Quantitative trait locus mapping identifies candidate alleles involved in adaptive introgression and range expansion in a wild sunflower

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作   者：

Whitney, Kenneth D.;  Broman, Karl W.;  Kane, Nolan C.;  Hovick, Stephen M.;  Randell, Rebecca A.;  Rieseberg, Loren H.; 

作者机构：

WI 53706 USA;  Boulder;  Indiana Univ;  EBIO Dept;  Madison;  Univ Colorado;  IN 47405 USA;  OH 43210 USA;  Univ New Mexico;  Univ Wisconsin;  Ohio State Univ;  Bloomington;  Columbus;  CO 80309 USA;  Albuquerque;  Dept Biostat & Med Informat;  NM 87131 USA;  Dept Biol;  Dept Evolut Ecol & Organismal Biol; 

关键词：

range expansion;  invasion;  single nucleotide polymorphism;  phenology;  herbivory;  quantitative trait locus;  adaptive trait introgression;  hybridization;  plant architecture;  seed predation; 

期刊名称：

Molecular ecology

i s s n：

0962-1083

年卷期：

2015 年 24 卷 9 期

页   码：

2194-2211

页   码：

摘   要：

The wild North American sunflowers Helianthus annuus and H.debilis are participants in one of the earliest identified examples of adaptive trait introgression, and the exchange is hypothesized to have triggered a range expansion in H.annuus. However, the genetic basis of the adaptive exchange has not been examined. Here, we combine quantitative trait locus (QTL) mapping with field measurements of fitness to identify candidate H.debilis QTL alleles likely to have introgressed into H.annuus to form the natural hybrid lineage H.a.texanus. Two 500-individual BC1 mapping populations were grown in central Texas, genotyped for 384 single nucleotide polymorphism (SNP) markers and then phenotyped in the field for two fitness and 22 herbivore resistance, ecophysiological, phenological and architectural traits. We identified a total of 110 QTL, including at least one QTL for 22 of the 24 traits. Over 75% of traits exhibited at least one H.debilis QTL allele that would shift the trait in the direction of the wild hybrid H.a.texanus. We identified three chromosomal regions where H.debilis alleles increased both female and male components of fitness; these regions are expected to be strongly favoured in the wild. QTL for a number of other ecophysiological, phenological and architectural traits colocalized with these three regions and are candidates for the actual traits driving adaptive shifts. GxE interactions played a modest role, with 17% of the QTL showing potentially divergent phenotypic effects between the two field sites. The candidate adaptive chromosomal regions identified here serve as explicit hypotheses for how the genetic architecture of the hybrid lineage came into existence.