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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.04.006 Byline: Jamie C. Moore (a), Darren J. Obbard (a), Caroline Reuter (b)(c), Stuart A. West (a), James M. Cook (b)(c) Abstract: Despite theoretical predictions, dishonest signalling has rarely been observed in aggressive interactions. We present evidence of such signalling in the nonpollinating fig wasp Philotrypesis sp. A ex Ficus rubiginosa. First, morphometric data indicated that an alternative 'atypical' male morph (17.8% of individuals) exists that tends to be larger in body size and has longer mandibles for a given body size than other 'typical' males. Second, behavioural observations suggested that males use mandible gape width (which depends on mandible length) as a cue to assess opponents before fights and retreat without escalating if they are unlikely to win, and, probably because their greater mandible gape width causes more opponents to retreat without escalating, that atypical males engaged in fewer fights than typical males for a given body size but had higher mating success. Third, atypical males were less likely to win fights than typical males of similar mandible length relative to opponents. In addition, we found that atypical males incur more injuries (greater receiver-dependent signal costs) than typical males of similar body size relative to rivals. We discuss the implications of our findings for future work on dishonest signalling. Author Affiliation: (a) Institute of Evolutionary Biology, University of Edinburgh, U.K. (b) Division of Biology, Imperial College, U.K. (c) School of Biological Sciences, University of Reading, U.K. Article History: Received 23 August 2008; Revised 4 November 2008; Accepted 9 April 2009 Article Note: (miscellaneous) MS. number: 08-00552R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.01.018 Byline: Jamie C. Moore, Darren J. Obbard, Caroline Reuter, Stuart A. West, James M. Cook Abstract: Although theory exists concerning the types of strategies that should be used in contests over resources, empirical work explicitly testing its predictions is relatively rare. We investigated male fighting strategies in two nonpollinating fig wasp species associated with Ficus rubiginosa figs. In Sycoscapter sp. A, males did not assess each other before or during fights over mating opportunities. Instead, fights continued until the loser reached an energetic cost threshold that was positively correlated with its body size (fighting ability) and retreated. In Philotrypesis sp. B, prefight assessment was indicated, with males attacking competitively inferior rivals to remove them from the competitor pool (they then continued to do so until they reached a cost threshold that was again positively correlated with body size). Using data on species ecology, we discuss our findings with respect to theory on when different fighting strategies should evolve. We argue that the type of strategy used by a fig wasp species is determined by its relative benefits in terms of inclusive fitness. Author Affiliation: (a) Institute of Evolutionary Biology, University of Edinburgh, U.K. (a ) Division of Biology, Imperial College London, U.K. (a ) School of Biological Sciences, University of Reading, U.K. Article History: Received 5 August 2007; Revised 28 September 2007; Accepted 9 January 2008 Article Note: (miscellaneous) MS. number: 9484

We evaluate the utility of coefficients of variation of response propensities (CVs) as measures of risks of survey variable non‐response biases when monitoring survey data collection. CVs quantify variation in sample response propensities estimated given a set of auxiliary attribute covariates observed for all subjects. If auxiliary covariates and survey variables are correlated, low levels of propensity variation imply low bias risk. CVs can also be decomposed to measure associations between auxiliary covariates and propensity variation, informing collection method modifications and post‐collection adjustments to improve dataset quality. Practitioners are interested in such approaches to managing bias risks, but risk indicator performance has received little attention. We describe relationships between CVs and expected biases and how they inform quality improvements during and post‐data collection, expanding on previous work. Next, given auxiliary information from the concurrent 2011 UK census and details of interview attempts, we use CVs to quantify the representativeness of the UK Labour Force Survey dataset during data collection. Following this, we use survey data to evaluate inference based on CVs concerning survey variables with analogues measuring the same quantities among the auxiliary covariate set. Given our findings, we then offer advice on using CVs to monitor survey data collection. [ABSTRACT FROM AUTHOR]

1. Fig wasps have proved extremely useful study organisms for testing how reproductive decisions evolve in response to population structure. In particular, they provide textbook examples of how natural selection can favour female-biased offspring sex ratios, lethal combat for mates and dimorphic mating strategies. 2. However, previous work has been challenged, because supposedly single species have been discovered to be a number of cryptic species. Consequently, new studies are required to determine population structure and reproductive decisions of individuals unambiguously assigned to species. 3. Microsatellites were used to determine species identity and reproductive patterns in three non-pollinating Sycoscapter species associated with the same fig species. Foundress number was typically one to five and most figs contained more than one Sycoscapter species. Foundresses produced very small clutches of about one to four offspring, but one foundress may lay eggs in several figs. 4. Overall, the data were a poor match to theoretical predictions of solitary male clutches and gregarious clutches with n − 1 females. However, sex ratios were male-biased in solitary clutches and female-biased in gregarious ones. 5. At the brood level (all wasps in a fig), a decrease in sex ratio with increasing brood size was only significant in one species, and sex ratio was unrelated to foundress number. In addition, figs with more foundresses contain more wasp offspring. 6. Finally, 10-22% of females developed in patches without males. As males are wingless, these females disperse unmated and are constrained to produce only sons from unfertilised eggs. [ABSTRACT FROM AUTHOR]

