No sex difference in yolk steroid concentrations of avian eggs at laying

Pilz, Kevin M.; Adkins‐Regan, Elizabeth; Schwabl, Hubert

doi:10.1098/rsbl.2005.0321

Cited by 45 publications

(35 citation statements)

References 31 publications

(56 reference statements)

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“…Using a competitive binding RIA with hormone specific antibodies (Endocrine Science, USA), hormone concentrations (pg steroid per mg yolk) were determined in five double radioimmunoassays over a period of two years. The average recovery rate for A4 was 55.5%, 27.1% for DHT and 37.5% for T. These recovery rates are relatively low, but still similar to those published in other studies (e.g., Reed & Vleck, 2001;Pilz et al, 2005). Since average hormone levels and the pattern over the laying sequence was similar as in other studies (see Results) we are confident that the data are meaningful.…”

Section: Hormone Analysessupporting

confidence: 65%

Maternal yolk androgens in European starlings: affected by social environment or individual traits of the mother?

Eising¹,

Pavlova²,

Groothuis³

et al. 2008

Behav

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SummarySocial competition among female birds has been shown to positively affect yolk androgen levels, perhaps providing a mechanism to communicate environmental conditions to offspring. Whether this relationship is due to social density or to differences among mothers that breed in different social situations is unclear. We manipulated breeding density to test these alternative explanations. Yolk androgens were measured in clutches of European starlings, Sturnus vulgaris, breeding in consecutive years in outdoor aviaries of different sizes and with varying numbers of breeding pairs. Testosterone (T) levels increased significantly with increasing density. Dihydrotestosterone (DHT) levels increased with the number of nest boxes available. The number of nest boxes monopolized by a breeding male negatively affected androstenedione (A4) levels, positively affected DHT levels and did not affect T levels. Other factors related to social interactions or competition among females (including polygyny) did not influence yolk hormone levels. Within-female yolk androgen levels were highly consistent over two consecutive years even though females were breeding in opposite breeding densities during each year, suggesting that individual characteristics are important determinants of variation in maternal androgen allocation in addition to potential effects of environmental conditions. This within-female consistency of yolk androgen levels across years has important implications.

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Section: Hormone Analysessupporting

confidence: 65%

Maternal yolk androgens in European starlings: affected by social environment or individual traits of the mother?

Eising¹,

Pavlova²,

Groothuis³

et al. 2008

Behav

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“…However, this scenario appears unlikely given that evidence for differential allocation of T to male and female eggs is weak across species [50], and absent in Japanese quail [51] (see also the electronic supplementary material, S2). Furthermore, although the T manipulation was performed within the natural range, it is possible that the lack of a difference might be due to dose-response effects [52].…”

Section: Discussionmentioning

confidence: 99%

Matrilineal inheritance of a key mediator of prenatal maternal effects

et al. 2016

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Sex-linkage is predicted to evolve in response to sex-specific or sexually antagonistic selection. In line with this prediction, most sex-linked genes are associated with reproduction in the respective sex. In addition to traits directly involved in fertility and fecundity, mediators of maternal effects may be predisposed to evolve sex-linkage, because they indirectly affect female fitness through their effect on offspring phenotype. Here, we test for sex-linked inheritance of a key mediator of prenatal maternal effects in oviparous species, the transfer of maternally derived testosterone to the eggs. Consistent with maternal inheritance, we found that in Japanese quail ( Coturnix japonica ) granddaughters resemble their maternal (but not their paternal) grandmother in yolk testosterone deposition. This pattern of resemblance was not due to non-genetic priming effects of testosterone exposure during prenatal development, as an experimental manipulation of yolk testosterone levels did not affect the females' testosterone transfer to their own eggs later in life. Instead, W chromosome and/or mitochondrial variation may underlie the observed matrilineal inheritance pattern. Ultimately, the inheritance of mediators of maternal effects along the maternal line will allow for a fast and direct response to female-specific selection, thereby affecting the dynamics of evolutionary processes mediated by maternal effects.

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“…We did not quantify maternal investment in the eggs, because we were interested in chick behavior and yolk biopsies can lead to lower hatching success (e.g., Pilz et al. 2005), thereby potentially decreasing our sample size. We further manipulated hatching order to allow chicks supposed to hatch in a junior position to gain a senior position and thus express more easily the effects of our prelaying feeding treatment on their behavior (full design described in Fig.…”

Section: Introductionmentioning

confidence: 99%

Maternal effects as drivers of sibling competition in a parent–offspring conflict context? An experimental test

Merkling

Perrot

Helfenstein

et al. 2016

Ecology and Evolution

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Maternal effects occur when the mother's phenotype influences her offspring's phenotype. In birds, differential allocation in egg yolk components can allow mothers to compensate for the competitive disadvantage of junior chicks. We hypothesize that the parent–older chick conflict peaks at intermediate conditions: parents benefit from the younger chick(s) survival, but its death benefits the older chick in terms of growth and survival. We thus expect maternal compensation to follow a bell‐shaped pattern in relation to environmental conditions. We studied a black‐legged kittiwake (Rissa tridactyla) population where previous results revealed increased allocation of yolk testosterone in younger as compared to older chicks in intermediate conditions, in line with our theoretical framework. We therefore predicted a maternally induced increase in aggressiveness, growth, and survival for younger chicks born in intermediate environmental conditions. Controlling for parental effects and chick sex, we manipulated food availability before egg laying to create a situation with intermediate (Unfed group) and good (Fed group) environmental conditions. Within each feeding treatment, we further created experimental broods where the natural hatching order was reversed to maximize our chances to observe an effect of feeding treatment on the younger chicks' aggressiveness. As predicted, we found that chick aggressiveness was higher in younger chicks born from the Unfed group (i.e., in intermediate environmental conditions), but only when they were put in a senior position, in reversed broods. Predictions on growth and survival were not confirmed. Mothers thus seem to favor the competitiveness of their younger chick in intermediate conditions via egg yolk components, but our study also suggests that hatching asynchrony need to be small for maternal compensation to be efficient. We emphasize the need for further studies investigating other chick behaviors (e.g., begging) and focusing on the relative role of different yolk components in shaping parent–offspring conflict over sibling competition.

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No sex difference in yolk steroid concentrations of avian eggs at laying

Cited by 45 publications

References 31 publications

Maternal yolk androgens in European starlings: affected by social environment or individual traits of the mother?

Maternal yolk androgens in European starlings: affected by social environment or individual traits of the mother?

Matrilineal inheritance of a key mediator of prenatal maternal effects

Maternal effects as drivers of sibling competition in a parent–offspring conflict context? An experimental test

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