Diverse evolution patterns of cooperative breeding in Australian birds

1.在为期3年的研究中，共发现灰冠穗鹛14-22个类群，平均类群数分别为4.21、3.85和4.59个，大多数类群为单配个体和1-7只辅助鸟。在所有成员每年都成功进行性别鉴定的群体中，性别比例几乎是统一的：分别为11：11（6个群体）、25：20（13个群体）和14：12（9个群体）。窝卵数为1-4枚（最多2枚），联合筑巢。失败的主要原因是捕食，但由于饥饿减少育雏是罕见的。没有帮手的配对根本无法生出羽翼丰满的后代。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。几乎所有的群体成员都提供雏鸟，而有几只鸟根本不提供帮助。一岁的鸟比两岁或更大的鸟提供更少的食物。总的提供率在较大的组高于s ...更多信息 小组间差异无统计学意义。2.在3年的研究期内，共对29窝45只雏鸟进行了DNA性别鉴定。雏鸟性别比以雄鸟为主，雄鸟30只（66.7%），雌鸟15只（33.3%）。几乎所有的育雏超过一个小鸡被占领的任何性别。对于雌性偏向的辅助性别比的组，育雏的性别比是男性偏向的，反之亦然。灰冠穗鹛的雌性父母很可能根据辅助个体的性比和辅助个体的数量与年龄的加权值来调节一窝灰冠穗鹛的性比。3.获得了热带季风区红背细尾鹩种群合作繁殖的证据。在2004年，观察到的17个群体中有5个与一只或多只辅助鸟（帮手鸟）相伴。雏鸡的总供给率在有帮手的组中高于无帮手的组。虽然男女都成为帮手，但男性数量超过女性。所有占统治地位的雄性都有黑色和红色的羽毛，而辅助雄性（=下属）有着像雌性一样的暗淡羽毛。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