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Abstract Sexual systems (i.e., separate vs. combined sexes) vary widely among eukaryotes and influence the evolution of reproductive systems, which shape genetic structure and evolutionary trajectories. In diploid‐dominant angiosperms, combined (i.e., hermaphroditism) and separate sexes are expected to correlate with selfing and outcrossing, respectively. When sex is determined in the haploid phase, selfing is possible even when there are separate sexes. The freshwater red macroalgal genusSheathia(Batrachospermales) displays sexual system variation within and among populations, but no prior data exist on the reproductive systems of these populations. We developed 16 polymorphic microsatellite loci to characterize the reproductive system and genetic structure of threeSheathiaspecies. We observed cross‐amplification of loci across the three targeted species, suggesting these markers may be useful in otherSheathiaspp. We observed variation in monoicy (i.e., hermaphroditism) versus dioicy (i.e., separate sexes) in each species, includingS. americana, which was previously believed to be obligately dioicous. Our data suggest thatS. americanaandS. involutadisplay more variation in their prevailing reproductive modes as compared toS. grandis. Generally, dioicy resulted in greater diversity in contrast to monoicy. We observed strong population structure that is likely driven by uniparental reproduction and limited dispersal; however, there is limited population connectivity that may be facilitated by long‐distance dispersal events. Overall, these data contribute to our knowledge of the relationship between the sexual system, reproductive system, and population genetic structure in haploid‐diploid taxa, thereby informing a broader understanding of the evolution of sex.
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This content will become publicly available on April 1, 2026
Underground bulbils in Sonerila (Melastomataceae): innovative reproductive strategies in three paleotropical species
This study elucidates the poorly known phenomenon of bulbil formation observed in three species ofSonerilaviz.,Sonerila tenella,S. ponmudianaandS. nairii.These bulbils represent clusters of 5–20 fleshy scales, developing adventitiously from roots or lower stem nodes, connected by a common stalk or immature stem, and predominantly occurring during early winter when plants are in fruiting or late flowering stages. Initially, these scales are white or vinaceous, but later turn into green, ciliate structures resembling leaves. The bulbils undergo rapid growth into independent plantlets, typically within a few weeks, with clusters up to 10 cm from the parent individual. While commonly associated with vivipary,Sonerilabulbils differ by their developmental origin and lack of connection to reproductive structures. Instead, their occurrence may contribute significantly to short‐distance dispersal and population persistence in fragmented habitats. This study generates hypotheses on the ecological significance of dispersal mechanisms in response to environmental heterogeneity, highlighting the unique adaptive features ofSonerilabulbil formation within the broader context of plant reproductive strategies.
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- Award ID(s):
- 2002270
- PAR ID:
- 10626338
- Publisher / Repository:
- Wiley and Sons
- Date Published:
- Journal Name:
- Nordic Journal of Botany
- Volume:
- 2025
- Issue:
- 4
- ISSN:
- 0107-055X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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