Teixeira Clarissa R, Botta Silvina, Cremer Marta J, Marcondes Milton C C, Pereira Luiza B, Newsome Seth D, Jorge Fábio G Daura, Simões-Lopes Paulo C
Laboratório de Mamíferos Aquáticos (LAMAQ), Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil.
Department of Fisheries, Wildlife, and Conservation Sciences, Marine Mammal Institute, Oregon State University, Newport, OR, USA.
Oecologia. 2023 Feb;201(2):397-408. doi: 10.1007/s00442-022-05312-7. Epub 2023 Jan 17.
Populations usually considered foraging generalists may include specialized individuals that feed on a restricted subset of the prey spectrum consumed by the population. By analyzing the time series of δC and δN values in sequential growth layer groups within tooth dentin, we measured population- and individual-level variation in resource use of three populations of Guiana dolphins (Sotalia guianensis)-Caravelas River, Babitonga Bay, and Norte Bay-along a latitudinal gradient in the southwestern Atlantic Ocean. We show that the Guiana dolphin at Caravelas River is a generalist population consisting of individual dietary specialists, likely due to the absence of other resident dolphin populations thus allowing individuals to target prey across a wide range of habitats. The Babitonga Bay population is also composed of individual specialists potentially due to the selective foraging behavior of some individuals on high-quality prey sources within and near the bay. In contrast, the Norte Bay population comprises individual generalists, which likely reflects its distinctive cohesive social organization, coexistence with two other dolphin species, and an opportunistic foraging strategy in response to resource fluctuations inherent to the southern limit of the species distribution. Although the Guiana dolphin is generally considered to be a dietary generalist at the population level, our findings reveal that the total niche width of populations and the degree of individual diet specialization are highly context dependent, suggesting dietary plasticity that may be related to a latitudinal gradient in resource availability and environmental conditions.
通常被认为是觅食通才的种群可能包括一些特化个体，它们以该种群所消耗猎物谱中的一个受限子集为食。通过分析牙本质中连续生长层组的δC和δN值的时间序列，我们测量了圭亚那海豚（Sotalia guianensis）的三个种群——卡拉韦拉斯河种群、巴比通加湾种群和北湾种群——在西南大西洋沿纬度梯度的资源利用在种群和个体水平上的变化。我们发现，卡拉韦拉斯河的圭亚那海豚种群是一个由个体饮食特化者组成的通才种群，这可能是因为没有其他常驻海豚种群，从而使个体能够在广泛的栖息地中捕食猎物。巴比通加湾种群也由个体特化者组成，这可能是由于一些个体对湾内和湾附近高质量猎物来源的选择性觅食行为。相比之下，北湾种群由个体通才组成，这可能反映了其独特的紧密社会组织、与其他两种海豚的共存以及对物种分布南部边界固有的资源波动的机会主义觅食策略。尽管圭亚那海豚在种群水平上通常被认为是饮食通才，但我们的研究结果表明，种群的总生态位宽度和个体饮食特化程度高度依赖于环境，这表明饮食可塑性可能与资源可用性和环境条件的纬度梯度有关。
