Two cytotype niche shifts are of different magnitude in Solidago gigantea

Abstract

Premise Polyploidy may serve to contribute to range size if autopolyploid cytotypes are adapted to differing ecological conditions. This study aims to establish the geographic distribution of cytotypes within the giant goldenrod (Solidago gigantea), and to assess whether cytotypes exhibit differing ecological tolerances and morphology. Methods A range‐wide set of 629 Solidago gigantea individuals was obtained through field collecting, sampling from herbarium specimens, and incorporating existing chromosome counts. Cytotype of each unknown sample was estimated by observing allele numbers at twelve microsatellite loci, a strategy that was assessed by comparing estimated to known cytotype in 20 chromosome‐counted samples. Abiotic ecological differentiation was assessed for two transitions: diploid‐tetraploid and tetraploid‐hexaploid. Morphological differentiation among cytotypes was assessed. Results Microsatellite repeat variation accurately estimated cytotype in 85% of samples for which ploidy was known. Applying this approach to samples of unknown ploidy established that the three cytotypes are non‐randomly distributed. Although niche modeling and MANOVA approaches identified significant differences in macro‐climatic conditions for both cytotype transitions, the tetraploid to hexaploid transition was more substantial. Leaf length and width did not differ among cytotypes. Although leaf vestiture exhibited strong trends, no absolute differences were observed among cytotypes. Conclusions With the largest such study to date, we established niche transitions among giant goldenrod cytotypes of differing magnitudes. Collectively, this suggests that whole‐genome duplication has contributed to Solidago gigantea’s large range.

Investigating the effects of whole genome duplication on phenotypic plasticity: implications for the invasion success of giant goldenrod Solidago gigantea

“…Only tetraploid cytotypes are found in parts of Eurasia (Schlaepfer et al 2008(Schlaepfer et al , 2010, where it is an exotic and highly invasive species that negatively affects local plant (Weber and Jakobs 2005) and soil microbial communities (Bobuľská et al 2019). Cytotypes and geographically separated populations show phenotypic (Martino et al 2020) and genetic (i.e. increases with ploidy level; Nagy et al 2018) differences, owing to shifts in niche space and tolerances following whole genome duplication (Nagy et al 2018, Martino et al 2020.…”

“…For example, several studies have shown that polyploidy results in the duplication of defense genes and that polyploids may experience less damage by pathogens and herbivores (Nuismer and Thompson 2001, Hannweg et al 2016, Hias et al 2018. Similarly, studies with S. gigantea have found that tetraploids tend to exhibit phenotypes intermediate of diploids and hexaploids for some traits such as abaxial leaf pubescence and height (Nagy et al 2018, Martino et al 2020 but not others, such as leaf length and width (Martino et al 2020). Here we found support for tetraploid intermediacy some traits such as photosynthetic capacities, water use efficiencies, and leaf pathogen resistance.…”

Polyploid goldback and silverback ferns (Pentagramma) occupy a wider, colder, and wetter bioclimatic niche than diploid counterparts

“…Pentagramma polyploids appear to follow the most general predictions in that they occupy a wider niche, or greater diversity of niches, than diploids. Measuring and comparing the shapes (in environmental space) of cytotype niches is complex (Brown and Carnaval, 2019; Hadle et al, 2019; Martino et al, 2020), and collapsing the individual bioclimatic variables into a composite measure potentially obscures insights into the ecology of the different cytotypes (Figures 4 and 6). However, by visually comparing histograms of individual bioclimatic variables in the all‐ Pentagramma data set (Appendix S5), we see that tetraploids have experienced niche expansion (e.g., in mean diurnal range, isothermality, and precipitation of driest quarter) and a niche shift into colder habitats, including annual mean temperature and mean temperature of both the wettest and the driest quarters).…”

“…However, chromosome counting is labor‐intensive, time‐consuming, and dependent on suitable material, potentially preventing the collection of ploidy data from geographically diverse samples. By integrating high‐throughput approaches for detecting cytotype variation with morphological and molecular studies, we can more accurately map cytotypes and taxa in geographic and ecological space, thereby leading to a better understanding of systematics, biodiversity metrics, niche evolution, and functional traits within a group (Broennimann et al, 2012; McIntyre, 2012; Glennon et al, 2014; Hadle et al, 2019; López‐Jurado et al, 2019; Castro et al, 2020; Decanter et al, 2020; Martino et al, 2020).…”

“…Previous work on polyploid plants has revealed conflicting patterns in the relative breadths of diploid and polyploid niches (e.g., Glennon et al, 2014; Marchant et al, 2016; Rushworth et al, 2018; Molina‐Henao and Hopkins, 2019; Baniaga et al, 2020). Some studies of autopolyploid systems found evidence for broader bioclimatic niches in polyploid vs. closely related diploid lineages (Molina‐Henao and Hopkins, 2019), while others identified a shift in niche median or optimum (Baniaga et al, 2020; Martino et al, 2020); still others found evidence for both a niche shift and broader niches in polyploids vs. diploids (McIntyre, 2012). Comparing abiotic niches among cytotypes in a large data set of angiosperms in Europe and North America, Glennon et al (2014) found that, contrary to theory and an expectation of frequent shifts in young polyploid lineages, the prevalent pattern across lineages supported niche conservatism and contraction.…”