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The mating system of non-native plant populations plays a role in determining the colonizing success following introduction into locations outside of the native distribution. For plant species capable of mixed-mating, both selfing and outcrossing can be advantageous and promote the establishment, persistence, and spread of newly arrived populations. To investigate how mating systems may contribute to the invasion process we estimated mating system parameters in perennial populations of the model plant species, Mimulus guttatus from its native range (West coast USA), non-native populations that are established but have not become invasive (East coast USA, >50 years), and populations in invasive regions (UK >200 years). Studies that include mating system data across the continuum of the invasion process are rare, thus here we utilize molecular markers to estimate outcrossing rates (t), inbreeding coefficients (F), and inbreeding depression in native, naturalized, and invasive populations. Overall, we found support for the persistence of mixed-mating across populations, variability in the relationship between outcrossing rates and inbreeding depression across populations, and evidence for the bridgehead process, where non-native populations may be the sources for the further establishment or reinforcement of additional non-native populations. The methodology we deployed had its own assumptions and sampling design constraints, that contributed to the variation in the parameter estimates. All M. guttatus populations likely rely on selfing through both within clone, and within flower and plant mating in addition to vegetative propagation. The results underscore the importance of introduction history in determining the role of both sexual and asexual reproduction in the successful establishment of a plant species outside its native range. [ABSTRACT FROM AUTHOR]

Background and Aims Allopolyploidy is an important driver of diversification and a key contributor to genetic novelty across the tree of life. However, many studies have questioned the importance of extant polyploid lineages, suggesting that the vast majority may constitute evolutionary 'dead ends'. This has important implications for conservation efforts where polyploids and diploid progenitors often compete for wildlife management resources. Isoetes appalachiana is an allotetraploid that is broadly distributed throughout the eastern USA alongside its diploid progenitors, I. valida and I. engelmannii. As such, this species complex provides an excellent opportunity to investigate the processes that underpin the formation and survival of allopolyploid lineages. Methods Here we utilized RADseq and whole-chloroplast sequencing to unravel the demographic and evolutionary history of hybridization in this widespread species complex. We developed a modified protocol for phasing RADseq loci from an allopolyploid in order to examine each progenitor's genetic contribution independently in a phylogenetic context. Additionally, we conducted population-level analyses to examine genetic diversity and evidence of gene flow within species. Key Results Isoetes appalachiana is the product of multiple phylogenetic origins, suggesting that formation and establishment of allopolyploids are common in this group. Hybridization appears to be unidirectional, with I. engelmannii consistently being the maternal progenitor. Additionally, we find that polyploid lineages are genetically isolated, rarely if ever experiencing gene flow between geographically distinct populations. Conclusions Allopolyploid lineages of I. appalachiana appear to form frequently and experience a high degree of genetic isolation following formation. Thus, our results appear to corroborate the hypothesis that the vast majority of recently formed polyploids may represent evolutionary dead ends. However, this does not necessarily lessen the evolutionary importance or ecological impact of polyploidy per se. Accordingly, we propose a conservation strategy that prioritizes diploid taxa, thus preserving downstream processes that recurrently generate allopolyploid diversity. [ABSTRACT FROM AUTHOR]