Recent speciation and secondary contact in endemic ants

Gene flow is the main force opposing divergent selection, and its effects are greater in populations in close proximity. Thus, complete reproductive isolation between parapatric populations is not expected, particularly in the absence of ecological adaptation and sharp environmental differences. Here, we explore the biogeographical patterns of an endemic ant species, Cataglyphis floricola, for which two colour morphs (black and bicolour) coexist in parapatry throughout continuous sandy habitat in southern Spain. Discriminant analyses of six biometric measurements of male genitalia and 27 cuticular hydrocarbons reveal high differentiation between morphs. Furthermore, the low number of shared alleles derived from nuclear markers (microsatellites) between the morphs at their contact zone suggests the absence of recent gene flow. Mitochondrial DNA (COI) phylogenetic analysis and median-joining networks show that the black morph is basal to the bicolour morph, with unique haplotypes recovere...

基因流（gene flow）是对抗歧化选择（divergent selection）的核心演化动力，且其作用强度在空间邻近的邻域种群（parapatric populations）间更为显著。因此，邻域种群间难以形成完全的生殖隔离（reproductive isolation），尤其当缺乏生态适应与显著环境差异时。本研究聚焦于特有蚁类Cataglyphis floricola的生物地理格局：该物种在西班牙南部的连续沙生生境中，存在两种以邻域分布共存的色型——黑色型与双色型。通过对雄性外生殖器（male genitalia）的6项形态测量参数与27种表皮碳氢化合物（cuticular hydrocarbons）开展判别分析，结果显示两种色型间存在高度分化。此外，在两种色型的接触带处，其共享的核标记（nuclear markers，微卫星microsatellites）等位基因数量极少，提示近期未发生基因流。线粒体DNA（mitochondrial DNA）COI基因的系统发育分析（phylogenetic analysis）与中介连接网络图（median-joining networks）显示，黑色型为双色型的基部类群，且二者均拥有独特的单倍型（haplotypes）……