On the origin of orphan hybrids between Aquilegia formosa and Aquilegia flavescens. Issue 1 (19th November 2018)

• Record Type: Journal Article
• Authors: Groh, Jeffrey S; Percy, Diana M; Björk, Curtis R; Cronk, Quentin C B
• Is Part Of: AoB plants. Volume 11:Issue 1(2019)
• Publication Date: 2018-11-19
• Subjects: Aquilegia -- genetic swamping -- herbarium -- hybridization -- introgression -- range boundaries; Plants -- Periodicals; Botany -- Periodicals; 580.5
• DOI: 10.1093/aobpla/ply071
• Languages: English
• ISSNs: 2041-2851

Abstract

Abstract: We report the investigation of an Aquilegia flavescens × A. formosa population in British Columbia that is disjunct from its parents—the latter species is present locally but ecologically separated, while the former is entirely absent. To confirm hybridity, we used multivariate analysis of floral characters of field-sampled populations to ordinate phenotypes of putative hybrids in relation to those of the parental species. Microsatellite genotypes at 11 loci from 72 parental-type and putative hybrid individuals were analysed to assess evidence for admixture. Maternally inherited plastid sequences were analysed to infer the direction of hybridization and test hypotheses on the origin of the orphan hybrid population. Plants from the orphan hybrid population are on average intermediate between typical A. formosa and A. flavescens for most phenotypes examined and show evidence of genetic admixture. This population lies beyond the range of A. flavescens, but within the range of A. formosa . No pure A. flavescens individuals were observed in the vicinity, nor is this species known to occur within 200 km of the site. The hybrids share a plastid haplotype with local A. formosa populations. Alternative explanations for this pattern are evaluated. While we cannot rule out long-distance pollen dispersal followed by proliferation of hybrid genotypes, we consider the spread of an A. formosa plastid during genetic swamping of a historical A. flavescens population to be more parsimonious. Abstract : The outcomes of natural hybridization are incredibly varied, ranging from hybrid speciation to extinction of parental taxa. This research describes the investigation of an 'orphan' hybrid population between Aquilegia formosa and Aquilegia flavescens, two western North American taxa, in which the latter species is absent both locally and regionally. We present analyses of floral morphology, nuclear admixture and maternally inherited plastid sequence to confirm hybridity and discuss possible origin scenarios. We suggest that A. flavescens may have formerly occupied the region and became extirpated through genetic assimilation by its congener.