Department of Zoology, University of Wisconsin, 250 N. Mills Street, Madison, Wisconsin 53706, USA.
Evolution. 2011 Sep;65(9):2592-605. doi: 10.1111/j.1558-5646.2011.01320.x. Epub 2011 Apr 29.
There are now a number of well-studied cases in which hybridization between closely related sympatric species has increased, sometimes resulting in the replacement of species pairs by hybrid swarms. Many of these cases have been linked to anthropogenic environmental change, but the mechanisms leading from environmental change to species collapse, and the long-term effects of hybridization on species pairs, remain poorly understood. We used an individual-based stochastic simulation model to explore the conditions under which disturbances that weaken premating barriers to reproduction patterns between sympatric species might lead to increased hybridization and to species collapse. Disturbances often resulted in bouts of hybridization, but in many cases strong reproductive isolation spontaneously reemerged. This was sometimes true even after hybrid swarms had replaced parental species. The reemergence of species pairs was most likely when disturbances were of short duration. Counterintuitively, incipient species pairs were more likely to reemerge after strong but temporary disturbances than after weaker disturbances of the same duration. Even temporary bouts of hybridization often led to substantial homogenization of species pairs. This suggests that ecosystem managers may be able to refill ecological niches, but in general will not be able to resurrect lost species after species collapse.
现在有许多经过深入研究的案例表明，在亲缘关系密切的同域物种之间发生杂交的情况有所增加，有时甚至会导致物种对被杂交群体所取代。这些案例中的许多都与人为的环境变化有关，但从环境变化到物种灭绝的机制，以及杂交对物种对的长期影响，仍了解甚少。我们使用基于个体的随机模拟模型来探讨环境变化削弱了同域物种之间繁殖模式的交配前障碍的情况下，可能会导致杂交增加和物种灭绝的条件。干扰通常会导致杂交的爆发，但在许多情况下，强烈的生殖隔离会自发重新出现。即使在杂交群体已经取代了亲代物种的情况下，这种情况也时有发生。当干扰持续时间较短时，物种对重新出现的可能性最大。与直觉相反的是，在经历了强烈但短暂的干扰后，初生的物种对比经历相同持续时间但较弱的干扰后更有可能重新出现。即使是短暂的杂交爆发也常常导致物种对的大量同质化。这表明生态系统管理者可能能够填补生态位，但通常在物种灭绝后无法复活失去的物种。
