杂交,定义为在两个不同的分类单位之间繁殖,可以对杂交育种分类群的进化模式产生重要影响。尽管种间杂交经常被认为是适应不良的过程,通过遗传沼泽和近亲繁殖抑郁症威胁物种遗传完整性和生存,在某些情况下,杂交可以引入新的适应性变异并增加适应性。迄今为止,大多数研究都集中在记录杂交事件并分析其原因上,虽然对杂交的后果及其对亲本物种的影响知之甚少。为了解决这个知识差距,我们对2010-2021年发表的哺乳动物杂交研究进行了系统综述,确定了115项相关研究.在这些研究中描述的13类杂交后果中,最常见的负面结果(21%的研究)是遗传沼泽,最常见的正面结果(8%)是获得新的适应性变异。负后果的总频率(49%)高于正后果(13%)和中性后果(38%)。这些频率因微卫星位点的检测可能性而有偏差,评估论文中使用的最常见的遗传标记。由于负面结果通常比正面结果更容易证明(例如,灭绝vs杂种物种形成),他们可能在出版物中代表过多。向涉及中性和适应性变异的基因组研究的过渡将提供对杂交的实际影响的更好了解。
Hybridization, defined as breeding between two distinct taxonomic units, can have an important effect on the evolutionary patterns in cross-breeding taxa. Although interspecific hybridization has frequently been considered as a maladaptive process, which threatens species genetic integrity and survival via genetic swamping and outbreeding depression, in some cases hybridization can introduce novel adaptive variation and increase fitness. Most studies to date focused on documenting hybridization events and analyzing their causes, while relatively little is known about the consequences of hybridization and its impact on the parental species. To address this knowledge gap, we conducted a systematic
review of studies on hybridization in mammals published in 2010-2021, and identified 115 relevant studies. Of 13 categories of hybridization consequences described in these studies, the most common negative consequence (21% of studies) was genetic swamping and the most common positive consequence (8%) was the gain of novel adaptive variation. The total frequency of negative consequences (49%) was higher than positive (13%) and neutral (38%) consequences. These frequencies are biased by the detection possibilities of microsatellite loci, the most common genetic markers used in the papers assessed. As negative outcomes are typically easier to demonstrate than positive ones (e.g., extinction vs hybrid speciation), they may be over-represented in publications. Transition towards genomic studies involving both neutral and adaptive variation will provide a better insight into the real impacts of hybridization.