Data from: Agonistic reciprocity is associated with reduced male reproductive success within haremic social networks

While individual variation in social behaviour is ubiquitous and causes social groups to differ in structure, how these structural differences affect fitness remains largely unknown. We used social network analysis of replicate bluebanded goby (Lythrypnus dalli) harems to identify the reproductive correlates of social network structure. In stable groups, we quantified agonistic behaviour, reproduction and steroid hormones, which can both affect and respond to social/reproductive cues. We identified distinct, optimal social structures associated with different reproductive measures. Male hatching success (HS) was negatively associated with agonistic reciprocity, a network structure that describes whether subordinates ‘reciprocated’ agonism received from dominants. Egg laying was associated with the individual network positions of the male and dominant female. Thus, males face a trade-off between promoting structures that facilitate egg laying versus HS. Whether this reproductive conflict is avoidable remains to be determined. We also identified different social and/or reproductive roles for 11-ketotestosterone, 17β-oestradiol and cortisol, suggesting that specific neuroendocrine mechanisms may underlie connections between network structure and fitness. This is one of the first investigations of the reproductive and neuroendocrine correlates of social behaviour and network structure in replicate, naturalistic social groups and supports network structure as an important target for natural selection.

尽管社会行为的个体差异普遍存在，并会导致社会群体的结构出现分化，但此类结构差异如何影响适合度（fitness），目前仍尚未明确。我们通过对重复设置的蓝带虾虎鱼（bluebanded goby, Lythrypnus dalli）一夫多妻群开展社交网络分析，以探明社交网络结构的繁殖相关性。在稳定的群体中，我们对争斗行为、繁殖情况以及类固醇激素进行了量化；这类激素既可以受到社会/繁殖信号的调控，也能反过来影响社会与繁殖过程。我们发现了与不同繁殖指标相关联的独特最优社交结构：雄性孵化成功率（hatching success, HS）与争斗互惠性呈负相关——该网络结构用于描述从属个体是否会对优势个体施加的争斗行为做出互惠回应；而产卵情况则与雄性以及优势雌性的个体网络位置相关。由此可见，雄性个体面临着一种权衡：需要在促进利于产卵的社交结构与利于提升孵化成功率的社交结构之间做出选择。这类繁殖冲突是否可避免，仍有待进一步探究。我们还明确了11-酮睾酮（11-ketotestosterone）、17β-雌二醇（17β-oestradiol）以及皮质醇（cortisol）各自不同的社会与/或繁殖功能，这表明特定的神经内分泌机制或许是网络结构与适合度之间关联的内在基础。本研究是首批在重复设置的自然化社会群体中，探究社会行为与网络结构的繁殖及神经内分泌相关性的研究之一，同时证实了社交网络结构是自然选择的重要作用靶标。