Abstract
The reduction in genetic diversity in polyploid lineages, formed from whole-genome duplication of a few individuals, can affect their long-term evolutionary potential. Because most polyploids originate multiple times, secondary contact and gene exchange among independently formed polyploids can create novel genetic combinations and reduce the severity of genetic bottlenecks. However, independently originated polyploids may be reproductively isolated from each other due to genetic and chromosomal differences predating the polyploidisation event, or evolving subsequently in the dynamic genomes of young polyploid populations. Here we conducted experimental crosses to investigate the phenotype and interfertility between two independently originated populations of the allopolyploid Mimulus peregrinus (Phrymaceae). We found that individuals from the two populations are phenotypically distinct, but that inter- and intrapopulation crosses are not statistically different. Interpopulation crosses produce viable and fertile offspring, although our results suggest the existence of partial reproductive barriers in the form of reduced pollen viability. We found no difference in pollen viability between F1 and F2 generations. In contrast, we detected a reduction in floral and vegetative size, and in the proportion of plants that flowered, between F1 and F2 generations for both intra- and interpopulation crosses. Together, our results indicate that populations of independent origin can partially exchange genes, producing variable offspring, and that the phenotype of M. peregrinus may be unstable in the early generations. Natural selection on genetically based variation may be required for the evolution of more stable and fertile individuals of this nascent allopolyploid.
Highlights
Whole-genome duplication (WGD), or polyploidisation, is an important phenomenon that characterises the evolutionary history of many plants lineages (Levin 2002; Soltis et al 2009; Jiao et al 2011)
We have shown that independently originated populations of the neo-allopolyploid Mimulus peregrinus are interfertile, i.e., produce viable, fertile offspring
There is ample genetic evidence of multiple origins across a variety of allopolyploid taxa (e.g. Wyatt et al 1988; Ashton and Abbott 1992; Franzke and Mummenhoff 1999; Segraves et al 1999; Soltis et al 2004; Beck et al 2012; Mavrodiev et al 2015; Servick et al 2015; Vallejo-Marın et al 2015), fewer studies have experimentally compared the interfertility of independently originated populations
Summary
Whole-genome duplication (WGD), or polyploidisation, is an important phenomenon that characterises the evolutionary history of many plants lineages (Levin 2002; Soltis et al 2009; Jiao et al 2011). Nascent polyploids may carry limited genetic diversity, which in turn might affect their long-term evolutionary potential (Soltis et al 2014b). This expected reduction in genetic diversity has led to some authors to propose that polyploidisation should be an evolutionary dead end (e.g. Stebbins 1950), and recent work suggests that polyploid lineages have lower rates of speciation than diploid lineages (Mayrose et al 2011; Arrigo and Barker 2012; but see Soltis et al 2014a). The successful establishment of some polyploid lineages indicates that the severity of the challenges associated with the origin of polyploids, including the loss of genetic diversity due to small population sizes at their origin, can sometimes be circumvented
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
