Lizard she-males get ahead
flatlizard.jpg
Augrabies Flat Lizard 'she-males' can
survive longer by avoiding competition from
older men.
Image: Martin Whiting, WITS

The Augrabies Flat Lizard (Platysaurus broadleyi), a star of Sir David Attenborough’s recent series Life in Cold Blood, adds another twist to its tale. A team of South African and Australian researchers have discovered that some males of this dramatically coloured lizard mimic females during early maturity and thereby avoid the costs of broadcasting their masculinity.

As juveniles, all males look like females before gradually developing extravagant adult male coloration at the onset of sexual maturity. These young males are most vulnerable to aggressive adult male rivals when these first tell-tale signs of masculinity begin to develop and adults are quick to capitalise on a soft target by chasing and sometimes biting these young males.

Assoc. Prof. Whiting pointed out that “by delaying the onset of colour to a more convenient period, these males (termed she-males) are making the best of a bad situation”. An immediate advantage is freedom of movement in the normally treacherous zones which make up the territories of highly aggressive males that already have extensive fighting experience. At the same time, these female mimics are able to court the myriad of females that share the territorial male’s residence.

The authors of this study (Assoc. Prof. Martin Whiting of the University of the Witwatersrand; Dr. Jonathan Webb of the University of Sydney; and Assoc. Prof. Scott Keogh of the Australian National University) also tested whether she-males are able to mimic the chemical ‘signature’ of females.

In a clever experiment performed in the wild, they removed all pheromones and skin lipids that might signal gender and relabelled a group of females and she-males with either male or female scent, before presenting them to typical adult males. Males use their tongues to sample chemical scent and responded by courting she-males labeled as females, but not she-males labeled as males. “Males are fooled by looks, but not by scent” said Dr. Webb.

She-males are able to maintain this deception by staying one step ahead of a prying male, and thereby avoiding a nosey tongue that might give the game away.  Assoc. Prof. Keogh said that “young transvestite males appear to have a dual advantage: the avoidance of potentially dangerous bouts with dominant males and access to normally inaccessible females”.