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4 - Analysis of animal contest data
- Edited by Ian C. W. Hardy, University of Nottingham, Mark Briffa, University of Plymouth
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- Book:
- Animal Contests
- Published online:
- 05 June 2013
- Print publication:
- 30 May 2013, pp 47-85
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- Chapter
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Summary
Summary
In this chapter we outline and discuss statistical approaches to the analysis of contest data, with an emphasis on testing key predictions and assumptions of the theoretical models described in Chapters 2 and 3. We use examples from an array of animal taxa, including cnidarians, arthropods and chordates, to illustrate these approaches and also the commonality of many key aspects of contest interactions despite the differing life histories and morphologies (including weaponry) of these organisms. We first deal with the analysis of contest outcomes, a useful approach for determining which traits contribute to an individual's resource holding potential (RHP). Here we outline alternative statistical approaches that treat the outcome as either an explanatory (independent) variable or as the response (dependent) variable. In both cases, we treat a single contest as one ‘experimental unit’ and consider ways in which multiple measures taken from the same experimental unit should be accounted for in the analysis. Thus, we introduce paired and repeated measures approaches for contest data and also the calculation of composite measures. We then discuss more complex mixed models, which are particularly useful for dealing with multi-party contests when multiple individuals from the same group occur in more than one observation. Having established what factors influence RHP, one might then ask questions about the roles of information-gathering and decision-making during contests. These questions are prompted by the theoretical models of dyadic contests discussed in Chapters 1 and 2, and we consider the advantages and limitations of using analysis of contest duration to distinguish between ‘mutual-’ and ‘self-assessment’ type contests. An additional tool that we can use to address this question is the analysis of escalation and de-escalation patterns, and we thus shift the focus to within-contest behavioural changes.
8 - Hymenopteran contests and agonistic behaviour
- Edited by Ian C. W. Hardy, University of Nottingham, Mark Briffa, University of Plymouth
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- Book:
- Animal Contests
- Published online:
- 05 June 2013
- Print publication:
- 30 May 2013, pp 147-177
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- Chapter
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Summary
Summary
The insect order Hymenoptera is speciose, diverse and common. Many wasps, bees and ants are well known for their ability, and propensity, to engage in agonistic interactions via biting and stinging (chemical injection), and may also interact using chemical deposition and volatile chemical release. Such behaviours are often exhibited during acquisition and defence of resources contested either by conspecifics or by allospecific hymenopterans. Here we examine the types of contests engaged in by social and non-social hymenopterans and highlight links between these and further aspects of evolutionary and applied biology. We first consider factors influencing the outcomes of contests between pairs of females over resources for reproduction. Studies of female–female contests in bethylids and several non-aculeate species of parasitoid wasps, especially scelionids, pteromalids and eupelmids, have addressed fundamental causes of the outcomes of contest interactions and have further linked contest behaviour to strategies of patch exploitation, clutch size and parental care. Further, we review links between the study of contest behaviour in parasitoids and their use as agents of biological pest control, particularly in terms of how contest behaviour may constitute intra-guild predation and influence strategic decisions to deploy single or multiple species of natural enemies. We then consider contests between males for access to mates, especially those engaged in by fig wasps and other wasps. Male–male contests are placed in the context of the evolution of alternative male morphs, mating systems, sex ratios and social behaviours. Finally, we return to female–female contests, this time examining them in the more complex context of the social Hymenoptera, in which both between-individuals (intra-colony) and between-group (inter-colony) contests occur.