Exploring the Diversity and Distribution of Neotropical Avian Malaria Parasites – A Molecular Survey from Southeast Brazil

Southeast Brazil is a neotropical region composed of a mosaic of different tropical habitats and mountain chains, which allowed for the formation of bird-rich communities with distinct ecological niches. Although this region has the potential to harbor a remarkable variety of avian parasites, there is a lack of information about the diversity of malarial parasites. We used molecular approaches to characterize the lineage diversity of Plasmodium and Haemoproteus in bird communities from three different habitats in southeast Brazil based on the prevalence, richness and composition of lineages. We observed an overall prevalence of 35.3%, with a local prevalence ranging from 17.2% to 54.8%. Moreover, no significant association between prevalence and habitat type could be verified (p>0.05). We identified 89 Plasmodium and 22 Haemoproteus lineages, with 86% of them described for the first time here, including an unusual infection of a non-columbiform host by a Haemoproteus (Haemoproteus) parasite. The composition analyses of the parasite communities showed that the lineage composition from Brazilian savannah and tropical dry forest was similar, but it was different from the lineage composition of Atlantic rainforest, reflecting the greater likeness of the former habitats with respect to seasonality and forest density. No significant effects of habitat type on lineage richness were observed based on GLM analyses. We also found that sites whose samples had a greater diversity of bird species showed a greater diversity of parasite lineages, providing evidence that areas with high bird richness also have high parasite richness. Our findings point to the importance of the neotropical region (southeast Brazil) as a major reservoir of new haemosporidian lineages.

巴西东南部属于新热带区（Neotropical Region），由多种热带生境与山脉镶嵌分布而成，孕育出拥有独特生态位的鸟类物种丰富群落。尽管该区域具备承载极为多样的鸟类寄生虫类群的潜力，但目前关于疟原虫类寄生虫多样性的研究资料仍较为匮乏。本研究基于寄生虫谱系的感染率、丰富度与组成特征，采用分子生物学方法对巴西东南部三种不同生境鸟类群落中的疟原虫属（Plasmodium）与血变原虫属（Haemoproteus）谱系多样性进行了解析。本研究测得总体感染率为35.3%，各生境局部感染率介于17.2%至54.8%之间。此外，统计检验未发现感染率与生境类型间存在显著关联（p>0.05）。本研究共鉴定出89个疟原虫谱系与22个血变原虫谱系，其中86%的谱系为本次研究首次报道，还发现了血变原虫亚属（Haemoproteus）寄生虫感染非鸽形目宿主的罕见案例。寄生虫群落组成分析显示，巴西稀树草原与热带旱生林的寄生虫谱系组成相似，但与大西洋雨林的谱系组成存在显著差异，这与前两类生境在季节节律与林分密度上的更高相似度相契合。基于广义线性模型（Generalized Linear Model, GLM）的分析结果显示，生境类型对寄生虫谱系丰富度无显著影响。本研究同时发现，样本中鸟类物种多样性更高的样地，其寄生虫谱系多样性也更高，这证明鸟类物种丰富度较高的区域，寄生虫类群丰富度同样较高。本研究结果表明，新热带区（巴西东南部）作为新型血孢子虫谱系的重要储存库，具有极高的研究价值。