p. ISBN 978-85-7455-441-9. Available from SciELO Books .All the contents of this work, except where otherwise noted, is licensed under a Creative Commons Attribution 4.0 International license.Todo o conteúdo deste trabalho, exceto quando houver ressalva, é publicado sob a licença Creative Commons Atribição 4.0.Todo el contenido de esta obra, excepto donde se indique lo contrario, está bajo licencia de la licencia Creative Commons Reconocimento 4.0. Prefácio Karl von Frisch, ganhador do prê-mio Nobel, biólogo comportamental e descobridor da comunicação pela dança em abelhas, observou que a vida desses insetos é como um poço mágico; quanto mais você tirar dele, mais ele se enche de água. Mas o que ele teria dito sobre o mundo das formigas, ou mesmo sobre o mundo das poneromorfas? Um único gê-nero de abelhas com apenas nove espécies é tão excitante e há tantas coisas para descobrir que dá para preencher a vida científi ca de centenas de geneticistas, etólogos e ecologistas, para não mencionar os milhares de apicultores e funcionários dos centros de pesquisa sobre abelhas. O que, então, podemos esperar dos aproximadamente 70 gêneros de Amblyoponinae, Ectatomminae, Heteroponerinae, Paraponerinae, Ponerinae e Proceratiinae, representados por cerca de 1.800 espécies? As formigas poneromorfas do BrasilMesmo uma rápida olhada nas fotografi as de microscopia eletrônica de varredura do catálogo de Bolton ilustrando os gêneros de formigas do mundo deveria despertar o interesse de qualquer um que gosta da natureza. O que Th aumatomyrmex está fazendo no mundo com os suas forquilhas faciais? Por que Discothyrea mantém constantemente seu abdômen enrolado? E como é a sensação de ser picado pelas tocandeiras gigantes do gênero Paraponera?Além destas refl exões espontâneas de amador, os mirmecólogos do mundo inteiro têm considerado as poneromorfas por muito tempo modelos ideais para estudar diversos aspectos da vida social das formigas, para desvendar sua função nos ecossistemas, e usá-las para redesenhar a evolução precoce da eusocialidade. Em particular, espécies sem nenhuma diferença morfológica entre reprodutores e não reprodutores, tais como as Dinoponera ou diversas Platythyrea, tornaram-se modelos estimulantes para pesquisar como indivíduos morfologicamente uniformes puderam alcançar uma divisão de trabalho reprodutivo estável e como confl itos familiares entre indivíduos totipotentes são resolvidos. Outros táxons foram utilizados para elucidar a ação de poderosos e, às vezes alergênicos, venenos, a fl exibilidade dos sistemas de comunicação química e acústica, ou a evolução do cariótipo.A presente compilação cobre grande parte do que é preciso saber sobre as formigas poneromorfas neotropicais. Seus 30 capítulos bem escolhidos dão uma visão geral apropriada sobre a sua história taxonômica, ecologia e comportamento, e serão de grande ajuda para todos qu...

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“…These colonies allocated a significantly greater proportion of their resources to gynes than did untreated colonies. Similarly, experimental supplements of seeds increased gyne production in the ant Aphaenogaster rudis (Morales and Heithaus 1998). Bono and Herbers (2003) showed that Myrmica brevispinosa colonies produced more gynes in response to supplemental sugar but supplemental protein had no effect on sex ratio or productivity.…”

Section: Introductionmentioning

confidence: 98%

Resource supplements cause a change in colony sex-ratio specialization in the mound-building ant, Formica exsecta

Brown

Keller

2006

Behav Ecol Sociobiol

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We examine the role of food resources on split sex ratios in Formica exsecta. Models of resource-based sex allocation predict that greater resources will cause an increase in the production of reproductive females (gynes) and an increase in overall size of offspring. We experimentally increased food resources for a subset of colonies in a polygynous population with a very malebiased sex ratio. This increase in food availability caused colonies that were male specialists the prior year to switch to female production. Overall, a significantly greater proportion of food-supplemented colonies produced gynes, compared to control colonies. Moreover, foodsupplemented colonies produced significantly larger workers and males (but not gynes), compared to those produced by control colonies. There was, however, no significant difference in the numerical productivity of food-supplemented and control colonies. We also measured the natural association between colony sex specialization and proximity to conifers, which typically harbor honeydew-bearing aphids (an important natural food source). In line with the view that resources play an important role for determining sex ratios in social insects, we found that female-producing colonies were significantly closer to conifers than were male-producing colonies.

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Food from Seed-Dispersal Mutualism Shifts Sex Ratios in Colonies of the Ant Aphaenogaster rudis

Cited by 67 publications

References 24 publications

Effects of Brood Manipulation Costs on Optimal Sex Allocation in Social Hymenoptera

Effects of Brood Manipulation Costs on Optimal Sex Allocation in Social Hymenoptera

As formigas poneromorfas do Brasil

Resource supplements cause a change in colony sex-ratio specialization in the mound-building ant, Formica exsecta

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