Maintenance of Species Differences in Closely Related Tetraploid Parasitic Euphrasia (Orobanchaceae) on an Isolated Island  

作　　者：Hannes Becher Max R.Brown Gavin Powell Chris Metherell Nick J.Riddifordand Alex D.Twyford 

机构地区：[1]University of Edinburgh,School of Biological Sciences,Institute of Evolutionary Biology,Charlotte Auerbach Road,Edinburgh EH93FL,UK [2]Royal Botanic Garden Edinburgh,20A Inverleith Row,Edinburgh EH35LR,UK [3]Botanical Society of Britain and Ireland,4 High Firs Crescent,Harpenden,Hertfordshire AL51NA,UK [4]Schoolton,Fair Isle,Shetland ZE29JU,UK

出　　处：《Plant Communications》2020年第6期85-99,共15页植物通讯（英文）

基　　金：funded by NERC grants(NE/R010609/1,NE/L011336/1,NE/N006739/1)awarded to A.D.T.

摘　　要：Polyploidy is pervasive in angiosperm evolution and plays important roles in adaptation and speciation.However,polyploid groups are understudied due to complex sequence homology,challenging genome assembly,and taxonomic complexity.Here,we study adaptive divergence in taxonomically complex eyebrights(Euphrasia),where recent divergence,phenotypic plasticity,and hybridization blur species boundaries.We focus on three closely related tetraploid species with contrasting ecological preferences that are sympatric on Fair Isle,a small isolated island in the British Isles.Using a common garden experiment,we show a genetic component to the morphological differences present between these species.Using wholegenome sequencing and a novel k-mer approach we call“Tetmer”,we demonstrate that the species are of allopolyploid origin,with a sub-genome divergence of approximately 5%.Using2 million SNPs,we show sub-genome homology across species,with a very low sequence divergence characteristic of recent speciation.This genetic variation is broadly structured by species,with clear divergence of Fair Isle heathland Euphrasia micrantha,while grassland Euphrasia arctica and coastal Euphrasia foulaensis are more closely related.Overall,we show that tetraploid Euphrasia is a system of allopolyploids of postglacial species divergence,where adaptation to novel environments may be conferred by old variants rearranged into new genetic lineages.

关 键 词：incipient speciation k-mer spectrum ALLOPOLYPLOIDY TETRAPLOID divergence with gene flow taxonomic complexity 

分 类 号：Q94[生物学—植物学]