Egg corticosterone can stimulate telomerase activity and promote longer telomeres during embryo development

Noguera, J.C., da Silva, A. and Velando, A., Egg corticosterone can stimulate telomerase activity and promote longer telomeres during embryo development. Molecular Ecology. https://doi.org/10.1111/mec.15694


It is often assumed that the transfer of maternal glucocorticoids (GCs; e.g. corticosterone or cortisol) to offspring is an inevitable cost associated with adverse or stressful conditions experienced by mothers. However, recent evidence indicates that maternal GCs may adaptively program particular physiological and molecular pathways during development to enhance offspring fitness. In this context, an important mechanism through which maternal GCs may lastingly affect offspring phenotypic quality and survival is via effects on embryo telomerase activity and so on offspring postnatal telomere length. Here, using a field experimental design for which we manipulated the corticosterone content in yellow‐legged gull (Larus michahellis) eggs, we show that embryos from corticosterone‐injected eggs not only had a higher telomerase activity but also longer telomeres just after hatching. A complementary analysis further revealed that gull hatchlings with longer telomeres had a higher survival probability during the period when most of the chick mortality occurs. Given the important role that telomere length and its restoring mechanisms have on ageing trajectories and disease risk, our findings provide a new mechanistic link by which mothers may presumably shape offspring life‐history trajectories and phenotype.


https://doi.org/10.1111/mec.15694

Gull chicks grow faster but lose telomeres when prenatal cues mismatch the real presence of sibling competitors

Noguera, J.C. and Velando, A., 2020. Gull chicks grow faster but lose telomeres when prenatal cues mismatch the real presence of sibling competitors. Proceedings of the Royal Society B, 287(1927), p.20200242.


During embryonic life, individuals should adjust their phenotype to the conditions that they will encounter after birth, including the social environment, if they have access to (social) cues that allow them to forecast future conditions. In birds, evidence indicates that embryos are sensitive to cues from clutch mates, but whether embryos adjust their development to cope with the expected level of sibling competition has not hitherto been investigated. To tackle this question, we performed a ‘match versus mismatch’ experimental design where we manipulated the presence of clutch mates (i.e. clutch size manipulation) and the real (postnatal) level of sibling competition (i.e. brood size manipulation) in the yellow-legged gull (Larus michahellis). We provide evidence that the prenatal cues of sibling presence induced developmental changes (such as epigenetic profiles) that had programming effects on chick begging behaviour and growth trajectories after hatching. While receiving mismatching information favoured chick begging and growth, this came at the cost of reduced antioxidant defences and a premature loss of telomeres. Our findings highlight the role of the prenatal social environment in developmental plasticity and suggest that telomere attrition may be an important physiological cost of phenotype–environment mismatch.


https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2020.0242

Parental food conditions affect sex-specific embryo mortality in the yellow-legged gull (Larus michahellis)

Pérez, C., Velando, A. & Domínguez, J. Parental food conditions affect sex-specific embryo mortality in the yellow-legged gull (Larus michahellis). Journal of Ornithology 147, 513–519 (2006).


Different mortality of males and females during early post-hatching development in sexually size-dimorphic bird species is usually attributed to different nutritional requirements of the sexes, because mortality is mostly biassed toward the larger sex. We investigated whether sex-specific embryo mortality in the yellow-legged gull (Larus michahellis), a size-dimorphic seabird, depends on parental condition. To test this, we experimentally modified parental nutritional conditions by supplementary feeding of yellow legged gulls during egg formation, to evaluate sex-biassed environmental sensitivity of gull embryos. We found that eggs were larger in supplemented clutches, but egg size did not affect embryo survival. Survival of male gull embryos was more related to parental food conditions than was survival of female embryos. Survival of male embryos in supplemented clutches was greater than in unsupplemented clutches whereas survival of female embryos was similar in both groups. Because size at hatching was similar in both sexes our results suggest that male phenotype disadvantage is not exclusively linked to the energy demands of size-dimorphic development at the embryo stage.