Organismal and Evolutionary Biology, University of Helsinki, Finland.
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
Philos Trans R Soc Lond B Biol Sci. 2020 Aug 31;375(1806):20190528. doi: 10.1098/rstb.2019.0528. Epub 2020 Jul 13.
Speciation, that is, the evolution of reproductive barriers eventually leading to complete isolation, is a crucial process generating biodiversity. Recent work has contributed much to our understanding of how reproductive barriers begin to evolve, and how they are maintained in the face of gene flow. However, little is known about the transition from partial to strong reproductive isolation (RI) and the completion of speciation. We argue that the evolution of strong RI is likely to involve different processes, or new interactions among processes, compared with the evolution of the first reproductive barriers. Transition to strong RI may be brought about by changing external conditions, for example, following secondary contact. However, the increasing levels of RI themselves create opportunities for new barriers to evolve and, and interaction or coupling among barriers. These changing processes may depend on genomic architecture and leave detectable signals in the genome. We outline outstanding questions and suggest more theoretical and empirical work, considering both patterns and processes associated with strong RI, is needed to understand how speciation is completed. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
物种形成，即生殖隔离的进化，最终导致完全隔离，是产生生物多样性的关键过程。最近的研究工作极大地促进了我们对生殖隔离如何开始进化以及在面对基因流时如何维持的理解。然而，对于从部分生殖隔离到强生殖隔离（RI）的转变以及物种形成的完成，我们知之甚少。我们认为，与第一个生殖隔离的进化相比，强 RI 的进化可能涉及不同的过程，或者是过程之间新的相互作用。向强 RI 的转变可能是由外部条件的变化引起的，例如，在二次接触之后。然而，RI 水平的不断提高为新的隔离障碍的进化以及障碍之间的相互作用或耦合创造了机会。这些变化的过程可能取决于基因组结构，并在基因组中留下可检测的信号。我们概述了悬而未决的问题，并建议进行更多的理论和实证工作，考虑到与强 RI 相关的模式和过程，以了解物种形成是如何完成的。本文是主题为“走向物种形成的完成：超越第一道障碍的生殖隔离进化”的一部分。
