Genetic and environmental components of growth in nestling blue tits (Parus caeruleus)
Article first published online: 25 DEC 2001
Journal of Evolutionary Biology
Volume 13, Issue 2, pages 199–212, March 2000
How to Cite
Kunz and Ekman (2000), Genetic and environmental components of growth in nestling blue tits (Parus caeruleus) . Journal of Evolutionary Biology, 13: 199–212. doi: 10.1046/j.1420-9101.2000.00158.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- developmental plasticity;
- genetic variation;
- genotype–environment interaction;
- reaction norm
We investigated the effect of brood-size mediated food availability on the genetic and environmental components of nestling growth in the blue tit (Parus caeruleus), using a cross-fostering technique.
We found genetic variation for body size at most nestling ages, and for duration of mass increase, but not of tarsus growth. Hence, nestling growth in our study population seems to have the potential to evolve further. Furthermore, significant genotype–environment interactions indicated heritable variation in reaction norms of growth rates and growth periods, i.e. that our study population had a heritable plasticity in the growth response to environmental conditions.
The decreasing phenotypic variance with nestling age indicated compensatory growth in all body traits. Furthermore, the period of weight increase was longer for nestlings growing up in enlarged broods, while there was no difference to reduced broods in the period of tarsus growth. At fledging, birds in enlarged broods had shorter tarsi and lower weights than birds in reduced broods, but there was no difference in wing length or body condition between the two experimental groups. The observed flexibility in nestling growth suggests that growing nestlings are able to respond adaptively to food constraint by protecting the growth of ecologically important traits.