Causes and consequences of individual variation in the cooperative breeding behaviour of the endangered El Oro Parakeet (Pyrrhura orcesi)

合作的成本是理解合作演变的一个根本难题。普遍的看法是，亲属之间的合作产生的直接和间接利益抵消了合作的成本。虽然这一模式总体上得到了支持，但它不能很容易地解释许多合作系统中即使在看似相同的条件下也会出现明显的个体差异。研究合作育种中个体变异的适合度结果提供了对合作的功能理解，因为合作与繁殖和适合度直接相关。虽然合作繁殖并不少见，但助手是否真的提高了繁殖者的健康，或者当他们自己的繁殖受到限制时，他们是否主要受益于群体生活，这是有争议的。在这里，我们调查了关于濒危的El Oro Parakeet(Pyrhura Orcesi)合作繁殖行为中个体差异的原因和后果的各种假设。我们确定个体在年内和年间以及在不同社会环境中的合作行为的一致性。这些数据揭示了个体对育儿的贡献是否是可变的，主要取决于状态，还是不变的，最好被视为一种人格特征。将行为分析与基因分析相结合，使我们能够在交叉培养实验中理清合作是由文化还是遗传效应塑造的问题。基于一个长期的数据集，我们研究了合作行为中个体差异的后果。特别是，我们研究非常合作的帮手是否养育了更多相关的后代，或者他们是否更快地达到繁殖位置。这将揭示合作育种是互惠互利的，还是只通过强迫或仅通过群体生活向帮助者提供健康益处。

The costs of cooperation pose a fundamental puzzle to understand the evolution of cooperation. The prevailing view is that direct and indirect benefits arising from cooperation among relatives offset the costs of cooperation. While this paradigm has overall been supported, it cannot easily account for the pronounced individual differences in many cooperative systems that occur even under seemingly identical conditions. Studying the fitness consequences of individual variation in cooperative breeding provides a functional understanding of cooperation because of the immediate link to reproduction and fitness. Although cooperative breeding is not rare, it is controversial whether helpers actually increase the fitness of breeders or whether they primarily benefit from group living when their own reproduction is constrained. Here, we investigate various hypotheses on the causes and consequences of individual variation in cooperative breeding behaviour in the endangered El Oro Parakeet (Pyrrhura orcesi). We determine individual consistency in cooperative behaviour within and among years and in different social environments. These data reveal whether individual contribution to brood care is variable and primarily state dependent or whether it is invariant and best seen as a personality trait. Combining behavioural with genetic analyses allows us to disentangle in cross-fostering experiments whether cooperation is shaped by cultural or genetics effects. Based on a long-term dataset we study the consequences individual variation in cooperative behaviour. In particular, we study whether very cooperative helpers raise more related offspring or whether they attain breeding position more quickly. This will reveal whether cooperative breeding is mutualistic yielding fitness benefits to breeders and helpers or whether it provides fitness benefits only to breeders through coercion or only to helpers through group living.