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Yolk hormones and sexual conflict over parental investment in the pied flycatcher.

Laaksonen T, Adamczyk F, Ahola M, Möstl E, Lessells CK - Behav. Ecol. Sociobiol. (Print) (2010)

Bottom Line: Females did not succeed in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within a pair and either original or foster egg androgen levels.The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young (45%) and females laid eggs with higher androgen levels when mated with a young male.Young males did not exhibit any responses to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males.

View Article: PubMed Central - PubMed

ABSTRACT
Female birds might be able to manipulate the parental effort of their male partner through elevated transfer of hormones to the eggs, since these hormones affect many chick traits that males might use as cues for adjusting the level of their investment. We experimentally studied whether female pied flycatchers Ficedula hypoleuca could manipulate male investment via yolk androgens. There is much more variation in yolk androgen levels between females than within clutches, and in order to change the androgen levels of the eggs, we swapped whole clutches between nests. To estimate the androgen levels of the clutch, we measured the androgen content of a single egg per clutch. Females did not succeed in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within a pair and either original or foster egg androgen levels. One of these relationships should have occurred if females were manipulating males. The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young (45%) and females laid eggs with higher androgen levels when mated with a young male. Young males did not exhibit any responses to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males. We suggest that females may allocate yolk androgens to adjust the growth trajectories of the chicks to poor growing conditions when mated with young males that are poor providers or occupying a poor territory.

No MeSH data available.


Related in: MedlinePlus

The predictions for the experiment. a If females can manipulate male investment using a cue to which only males respond, proportional investment by the male should increase with increasing androgen level in the foster eggs. There is no clear prediction for the relationship between proportional investment by the male and the original egg androgen levels. b If females can manipulate male investment using a cue to which both sexes respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should reduce her responsiveness to the androgen-mediated cue(s) of the chicks. There is no clear prediction for the relationship between the proportional investment by the male and foster egg androgen levels
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Fig1: The predictions for the experiment. a If females can manipulate male investment using a cue to which only males respond, proportional investment by the male should increase with increasing androgen level in the foster eggs. There is no clear prediction for the relationship between proportional investment by the male and the original egg androgen levels. b If females can manipulate male investment using a cue to which both sexes respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should reduce her responsiveness to the androgen-mediated cue(s) of the chicks. There is no clear prediction for the relationship between the proportional investment by the male and foster egg androgen levels

Mentions: There are two alternative ways on how male effort could be manipulated by females using yolk androgens: (1) the cue (offspring trait) used by parents to adjust their parental investment could be male-specific, i.e. only the male parent responds to changes in the cue; or (2) the cue could be general, i.e. the female also responds. In the latter case, females laying eggs with high androgen levels are expected to reduce their own responsiveness to the offspring so that only their males make a higher parental investment (Müller et al. 2007). These two mechanisms have different consequences for co-evolution of male and female strategies (Müller et al. 2007) and our second aim was therefore to determine which of them the females might use. We predicted that if females could manipulate males, one of the following two patterns should appear as shown in Fig. 1: (1) If females could manipulate males using a cue to which only the males respond, the proportional investment by the male should increase with increasing androgen level in the foster eggs. (2) Alternatively, if females could manipulate male investment using a cue to which both sex parents respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should have low responsiveness to the androgen-mediated cue(s) of the chicks (in other words, she should be more insensitive to the cue that would otherwise make her feed more).Fig. 1


Yolk hormones and sexual conflict over parental investment in the pied flycatcher.

Laaksonen T, Adamczyk F, Ahola M, Möstl E, Lessells CK - Behav. Ecol. Sociobiol. (Print) (2010)

The predictions for the experiment. a If females can manipulate male investment using a cue to which only males respond, proportional investment by the male should increase with increasing androgen level in the foster eggs. There is no clear prediction for the relationship between proportional investment by the male and the original egg androgen levels. b If females can manipulate male investment using a cue to which both sexes respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should reduce her responsiveness to the androgen-mediated cue(s) of the chicks. There is no clear prediction for the relationship between the proportional investment by the male and foster egg androgen levels
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3197946&req=5

Fig1: The predictions for the experiment. a If females can manipulate male investment using a cue to which only males respond, proportional investment by the male should increase with increasing androgen level in the foster eggs. There is no clear prediction for the relationship between proportional investment by the male and the original egg androgen levels. b If females can manipulate male investment using a cue to which both sexes respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should reduce her responsiveness to the androgen-mediated cue(s) of the chicks. There is no clear prediction for the relationship between the proportional investment by the male and foster egg androgen levels
Mentions: There are two alternative ways on how male effort could be manipulated by females using yolk androgens: (1) the cue (offspring trait) used by parents to adjust their parental investment could be male-specific, i.e. only the male parent responds to changes in the cue; or (2) the cue could be general, i.e. the female also responds. In the latter case, females laying eggs with high androgen levels are expected to reduce their own responsiveness to the offspring so that only their males make a higher parental investment (Müller et al. 2007). These two mechanisms have different consequences for co-evolution of male and female strategies (Müller et al. 2007) and our second aim was therefore to determine which of them the females might use. We predicted that if females could manipulate males, one of the following two patterns should appear as shown in Fig. 1: (1) If females could manipulate males using a cue to which only the males respond, the proportional investment by the male should increase with increasing androgen level in the foster eggs. (2) Alternatively, if females could manipulate male investment using a cue to which both sex parents respond, the proportional investment by the male should increase with increasing androgen level in the original eggs of the nest. This is because a female that lays eggs with high androgen levels should have low responsiveness to the androgen-mediated cue(s) of the chicks (in other words, she should be more insensitive to the cue that would otherwise make her feed more).Fig. 1

Bottom Line: Females did not succeed in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within a pair and either original or foster egg androgen levels.The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young (45%) and females laid eggs with higher androgen levels when mated with a young male.Young males did not exhibit any responses to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males.

View Article: PubMed Central - PubMed

ABSTRACT
Female birds might be able to manipulate the parental effort of their male partner through elevated transfer of hormones to the eggs, since these hormones affect many chick traits that males might use as cues for adjusting the level of their investment. We experimentally studied whether female pied flycatchers Ficedula hypoleuca could manipulate male investment via yolk androgens. There is much more variation in yolk androgen levels between females than within clutches, and in order to change the androgen levels of the eggs, we swapped whole clutches between nests. To estimate the androgen levels of the clutch, we measured the androgen content of a single egg per clutch. Females did not succeed in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within a pair and either original or foster egg androgen levels. One of these relationships should have occurred if females were manipulating males. The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young (45%) and females laid eggs with higher androgen levels when mated with a young male. Young males did not exhibit any responses to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males. We suggest that females may allocate yolk androgens to adjust the growth trajectories of the chicks to poor growing conditions when mated with young males that are poor providers or occupying a poor territory.

No MeSH data available.


Related in: MedlinePlus