We are working with a tri-trophic food web involving trees, caterpillars and blue tits.
Some of the questions we are currently working on are outlined below. Click on each for more details.
1. Experimentally determine the causal relationship between lay date and fitness
Rationale To understand how temperature change may affect selection on lay date requires that we first understand the causal relationship between lay date and fitness.
We are conducting a large-scale clutch-swap experiment along the transect whereby we cause some birds to advance their hatch date and others to delay their hatch date. This experiment will allow us to separate the effects of timing from the effect of individual quality.
2. Quantify intraspecific spatial variation in B, the environmental sensitivity of selection
Rationale B is the environmental sensitivity of selection and in the context of our work it is defined as the change in optimum lay date for a change in spring temperature. If we want to predict how populations may respond to warming then B is an important parameter to estimate. Spatial variation in B reveals the degree to which we can generalise from one population to others.
We are estimating the average B in the blue tit and distinguishing between the following hypotheses:
(i) B is a property of a species (i.e. it shows little intraspecific variation among sites);
(ii) B is a property of a population and it varies substantially among sites.
3. Understand the mechanistic basis of spatial variation in B
Rationale Our ability to extrapolate insights into selection from one ecological context to another depends on understanding spatial variation in the mechanism that link phenology to fitness.
In woodland passerine birds temperature-mediated seasonal food availability is often assumed to be the mechanism that links phenology to fitness. We are looking at the composition of nestling diet to address this question.
We have established a transect along a latitudinal gradient in Scotland. During the field season, we visit 44 sites along the transect to track tree, invertebrate and bird phenology. To get further insight into what the field season is like for us, you can read through our blog posts and take a look at the video below.
1. Shutt, J.D (2017) Expanding a classic woodland food chain into a geographically variable food web. PhD thesis. University of Edinburgh
You can find more information about opportunities to join Phenoweb here.