Differentiation between two self-compatible cytotypes of Herbertia lahue (Iridaceae): evidence from genotypic and phenotypic variation

Abstract

The polyploid species Herbertia lahue (Molina) Goldblatt is widespread in the grassland areas of southern America. In this study, genotypic and phenotypic variations among hexaploids and octoploids from H. lahue were assessed based on quantitative floral traits and ISSR markers. Additionally, gynoecium and breeding systems were analysed through anatomical analysis and hand-pollination experiments. Cytotypes are self-compatible, and the anatomy of the embryo sac remains similar in hexaploids and octoploids. AMOVA indicates that hexaploid populations are less genetically variable than octoploids (respectively 4 and 22 %, P \ 0.001), thus the largest source of genetic variation for H. lahue lies among populations (82 %, P \ 0.001), probably a combined effect of selfing, changes in population size, and local adaptation. Genetic variation between cytotypes was significant (16 %, P \ 0.001), though unclear segregation among cytotypes was discovered through PCoA. A Mantel test indicated no relationship between geographic and genetic distances (r = 0.04; P = 0.37), possibly as a result of the combined effect of the recurrent origin of polyploids, gene flow restricted by selfing, and poor capacity for seed dispersal. In terms of floral measurements, eight measures of perigonium, androecium, and gynoecium varied significantly between cytotypes, though no clear grouping was defined by PCA. Presumably, complex variation in floral characters across cytotypes may result in the absence of distinct grouping by PCA. The combined use of ISSR markers and morphological characters revealed a complex relationship between H. lahue cytotypes shaped by both intrinsic and extrinsic factors.

Genetic and ecological niche modeling of Calydorea crocoides (Iridaceae): an endemic species of Subtropical Highland Grasslands

“…Although the global F ST values point to more structured populations, which is consistent with other species of Iridaceae ( Hannan and Orick, 2000 ; Wróblewska et al , 2003 ; Wang et al , 2009 ; Tacuatiá et al , 2012a ; Stiehl-Alves et al , 2016 , 2017 ), the pairwise comparison of F ST revealed that some populations are less differentiated from each other ( F ST < 0.20) and retain residual gene flow among them ( N m > 1) ( Table 5 ). The population genetic structure in plants reflects the interaction of many evolutionary processes, including habitat fragmentation and population isolation, mutation, genetic drift, mating system, gene flow, and selection ( Hamrick and Godt, 1996 ; Hannan and Orick, 2000 ; Nybom and Bartish, 2000 ; Nybom, 2004 ; Stiehl-Alves et al , 2016 ). In this sense, although the STRUCTURE analysis detected two genetic clusters for the molecular dataset ( Figure 2 ), consistent with the UPGMA dendrogram ( Figure 3 ), the estimates of pairwise gene flow support the result of the STRUCTURAMA analysis ( K = 1), since gene flow was detected even for the most differentiated populations (ESC218 and ESC661).…”

“…As revealed by ISSR, C. crocoides has a relatively high genetic diversity at the species level ( Table 3 ) compared to other herbaceous or endemic species ( Hamrick and Godt 1990 ; Nybom and Bartish, 2000 ; Nybom, 2004 ). High levels of genetic diversity were also detected for other native species from South American grasslands ( Jakob et al , 2009 ; Lorenz-Lemke et al , 2006 , 2010 ; Sede et al , 2012 ; Fregonezi et al , 2013 ; Turchetto et al , 2014 ; 2016 ; Barros et al , 2015 ; Stiehl-Alves et al , 2017 ), some of these being species with restricted geographical distribution ( Lorenz-Lemke et al , 2006 , 2010 ). At the population level, AMOVA ( Table 4 ) showed that most of the genetic variation was found within populations, suggesting a genetic structure characteristic of outcrossing plants ( Nybom and Bartish, 2000 ; Nybom, 2004 ).…”

“…The size of the fragments was estimated using Ladder 100 bp (Ludwig Biotec, Porto Alegre, RS). Similar to the approach employed by Stiehl-Alves et al (2016 , 2017 ) and by Ng and Tan (2015) , reproducibility of ISSR banding patterns was tested with three repeated amplifications of five samples per population. These did not show differences in the pattern of amplified DNA fragments.…”

“…The fast pace of technological advances in the genomic and postgenomic eras has been greatly important for fostering knowledge on plant biology, but, when such data are not available, classical genetic analyses are still needed as a first step towards the description of biodiversity, especially for wild species ( Pérez et al , 2015 ). Studies concerning the estimation of genetic diversity have been done for several species of Iridaceae ( Hannan and Orick, 2000 ; Wróblewska et al , 2003 ; Sik et al , 2008 ; Wang et al , 2009 ; Tacuatiá et al , 2012a , b ; Stiehl-Alves et al , 2016 , 2017 ). Many molecular markers can be used as tools for population genetics studies in plants.…”

Cytological and genome size data analyzed in a phylogenetic frame: Evolutionary implications concerning Sisyrinchium taxa (Iridaceae: Iridoideae)

“…Polyploid cytotypes have been reported in some Iridaceae species, such as S. micranthum (4 x and 6 x ; Tacuatiá et al , 2012 ), S. sellowianum Klatt (4 x ; Fachinetto et al , 2018 ) and Herbertia lahue (Molina) Goldblatt (4 x , 6 x and 8 x ; Moraes et al , 2015 ; Stiehl-Alves et al , 2016 ). However, in this study we did not find any cytotypes within taxa.…”