Individual variation in ontogenetic niche shifts in habitat use and movement patterns of a large estuarine predator (Carcharhinus leucas)
Individual variation in ontogenetic niche shifts in habitat use and movement patterns of a large estuarine predator (Carcharhinus leucas)
复制标题
大型河口捕食者（Carcharhinus leucas）栖息地利用和运动模式的个体发生生态位变化的个体差异
DOI：
10.1007/s00442-015-3253-2
复制
发表时间：
2015
期刊：
影响因子：
2.7
通讯作者：
M. Heithaus
中科院分区：
文献类型：
--
作者：
P. Matich;M. Heithaus
个体发生生态位转移在动物中很常见，但大多数研究仅在种群水平上研究生态位转移，这可能会忽略个体之间在这些转移的时间和动态方面的显著差异。大小/年龄组内的这种不同行为对种群和特定年龄组在各自生态系统中的作用具有重要意义。使用声学遥测技术，我们跟踪了少年牛鲨的运动在鲨鱼河河口的大沼泽地国家公园，佛罗里达，并发现鲨鱼增加了他们的使用海洋微栖息地的年龄，以利用更丰富的资源，但继续使用淡水和河口微栖息地作为避难所从海洋捕食者。然而，在这种种群水平的个体发育生态位转变中，个体鲨鱼的运动模式各不相同，47%的鲨鱼表现出依赖于条件的栖息地使用，53%的鲨鱼表现出规避风险的行为，无论身体状况如何。在0岁以上的鲨鱼中，50%的鲨鱼在河口的相邻区域之间进行定期运动，而另一半则进行不太可预测的运动，这些运动通常以长期居住在特定区域为特征。个体差异显然是由内在和外在因素形成的，包括个体对食物风险权衡和身体状况的反应。这些差异似乎在牛鲨生命的早期就形成了，并在它们的苗圃栖息地中持续存在。在移动的类群中广泛发生的种内行为变异表明，它在塑造至少某些物种的种群动态方面很重要，阐明它发展和持续的背景和时间对于理解它在群落中的作用很重要。
Ontogenetic niche shifts are common among animals, yet most studies only investigate niche shifts at the population level, which may overlook considerable differences among individuals in the timing and dynamics of these shifts. Such divergent behaviors within size-/age-classes have important implications for the roles a population—and specific age-classes—play in their respective ecosystem(s). Using acoustic telemetry, we tracked the movements of juvenile bull sharks in the Shark River Estuary of Everglades National Park, Florida, and found that sharks increased their use of marine microhabitats with age to take advantage of more abundant resources, but continued to use freshwater and estuarine microhabitats as refuges from marine predators. Within this population-level ontogenetic niche shift, however, movement patterns varied among individual sharks, with 47 % of sharks exhibiting condition-dependent habitat use and 53 % appearing risk-averse regardless of body condition. Among sharks older than age 0, fifty percent made regular movements between adjacent regions of the estuary, while the other half made less predictable movements that often featured long-term residence in specific regions. Individual differences were apparently shaped by both intrinsic and extrinsic factors, including individual responses to food-risk trade-offs and body condition. These differences appear to develop early in the lives of bull sharks, and persist throughout their residencies in nursery habitats. The widespread occurrence of intraspecific variation in behavior among mobile taxa suggests it is important in shaping population dynamics of at least some species, and elucidating the contexts and timing in which it develops and persists is important for understanding its role within communities.