Abstract
Body shrinkage is a recently discovered, but already considered universal response to global warming. We know very little about the causes of body size reductions, in spite of the fact that currently two out of three species are becoming smaller. There are two untested mechanistic views. (1) Body shrinkage is a micro-evolutionary response to warming, as smaller individuals are better able to dissipate body heat with their higher surface/volume ratio. (2) Climate change disrupts trophic interactions, causing poor juvenile growth and stunted adult bodies. Given these contrasting views, there is an urgent need to establish links between growth, survival and climate-induced variations in body size. Shrinkage is expected to be most pronounced in the region warming up fastest, the Arctic. Indeed, Arctic-breeding juvenile shorebirds (red knot, Calidris canutus) are known to be smaller after warm Arctic summers. However, we don’t know what happens during warm Arctic summers that actually produce smaller birds. The aim is to experimentally unravel mechanisms of body shrinkage in red knots at their High-Arctic breeding grounds. To achieve this, we will investigate: (i) how a warming Arctic alters the food supply for neonatal red knots; (ii) how the altered food supply and climate affect growth and development in young knots. This project will unveil important mechanistic insights into Arctic-warming induced body shrinkages, insights that may help us generalize across other species. Moreover, as shrinkage often precedes population collapses, these insights may help us designing conservation programs to safeguard shrinking species in our rapidly changing world.
Netherlands