Negative effects of yolk testosterone and ticks on growth in canaries

Vergauwen, Jonas; Heylen, Dieter; Eens, Marcel; Müller, Wendt

doi:10.1002/jez.704

Cited by 12 publications

(6 citation statements)

References 68 publications

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“…However, androgen levels that are too high might have higher associated costs to fuel metabolism, like excessive energy expenditure or increased susceptibility to oxidative damage as a consequence of free radical production (Alonso-Alvarez et al, 2007), and this could ultimately result in a loss of body mass at hatching. Furthermore, the effects of elevated yolk androgens on growth may be dependent on egg quality, relating to a likely prenatal context dependency (Williams, 1994;Vergauwen et al, 2011). For a better understanding of the effects of maternal yolk steroids, we need a broader and more specific knowledge of the mechanisms of androgen actions in the embryo.…”

Section: Discussionmentioning

confidence: 99%

Diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine

Muriel

Pérez‐Rodríguez

Puerta

et al. 2015

Journal of Experimental Biology

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Avian egg yolks contain various amounts of maternally derived androgens that can modify offspring phenotype and adjust their development to the post-hatching environment. Seemingly adaptive variation in yolk androgen levels with respect to breeding density conditions or male attractiveness has been found in numerous studies. One important consideration that has been overlooked in previous research is the likely non-linear nature of hormone effects. To examine possible complex dose-response effects of maternal androgens on chick development, we experimentally administered three different androgen doses of the naturally occurring mixture of yolk testosterone and androstenedione to spotless starling eggs (Sturnus unicolor). We found that yolk androgens induce a non-linear dose-response pattern in several traits. Androgens had a stimulatory effect on hatchling body mass and nestling skeletal growth, but maximum values were found at intermediate doses, whereas our highest dose resulted in a decrease. However, the opposite U-shaped effect was found on nestling body mass. We also detected linear negative and positive effects on embryonic development period and nestling gape width, respectively. Our results suggest differential tissue responsiveness to yolk androgens, which may result in compromises in maternal allocation to produce adapted phenotypes. Because of the non-linear doseresponse pattern, future investigations should carefully consider a wide range of concentrations, as the balance of costs and benefits may strongly differ depending on concentration.

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Section: Discussionmentioning

confidence: 99%

Diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine

Muriel

Pérez‐Rodríguez

Puerta

et al. 2015

Journal of Experimental Biology

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“…The injected dose elevated the testosterone levels of the first-laid eggs to the levels of the last laid eggs [first/s egg: 45.01 ± 26.57 ng/yolk, N = 14; third/fourth egg: 68.09 ± 44.16 ng/yolk, N = 11; both mean ± standard deviation, Müller et al, 2010]. We used a previously established injection protocol (Vergauwen et al, 2011). Briefly, eggs were cleaned before injecting the respective solution directly into the yolk of the egg.…”

Section: History Of the Experimental Animalsmentioning

confidence: 99%

“…In addition, here dyads have been matched for body mass, which may mask effects that result from yolk testosterone stimulated offspring growth and thus adult size (e.g. in canaries: Müller et al, 2010;Schwabl, 1996;Vergauwen et al, 2011). However, it remains as yet unclear why the effects on social dominance tend to differ among studies and study species.…”

Section: Initial Differences Between Yt-and Yc-males Prior To Testostmentioning

confidence: 99%

Testosterone influences song behaviour and social dominance – But independent of prenatal yolk testosterone exposure

Vergauwen

Groothuis

Eens

et al. 2014

General and Comparative Endocrinology

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a b s t r a c tIn the last two decades, maternally derived yolk androgens have been shown to significantly alter offspring development, and a number of these effects persist into adulthood. However, little is known about their underlying mechanisms. Mechanisms that have been suggested are changes in the endogenous androgen production post-hatching or changes in the sensitivity towards circulating androgens.We tested the effects of yolk testosterone on the plasma testosterone levels and the sensitivity to testosterone in 5 months old male canaries that hatched from eggs that were either injected with testosterone (yT-males) or with a control solution (yC-males). Changes in sensitivity were investigated via the behavioural response to an experimental elevation of the plasma testosterone levels. We performed the experiment in fall (low endogenous testosterone production), focusing on testosterone dependent response traits (aggression and song).Before implantation, there was a non-significant trend that the plasma testosterone levels were lower in yT-males than in yC-males. Elevating the plasma testosterone concentrations increased aggressiveness, song bout length and similarity of repeated song elements (=consistency), with the latter likely being a consequence of testosterone-driven song crystallization. However, these effects were not different among yT-or yC-males in any of the parameters. Thus, our findings render it unlikely that changes in the sensitivity to testosterone post-hatching would form the main underlying mechanism of hormonemediated maternal effects in birds. Further experiments are urgently needed in order to understand the nature of the phenotypic effects resulting from embryonic exposure to maternal yolk testosterone.

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“…This is supported by the fact that yolk A 4 occurs in relatively low levels in canary eggs compared to other species such as gulls (e.g. [18,47,54], this study), while it is known that yolk testosterone modulates early growth in this species [34,35,48,55]. The latter has been shown to particularly benefit chicks that were competing with heavier and older siblings, as occurs in the context of hatching asynchrony [34].…”

Section: Hormone Allocationmentioning

confidence: 51%

Food conditions affect yolk testosterone deposition but not incubation attendance

Vergauwen

Goerlich

Groothuis

et al. 2012

General and Comparative Endocrinology

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In many bird species with hatching asynchrony, yolk androgens increase across the laying sequence. This has been hypothesized to represent a compensatory mechanism for disadvantages of later-hatching chicks - via positive effects of yolk androgens on early competitiveness and growth. However, the costs and benefits of this compensatory strategy probably depend on environmental factors determining the survival chances of the chicks such as the food conditions, which should, therefore, influence maternal yolk androgen deposition. We studied the consequences of manipulated food conditions on the expected level of hatching asynchrony in canaries (Serinus canaria) assigning females to either a low (=LQ) or high quality (=HQ) diet. We measured the incubation behaviour (as incubation attendance) and the yolk androgen deposition in order to investigate whether and how females modulate hatching asynchrony in relation to the food conditions. Females on a HQ diet laid larger and heavier clutches, showed a stronger increase in yolk testosterone content towards the last-laid eggs, but did not alter their incubation attendance. Thus, females on a HQ diet seem to favour the survival of later hatching chicks, as indicated by their yolk testosterone deposition pattern. However, females on a HQ diet laid larger clutches and might need to compensate more in order to achieve a similar degree of hatching asynchrony than females on a LQ diet, given the lack of plasticity in incubation attendance. This suggests that canary females respond to food manipulations mainly via changes in clutch size rather than by altering the degree of hatching asynchrony.

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Negative effects of yolk testosterone and ticks on growth in canaries

Cited by 12 publications

References 68 publications

Diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine

Diverse dose-response effects of yolk androgens on embryo development and nestling growth in a wild passerine

Testosterone influences song behaviour and social dominance – But independent of prenatal yolk testosterone exposure

Food conditions affect yolk testosterone deposition but not incubation attendance

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