| 许姝娟,柳鹏飞,韩亚鹏.2021.灰椋鸟身体大小和内脏器官形态的两性差异.动物学杂志,56(3):393-398. |
| 灰椋鸟身体大小和内脏器官形态的两性差异 |
| Sexual Size Dimorphism Were Determined in a Flock Living Passerine Bird: White-cheeked Starling |
| 投稿时间：2020-10-21 修订日期：2021-05-11 |
| DOI：10.13859/j.cjz.202103009 |
| 中文关键词: 身体大小 性二态 内脏器官 灰椋鸟 |
| 英文关键词:Body size Sexual dimorphism Internal organ White-cheeked Starling, Sturnus cineraceus |
| 基金项目:甘肃省高等学校创新基金项目（No. 2020B-221） |
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| 中文摘要: |
| 鸟类性二态现象广泛存在，比如身体大小、羽色等，性二态很可能是自然选择和性选择共同作用的结果。为了探索和更好地了解雀形目鸟类身体大小性二态的进化，在2019年繁殖季节早期研究了灰椋鸟（Sturnus cineraceus）野外种群身体大小和内脏器官形态的两性差异。结果表明，除嘴宽外，其他身体特征参数均雄性显著大于雌性，表现出雄性偏向的身体大小二态性。内脏器官大小两性间无显著差异。灰椋鸟是聚群生活的鸟类，雌雄鸟常一起觅食，食性相似，雌雄鸟内脏器官和消化道形态差异不显著，暗示食性分化在灰椋鸟身体大小性二态进化中的作用并不明显；雄鸟体型较大的原因可能是其在巢址竞争、配偶保护中适应进化的结果。本研究明确了灰椋鸟身体大小的两性差异，对于该物种身体大小性二态进化的确切原因，尚需更多研究。 |
| 英文摘要: |
| Sexual dimorphism is very common in nature, and possibly evolved under the pressures of natural and sexual selection, however, the underlying mechanisms are still confusing. Many hypotheses were proposed to explain this phenomenon, such as explanations from dietary niche divergence, intra-sexual competition and mate choice, fecundity selection. To understand the evolution of sexual dimorphism in passerine birds, in present study, we measured the morphometrics (culmen length, bill width, bill depth, wing length, tail length, tarsus length, body mass) of 122 individuals (68 males and 54 females) and compared the difference of these morphological traits between sexes in a wild population of White-cheeked Starling Sturnus cineraceus, during early breeding season of the year 2019. Meanwhile, we also measured the morphology of internal organs of 28 dead birds which provided by the Forest Public Security Bureau of Qingyang City, and compared the difference between males and females. We used independent sample T-test to analyze the data, and calculated the dimorphism index and coefficient of variation for each sex and all variables to indicate the variability of each measurement. The results showed that in all body measurements except bill width, adult males were significantly larger than females (P < 0.05) (Table 1), exhibiting slightly male-biased sexual size dimorphism. By contrast, internal digestive organs showed no significant difference between sexes (all P values > 0.05) (Table 2). As a flock living bird, male and female starlings always forage together, and their food habits might be similar. The anatomical evidences of lacking sexual size dimorphism in internal organs suggest that food habit partition may have played a little role in the evolution of size divergence in this bird. Males compete potential nesting holes and guard mates in breeding season, the larger size might be advantageous in sexual selection. Our findings suggest that the larger body size of males is likely resulted from intra-sexual competition for nest sites and mates, however, more researches are needed to figure out the evolutionary mechanisms of sexual dimorphism in this bird. |
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