Does testosterone or coloration affect growth rates of adult males of the lizard Psammodromus algirus?

Elevation of circulating testosterone levels during the breeding season sti mulates the development of breeding coloration and favors traits that maxim ize reproductive success, but it may have several costs. Retardation of gro wth by testosterone has been proposed as one of these costs to males of lon g-lived species. We examine the results of a field experiment on the short- term (within the breeding season) and long-term (1 year) effects of heighte ning levels of testosterone on the growth of males of the lacertid lizard P sammodromus algirus. Testosterone did not affect the mass gain of males dur ing the reproductive period or between years. The between-years increase in snout-vent length in testosterone-supplemented males tended to be less tha n in control individuals. Within-season individual mass gain was mainly det ermined by body mass at emergence: the lower the body mass the higher the m ass gain. Our results do not support the idea that the production of orname ntal traits limits growth, as the negative correlation between degree of he ad coloration and mass gain disappeared when body mass was controlled for.