Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil.
Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, Distrito Federal, Brazil.
PeerJ. 2023 Aug 30;11:e15915. doi: 10.7717/peerj.15915. eCollection 2023.
Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (C and N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.
种内变异调节了物种的资源利用模式，可能影响食物网的结构和稳定性。在人为改造的景观中，生境干扰改变了营养相互作用和种内生态位变异，从而影响了种群的持续存在。在这里，我们研究了性、个体发育和生境因素与在农业景观中的营养生态位的关系。我们通过不同身体组织的碳和氮稳定同位素分析来评估营养生态位参数的时间变化。我们发现，凯门鳄通过时间利用相同的碳和氮库，季节之间的同位素变异性低，部分原因是鳄鱼组织的同位素周转率较慢。相反，凯门鳄的营养生态位在不同的生境中发生了变化，但在自然和人为生境之间没有差异的证据。这显然是由于栖息地适宜性、连通性和觅食期间凯门鳄的运动的影响。我们的研究结果突出了幼年凯门鳄相对于成年凯门鳄更广泛的生态位，可能是由于领土主义和机会主义觅食策略的反应。尽管使用类似的资源，但雌性的生态位比雄性大，可能与筑巢期间的觅食策略有关。考虑到性别和体型类别，在一些生境中，凯门鳄占据了不同的同位素区域，表明存在明显的生态位分离。同位素（C 和 N）的营养生态位的个体发育变化取决于性别，导致资源的分区，这可能减少种内竞争。决策者和利益相关者应该考虑性别和体型群体的营养动态，以实现凯门鳄种群的可持续管理和保护，这意味着需要维持湿地生境和福尔摩沙河泛滥平原的景观异质性。
