It can be difficult to work out if a reptile is a male or female as often there is very little if any external differences between the sexes. This is in contrast to most mammals where gender determination is generally straight forward. Birds are also becoming increasingly easier to sex as we now have access to incredible DNA technology where we can tell the sex of your bird from 1 drop of blood — unfortunately this technology is not yet available for reptiles. A good example is if your reptile is a male it cannot suffer from conditions like dystocia difficulty giving birth but may be more aggressive towards other males in the cage. If you have a male python it may be more prone to brumating similar to hibernating and not eating for longer than a female during the cooler months of the year. Visual sex determination Some reptiles have obvious sexual dimorphism where the males look quite different to the females. Many geckos are a good example of this as the males develop a much larger bulge just caudal towards the tail to their cloaca. Several dragon and monitor species also have external differences with the males often having larger heads, more obvious femoral pores, growing to a larger size and in some cases having larger spurs at their tail base.
Xs and Ys, Ws and Zs
Simon P. Males and females from several animal taxa differ in locomotor performance traits such as sprinting and jumping. These performance dimorphisms may be explained at least partially by sexual differences in physiology or morphology. In ectotherms such as reptiles, however, thermal ecology places an additional constraint on realized locomotor performance. I review recent studies on reptiles examining sexual differences in locomotor capacity and related thermoregulatory behavior, and discuss potential causes, constraints, and selective pressures that might drive intersexual divergence in capacity for locomotor performance in reptiles. In several cases where such differences occur, sexual dimorphisms in body size do not account for all the observed variation in performance. However, while sex-specific locomotor capacities might be evident in the laboratory, ecological performance in nature is likely the result of complex interactions among sex, thermal sensitivity, habitat type, and behavioral locomotor compensation. Results from laboratory studies of dimorphisms in maximum locomotor capacity are therefore likely to be poor predictors of realized ecological differences in performance. Nonetheless, sex differences in performance are potentially important modifiers of male and female behavioral strategies and overall fitness, and consequently are deserving of more attention than they have thus far received. Locomotor performance has long been considered of prime importance in determining overall individual fitness Huey and Stevenson ; Arnold ; Irschick and Garland and a growing number of studies have attempted to quantify the effects of locomotor capacities on various fitness components, including survival and reproduction Jayne and Bennett ; O'Steen et al.
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Sexual selection in scaled reptiles studies how sexual selection manifests in snakes and lizards , which constitute the order Squamata of reptiles. Each of the over three thousand snakes use different tactics in acquiring mates. It is common for neck biting to occur while the snakes are entwined. In the species Japanese striped snake Elaphe quadrivirgata , competition involves males maintaining body contact with their opponent and exerting pressure by pushing, topping, or entwining in order to subdue him. Male snakes employ a variety of strategies to help them entice the female into mating. The red-sided garter snake Thamnophis sirtalis population in Alberta , Canada hibernates for the majority of the year, emerging in early May to copulate and feed. The communal dens have been observed to reach populations of thousands, with females often dispersing from the den rapidly to try to avoid being attacked by a flurry of males.
Alex Quinn, a Ph. Sex-determining mechanisms in reptiles are broadly divided into two main categories: genotypic sex determination GSD and temperature-dependent sex determination TSD. Species in the genotypic group, like mammals and birds, have sex chromosomes, which in reptiles come in two major types. Many species—such as several species of turtle and lizards, like the green iguana—have X and Y sex chromosomes again, like mammals , with females being "homogametic," that is, having two identical X chromosomes. Males, on the other hand, are "heterogametic," with one X chromosome and one Y chromosome. Other reptiles governed by GSD have a system, similar to one found in birds, with Z and W sex chromosomes.