两性异型红隼的子代性比研究(英文)

Offspring sex ratio in Eurasian Kestrel(Falco tinnunculus)with reversed sexual size dimorphism

Fisher经典的性比分配理论预测:如果双亲繁殖雄性和雌性子代的代价相同,那么子代的性比应趋于平衡。然而,性比组成是长期进化的结果,常因不同因素的影响而出现偏离。文献报道猛禽由于存在不同形式的两性异型现象而导致子代性比常出现偏离,但子代性比偏离方向因种而异。本研究中我们对红隼(Falco tinnunculus)子代的性比组成进行了调查,目的是检验红隼子代性比是否受产卵日期、产卵顺序、卵重、出雏顺序或窝卵数影响。在窝水平上,红隼(雄性)的初级性比为47.0%,没有偏离0.5,但次级性比为40.8%,显著偏离0.5(p=0.029)。在种群水平上,初级性比和次级性比都没有出现偏离。窝卵数和卵重影响红隼的次级性比组成,窝卵数越大,雄性后代数量越多,且发育为雄性后代的卵重较发育为雌性后代的重。初级性比和次级性比都受到产卵日期的影响,产卵越早,雄性后代比例越高。

Fisher's theory predicts equal sex ratios at the end of parental care if the cost associated with raising offspring of each sex is equal.However,sex ratios have important evolutionary consequences and are often biased for many factors.Reported sex ratios are often biased in raptors,which display various degrees of reversed sexual dimorphism,but there seems no consistent pattern in their offspring sex ratios.In this study,we investigated the offspring sex ratio of the Eurasian Kestrel(Falco tinnunculus) and tested whether the patterns of biased sex ratios were related to laying order,egg mass,hatching order,laying date or clutch size.The brood sex ratio of the Eurasian Kestrel(male) in eggs was 47.0%,not statistically biased from 0.5,but in fledglings it was 40.8%,significantly biased from 0.5(p = 0.029).At population level,both primary and secondary sex ratios did not depart from parity.We found that clutch size and egg mass affected the secondary brood sex ratio,i.e.,the larger the clutch size,the larger the number of males and eggs producing sons were heavier than eggs producing daughters.Laying date affected both the primary and secondary sex ratios,and laying earlier is associated with a greater proportion of males.