Patterson C, Brennan A, Cowling H, González-Rodríguez A, Grether G F, Mendoza Cuenca L, Springer M, Vega-Sánchez Y M, Drury J
Department of Biosciences, Durham University, Durham, UK.
Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, México.
Mol Ecol. 2025 Jun;34(12):e17797. doi: 10.1111/mec.17797. Epub 2025 May 15.
Non-ecological speciation is a common mode of speciation, which occurs when allopatric lineages diverge in the absence of pronounced ecological differences. Yet, relative to other speciation mechanisms, non-ecological speciation remains understudied. Numerous damselfly clades are characterised as non-adaptive radiations (the result of several rounds of non-ecological speciation without subsequent divergence), but there are few damselfly lineages for which we have a detailed understanding of the spatiotemporal dynamics of divergence. Recent phylogeographic analyses demonstrate that American rubyspot damselflies (Hetaerina americana sensu lato) actually comprise at least two cryptic lineages that coexist sympatrically across most of Mexico. To broaden our understanding of the dynamics of diversification to other rubyspot lineages, we investigated the phylogeographic history of smoky rubyspot damselflies (Hetaerina titia) using genomic data collected across Central and North America. Unexpectedly, we found evidence of reproductive isolation between the highly genetically differentiated Pacific and Atlantic lineages of H. titia in a narrow secondary contact zone on the Isthmus of Tehuantepec, Mexico. We then fit models of historical demography to both H. americana sensu lato and H. titia to place these comparisons in a temporal context. Our findings indicate that Pacific and Atlantic lineages of H. titia split more recently than the broadly sympatric lineages within H. americana sensu lato, supporting key assumptions of the non-ecological speciation model and demonstrating that these two pairs of sister lineages are at different stages of the speciation cycle.
非生态物种形成是一种常见的物种形成模式，当异域谱系在没有明显生态差异的情况下发生分化时就会出现这种情况。然而，相对于其他物种形成机制，非生态物种形成仍未得到充分研究。许多豆娘类群被描述为非适应性辐射（几轮非生态物种形成但随后没有分化的结果），但对于豆娘谱系，我们详细了解其分化时空动态的却很少。最近的系统地理学分析表明，美洲赤斑豆娘（广义的美洲赤斑豆娘）实际上至少包括两个隐秘谱系，它们在墨西哥大部分地区同域共存。为了拓宽我们对其他赤斑豆娘谱系多样化动态的理解，我们利用从中美洲和北美洲收集的基因组数据，研究了烟赤斑豆娘（Hetaerina titia）的系统地理历史。出乎意料的是，我们在墨西哥特万特佩克地峡的一个狭窄的二次接触带中发现了高度遗传分化的太平洋和大西洋H. titia谱系之间存在生殖隔离的证据。然后，我们将历史人口统计学模型应用于广义的美洲赤斑豆娘和H. titia，以便在时间背景下进行这些比较。我们的研究结果表明，H. titia的太平洋和大西洋谱系的分化时间比广义的美洲赤斑豆娘中广泛同域的谱系更近，这支持了非生态物种形成模型的关键假设，并表明这两对姐妹谱系处于物种形成周期的不同阶段。
