Striped mouse

Striped mouse

Striped mouse (Rhabdomys pumilio) on the cover of the August edition of Behaviour

Striped mouse (Rhabdomys pumilio) on the cover of the August edition of Behaviour
My photo and the accompanying paper (see List of publications) were published in this issue.

Tuesday, January 31, 2012

Summary: Mateos (2005)

In vertebrates, the relationship between glucocorticoids, testosterone, social and sexual behaviours is often complicated and incompletely understood. The subordination stress paradigm predicts that subordinate individuals should show higher levels of glucocorticoids, dominants should have higher levels of testosterone and there should be an inverse relationship between glucocorticoid concentration and testosterone. Mateos (2005) studied male ring-necked  pheasants, Phasianus colchicus, and found that dominants and  high-displaying males had higher levels of testosterone, but, in contrast to expectations, also had higher levels of corticosterone. This indicates a positive correlation between testosterone and glucocorticoids. She suggests that the results support a stress-mediated version of the immunocompetence handicap hypothesis.

Monday, January 9, 2012

Summary: Mateos (2005)

The relationship between testosterone, glucocorticoids, social and sexual behaviour is complicated and poorly understood in vertebrates. It is thought that subordinates should have higher glucocorticoid levels (known as the subordination stress paradigm) and that dominant, more active, males should have higher concentrations of testosterone during the breeding season. It has thus been suggested that glucocorticoid and testosterone concentration should be inversely related. Mateos (2005) investigated the relationship between behaviour and hormone concentration in male ring-necked pheasants, Phasianus colchicus. She found that dominant and high-displaying males had higher levels of testosterone and corticosterone (a glucocorticoid) throughout the mating period, indicating that these two hormones are positively correlated. Mateos (2005) indicates that the results do not support the subordination stress paradigm, but she indicates that they may support the immunocompetence handicap hypothesis (through stress-mediation).

Tuesday, January 3, 2012

Summary: Garcia-Fernandez et al. (2010)

Eggs constitute most of the maternal investment in precocial birds as parents do not feed young post-hatching. The embryo and chick development are influenced by maternal testosterone in the yolk. Testosterone is deposited in eggs by females in response to the environment experienced during the laying period, which includes the quality of the mate. Garcia-Fernandez et al. (2010) assessed the relevance of female mate choice on egg characteristics in the grey partridge Perdix perdix. Females were allowed to choose between males in choice trials and were then mated with either preferred or non-preferred males. They found that eggs from both groups did not differ significantly in mass, but females mated to preferred males produced eggs with higher testosterone levels. They suggest that partner attractiveness is important in the transfer of maternally derived egg components.