AI Article Synopsis
- The study investigates how whole-genome duplication impacts the reproductive isolation and phenotypic differences between diploid plants and both natural and synthesized tetraploids of Chamerion angustifolium.
- It finds that while neotetraploids exhibit some similarities to diploids, they differ significantly in traits like flowering time and height, and reproductive isolation is weaker between diploids and neotetraploids compared to natural tetraploids.
- The results suggest that polyploidy leads to immediate phenotypic changes and some prezygotic barriers, but forming new species through genome duplication is a complex process requiring selection pressures to enhance reproductive isolation over time.
Article Abstract
Premise Of The Study: The depiction of polyploid speciation as instantaneous implies that strong prezygotic and postzygotic isolation form as a direct result of whole-genome duplication. However, the direct vs. indirect contributions of genome duplication to phenotypic divergence and prezygotic isolation are rarely quantified across multiple reproductive barriers.
Methods: We compared the phenotypic differences between diploid and both naturally occurring and synthesized tetraploids (neotetraploids) of the plant Chamerion angustifolium. Using this information and additional published values for this species, we compared the magnitude of isolation (ecological, flowering, pollinator, and gametic) between diploids and natural-occurring tetraploids to that between diploids and neotetraploids.
Key Results: Differences among ploidy cytotypes were observed for eight of 12 vegetative and reproductive traits measured. Neotetraploids resembled diploids but differed from natural tetraploids with respect to four traits, including flowering time and plant height. Diploid-neotetraploid (2x-4xneo) experimental arrays exhibited lower pollinator fidelity to cytotype and seed set compared with 2x-4xnat arrays. Based on these results and published evidence, reproductive isolation between diploids and neotetraploids across all four life stages averaged 0.48 and deviated significantly from that between diploids and natural tetraploids (RI = 0.96).
Conclusions: Genome duplication causes phenotypic shifts and contributes directly to prezygotic isolation for some barriers (gametic isolation) but cannot account for the cumulative isolation from diploids observed in natural tetraploids. Therefore, conditions for species formation through genome duplication are not necessarily instantaneous and selection to strengthen prezygotic barriers in young polyploids is critical for the establishment of polyploid species in sympatry.
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| http://dx.doi.org/10.3732/ajb.1600097 | DOI Listing |
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