Ross Kenneth G, Trager James C
Department of Entomology, University of Georgia, Athens, GA, 30602, USA.
Department of Biology, University of Missouri-St. Louis, St. Louis, MO, 63121, USA.
Evolution. 1990 Dec;44(8):2113-2134. doi: 10.1111/j.1558-5646.1990.tb04316.x.
Specimens of seven fire ant species collected from their native ranges in Argentina were studied by protein electrophoresis and morphological analysis. Concordance between the genetic and morphological character sets is strong (96% agreement on identifications), suggesting that recognition of reproductively isolated populations and partitioning of intra- and interspecific variation can in most cases be achieved using appropriate characters of either type in this taxonomically difficult group. Genetic differentiation between native (Argentina) and introduced (USA) conspecific populations of two species, Solenopsis invicta and S. richteri, is rather typical of the differentiation existing between conspecific populations found within either country. Furthermore, there appears to have been little reduction of variability (heterozygosity) at enzyme loci following colonization by either species of the United States, although some rare alleles have been lost in the introduced populations. Hybridization is rare between S. invicta and S. richteri where their native ranges overlap in central Argentina, in contrast to the extensive hybridization of these species in the United States, suggesting that prezygotic barriers to gene flow have been compromised in introduced populations. Phylogenetic analysis of the seven species indicates that S. invicta and S. richteri are relatively distantly related within the S. saevissima complex. Given that hybrids between these species in the United States suffer little apparent loss of fitness, genomic incompatibilities generally may be insufficient to create effective postzygotic barriers to interspecific gene flow in this group of ants.
通过蛋白质电泳和形态学分析，对从阿根廷原生地采集的7种火蚁物种的样本进行了研究。遗传特征集和形态特征集之间的一致性很强（鉴定结果的一致性为96%），这表明在这个分类困难的群体中，在大多数情况下，使用任何一种类型的适当特征都可以实现对生殖隔离种群的识别以及种内和种间变异的划分。两种火蚁，即红火蚁（Solenopsis invicta）和黑火蚁（S. richteri），其原产于阿根廷的种群与引入美国的同种种群之间的遗传分化，相当典型地体现了两国境内同种种群之间存在的分化情况。此外，在美国，这两种火蚁中的任何一种在定殖后，酶位点的变异性（杂合性）似乎都没有明显降低，尽管在引入的种群中一些稀有等位基因已经丢失。在阿根廷中部，红火蚁和黑火蚁的原生地范围重叠的地方，它们之间的杂交很少见，这与它们在美国广泛杂交形成对比，这表明在引入的种群中，基因流动的合子前障碍已经受到破坏。对这7个物种的系统发育分析表明，在凶猛火蚁复合体（S. saevissima complex）中，红火蚁和黑火蚁的亲缘关系相对较远。鉴于这两种火蚁在美国的杂交后代几乎没有明显的适应性损失，一般来说，基因组不相容性可能不足以在这组蚂蚁中形成有效的种间基因流动的合子后障碍。
