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The contribution of hybridization to range‐wide population genetic structure in a Pacific coastal dune plant
Author(s) -
LópezVillalobos Adriana,
Eckert Christopher G.
Publication year - 2019
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/ajb2.1396
Subject(s) - biology , range (aeronautics) , population , evolutionary biology , ecology , demography , sociology , materials science , composite material
Premise Interspecific hybridization can cause genetic structure across species ranges if the mating system and degree of sympatry/parapatry with close relatives varies geographically. The coastal dune endemic Camissoniopsis cheiranthifolia (Onagraceae) exhibits genetic subdivisions across its range, some of which are associated with shifts in mating system from outcrossing to selfing, while others are not. For instance, strong differentiation between large‐flowered, self‐incompatible ( LF ‐ SI ) and large‐flowered, self‐compatible ( LF ‐ SC ) populations occurs without much reduction in outcrossing or obvious barriers to gene flow. We hypothesized that LF ‐ SI diverged from LF ‐ SC via hybridization with the predominantly inland SI sister species C. bistorta . Methods We analyzed spatial proximity using 1460 herbarium records and genetic variation at 12 microsatellites assayed for 805 and 404 individuals from 32 C. cheiranthifolia and 18 C. bistorta populations, respectively. We also assayed nine chloroplast microsatellites for 124 and 111 individuals from 27 and 19 populations, respectively. Results Closer parapatry was associated with unexpectedly high genetic continuity between LF ‐ SI C. cheiranthifolia and C. bistorta . LF ‐ SI genotypes clustered with C. bistorta exclusive of other C. cheiranthifolia genotypes. Similarly, pairwise F ST among SI C. cheiranthifolia and C. bistorta , adjusted for geographic proximity, was not higher between heterospecific than conspecific populations. Conclusions The lack of genetic differentiation between LF ‐ SI C. cheiranthifolia and C. bistorta populations, even those located away from the zone of parapatry, suggests that, instead of hybridizing with C. bistorta , LF ‐ SI C. cheiranthifolia is rather an ecotype of C. bistorta that has adapted to coastal dune habitat independent of other lineages in C. cheiranthifolia proper.