Diverse evolution patterns of cooperative breeding in Australian birds

1.在为期3年的研究中，我们发现了14-22群灰冠须眉，并进行了观察：平均群大小分别为4.21、3.85和4.59：大多数群由单一的单性配对和1-7只辅鸟组成。性别比为11：11(6组)、25：20(13组)和14：12(9组)。窝卵数为1~4枚(最多2枚)，并观察到联巢现象。失败的主要原因是捕食，但由于饥饿导致的孵化减少很少见。没有帮手的双胞胎根本无法产下后代。然而，对于有帮手的群体，雏鸟的数量和帮手的数量之间没有显著的相关性。几乎所有的组织成员都为雏鸟提供食物，而有几只鸟根本没有提供任何帮助。一岁的鸟比两岁或更大的鸟提供的食物更少。规模较大组的总拨备率高于S…更多的小群体，但差异不显著。在3年的研究期间，共对29只雏鸟(45只雏鸟)进行了DNA性别鉴定。雏鸟性别比偏向雄性：雄性30只(66.7%)，雌性15只(33.3%)。几乎所有有一只以上幼鸟的雏鸟都是由两性占据的。在女性偏向帮手性别比的群体中，育雏者的性别比偏向男性，反之亦然。这很可能是由于灰冠莺的雌性父母根据帮助者的性别比例和帮助者年龄所加权的帮助者的数量来调整幼鸟的性别比例。3.我们获得了热带季风区红背仙女种群合作繁殖的证据。2004年，观察的17组中有5组有一只或多只辅助鸟(助手)陪同。有帮手的组鸡的总配给率高于没有帮手的组。尽管男性和女性都成为了帮手，但男性的数量超过了女性。所有占主导地位的雄性都有黑色和红色的羽毛，而辅助雄性(=下属)有类似雌性的暗淡的羽毛。较少

1.During the 3-year study period, we found 14-22 groups of the Grey-crowned Babbler and conducted observations : Mean group sizes were 4.21,3.85 and 4.59 respectively : most groups comprising single monogamous pairs with 1-7 auxiliary birds. Sex ratio was almost unity for groups in which all members were successfully sexed for each year : 11:11(six groups), 25:20(13 groups), and 14:12 (nine groups), respectively. Clutch size was 1-4 eggs (two was commonest) and joint-nesting was observed. Major cause of failure was predation but brood reduction due to starvation was rare. Pairs without helpers could not fledge offspring at all. However, for groups with helpers, there was no significant correlation between the number of fledglings and that of helpers. Almost all members of groups provisioned chicks, while there were a few birds giving no help at all. Birds of one-year old provisioned less than those of two-year old or older. Total provision rate was higher in the larger group than the s … More maller groups, but the difference was not significant. This species could be an obligate cooperative breeder, but the number of helpers did not influence the reproductive success remarkably.2.During the 3-year study period, 29 broods (45 nestlings) in total were sexed with the DNA sexing method. Sex ratio of nestlings was male biased : 30 (66.7%) were males and 15 (33.3%) were females. Almost all broods with more than one chick were occupied by either sex. For groups with female-biased helper sex ratio, the sex ratio of broods was male-biased, and vice versa. It is likely that female parents of the Grey-crowned Babbler adjust the sex ratio of a brood according to the sex ratio of helpers and the number of helpers weighted by the age of helpers.3.We obtained the evidence about the cooperative breeding in the population of the Red-backed Fairy-wren in the tropic monsoon area. In 2004, five of 17 groups observed accompanied with one or more auxiliary birds (helpers). Total provisioning rate for chicks was higher in the groups with helpers than in the groups without helpers. Although both sexes became helpers, males outnumbered females. All dominant males had black and red plumage, while helper males (=subordinates) had female-like dull plumage. Less