Tracking the progression of speciation: variable patterns of introgression across the genome provide insights on the species delimitation between progenitor–derivative spruces (Picea mariana × P. rubens)

摘要: The genic species concept implies that while most of the genome can be exchanged somewhat freely between through introgression, some genomic regions remain impermeable to interspecific gene flow. Hence, differences maintained despite ongoing exchange within contact zones. This study assessed heterogeneous patterns introgression at loci across hybrid zone an incipient progenitor–derivative pair, Picea mariana (black spruce) and rubens (red spruce). spruce taxa likely diverged in geographic isolation during Pleistocene came into secondary late Holocene. A total 300 SNPs distributed 12 linkage groups (LG) black were genotyped for 385 individual trees from 33 populations allopatric each sympatry. An integrative framework combining three population approaches was used scan genomes, revealing introgression. 23 scattered over 10 LG considered putatively under diverging selection. These revealed existence forming boundary are thus indicative speciation these two genetic lineages. Another 238 reflected selectively neutral diffusion porous barrier. Finally, 39 highly permeable suggested ancestral polymorphism along with balancing indicated process red is young incomplete, albeit maintained, allowing divergence even approach developed this track progression processes.