PhD Projects available

The second round of PhD recruitment is now under way here in St Andrews, and I am advertising two possible projects. Applicants will be short-listed and invited for (competitive) interview. Given the current availability of funding, only one position (at most) would be awarded, and full fees/stipend covered for UK applicants only. The deadline for applications is the end of Sunday 10th April 2016.

The two projects are:

(1) The evolutionary causes and consequences of mating failure in insects.

(2) The evolutionary and ecological costs of neonicotinoids: understanding sex allocation in a beneficial parasitoid wasp.

For more details please see below, or visit findaphd.com where the positions will also be advertised shortly. All applications must be made via the University’s PhD application portal which can be found here: https://www.st-andrews.ac.uk/pgr/home.htm

(1) The evolutionary causes and consequences of mating failure in insects.

Why do so many matings fail? It is becoming increasingly clear that copulations across a Mating competition in Lygaeus equestris, Sicily 2011broad range of animals often do not involve successful sperm transfer – in other words, they fail (García-González 2004; Greenway et al. 2015). Mating failure represents a significant evolutionary puzzle. First, we should expect natural selection on primary sexual function to reduce or eliminate infertile individuals from populations. Second, sexual selection should similarly act to reduce the occurrence of reproductively incompetent or infertile individuals. Together then, natural and sexual selection should mean that mating failure is either extremely rare or entirely absent, but this does not appear to be the case. In this project, the PhD student will explore the behavioural ecology of mating failure in the polyandrous insect Lygaeus simulans. Mating failure is remarkably common in this species, with around 40% of matings failing. We have recently shown that mating failure is repeatable, i.e. males are predictably good or bad at successfully transferring sperm during copulations (Greenway & Shuker 2015). This means that mating failure seems to be a “real phenotype”, and not just an unlucky chance event between a male and a female. The student will explore the morphological, behavioural and ecological correlates of mating failure to test a number of hypotheses relating to sexual selection and sexual conflict. For instance, is mating failure a result of the extremely elongated genitalia of male Lygaeus bugs (Dougherty et al. 2015)? And if it is, why are male genitalia so long? In particular, the project will examine the role of females in mating failure, and ask whether mating failure can be adaptive from the female perspective. Whilst this project will focus on mating failure in an insect system, our work will also draw on the broader patterns of mating failure we see across the animal kingdom, including in terms of human infertility. For instance, is the well-characterised pattern of human infertility as unusual as we might think?

The project will provide a number of key training opportunities for the successful candidate: (1) training in experimental design and behavioural techniques; (2) quantitative skills, from data management through to statistical analysis; (3) communication skills, in terms of presenting work to both academic and non-technical audiences through a variety of media. There will also be opportunities for the use of molecular techniques to explore patterns of paternity, and to develop meta-analytical tests of hypotheses for mating failure, depending on the interests of the student.

For further details of the work in the Insect Behavioural Ecology lab, please visit our website: http://insects.st-andrews.ac.uk. To make informal enquiries before applying, please also email Dr David Shuker (david.shuker@st-andrews.ac.uk).

Relevant references

(1) Greenway, E.V. & Shuker, D.M. (2015) The repeatability of mating failure in a polyandrous insect. Journal of Evolutionary Biology, 28: 1578-1582.

(2) Greenway, E.V., Dougherty, L.R. & Shuker, D.M. (2015) Mating failure. Current Biology, 25: R534-R536.

(3) García-González, F. (2004) Infertile matings and sperm competition: the effect of “nonsperm representation” on intraspecific variation in sperm precedence patterns. American Naturalist, 164: 457–472.

(4) Dougherty, L.R., Rahman, I.A., Burdfield-Steel, E.R, Greenway, E.V. & Shuker, D.M. (2015) Experimental reduction of intromittent organ length reduces male reproductive success in a bug. Proceedings of the Royal Society, Series B, 282: 201507824.

(2) The evolutionary and ecological costs of neonicotinoids: understanding sex allocation in a beneficial parasitoid wasp.

Deciding what sex your offspring should be is a crucial reproductive decision. Nasonia red-eyed femaleUnderstanding the costs and benefits of producing either sons or daughters is at the heart of unravelling variation in patterns of sex allocation, and evolutionary biologists have made terrific theoretical and empirical progress in explaining sex allocation across a broad range of organisms (West 2009). One of the best examples comes from Hamilton’s enormously influential theory of Local Mate Competition (LMC), whereby competition amongst related males (such as brothers) for mates favours female-biased sex allocation (e.g. Burton-Chellew et al. 2008). LMC theory successfully predicts sex allocation in all sorts of organisms where there is competition amongst kin for mates, from malarial parasites to parasitoid wasps. In this project, we will explore sex allocation under LMC in the parasitoid wasp Nasonia vitripennis, focusing in particular on how controversial neonicotinoid pesticides disrupt adaptive sex ratio decision making. We have recently shown that sub-lethal exposure to the neonicotinoid imidacloprid ablates the LMC response in Nasonia (Whitehorn et al. 2015), but we currently do not know how sex allocation is disrupted or what the broader ecological consequences might be for parasitoid wasps. This is important as parasitoids are crucial natural enemies of arthropod pests, and they are commonly released as biological control agents in a variety of agricultural and horticultural settings. Whilst the negative effects of neonicotinoids have thus far focused on pollinating insects (such as honey bees and bumblebees), parasitoids are also important “beneficial insects”, providing valuable ecosystem services that we need to maintain in our landscapes.

In this project, the PhD student will explore how neonicotinoids such as imidacloprid disrupt sex allocation. Neonicotinoids are potent neurotoxins, irreversibly binding to nicotinic acetylcholine receptors. The student will: (1) test hypotheses that neonicotinoids disrupt the information gathering and information processing required by female Nasonia when allocating sex under LMC; (2) identify the location of the targets of neonicotinoids across the wasp, comparing and contrasting different neonicotinoids; (3) test the ecological consequences of neonicotinoid disruption in semi-natural environments. As well as advancing our understanding of the effects of neonicotinoids, this project will also offer new insights into the mechanisms by which female Nasonia allocate sex in response to LMC. This project therefore provides a unique opportunity to combine cutting-edge behavioural ecology with applied entomology, and highlights the importance of understanding the evolution of life-history strategies when considering the social and economic costs of ecosystem interventions.

The project will provide a number of key training opportunities: (1) experimental design and behavioural techniques in the lab and field; (2) quantitative skills, from data management through to statistical analysis; (3) neuroscience training, in terms of the analysis of neural substrates and neurophysiology; (4) communication skills, to academic, industrial and non-technical audiences.

For further details of the research carried out in the Insect Behavioural Ecology lab, please visit our website: http://insects.st-andrews.ac.uk. We also strongly recommend making informal enquiries showing your interest by emailing Dr David Shuker (david.shuker@st-andrews.ac.uk).

Relevant references

Burton-Chellew, M.N., Koevoets, T., Grillenberger, B.K., Sykes, E.M., Underwood, S.L., Bijlsma, K., Gadau, J., van de Zande, L., Beukeboom, L.W., West, S.A. & Shuker, D.M. (2008) Facultative sex ratio adjustment in natural populations of wasps: cues of local mate competition and the precision of adaptation. American Naturalist, 172: 393-404.

West, S.A. (2009) Sex Allocation. Princeton University Press, Princeton.

Whitehorn, P.R., Cook, N., Blackburn, C., Gill, S., Green, J. & Shuker, D.M. (2015) Neonicotinoids disrupt adaptive facultative sex allocation in a beneficial insect. Proceedings of the Royal Society, Series B, 282: 20150389.

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