We studied the door‐snail genus Alopia in the Southern Carpathians in Romania to better understand non‐adaptive radiations and the processes that determine their course. Alopia in the Bucegi Mountains offers the opportunity to study all stages of a radiation within a few kilometres. The species (as defined by the differential fitness species concept) in the most advanced stage of the radiation differs from other species in the genitalia and co‐occurs with other species. The least advanced stages are genetically differentiated clusters of populations that are geographically separated from other clusters but are not yet morphologically differentiated. Differentiation does not increase with a constant rate as shown by a lineage that was separated early in the evolution of the genus but fused with other taxa upon secondary contact. Since non‐adaptive radiation cannot be accelerated by divergent natural selection beyond the slow pace of speciation that is possible by genetic drift alone, sexual selection plays a crucial role in non‐adaptive radiations. This is supported by the differences in the genitalia found in the most advanced stage of the speciation which indicate that the speciation process was accelerated by a co‐evolutionary arms race resulting in the elongation of spermatophore‐producing and spermatophore‐receiving organs. Another process that facilitates non‐adaptive radiation is long‐distance dispersal that results in geographically isolated populations that can differentiate without gene flow and that have a higher likelihood of speciation due to the founder event. Several taxa that were considered distinct species until now, but fuse upon contact should better be classified as subspecies of a polytypic species.

中文翻译：

---

非适应性辐射中的模式和过程：布切吉山脉的 Alopia (Gastropoda, Clausiliidae)

我们研究了罗马尼亚南部喀尔巴阡山脉的门蜗牛属 Alopia，以更好地了解非适应性辐射和决定其进程的过程。Bucegi 山脉的 Alopia 提供了研究几公里内辐射的所有阶段的机会。处于辐射最晚期阶段的物种（由差异适应度物种概念定义）与生殖器中的其他物种不同，并与其他物种共同发生。最不先进的阶段是遗传分化的种群集群，它们在地理上与其他集群分开，但尚未在形态上分化。分化不会以恒定速率增加，如在属进化早期分离但在二次接触时与其他分类群融合的谱系所示。由于除了遗传漂变可能导致的缓慢物种形成速度之外，发散自然选择无法加速非适应性辐射，因此性选择在非适应性辐射中起着至关重要的作用。在物种形成的最高级阶段发现的生殖器差异支持了这一点，这表明共同进化的军备竞赛加速了物种形成过程，导致产生精子的器官和接受精子的器官伸长。另一个促进非适应性辐射的过程是长距离扩散，这导致地理上孤立的种群可以在没有基因流动的情况下进行分化，并且由于创始人事件而具有更高的物种形成可能性。几个迄今为止被认为是不同物种的分类群，