Illustration by Jan Heuschele
Small-scale movements in response to global threats
Natural selection
shapes behaviour, such as movement and migration in all organisms, but this is
difficult to study in small, millimetre-sized, organisms. With novel labelling
and tracking techniques, based on nanotechnology, we show in a recent paper
published in Proc. R. Soc. B (enclosed), how movement in a common zooplankton
species (Daphnia magna) is affected by size, morphology and previous exposure
to detrimental ultraviolet radiation (UVR). As illustrated by the artwork
(kindly provided by Jan Heuschele), all individuals responded with an immediate
movment away from the UVR (sun) exposure, but when released from the threat
they rapidly returned to the surface. Large individuals swam faster and
generally travelled longer distances than small (young) individuals, suggesting
ontogenetic differences in movement. Interestingly, individuals previously
exposed to UVR (during several generations) showed a more relaxed response to
UVR and travelled shorter total distances than those that were naive to UVR,
suggesting induced tolerance to the threat. We also show that smaller
individuals have lower capacity to avoid UVR which could explain patterns in
natural systems of lower migration amplitudes in small individuals. The ability
to change behavioural patterns in response to a threat, in this case UVR, adds
to our understanding of how organisms navigate in the ‘landscape of fear’, and
this has important implications for individual fitness and for interaction
strengths in biotic interactions.
HylanderProc.2014
Lars-Anders Hansson
Prof. Limnology
Lund University, Sweden
http://www.lu.se/aquaticecology
