Mating opportunities and energetic constraints drive variation in age‐dependent sexual signalling

Houslay, Thomas M.; Houslay, Kirsty F; Rapkin, James; Hunt, John; Bussière, Luc F.

doi:10.1111/1365-2435.12766

Cited by 19 publications

(23 citation statements)

References 100 publications

(182 reference statements)

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“…The ZAP model includes a logistic regression for the zeroes in the data, and an overdispersed Poisson regression for the zerotruncated counts. This type of model enabled us to answer two distinct questions within a single statistical structure: (1) what factors affect whether a male chooses to call, and (2) if a male calls, what factors affect the amount of calling (Houslay et al 2015(Houslay et al , 2017? Our predictors for the model were treatment (naive, sham, low, moderate, and high infection cue doses), age class (young and old males), and the interaction between treatment and age.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…Although critical to male mating success, calling is associated with numerous costs including increased metabolic demands (Hoback and Wagner ; Houslay et al. ), increased attraction of parasitoids (Cade ), increased risk of predation (Sakaluk and Belwood ), decreased immune function (Adamo et al. ), and accelerated senescence (Hunt et al.…”

mentioning

confidence: 99%

“…Previous studies have documented significant sexual selection on both song structure (Ower et al 2013) and male calling effort, measured as the time invested in signaling (Gray and Cade 1999;Hunt et al 2004). Although critical to male mating success, calling is associated with numerous costs including increased metabolic demands (Hoback and Wagner 1997;Houslay et al 2017), increased attraction of parasitoids (Cade 1975), increased risk of predation (Sakaluk and Belwood 1984), decreased immune function (Adamo et al 2001), and accelerated senescence (Hunt et al 2004). Because of these costs, selection should act on males to adopt an optimized pattern of calling over the course of their reproductive lifetime.…”

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confidence: 99%

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Age‐dependent variation in the terminal investment threshold in male crickets

et al. 2018

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The terminal investment hypothesis proposes that decreased expectation of future reproduction (e.g., arising from a threat to survival) should precipitate increased investment in current reproduction. The level at which a cue of decreased survival is sufficient to trigger terminal investment (i.e., the terminal investment threshold) may vary according to other factors that influence expectation for future reproduction. We test whether the terminal investment threshold varies with age in male crickets, using heat-killed bacteria to simulate an immune-inducing infection. We measured calling effort (a behavior essential for mating) and hemolymph antimicrobial activity in young and old males across a gradient of increasing infection cue intensity. There was a significant interaction between the infection cue and age in their effect on calling effort, confirming the existence of a dynamic terminal investment threshold: young males reduced effort at all infection levels, whereas old males increased effort at the highest levels relative to naïve individuals. A lack of a corresponding decrease in antibacterial activity suggests that altered reproductive effort is not traded against investment in this component of immunity. Collectively, these results support the existence of a dynamic terminal investment threshold, perhaps accounting for some of the conflicting evidence in support of terminal investment.

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Section: Statistical Analysesmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Age‐dependent variation in the terminal investment threshold in male crickets

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“…Owing to this uncertainty, we used both call syllable rate and syllable number as an index of the call trait in our analyses. Studies of other orthopterans have shown that available energy resources influence male calling effort as measured by the total amount of song during the daily activity period (Hunt et al ., ; Houslay et al ., ).…”

Section: Methodsmentioning

confidence: 97%

When do trade‐offs occur? The roles of energy constraints and trait flexibility in bushcricket populations

Barbosa

Rebar

Greenfield³

2017

J of Evolutionary Biology

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In many animal species, the expression of sexually selected traits is negatively correlated with traits associated with survival such as immune function, a relationship termed a 'trade-off'. But an alternative in which sexually selected traits are positively correlated with survival traits is also widespread. We propose that the nature of intertrait relationships is largely determined by overall energy expenditure, energy availability and trait flexibility, with trade-offs expected when individuals are subject to energy constraints. We tested this hypothesis in Ephippiger diurnus, a European bushcricket in which males are distinguished by two prominent sexually selected traits, acoustic calls and a large spermatophore transferred to the female at mating, and where immune function may be critical in survival. Ephippiger diurnus are distributed as small, isolated populations that are differentiated genetically and behaviourally. We analysed songs, spermatophores and the immune function in male individuals from eight populations spanning a range of song types. As predicted, we only found trade-offs in those populations that expended more energy on song and were less flexible in their ability to adjust that expenditure. Ultimately, energy constraints and resulting trade-offs may limit the evolution of song exaggeration in E. diurnus populations broadcasting long calls comprised of multiple 'syllables'.

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“…The ZAP model includes a logistic regression for the zeroes in the data and an over‐dispersed Poisson regression for the zero‐truncated counts. This type of model enabled us to answer two distinct questions within a single statistical structure: (a) what factors affect whether a male chooses to call and (b) if a male calls, what factors affect the amount of calling (Duffield et al., ; Houslay, Houslay, Rapkin, Hunt, & Bussière, ; Houslay, Hunt, Tinsley, & Bussière, )?…”

Section: Methodsmentioning

confidence: 99%

Inbreeding alters context‐dependent reproductive effort and immunity in male crickets

Duffield

Hampton

Houslay

et al. 2019

J of Evolutionary Biology

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Infection can cause hosts to drastically alter their investment in key life-history traits of reproduction and defence. Infected individuals are expected to increase investment in defence (e.g., by increasing immune function) and, due to trade-offs, investment in other traits (e.g., current reproduction) should decrease. However, the terminal investment hypothesis postulates that decreased lifespan due to infection and the associated reduction in the expectation for future offspring will favour increased investment towards current reproduction. Variation in intrinsic condition will likely influence shifts in reproductive investment post-infection, but this is often not considered in such assessments. For example, the extent of inbreeding can significantly impact an individual's lifetime fitness and may influence its reproductive behaviour following a threat of infection. Here, we investigated the effects of inbreeding status on an individual's reproductive investment upon infection, including the propensity to terminally invest. Male crickets (Gryllodes sigillatus) from four genetically distinct inbred lines and one outbred line were subjected to a treatment from an increasing spectrum of simulated infection cue intensities, using heat-killed bacteria. We then measured reproductive effort (calling effort), survival and immune function (antibacterial activity, circulating haemocytes and haemocyte microaggregations). Inbred and outbred males diverged in how they responded to a low-dose infection cue: relative to unmanipulated males, outbred males decreased calling effort, whereas inbred males increased calling effort. Moreover, we found that inbred males exhibited higher antibacterial activity and numbers of circulating haemocytes compared with outbred males. These results suggest that an individual's inbreeding status may have consequences for context-dependent shifts in reproductive strategies, such as those triggered by infection. K E Y W O R D S fecundity compensation, genotype-by-environment interaction, life-history theory, residual reproductive value S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Duffield KR, Hampton KJ, Houslay TM, Hunt J, Sadd BM, Sakaluk SK. Inbreeding alters contextdependent reproductive effort and immunity in male crickets.

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Mating opportunities and energetic constraints drive variation in age‐dependent sexual signalling

Cited by 19 publications

References 100 publications

Age‐dependent variation in the terminal investment threshold in male crickets

Age‐dependent variation in the terminal investment threshold in male crickets

When do trade‐offs occur? The roles of energy constraints and trait flexibility in bushcricket populations

Inbreeding alters context‐dependent reproductive effort and immunity in male crickets

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