Abstract：
Ectothermic vertebrates such as reptiles were assumed to be indeterminate growers, which means that there is no terminal point in time or size for growth in their lifetime. In recent years, evidence for the determinate nature of growth in lizards has accumulated, necessitating a re-examination of models of their ontogeny and evolution of sexual size dimorphism (SSD). In the female-larger gecko Paroedura vazimba, we monitored post-embryonic growth over a period of 15 months. After hatching, females grew faster than males but also reached their final body size, that is, closed growth of their vertebrae, earlier than males. The closure of bone growth in females correlates with the onset of reproductive maturation. We compared this pattern with the previously minutely studied, male-larger species Paroedura picta, where we documented determinate growth as well. We propose a model to explain the evolutionary switches in the direction of SSD in lizards based on bipotential effects of ovarian hormones on growth. In this model, male growth is assumed to require no male-specific growth modifier, such as sex-limited hormonal regulators, while growth is feminized by ovarian hormones in females. Low levels of ovarian hormones can promote bone growth, but high levels associated with maturation of the reproductive organs promote senescence of bone growth plates and thus cessation of bone growth. We suggest that models on growth, life-history and evolution of body size in many lizards should acknowledge their determinate nature of growth.
摘要：
温生脊椎动物如爬行动物被认为是不确定的种植者，这意味着在它们的寿命中没有增长的时间或大小的终点。近年来,已经积累了蜥蜴生长的确定性的证据，需要重新检查其个体发育和性别大小二态（SSD）进化的模型。在雌性较大的壁虎Paroeduravazimba中，我们监测了15个月的胚胎后生长。孵化后，雌性比雄性生长得更快，但也达到了最终的体型，也就是说,他们椎骨的封闭生长，比男性早。女性骨骼生长的闭合与生殖成熟的开始有关。我们将这种模式与先前研究的模式进行了比较，雄性较大的物种Paroedurapicta，我们也记录了确定的增长。基于卵巢激素对生长的双电位影响，我们提出了一个模型来解释蜥蜴中SSD方向的进化转换。在这个模型中,假设男性生长不需要男性特定的生长调节剂，比如性别有限的荷尔蒙调节剂，而女性的卵巢激素使生长女性化。低水平的卵巢激素可以促进骨骼生长，但是与生殖器官成熟相关的高水平促进骨生长板的衰老，从而停止骨生长。我们建议关于增长的模型，许多蜥蜴的生活史和体型的进化应该承认它们生长的决定性。
