Between-Year Variation in Population Sex Ratio Increases with Complexity of the Breeding System in Hymenoptera

Kümmerli, Rolf; Keller, Laurent

doi:10.1086/659951

Cited by 6 publications

(6 citation statements)

References 104 publications

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“…As with any wide‐ranging theory applied to complex phenomena, its predictions are not universally successful (e.g. Kümmerli & Keller, ). But, overall, the fit to data is strong (Bourke, ; Meunier et al ., ; West, ).…”

Section: Resultsmentioning

confidence: 99%

“…These factors do not explain all cases of split sex ratios (e.g. Wiernasz & Cole, ; Debout et al ., ), and inclusive fitness theory recognizes that sex ratios at both population and colony levels are affected by many factors (Bourke, ; Meunier et al ., ; West, ; Kümmerli & Keller, ). However, in cases that are discriminating, available data support inclusive fitness theory but not the Wilson–Nowak sex ratio hypothesis.…”

Section: Critique Of the Wilson–nowak Sex Ratio Hypothesismentioning

confidence: 99%

“…Indeed, sex investment ratios in ants often appear to be evolutionary compromises arising from ongoing queen-worker conflict over sex allocation (Helms, 1999;Ratnieks et al, 2006;Rosset & Chapuisat, 2006;Helanter€ a & Ratnieks, 2009;Aron, 2012). It has also been recognized that many other factors aside from relatedness asymmetry and queen-worker conflict influence variation in sex investment ratio at both population and colony levels (Bourke, 2005;Meunier et al, 2008;West, 2009;K€ ummerli & Keller, 2011). For example, in polygynous ants (with multiple queens per colony), unbiased sex investment ratios are thought to arise from either reduced workers' relatedness asymmetry, or local resource competition between related queens to head new colonies, or a combination of these factors (Bourke & Franks, 1995;Crozier & Pamilo, 1996;Bourke, 2005).…”

Section: Inclusive Fitness Theory's Explanation Of Sex Investment Ratmentioning

confidence: 99%

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Sex investment ratios in eusocial Hymenoptera support inclusive fitness theory

Bourke

2015

J of Evolutionary Biology

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Inclusive fitness theory predicts that sex investment ratios in eusocial Hymenoptera are a function of the relatedness asymmetry (relative relatedness to females and males) of the individuals controlling sex allocation. In monogynous ants (with one queen per colony), assuming worker control, the theory therefore predicts female-biased sex investment ratios, as found in natural populations. Recently, E.O. Wilson and M.A. Nowak criticized this explanation and presented an alternative hypothesis. The WilsonNowak sex ratio hypothesis proposes that, in monogynous ants, there is selection for a 1 : 1 numerical sex ratio to avoid males remaining unmated, which, given queens exceed males in size, results in a female-biased sex investment ratio. The hypothesis also asserts that, contrary to inclusive fitness theory, queens not workers control sex allocation and queen-worker conflict over sex allocation is absent. Here, I argue that the Wilson-Nowak sex ratio hypothesis is flawed because it contradicts Fisher's sex ratio theory, which shows that selection on sex ratio does not maximize the number of mated offspring and that the sex ratio proposed by the hypothesis is not an equilibrium for the queen. In addition, the hypothesis is not supported by empirical evidence, as it fails to explain 'split' (bimodal) sex ratios or data showing queen and worker control and ongoing queen-worker conflict. By contrast, these phenomena match predictions of inclusive fitness theory. Hence, the Wilson-Nowak sex ratio hypothesis fails both as an alternative hypothesis for sex investment ratios in eusocial Hymenoptera and as a critique of inclusive fitness theory.

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Section: Resultsmentioning

confidence: 99%

Section: Critique Of the Wilson–nowak Sex Ratio Hypothesismentioning

confidence: 99%

Section: Inclusive Fitness Theory's Explanation Of Sex Investment Ratmentioning

confidence: 99%

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Sex investment ratios in eusocial Hymenoptera support inclusive fitness theory

