Demographic expansion and genetic load of the halophyte model plant Eutrema salsugineum

• Published in: Molecular Ecology
• Main Authors: Wang, Xiao-Juan, Hu, Quan-Jun, Guo, Xin-Yi, Wang, Kun, Ru, Da-Fu, German, Dmitry A., Weretilnyk, Elizabeth A., Abbott, Richard J., Lascoux, Martin, Liu, Jian-Quan
• Other Authors: University of St Andrews.School of Biology
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Eutrema salsugineum; Migration; Hybrid lineage; Long-distance dispersal; Expansion; Deleterious variant; QH301 Biology; DAS; QH301; Subarctic
• Online Access: https://hdl.handle.net/10023/17945; https://doi.org/10.1111/mec.14738

This work was supported by National Natural Science Foundation of China (31590821, 91331102, 91731301) and the Youth Science and Technology Innovation Team of Sichuan Province (2014TD003). The halophyte model plant Eutrema salsugineum (Brassicaceae) disjunctly occurs in temperate to subarctic Asia and North America. This vast, yet extremely discontinuous distribution constitutes an ideal system to examine long‐distance dispersal and the ensuing accumulation of deleterious mutations as expected in expanding populations of selfing plants. In this study, we re‐sequenced individuals from 23 populations across the range of E. salsugineum. Our population genomic data indicate that E. salsugineum migrated ‘out of the Altai region’ at least three times to colonize northern China, northeast Russia and western China. It then expanded its distribution into North America independently from northeast Russia and northern China, respectively. The species colonized northern China around 33.7 thousand years ago (kya) and underwent a considerable expansion in range size approximately 7‐8 kya. The western China lineage is likely a hybrid derivative of the northern China and Altai lineages, originating approximately 25‐30 kya. Deleterious alleles accumulated in a stepwise manner from (i) Altai to northern China and North America, and (ii) from Altai to northeast Russia and North America. In summary, E. salsugineum dispersed from Asia to North America and deleterious mutations accumulated in a stepwise manner during the expansion of the species’ distribution. Peer reviewed