ABSTRACT There are notable examples of repeated evolution of ecomorphs within groups of closely related species, these are typically viewed as remarkable cases of natural selection. In most cases, directional selection for certain phenotypic traits under specific (and differing) environmental conditions is implicated. Differing ecomorphological forms for closely related species (or for populations within a species) have been documented for several lineages of South African dwarf chameleons (Bradypodion), although this pattern is not ubiquitous across the genus. Within one species, Bradypodion pumilum, two ecomorphs have been observed, these differ in terms of morphology, performance, ecology and habitat, yet genetic differences (mtDNA) were not apparent, with shared haplotypes across the ecomorphs. We investigated whether more sensitive genetic markers (eight microsatellite loci) would show population level structure between ecomorphs, which could indicate lack of gene flow across the ecological (habitat) boundary. Our results suggest that the two ecomorphs are distinct at a population level, implying that gene flow is absent or reduced and that the two ecomorphs are on separate evolutionary trajectories. Given that mtDNA could not detect population structure, we infer that the ecological boundary between ecomorphs is relatively recent in evolutionary history. The two ecomorphs are distinctive in terms of their morphology, ecology, habitat and functional traits, these differences are likely driven and maintained by reproductive isolation across the habitat boundary.

中文翻译：

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与栖息地多样化相关的遗传结构支持 Bradypodion pumilum 生态形态的独立进化

摘要 在密切相关的物种群内，生态形态的重复进化有显着的例子，这些通常被视为自然选择的显着案例。在大多数情况下，涉及特定（和不同）环境条件下某些表型性状的定向选择。南非矮变色龙（Bradypodion）的几个谱系已经记录了密切相关物种（或物种内的种群）的不同生态形态学形式，尽管这种模式在整个属中并不普遍。在一个物种中，Bradypodion pumilum，已经观察到两种生态形态，它们在形态、性能、生态和栖息地方面有所不同，但遗传差异 (mtDNA) 并不明显，在整个生态形态中具有共享的单倍型。我们调查了更敏感的遗传标记（八个微卫星位点）是否会显示生态形态之间的种群水平结构，这可能表明缺乏跨越生态（栖息地）边界的基因流。我们的结果表明，这两种生态形态在种群水平上是不同的，这意味着基因流不存在或减少，并且这两种生态形态处于不同的进化轨迹上。鉴于 mtDNA 无法检测种群结构，我们推断生态形态之间的生态边界在进化史上相对较新。这两种生态形态在形态、生态、栖息地和功能特征方面是不同的，这些差异很可能是由跨越栖息地边界的生殖隔离驱动和维持的。