Bourke

2015

J of Evolutionary Biology

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“…Reproductive replacements normally occur in a smaller fraction of termite colonies than observed in this study (Hellemans, Fournier, et al., 2019; Kobayashi et al., 2013; Vargo et al., 2012), and replacements are thought to be uncommon in Cubitermes (Myles, 1999; Noirot, 1956). Alternatively, sex allocation may be biased if fitness of the sexes varies with environmental quality, such that the sex that reaps higher fitness benefits from a better environment should receive greater allocation in good conditions (Kümmerli & Keller, 2011; Trivers & Willard, 1973). Thus, termites could theoretically invest more in females if they had greater fitness under favorable environmental conditions, reinforcing the production of this energetically costly sex.…”

Section: Discussionmentioning

confidence: 99%

Female‐biased sex allocation and lack of inbreeding avoidance in Cubitermes termites

Conlon

Seibel

Schwitalla

et al. 2021

Ecology and Evolution

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“…However, the sex ratio did not vary seasonally for any of the studied groups in the submontane zone. The strong dependence of bees on flowering plants was reflected in higher proportion of males when resource availability was low (Bosch 2008, Kümmerli andKeller 2011), in line with hypothesis 4. The higher proportion of males in correlation with lower amount of food resources has also been reported for wasps (Strohm and Linsenmair 1997), but in our study resources for wasps did not seem to be limiting in a way that the sex ratio was affected.…”

Section: Seasonality In Life-history Traitsmentioning

confidence: 57%

Seasonal variation in the ecology of tropical cavity-nesting Hymenoptera on Mt. Kilimanjaro

Mayr¹,

Réquier²,

Peters³

et al. 2021

Frontiers of Biogeography

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Insect communities vary seasonally with changing climatic conditions and related changes in resource availability, strength of competition, or pressure by natural antagonists. But seasonal dynamics, particularly in tropical mountain ecosystems, are not well understood. We monitored cavity-nesting Hymenoptera communities on Mt. Kilimanjaro, Tanzania, to analyse temporal patterns of nest-building activity, ecological rates, and life-history traits in relation to seasonal climatic variation and elevation. We installed trap nests on 25 study sites in natural and disturbed habitat types covering the colline (<1,300 m) and submontane zones (≥1,300 m a.s.l). We analysed patterns of seasonality in the cavity-nesting ecology of Hymenoptera at three different trophic levels-bees, caterpillar-hunting wasps and spider-hunting wasps-over a complete annual period, covering two rainy and two dry seasons. Nest-building activity showed strong seasonal trends in all three investigated trophic levels and peaked at the end of the short rainy season at low elevations. Nest-building activity was considerably higher and seasonal trends were better synchronised between the different trophic levels in the colline zone at low This paper is part of an Elevational Gradients and Mountain Biodiversity Special Issue elevations. We also detected seasonal patterns for parasitism and natural mortality rates, sex ratio, and development time, which varied with trophic level and between elevation levels. Climate and flower abundance were important predictors for seasonal patterns in nest-building activity, ecological rates and life-history traits. These results reveal that seasonal trends in nestbuilding activity of lowland Hymenoptera seem to be linked to changes in climate and resource availability that reflect the seasonal patterns in plant growth and flowering documented in lowland savanna ecosystems. Higher resource availability also increased the sex ratio in bees towards the more costly females and enhanced their survival rates. These spatiotemporal links between climate, resources, ecological rates, and life-history traits indicate high sensitivity of plant-host-antagonist interactions to environmental changes. Highlights • Nest-building activity of cavity-nesting Hymenoptera on Mt. Kilimanjaro showed distinct seasonality at low and high elevations with concordant peaks across trophic levels. • Ecological rates, such as parasitism or natural mortality, showed seasonality, while lifehistory traits more often did not. • Seasonal patterns were more common in the colline than in the submontane zone. • Bees, caterpillar-hunting and spider-hunting wasps showed different seasonal patterns in ecological rates and life-history traits. • Climatic conditions and flower availability partly explained the seasonal patterns in activity of Hymenoptera, with different variables driving different rates, traits, and activity.

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Between-Year Variation in Population Sex Ratio Increases with Complexity of the Breeding System in Hymenoptera

Cited by 6 publications

References 104 publications

Sex investment ratios in eusocial Hymenoptera support inclusive fitness theory

Sex investment ratios in eusocial Hymenoptera support inclusive fitness theory

Female‐biased sex allocation and lack of inbreeding avoidance in Cubitermes termites

Seasonal variation in the ecology of tropical cavity-nesting Hymenoptera on Mt. Kilimanjaro

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