P. vlangalii exhibits extreme sexual allometric dimorphism and exhibits positive assortative mating patterns (Qi et al. 2012). The positive assortative mating indicates that only larger males can win the reproductive competition in the mating pairs. Individuals with larger body sizes have been found to have stronger and longer tails (Qi et al. 2011a). We recently found a positive correlation between tail length and the size of the belly patch (the male tail-tip badge) in male P. vlangalii (Y. Qi, unpubl. data). Males also use their tail length and abdominal patch size in tail displays, and we found that larger males have longer tails and larger and more obvious belly patches (Fig. 2,3; Qi et al. 2011a). Tail length may also be used to signal male body condition and thus affect male competitiveness for female mates (Qi et al. 2012). We further found that tail length is positively correlated with individual bite force, and are consistent with previous studies (Ghafoor et al. 2009; Ghafoor et al. 2011; Qi et al. 2011a). Some previous studies showed that a longer tail is strongly associated with male aggressiveness and territoriality (Todd et al. 2010; Vonholdt et al. 2010), but this study found no correlation between male sex and tail length (Qi et al. 2011a). Tail length is primarily associated with male-biased dispersal in a wide range of lizard groups (Warkentin and Wheeler 1996; Piersma 2007; Bibiloni et al. 2012), and this may explain why only larger males but not smaller males were found to disperse from the study population. Thus, although males have longer tails and larger and more obvious social interaction-related traits than females, they do not have a greater ability to drive female dispersal. This will lead to moderating aggression between the sexes, which will reduce the costs of female dispersal.
Male P. vlangalii are larger than females; therefore, we used body dry mass as an indicator of individual condition in this study. Both male and female body dry mass was more strongly correlated with body length than total body length, probably because small-body size is disadvantageous by increasing the cost of reproduction and by decreasing the likelihood of escape from larger and more predators (Komdeur 2004). Furthermore, because male courtship behaviors were observed in the field, we included male body dry mass in our analyses to account for its potential effect on dispersal decision-making. d2c66b5586