马勒沙蜥（Ctenophorus fordi）的性别比例变化与性别决定

Sex ratio variation and sex determination in the mallee dragon Ctenophorus fordi.

作者信息

Uller Tobias, Odierna Gaetano, Olsson Mats

机构信息

School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia Department of Structural and Functional Biology, University of Naples Federico II, Naples, Italy.

出版信息

Integr Zool. 2008 Sep;3(3):157-65. doi: 10.1111/j.1749-4877.2008.00109.x.

DOI:10.1111/j.1749-4877.2008.00109.x

PMID:21396064

Abstract

Recent evidence suggests that many Australian agamids show temperature-dependent sex determination (TSD) with variation in sex determining mechanisms among closely related taxa. However, as shown in other vertebrates, sex ratios can also be influenced by genetic or phenotypic differences among females in their propensity to produce sons or daughters, and these influences might confound any thermal effects of incubation per se. To address these issues, we investigated the determinants of sex ratios in the mallee dragon Ctenophorus fordi, together with a detailed analysis of karyotypes. There was no detectable variation in sex ratios arising from variation among females, clutches or incubation temperatures, which might indicate genetic sex determination for this species. However, there was no evidence of cytologically distinct sex chromosomes using standard banding techniques. The sex ratio pattern in C. fordi strongly contrasts with the results for the congener Ctenophorus pictus, where sex ratios show variation among females. Thus, Australian agamids offer promising opportunities to address fundamental issues in sex ratio biology.

摘要

最近的证据表明，许多澳大利亚鬣蜥表现出温度依赖型性别决定（TSD），且在亲缘关系密切的类群中性别决定机制存在差异。然而，正如在其他脊椎动物中所显示的那样，性别比例也可能受到雌性在生儿育女倾向上的遗传或表型差异的影响，而这些影响可能会混淆孵化本身的任何热效应。为了解决这些问题，我们研究了马勒沙蜥（Ctenophorus fordi）性别比例的决定因素，并对其核型进行了详细分析。未检测到雌性、窝卵数或孵化温度的变化导致的性别比例差异，这可能表明该物种为遗传性别决定。然而，使用标准显带技术未发现细胞学上不同的性染色体的证据。马勒沙蜥的性别比例模式与同属的彩绘沙蜥（Ctenophorus pictus）的结果形成强烈对比，后者的性别比例在雌性之间存在差异。因此，澳大利亚鬣蜥为解决性别比例生物学中的基本问题提供了有前景的机会。