Consequences of life history variation for demographic and phenological responses to environmental change

Supervisors: Luc Bussière (University of Stirling), Philip Stephens (University of Durham), Mario Vallejo-Marin (University of Stirling), Lynsey Bunnefeld (University of Stirling), Will Pearse (Utah State University)

Although shifts in phenology (the timings of recurrent biological phenomena) are among the clearest and best-supported consequences of climate change, both the factors predicting phenological shifts and the community consequences of such transitions remain far from clear. Life history traits (which affect age-specific probabilities of survival and reproduction) should play a central role in phenological evolution, but we need research that explores their possible contributions to interspecific diversity in the timing, duration and rate of progression of developmental stages. Assessing the likely consequences of phenological shifts for communities further requires empirical assessments of how shifts in phenology affect the fitness of interacting symbionts, and modelled simulations that explore the demographics of participants under alternate climate change scenarios.
This PhD project will assess whether phenological shifts predictably differ among species characterized by contrasting life histories, the evolutionary lability of traits affecting phenology, and the consequences of these findings for the prospects of symbionts. We focus on two groups with extraordinary variation in life history traits (hoverflies and dance flies) who provide a valuable pollination service to symbiotic flowering plants (flies are the main pollinators of many plants including members of the family Brassicaceae). Many hoverfly adults feed mainly on pollen and nectar (hence their value as pollinators), but their larvae have tremendously diverse habits, ranging from filter feeders living within rotting vegetation through to predaceous forms that devour other insects. These differences in larval diet could change the sensitivity of species to phenological cues, or alter adult requirements for pollen feeding. Dance flies are also important pollinators (especially in some habitats like alpine regions and the high arctic), and are known for unusual variation in sexual behaviour, including some taxa where elaborately adorned females compete for access to male-provisioned nutritious nuptial gifts. These differences in mating systems have strong implications for the timing and duration of adult activity.

The PhD project will have three main aims, each dedicated to an important aim:
Aim 1: assess covariance between life history traits and phenology. The candidate will use long-term historical data of species of hover flies and dance flies (from museums, recording schemes, and the Rothamsted Insect Survey) to identify key life history traits of interest: those most likely to affect nutritional status and reproductive periods. The candidate will then assess phylogenetic signal of traits and use phylogenetically-aware regression models to parameterize the relationship between life history and phenology.
Aim 2: quantify intraspecific spatial and temporal phenotypic variation in phenology. The candidate will identify fly species with the most comprehensive UK-wide historical observational datasets (from the Rothamsted Insect Survey). Using data from multiple sites and years, the candidate will use mixed-effects models to quantify the relative importance of phenotypic plasticity and local adaptation to within-species variation in phenological responses, and regress responses among species on life history traits as identified in aim 1.
Aim 3: measure the consequences of variation in life history and phenology for pollination efficiency and seed set. We will plant experimental arrays of brassicas that vary in abundance and flowering phenology duration, and manipulate plant phenology by varying planting time throughout the summer (thus isolating confounding factors that affect variation in seed set among populations and species). We will measure measure pollen limitation, the extent to which female reproductive success is constrained by pollination services over time, by monitoring pollinator populations over two flowering seasons using suction traps, malaise traps and observations of pollinating interactions. These results will provide some of the first evidence for the sensitivity of this ancient plant-pollinator network to phenological mismatches wrought through climate change, and could be fed into a simulation model of projected effects on the network of various climate-change scenarios.

To apply, contact Dr. Bussiere ([Email Address Removed]) ASAP to indicate your interest and obtain further instructions. The formal application to the University of Stirling Graduate School (including a current CV, personal statement, two references, and full transcripts) is due no later than Friday, 20 January 2017 (23:59 GMT), but you will want to discuss your candidacy with Dr. Bussière well before submitting. Informal enquiries are welcome. http://lucbussiere.com/