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Early-Life Telomere Dynamics Differ between the Sexes and Predict Growth in the Barn Swallow (Hirundo rustica).

Parolini M, Romano A, Khoriauli L, Nergadze SG, Caprioli M, Rubolini D, Santagostino M, Saino N, Giulotto E - PLoS ONE (2015)

Bottom Line: Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual's siblings was female-biased.Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex.Furthermore, it shows that the positive covariation between growth and relative telomere length depends on sex as well as social environment, in terms of sibling sex ratio.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, University of Milan, Milan, Italy.

ABSTRACT
Telomeres are conserved DNA-protein structures at the termini of eukaryotic chromosomes which contribute to maintenance of genome integrity, and their shortening leads to cell senescence, with negative consequences for organismal functions. Because telomere erosion is influenced by extrinsic and endogenous factors, telomere dynamics may provide a mechanistic basis for evolutionary and physiological trade-offs. Yet, knowledge of fundamental aspects of telomere biology under natural selection regimes, including sex- and context-dependent variation in early-life, and the covariation between telomere dynamics and growth, is scant. In this study of barn swallows (Hirundo rustica) we investigated the sex-dependent telomere erosion during nestling period, and the covariation between relative telomere length and body and plumage growth. Finally, we tested whether any covariation between growth traits and relative telomere length depends on the social environment, as influenced by sibling sex ratio. Relative telomere length declined on average over the period of nestling maximal growth rate (between 7 and 16 days of age) and differently covaried with initial relative telomere length in either sex. The frequency distribution of changes in relative telomere length was bimodal, with most nestlings decreasing and some increasing relative telomere length, but none of the offspring traits predicted the a posteriori identified group to which individual nestlings belonged. Tail and wing length increased with relative telomere length, but more steeply in males than females, and this relationship held both at the within- and among-broods levels. Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual's siblings was female-biased. Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex. Furthermore, it shows that the positive covariation between growth and relative telomere length depends on sex as well as social environment, in terms of sibling sex ratio.

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Relative telomere length (T/S ratio: mean ± s.e.) of male and female barn swallow nestlings 7 or 16 days after hatching.Values for relative telomere length at day 7 and day 16 for each individual are shown as a line.
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pone.0142530.g001: Relative telomere length (T/S ratio: mean ± s.e.) of male and female barn swallow nestlings 7 or 16 days after hatching.Values for relative telomere length at day 7 and day 16 for each individual are shown as a line.

Mentions: We first analyzed variation of relative TL between age 7 and 16 in a LMM where we included sex, age and sibling sex ratio as predictors together with their two-way interactions. A simplified model excluding the non-significant two-way interactions showed that relative TL decreased significantly, by ca. 10%, between age 7 and age 16 (Fig 1). Hence, there was a decrease in relative TL during the 9 days including the phase of maximal growth of nestling barn swallows, and such decline did not depend on sex, brood size or social nest environment in terms of sex ratio (see Statistical analyses).


Early-Life Telomere Dynamics Differ between the Sexes and Predict Growth in the Barn Swallow (Hirundo rustica).

Parolini M, Romano A, Khoriauli L, Nergadze SG, Caprioli M, Rubolini D, Santagostino M, Saino N, Giulotto E - PLoS ONE (2015)

Relative telomere length (T/S ratio: mean ± s.e.) of male and female barn swallow nestlings 7 or 16 days after hatching.Values for relative telomere length at day 7 and day 16 for each individual are shown as a line.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643985&req=5

pone.0142530.g001: Relative telomere length (T/S ratio: mean ± s.e.) of male and female barn swallow nestlings 7 or 16 days after hatching.Values for relative telomere length at day 7 and day 16 for each individual are shown as a line.
Mentions: We first analyzed variation of relative TL between age 7 and 16 in a LMM where we included sex, age and sibling sex ratio as predictors together with their two-way interactions. A simplified model excluding the non-significant two-way interactions showed that relative TL decreased significantly, by ca. 10%, between age 7 and age 16 (Fig 1). Hence, there was a decrease in relative TL during the 9 days including the phase of maximal growth of nestling barn swallows, and such decline did not depend on sex, brood size or social nest environment in terms of sex ratio (see Statistical analyses).

Bottom Line: Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual's siblings was female-biased.Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex.Furthermore, it shows that the positive covariation between growth and relative telomere length depends on sex as well as social environment, in terms of sibling sex ratio.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, University of Milan, Milan, Italy.

ABSTRACT
Telomeres are conserved DNA-protein structures at the termini of eukaryotic chromosomes which contribute to maintenance of genome integrity, and their shortening leads to cell senescence, with negative consequences for organismal functions. Because telomere erosion is influenced by extrinsic and endogenous factors, telomere dynamics may provide a mechanistic basis for evolutionary and physiological trade-offs. Yet, knowledge of fundamental aspects of telomere biology under natural selection regimes, including sex- and context-dependent variation in early-life, and the covariation between telomere dynamics and growth, is scant. In this study of barn swallows (Hirundo rustica) we investigated the sex-dependent telomere erosion during nestling period, and the covariation between relative telomere length and body and plumage growth. Finally, we tested whether any covariation between growth traits and relative telomere length depends on the social environment, as influenced by sibling sex ratio. Relative telomere length declined on average over the period of nestling maximal growth rate (between 7 and 16 days of age) and differently covaried with initial relative telomere length in either sex. The frequency distribution of changes in relative telomere length was bimodal, with most nestlings decreasing and some increasing relative telomere length, but none of the offspring traits predicted the a posteriori identified group to which individual nestlings belonged. Tail and wing length increased with relative telomere length, but more steeply in males than females, and this relationship held both at the within- and among-broods levels. Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual's siblings was female-biased. Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex. Furthermore, it shows that the positive covariation between growth and relative telomere length depends on sex as well as social environment, in terms of sibling sex ratio.

Show MeSH
Related in: MedlinePlus