Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
PLoS One. 2012;7(7):e40807. doi: 10.1371/journal.pone.0040807. Epub 2012 Jul 30.
Many grasshopper species are considered of agronomical importance because they cause damage to pastures and crops. Comprehension of pest population dynamics requires a clear understanding of the genetic diversity and spatial structure of populations. In this study we report on patterns of genetic variation in the South American grasshopper Dichroplus elongatus which is an agricultural pest of crops and forage grasses of great economic significance in Argentina. We use Direct Amplification of Minisatellite Regions (DAMD) and partial sequences of the cytochrome oxydase 1 (COI) mitochondrial gene to investigate intraspecific structure, demographic history and gene flow patterns in twenty Argentinean populations of this species belonging to different geographic and biogeographic regions. DAMD data suggest that, although genetic drift and migration occur within and between populations, measurable relatedness among neighbouring populations declines with distance and dispersal over distances greater than 200 km is not typical, whereas effective gene flow may occur for populations separated by less than 100 km. Landscape analysis was useful to detect genetic discontinuities associated with environmental heterogeneity reflecting the changing agroecosystem. The COI results indicate the existence of strong genetic differentiation between two groups of populations located at both margins of the Paraná River which became separated during climate oscillations of the Middle Pleistocene, suggesting a significant restriction in effective dispersion mediated by females and large scale geographic differentiation. The number of migrants between populations estimated through mitochondrial and DAMD markers suggest that gene flow is low prompting a non-homogeneous spatial structure and justifying the variation through space. Moreover, the genetic analysis of both markers allows us to conclude that males appear to disperse more than females, reducing the chance of the genetic loss associated with recent anthropogenic fragmentation of the D. elongatus studied range.
许多蚱蜢物种被认为具有农业重要性，因为它们会对牧场和作物造成损害。要了解害虫种群动态，就必须清楚了解种群的遗传多样性和空间结构。在这项研究中，我们报告了南美洲蚱蜢 Dichroplus elongatus 的遗传变异模式，该物种是阿根廷对农作物和饲料草具有重大经济意义的农业害虫。我们使用直接扩增微卫星区（DAMD）和细胞色素氧化酶 1（COI）线粒体基因的部分序列来研究该物种的二十个阿根廷种群的种内结构、种群历史和基因流动模式，这些种群属于不同的地理和生物地理区域。DAMD 数据表明，尽管遗传漂变和迁移在种群内和种群间发生，但相邻种群之间的可测量亲缘关系随距离而下降，超过 200 公里的扩散并不常见，而对于相隔不到 100 公里的种群，则可能发生有效的基因流动。景观分析有助于检测与反映不断变化的农业生态系统的环境异质性相关的遗传不连续性。COI 结果表明，在位于巴拉那河两岸的两组种群之间存在强烈的遗传分化，这些种群在中更新世气候振荡期间分离，这表明雌性介导的有效扩散受到严重限制，以及大尺度的地理分化。通过线粒体和 DAMD 标记估计的种群间迁移者数量表明基因流动较低，导致空间结构不均匀，并证明了空间变异的合理性。此外，两种标记的遗传分析使我们能够得出结论，雄性似乎比雌性更容易扩散，从而减少了与最近人为干扰 D.elongatus 研究范围的遗传损失相关的机会。
