Karsten M, Addison P, Jansen van Vuuren B, Terblanche J S
Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
Department of Zoology, Molecular Zoology Laboratory, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa.
Mol Ecol. 2016 Jul;25(13):3019-32. doi: 10.1111/mec.13646. Epub 2016 May 21.
The distribution, spatial pattern and population dynamics of a species can be influenced by differences in the environment across its range. Spatial variation in climatic conditions can cause local populations to undergo disruptive selection and ultimately result in local adaptation. However, local adaptation can be constrained by gene flow and may favour resident individuals over migrants-both are factors critical to the assessment of invasion potential. The Natal fruit fly (Ceratitis rosa) is a major agricultural pest in Africa with a history of island invasions, although its range is largely restricted to south east Africa. Across Africa, C. rosa is genetically structured into two clusters (R1 and R2), with these clusters occurring sympatrically in the north of South Africa. The spatial distribution of these genotypic clusters remains unexamined despite their importance for understanding the pest's invasion potential. Here, C. rosa, sampled from 22 South African locations, were genotyped at 11 polymorphic microsatellite loci and assessed morphologically using geometric morphometric wing shape analyses to investigate patterns of population structure and determine connectedness of pest-occupied sites. Our results show little to no intraspecific (population) differentiation, high population connectivity, high effective population sizes and only one morphological type (R2) within South Africa. The absence of the R1 morphotype at sites where it was previously found may be a consequence of differences in thermal niches of the two morphotypes. Overall, our results suggest high invasion potential of this species, that area-wide pest management should be undertaken on a country-wide scale, and that border control is critical to preventing further invasions.
一个物种的分布、空间格局和种群动态会受到其分布范围内环境差异的影响。气候条件的空间变化会导致当地种群经历分裂选择并最终导致局部适应。然而，局部适应可能会受到基因流的限制，并且可能更有利于本地个体而非迁移个体——这两个因素对于评估入侵潜力至关重要。纳塔尔果蝇（Ceratitis rosa）是非洲的一种主要农业害虫，有岛屿入侵的历史，尽管其分布范围主要局限于非洲东南部。在整个非洲，蔷薇果实蝇在基因上分为两个簇（R1和R2），这两个簇在南非北部同域分布。尽管这些基因型簇对于理解该害虫的入侵潜力很重要，但其空间分布仍未得到研究。在这里，从南非22个地点采集的蔷薇果实蝇样本在11个多态性微卫星位点进行了基因分型，并使用几何形态测量翼形分析进行形态学评估，以研究种群结构模式并确定害虫占据地点的连通性。我们的结果显示，种内（种群）分化很小或没有，种群连通性高，有效种群规模大，并且在南非境内只有一种形态类型（R2）。以前发现有R1形态类型的地点现在没有该形态类型，可能是这两种形态类型热生态位差异的结果。总体而言，我们的结果表明该物种具有很高的入侵潜力，应在全国范围内进行区域害虫管理，并且边境管控对于防止进一步入侵至关重要。
