McKenzie Jessica L, Araújo H Andrés, Smith Jack L, Schluter Dolph, Devlin Robert H
Centre for Aquaculture and Environmental Research, Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, British Columbia, Canada V7V 1N6.
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4.
Proc Biol Sci. 2021 May 12;288(1950):20203020. doi: 10.1098/rspb.2020.3020. Epub 2021 May 5.
Global change is altering ecosystems at an unprecedented rate. The resulting shifts in species ranges and reproductive timing are opening the potential for hybridization between closely related species which could dramatically alter the genetic diversity, adaptive capacity and evolutionary trajectory of interbreeding taxa. Here, we used behavioural breeding experiments, fertilization experiments, and whole-transcriptome gene expression data to assess the potential for and consequences of hybridization between Chinook and Coho salmon. We show that behavioural and gametic prezygotic barriers between socio-economically valuable Chinook and Coho salmon are incomplete. Postzygotically, we demonstrate a clear transcriptomic response to hybridization among F Chinook-Coho offspring. Genes transgressively expressed within hybrids were significantly enriched with genes encoded in the nucleus but localized to the mitochondrion, suggesting a potential role for mito-nuclear incompatibilities as a postzygotic mechanism of hybrid breakdown. Chinook and Coho salmon are expected to continue to respond to climate change with shifts in migration timing and habitat use, potentiating hybridization between these species. The downstream consequences of hybridization on the future of these threatened salmon, and the ecosystems they inhabit, is unknown.
全球变化正在以前所未有的速度改变生态系统。物种分布范围和繁殖时间的相应变化为亲缘关系密切的物种之间的杂交创造了可能性，这可能会极大地改变杂交类群的遗传多样性、适应能力和进化轨迹。在此，我们利用行为育种实验、受精实验以及全转录组基因表达数据，来评估奇努克鲑和银鲑杂交的可能性及后果。我们发现，具有社会经济价值的奇努克鲑和银鲑之间的行为和配子前合子屏障并不完全。在合子后阶段，我们证明了奇努克 - 银鲑杂交后代对杂交有明显的转录组反应。在杂交种中过度表达的基因显著富集了那些在细胞核中编码但定位于线粒体的基因，这表明线粒体 - 核不兼容性作为杂交衰退的合子后机制可能发挥了作用。预计奇努克鲑和银鲑将继续随着洄游时间和栖息地利用的变化对气候变化做出反应，从而增强这些物种之间的杂交。杂交对这些濒危鲑鱼及其栖息的生态系统未来的下游影响尚不清楚。