1. In many fig wasp species, armoured wingless males regularly engage in lethal fights for access to females inside figs, which act as discrete mating patches. 2. Kin selection generally opposes killing brothers, because their reproductive success provides indirect genetic benefits (inclusive fitness). However, siblicide may be avoided if (i) brothers do not occur in the same figs, or (ii) males avoid fighting brothers in the same fig. Alternatively, (iii) siblicide may occur because intense mate competition between brothers at the local scale overcomes kin selection effects, or (iv) males do not recognise kin. 3. A fig may also contain wasps from other closely related species and it is not known if males also fight with these individuals. 4. Nine microsatellite loci were used in the first genetic analysis of fighting in fig wasps. We assigned species and sibling identities to males and tested alternative fighting scenarios for three Sycoscapter wasp species in figs of Ficus rubiginosa. 5. Approximately 60% of figs contained males from more than one Sycoscapter species and approximately 80% of fights were between conspecifics, but a surprising 20% were between heterospecific males. 6. Within species, few figs contained brothers, suggesting that females typically lay one son per fig. Overall, most males do not compete with brothers and all fights observed were between unrelated males. [ABSTRACT FROM AUTHOR]

Summary: Darwin''s theory of evolution by natural selection provided an immediately convincing explanation for the close fit between form and function in nature that had previously only been explicable in terms of supernatural design. Traits evolved in a way that improved their bearer''s chances of survival and its success at producing offspring. But what could be said of exaggerated ornamental traits such as the long and lurid tail feathers of many male birds and the ferocious looking mandibles and horned protuberances of various male insects, which were almost certain to compromise their bearer''s survival? To explain these traits, Darwin proposed the theory of sexual selection, first in ‘Origin of Species’ and then, at greater length, in ‘The Descent of Man’. In a nutshell, he argued that certain traits (secondary sex characters) will be favoured not because they improve survivorship or fecundity (i.e., by natural selection), but because they improve an individual''s mating success. This basic idea has been broadly accepted by zoologists, but it has been contentious when applied to plants, not least because they are often hermaphrodites. In this Primer, we explain the application of sexual-selection ideas to both dioecious and hermaphroditic plants. We point out that, far from being irrelevant to their study, sexual selection to increase male mating success can be interpreted as a major selective force in the evolution of floral diversity (). [Copyright &y& Elsevier]

Abstract: Under local mate competition, sex ratio theory predicts that increasing numbers of ovipositing females (foundresses) on a site should lead to higher proportions of males in their broods. Fig pollinators have confirmed this prediction. It is also predicted that with decreasing clutch size, solitary foundresses should produce increasing proportions of sons. We show this to be true. Further, when several females compete, brood size decreases. As a result, the proportion of males increases, and this could provide a mechanistic explanation of sex ratio response to numbers of colonizing females. Therefore, sex ratio data on fig wasps need to be reassessed to determine whether females ‘count’ other foundresses, as is generally accepted, or whether they simply ‘count’ the number of eggs that they lay. To cite this article: F. Kjellberg et al., C. R. Biologies 328 (2005). [Copyright &y& Elsevier]

Despite theoretical predictions, there is little empirical evidence that kin competition avoidance promotes dispersal. We show that dispersal by male Platyscapa awekei pollinating fig wasps is promoted by both low returns in the natal fig and kin competition avoidance, with strategies depending on the interaction between phenotype (body size) and local conditions. We discuss the paucity of similar work, how males might assess conditions, and then contrast male dispersal and fighting behaviour. This indicates that differences in the scale at which behaviours affect competition can mean that they are the product of dissimilar selective forces even when they have the same recipients. More generally, this could explain why other social interactions are often mixtures of cooperation and conflict.

A classic example of a mutualism is the one between fig plants (Ficus) and their specialized and obligate pollinating wasps. The wasps deposit eggs in fig ovules, which the larvae then consume. Because the wasps derive their fitness only from consumed seeds, this mutualism can persist only if the wasps are prevented from laying eggs in all ovules. The search for mechanisms that can limit oviposition and stabilize the wasp-seed conflict has spanned more than three decades. We use a simple foraging model, parameterized with data from two Ficus species, to show how fig morphology reduces oviposition rates and helps to resolve the wasp-seed conflict. We also propose additional mechanisms, based on known aspects of fig biology, which can prevent even large numbers of wasps from ovipositing in all ovules. It has been suggested that in mutualistic symbioses, the partner that controls the physical resources, in this case Ficus, ultimately controls the rate at which hosts are converted to visitors, regardless of relative evolutionary rates. Our approach provides a mechanistic implementation of this idea, with potential applications to other mutualisms and to theories of virulence.