Data from: Temporal constraints on the potential role of fry odors as cues of past reproductive success for spawning lake trout

Deciding where to reproduce is a major challenge for most animals. Many select habitats based upon cues of successful reproduction by conspecifics, such as the presence of offspring from past reproductive events. For example, some fishes select spawning habitat following odors released by juveniles whose rearing habitat overlaps with spawning habitat. However, juveniles may emigrate before adults begin to search for spawning habitat; hence, the efficacy of juvenile cues could be constrained by degradation or dissipation rates. In lake trout (Salvelinus namaycush), odors deposited by the previous year's offspring have been hypothesized to guide adults to spawning reefs. However, in most extant populations, lake trout fry emigrate from spawning reefs during the spring and adults spawn during the fall. Therefore, we postulated that the role of fry odors in guiding habitat selection might be constrained by the time between fry emigration and adult spawning. Time course chemical, physiological, and behavioral assays indicated that the odors deposited by fry likely degrade or dissipate before adults select spawning habitats. Furthermore, fry feces did not attract wild lake trout to constructed spawning reefs in Lake Huron. Taken together, our results indicate fry odors are unlikely to act as cues for lake trout searching for spawning reefs in populations whose juveniles emigrate before the spawning season, and underscore the importance of environmental constraints on social cues.

对于绝大多数动物而言，选定适宜的繁殖场所均为一项核心挑战。诸多动物会依据同种个体成功繁殖的相关线索来遴选栖息地，例如过往繁殖事件中留存的幼体存在痕迹。以部分鱼类为例，它们会借助幼鱼释放的气味来选择产卵栖息地——这类幼鱼的抚育栖息地与产卵栖息地存在重叠。然而，幼鱼往往会在成年个体启动产卵栖息地搜寻前便已迁出，因此幼体线索的有效性可能会受到气味降解或消散速率的制约。针对湖鳟（Salvelinus namaycush），已有假说提出上一年产出的幼体所释放的气味，可引导成年个体前往产卵礁；但在现存的多数湖鳟种群中，幼鳟会于春季从产卵礁迁出，而成年个体的产卵行为则发生在秋季。据此我们推测，幼体气味在引导栖息地选择过程中的作用，可能会受到幼体迁出与成体产卵之间的时间间隔的制约。我们开展的时间序列化学检测、生理与行为学实验结果显示，幼鳟释放的气味极有可能在成年个体选定产卵栖息地前就已发生降解或消散。此外，在休伦湖的人工产卵礁开展的野外实验表明，幼鳟粪便并未对野生湖鳟产生吸引作用。综合来看，本研究结果表明，对于幼体在产卵季前便已迁出的湖鳟种群而言，幼体气味不太可能作为成年个体搜寻产卵礁的线索；同时本研究也凸显了环境约束对社会线索应用的重要性。