Life-history trade-offs, density, lay date—not personality—explain multibroodedness in great tits

In various taxa, multibroodedness is a common breeding strategy. Life-history theory predicts that individuals can increase fitness by producing multiple broods within a season. Despite the apparent increase in the number of offspring parents might produce per season, not all individuals are multibrooded, suggesting a trade-off. We studied ecological and behavioral factors influencing the initiation of second clutches in great tits (Parus major), an optionally multibrooded bird species, by distinguishing two types of clutches: replacement vs. true second clutches, produced after failure vs. successful first breeding attempts, respectively. We predicted that lay date, density, and investment in first clutches would decrease the probability of initiating a second clutch, but that faster exploring behavioral types with a faster pace-of-life would be more likely to be multibrooded. The probability of initiating true second clutches varied negatively within-individuals with lay date and bree...

在诸多生物分类群(taxa)中，多窝繁殖(multibroodedness)是一种常见的繁殖策略。生活史理论(life-history theory)预测，个体可通过在一个繁殖季内产出多窝后代提升自身适合度(fitness)。尽管亲本单季可产出的后代数量看似有所提升，但并非所有个体都会进行多窝繁殖，这暗示存在权衡(trade-off)。我们以具有兼性多窝繁殖特性的大山雀(Parus major)——一种可选性多窝繁殖的鸟类为研究对象，通过区分两类第二窝卵：替换型第二窝卵(replacement second clutches)与真实型第二窝卵(true second clutches)，前者对应首次繁殖失败后产出的窝卵，后者对应首次繁殖成功后产出的窝卵，以此探究影响其启动第二窝繁殖的生态与行为因素。我们提出如下研究假设：产卵日期(lay date)、种群密度以及对第一窝卵的繁殖投入，会降低个体启动第二窝繁殖的概率；而行为探索速度更快、生活节奏(pace-of-life)更快的个体，更有可能进行多窝繁殖。启动真实型第二窝卵的概率在个体内部随产卵日期与繁殖...