Nyssorhynchus darlingi Brazil (7 localities) 2019 nextRADseq. Anopheles darlingi

BackgroundNyssorhynchus darlingi (also known as Anopheles darlingi) is the primary malaria vector in the Amazon River Basin. In Brazil, analysis of single nucleotide polymorphisms (SNPs) previously detected three major population clusters, and a common garden experiment in a laboratory setting revealed significant population variation in life history traits. Increasing temperatures and local level variation can affect life history traits, i.e., adult longevity, that alter vectorial capacity with implications for malaria transmission in Ny. darlingi.MethodsWe investigated the population structure of Ny. darlingi from 7 localities across Brazil utilizing SNPs and compared them to a comprehensive Ny. darlingi catalog. To test the effects of local level variation on life history traits, we reared F1 progeny from the 7 localities at three constant temperatures (20, 24, 28°C), measuring key life-history traits (larval development, food-starved adult lifespan, adult size, daily survival).ResultsUsing nextRAD genotyping-by-sequencing, 93 of the field-collected Ny. darlingi were genotyped at 33,759 loci. Results revealed three populations (K=3), congruent with major biomes (Amazonia, Cerrado, Mata Atlântica), with greater FST values between biomes than within. In the life history experiments, increasing temperature reduced larvae development time, adult lifespan, and wing length in all localities. The variation of family responses of all traits within four localities of the Amazonia biome was significant (ANOVA, pConclusionsSNP analysis of several Brazilian localities provided results in support of a previous study wherein populations of Ny. darlingi were clustered by three major Brazilian biomes. Our laboratory results of temperature effects demonstrated that population variation in life history traits of Ny. darlingi exists at the local level, supporting previous research demonstrating the high plasticity of this species. Understanding this plasticity and inherent variation between families of Ny. darlingi at the local level should be considered when deploying intervention strategies and may improve the likelihood of successful malaria elimination in South America.

【背景】达林努斯蚊（Nyssorhynchus darlingi，又名Anopheles darlingi）是亚马孙河流域的主要疟疾传播媒介。在巴西，既往基于单核苷酸多态性（Single Nucleotide Polymorphisms，SNPs）的分析已检测到3个主要种群聚类，而实验室同质园实验揭示了其生活史性状存在显著的种群变异。随着气温升高及局域环境变异，该物种的生活史性状——如成虫寿命——会发生改变，进而影响媒介能量，对达林努斯蚊介导的疟疾传播产生潜在影响。
【方法】我们利用SNPs对巴西境内7个采样点的达林努斯蚊种群结构进行了分析，并将结果与全面的达林努斯蚊种群目录进行比对。为验证局域环境变异对生活史性状的影响，我们将来自7个采样点的F1子代在三种恒定温度（20、24、28℃）下饲养，测定了关键生活史性状：幼虫发育时长、饥饿成虫寿命、成虫体型及每日存活率。
【结果】通过nextRAD测序分型（nextRAD genotyping-by-sequencing）技术，我们对93份野外采集的达林努斯蚊样本在33759个基因位点上完成了基因分型。结果显示存在3个种群（K=3），与巴西三大主要生物群系（亚马孙雨林、塞拉多稀树草原、大西洋沿岸森林）高度吻合，且不同生物群系间的种群遗传分化系数（FST）显著高于群系内部。在生活史实验中，温度升高可缩短所有采样点的幼虫发育时长、成虫寿命以及翅长。在亚马孙雨林生物群系的4个采样点内，各性状的家系响应变异均具有统计学显著性（方差分析，p值未完整给出）。
【结论】对巴西多个采样点的SNPs分析结果支持既往研究结论，即达林努斯蚊种群可按照巴西三大主要生物群系进行聚类。我们的实验室温度效应实验证实，达林努斯蚊的生活史性状存在局域种群水平的变异，支持了该物种具有高度表型可塑性的既往研究成果。在部署疟疾干预策略时，应考虑到达林努斯蚊的这种表型可塑性以及其家系间的局域变异，这或可提升南美洲疟疾消除工作的成功率。