Data from: Social network analysis of mating patterns in American black bears (Ursus americanus)

Nonrandom mating can structure populations and has important implications for population-level processes. Investigating how and why mating deviates from random is important for understanding evolutionary processes as well as informing conservation and management. Prior to the implementation of parentage analyses, understanding mating patterns in solitary, elusive species like bears was virtually impossible. Here, we capitalize on a long-term genetic data set collected from black bears (Ursus americanus) (N = 2422) in the Northern Lower Peninsula (NLP) of Michigan, USA. We identified mated pairs using parentage analysis and applied logistic regression (selection) models that controlled for features of the social network, to quantify the effects of individual characteristics, and spatial and population demographic factors on mating dynamics. Logistic regression models revealed that black bear mating was associated with spatial proximity of mates, male age, the time a pair had coexisted, local population density and relatedness. Mated pairs were more likely to contain older males. On average, bears tended to mate with nearby individuals to whom they were related, which does not support the existence of kin recognition in black bears. Pairwise relatedness was especially high for mated pairs containing young males. Restricted dispersal and high male turnover from intensive harvest mortality of NLP black bears are probably the underlying factors associated with younger male bears mating more often with female relatives. Our findings illustrate how harvest has the potential to disrupt the social structure of game species, which warrants further attention for conservation and management.

非随机交配可塑造种群结构，并对种群水平过程具有重要意义。探究交配偏离随机模式的机制与原因，对于理解进化过程以及为保护与管理提供参考均具有重要价值。在亲权分析（parentage analysis）技术应用之前，想要了解熊类这类独居、难以观测物种的交配模式几乎是不可能的。本研究依托美国密歇根州下半岛北部（NLP）收集的美洲黑熊（Ursus americanus）长期遗传数据集（样本量N=2422）展开分析。我们通过亲权分析鉴定交配配对，并采用控制社交网络特征的逻辑回归（logistic regression）选择模型，量化个体特征、空间与种群人口统计因素对交配动态的影响。逻辑回归模型结果显示，美洲黑熊的交配行为与配偶间的空间邻近性、雄性年龄、配对共存时长、当地种群密度以及亲缘关系显著相关。交配配对更大概率包含年长雄性。平均而言，黑熊倾向于与邻近的亲缘个体交配，这一结果不支持美洲黑熊存在亲缘识别机制。包含年轻雄性的交配配对，其两两间的亲缘关系尤其高。下半岛北部黑熊的扩散受限以及高强度狩猎死亡率导致的雄性种群高更替率，可能是年轻雄性更频繁与雌性亲属交配的潜在驱动因素。本研究结果揭示了狩猎行为可能如何破坏猎物种群的社会结构，这一发现值得在保护与管理中进一步关注。