The Diet and Sexual Differences of the Caspian Bent-Toed Gecko, Tenuidactylus caspius (Squamata: Gekkonidae), in Northern Iran

The Caspian bent-toed gecko, Tenuidactylus caspius, is one of the most common nocturnal lizards of Iran with widespread distribution especially in the northern provinces. This research was done in order to study the diet and sexual dimorphism of this species in Sari County from 5 May to 20 October. During this research, 40 specimens of them including 20 males and 20 females were studied for diet and 140 specimens including 70 adult males and 70 adult females were studied for sexual dimorphism. Prey items identified were insects that belong to 15 species of 8 families and 6 orders. The most common prey items were Culex pipiens and Musca domestica. There is no significant difference between diets of males and females. Results show that the adult males in addition of having the apparent femoral and preanal pores are heavier than females and have larger body, head, and tail length. 1. Introduction Sexual dimorphism in size, morphology, coloration, and aggression is widespread among lizard species and may result from three mechanisms: sexual selection, reproductive role mechanisms (e.g., fecundity selection), and intersexual food competition [1, 2]. Variation among male lizards in sizes of bodies, heads, and other structures in coloration and in courtship and aggression displays may be related to differences among males in reproductive success [3]. Larger male lizards win male-male aggressive encounters and gain greater access to females or they are chosen as mates either because of their size or characteristic that is correlated with large size [4]. However, sexual body size dimorphism may have causes other than sexual selection. The differential mortality between the sexes may cause an apparent size dimorphism because of unequal age of the sexes [5]. Males moving out in search of females must have a high rate of encounter with predators, so large body size of males would enhance their changes of evading some predators and of being too large for other. Two other possible reasons for males being larger than females are intersexual food resource partitioning [6] and forcible insemination of females [7]. The Caspian bent-toed gecko, Tenuidactylus caspius, is one of the most common lizards in northern Iran. This species is nocturnal and oviparous. Recently, some studies have been done on sexual dimorphism of lizards of Iran [8, 9]. Also, there is no work on the diet of this species. This study was conducted to provide information on sexual dimorphism and food habits of T. caspius in northern Iran. 2. Material and Methods 2.1. Study Area The study locality was