How mothers and early-life factors shape later development: investigating a pervasive phenomenon in an unusual model system
Supervisors: Dr Sinead English, Prof Rebecca Kilner
Importance of the area of research:
Experiences in early life have lasting impacts on behaviour, health and reproductive success across a great many species. For organisms starting life in the womb, the diet and environment experienced by the mother contributes significantly to these long-term effects. These delayed life-history effects, whereby the environment early in life or in the previous generation affects an organism's phenotype, have important implications for predicting how organisms will respond to environmental change, either by constraining plasticity or by priming individuals to adapt more rapidly. While there is extensive research across the natural world documenting the diversity and pervasiveness of these parental and early-life effects, important questions remain. For example, how do maternal and post-natal early-life influences interact to contribute to later development? To what extent are these early-life effects reversible when conditions change? Why are certain periods of development more sensitive to external experiences than others?
This project will investigate long-term effects of early experiences in an exciting system, the lactating and live-bearing Pacific beetle cockroach, Diploptera punctata. Females give birth to a brood of 7-13 nymphs after a 60-day gestation, during which developing young feed from a milk-like secretion from the female's intrauterine tract. Studies have shown that maternal nutrition and early social experiences have lasting effects on offspring development rate and body size. Males are more susceptible to these effects, although it is unclear why. The PhD will explore these effects by manipulating maternal nutrition and offspring environment in the laboratory.
What the student will be doing:
The scope of the project is flexible and a range of manipulations is possible. Maternal and offspring nutrition can be manipulated by varying the amount of standard laboratory food provided, or the composition of protein to sugar. Early-life social experience can be varied by adding or removing nymphs from a clutch after birth. By monitoring the growth and social behaviour of individuals from birth through to sexual maturity, the long-term effects of early-life manipulations can be contrasted with manipulations repeated later in development. Maternal investment can be monitored across subsequent broods to assess the extent to which females trade-off current investment versus future reproduction, and the role of infanticide or siblicide in these adjustments under food stress.
Fawcett, T. W. & Frankenhuis, W. E. Adaptive explanations for sensitive windows in development. Frontiers in zoology 12.1 (2015): 1.
Holbrook, G. L. & Schal, C. 2004 Maternal investment affects offspring phenotypic plasticity in a viviparous cockroach. Proc. Natl. Acad. Sci. U. S. A. 101, 5595–5597. (doi:10.1073/pnas.0400209101)
Holbrook, G. L. & Schal, C. 1998 Social influences on nymphal development in the cockroach, Diploptera punctata. Physiol. Entomol. 23, 121–130
Applicants may apply to the NERC DTP for funding for this project.