Sexual dimorphism in the lizard Sceloporus siniferus: support for the intraspecific niche divergence and sexual selection hypotheses

作者：Hierlihy Catherine A; Garcia Collazo Rodolfo; Chavez Tapia Catalina B; Mallory Frank F^*

来源：Salamandra, 2013, 49(1): 1-6.

• Squamata
• Phrynosomatidae
• sexual dimorphism
• intraspecific divergence
• sexual selection
• foraging strategies

Two hypotheses that attempt to explain the evolution of sexual size dimorphism in vertebrates are those of: (1) sexual selection and (2) intraspecific niche divergence. Sexual selection is most often attributed to female mate selection or male/male competition for females and results in variation in morphological characteristics (e.g., body size, secondary sex traits). Intraspecific niche divergence may occur when the sexes differ in dietary or habitat requirements and can lead to dietary and trophic morphological differences (e.g., internal organs etc.). In this study, we examined diet composition, trophic morphology and sexual dimorphism in the lizard Sceloporus siniferus from Huatulco, Mexico. Results support the conclusion that the biased size dimorphism in favour of males (male mean body mass 6.72 g vs. female mean body mass 5.67 g) is a result of sexual selection; however, trophic morphological differences, such as the larger gastrointestinal system of females and differences in diet composition between the sexes may be the result of intraspecific niche divergence and appear to be adaptations for increased nutritional acquisition associated with the elevated reproductive energy requirements of females. These results support the conclusion that both sexual selection and intraspecific niche divergence selective processes occur in S. siniferus.

• 出版日期2013-4-30