• Allopolyploids represent natural experiments in which DNA sequences from different species are combined into a single nucleus and then coevolve, enabling us to follow the parental genomes, their interactions and evolution over time. Here, we examine the fate of satellite DNA over 5 million yr of divergence in plant genus Nicotiana (family Solanaceae). • We isolated subtelomeric, tandemly repeated satellite DNA from Nicotiana diploid and allopolyploid species and analysed patterns of inheritance and divergence by sequence analysis, Southern blot hybridization and fluorescent in situ hybridization (FISH). • We observed that parental satellite sequences redistribute around the genome in allopolyploids of Nicotiana section Polydicliae, formed c. 1 million yr ago (Mya), and that new satellite repeats evolved and amplified in section Repandae, which was formed c. 5 Mya. In some cases that process involved the complete replacement of parental satellite sequences. • The rate of satellite repeat replacement is faster than theoretical predictions assuming the mechanism involved is unequal recombination and crossing-over. Instead we propose that this mechanism occurs with the deletion of large chromatin blocks and reamplification, perhaps via rolling circle replication.

Interspecific hybridization is a primary cause of extensive morphological and chromosomal variation and plays an important role in plant species diversification. However, the role of interploidal hybridization in the formation of hybrid swarms is less clear.Epidendrumencompasses wide variation in chromosome number and lacks strong premating barriers, making the genus a good model for clarifying the role of chromosomes in postzygotic barriers in interploidal hybrids. In this sense, hybrids from the interploidal sympatric zone betweenE. fulgens(2n = 2x = 24) andE. puniceoluteum(2n = 4x = 56) were analyzed using cytogenetic techniques to elucidate the formation and establishment of interploidal hybrids. Hybrids were not a uniform group: two chromosome numbers were observed, with the variation being a consequence of severe hybrid meiotic abnormalities and backcrossing withE. puniceoluteum. The hybrids were triploids (2n = 3x = 38 and 40) and despite the occurrence of enormous meiotic problems associated with triploidy, the hybrids were able to backcross, producing successful hybrid individuals with broad ecological distributions. In spite of the nonpolyploidization of the hybrid, its formation is a long‐term evolutionary process rather than a product of a recent disturbance, and considering other sympatric zones inEpidendrum, these events could be recurrent.

Events of both hybridization and polyploidy are capable of completely restructuring the genome, modifying phenotypic traits and affecting ecological interactions. For plants, these changes may affect floral traits that are important for interactions with pollinators, which could lead to shifts in pollinator behavior and taxa between hybrids/polyploids and parental/diploid species. Such pollinator shifts have great ecological and evolutionary relevance since they play a key role in the diversification of angiosperms. There is a growing number of studies that explicitly address the relationship between plant hybridization/polyploidy and pollinator shifts. However, questions remain about how often hybridization and polyploidy lead to pollinator shifts and what are the mechanisms that mediate this process. We reviewed studies that compared the reproductive biology of hybrids/polyploid with that of parental/diploid species. These studies are based on modifications of floral traits involved in attracting and rewarding pollinators. We also discussed how such changes in flower traits are widespread among plant taxa and affect pollinator visitation rates, pollinator fidelity, pollen movement, and could lead to pollinator shifts. All of these consequences are underexplored, especially from the perspective of pollinators, which foster future research that integrates genetics, ecology, and evolution of plant-pollinator interactions.