2 research outputs found
Egg colouration predicts brood size, telomere length and body condition of spotless starling fledglings
Understanding the impressive interspecific variation in avian eggshell colouration has
attracted the attention of evolutionary ecologists for more than a century. Several functional
explanations predict positive covariation between eggshell pigmentation and
phenotypic quality of nestlings. We test this prediction in spotless starlings Sturnus
unicolor by using biometric measurements and telomere length of hatchlings and
fledglings as proxies of phenotypic quality. Female spotless starlings lay immaculate
blue-green eggs, a sexually selected signal directed to males. Pigmentation predicts
positive associations with concentration of antioxidants and testosterone in the yolk
and with paternal provisioning effort during nestling growth. Eggshell pigmentation
(blue-green chroma) is not associated with telomere length of hatchlings, which suggests
weak maternal effects on this trait. However, we find negative associations of
eggshell colouration with both body condition and telomere length of fledglings.
Moreover, we find positive associations between eggshell colouration and clutch size,
which suggests that sibling competition is higher in nests with more coloured eggshells.
Previous works demonstrated that level of sibling competition is positively related to
telomere erosion and, thus, the detected negative associations between eggshell colouration,
body condition and telomere length of fledglings would reflect higher level of
competition in nests with more coloured eggshells. We therefore speculate with the
possibility that females that lay larger clutches also lay more coloured eggshells that
elicit increased paternal provisioning effort and, thus, raise larger broods at the expense
of telomere erosion of their offspring.Funding was provided by the Spanish Ministerio de
Economia y Competitividad and European funds (FEDER)
(CGL2013-48193-C3-1-P, CGL2013-48193-C3-2-P, CGL2012-
30759, CGL2015-65055-P). JMP, GT and MRR were supported
by Juan de la Cierva, Ramón & Cajal and Talentia postdoctoral
contracts, respectively. JMP was partially supported by a 2017
Leonardo Grant for Researchers and Cultural Creators, BBVA
Foundation.Peer reviewe