As DCs are key modulators of the host adaptive immune response, they are ideal targets for the pathogen's immunity-manipulating efforts.
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.
Furthermore, it has recently been suggested that experimentally manipulating reproductive effort is the only way to properly test a key prediction of the oxidative stress theory of tradeoffs: that increased reproductive effort is associated with (or directly causes) increased oxidative damage; e.g., [ 21].
> -wrap-foot> degreesees of freedom; χ 2 chi-square statistic Our results indicate that female pied flycatchers do 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.
For example, females could try to manipulate male effort when they are mated with a male that is a poor-quality provider (e.g. an inexperienced young male), in order to make the male compensate for his poor parental skills with higher parental effort (Michl et al. 2005; Navara et al. 2006).
This indicates that a potential attempt by the female to manipulate male effort through yolk androgens does not depend on male attractiveness (as measured by UV reflectance, forehead patch size or dorsal coloration).
However, we suggest here that the absence of the predicted relationships could be due to a fundamental problem in the design of all of the published empirical studies, namely a failure to manipulate reproductive effort.
Relative to reward processing, very few studies have directly manipulated physical effort while recording the activity of frontal neurons.
It has therefore been suggested that female birds might be able to manipulate male effort to their benefit through elevated transfer of these hormones to the eggs (Lessells 2006; Moreno-Rueda 2007; Müller et al. 2007).
Although we found no evidence that females could manipulate the effort of young males, one possible explanation for the observed pattern is that females evolved to exploit young males but the males then evolved to neglect the cues that females could use for exploitation.
The case underscores how even investments by a private entity, this one with ties to Beijing, can be manipulated to undermine efforts to support human rights standards.
