Morphological and genetic perspectives of hybridization in two contact zones of closely related species of Petunia (Solanaceae) in southern Brazil

Teixeira, Marcelo Costa; Turchetto, Caroline; Hartke, Sara; Schnitzler, Carolina K.; Freitas, Loreta B.

doi:10.1590/0102-33062019abb0143

Cited by 7 publications

(4 citation statements)

References 39 publications

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“…axillaris and P. exserta in the Guaritas region of Brazil: contact zone 1 (30° 53′ 48″ S, 53° 25′ 16″ W) and contact zone 2 (30° 50′ 14″ S, 53°30′ 15″ W). These contact zones have been described in much detail before [ 44 , 45 , 47 , 50 , 51 , 53 , 60 , 64 ]. We collected seeds from all 30 mother plants carrying seed pods at the time of our visit (November 2011).…”

Section: Methodsmentioning

confidence: 99%

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

et al. 2023

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Background Theory suggests that the genetic architecture of traits under divergent natural selection influences how easily reproductive barriers evolve and are maintained between species. Divergently selected traits with a simple genetic architecture (few loci with major phenotypic effects) should facilitate the establishment and maintenance of reproductive isolation between species that are still connected by some gene flow. While empirical support for this idea appears to be mixed, most studies test the influence of trait architectures on reproductive isolation only indirectly. Petunia plant species are, in part, reproductively isolated by their different pollinators. To investigate the genetic causes and consequences of this ecological isolation, we deciphered the genetic architecture of three floral pollination syndrome traits in naturally occurring hybrids between the widespread Petunia axillaris and the highly endemic and endangered P. exserta. Results Using population genetics, Bayesian linear mixed modelling and genome-wide association studies, we found that the three pollination syndrome traits vary in genetic architecture. Few genome regions explain a majority of the variation in flavonol content (defining UV floral colour) and strongly predict the trait value in hybrids irrespective of interspecific admixture in the rest of their genomes. In contrast, variation in pistil exsertion and anthocyanin content (defining visible floral colour) is controlled by many genome-wide loci. Opposite to flavonol content, the genome-wide proportion of admixture between the two species predicts trait values in their hybrids. Finally, the genome regions strongly associated with the traits do not show extreme divergence between individuals representing the two species, suggesting that divergent selection on these genome regions is relatively weak within their contact zones. Conclusions Among the traits analysed, those with a more complex genetic architecture are best maintained in association with the species upon their secondary contact. We propose that this maintained genotype–phenotype association is a coincidental consequence of the complex genetic architectures of these traits: some of their many underlying small-effect loci are likely to be coincidentally linked with the actual barrier loci keeping these species partially isolated upon secondary contact. Hence, the genetic architecture of a trait seems to matter for the outcome of hybridization not only then when the trait itself is under selection.

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Section: Methodsmentioning

confidence: 99%

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

et al. 2023

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“…All taxa in LT have high levels of genetic polymorphism sharing ( Kulcheski et al, 2006 ; Fregonezi et al, 2013 ; Reck-Kortmann et al, 2014 ; Turchetto et al, 2016 ), and interspecific hybridization has been observed among them ( Lorenz-Lemke et al, 2006 ; Segatto et al, 2014 ; Turchetto et al , 2015 , 2019a , b ; Giudicelli et al, 2019 ; Teixeira et al, 2019 ; Schnitzler et al, 2020 ; Caballero-Villalobos et al, 2021 ). Intraspecific morphological diversity was also observed ( Turchetto et al , 2016 ; Giudicelli et al , 2019 ; Teixeira et al , 2020 ), even in taxa that did not display differentiated genetic lineages as P. axillaris ( Turchetto et al , 2014b ), which has a morphotype from coastal (A1) and another from inland (A2) distribution.…”

Section: Introductionmentioning

confidence: 99%

Shades of white: The Petunia long corolla tube clade evolutionary history

Backes,

Turchetto,

Mäder

et al. 2024

Genet. Mol. Biol.

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Delimiting species is challenging in recently diverged species, and adaptive radiation is fundamental to understanding the evolutionary processes because it requires multiple ecological opportunities associated with adaptation to biotic and abiotic environments. The young Petunia genus (Solanaceae) is an excellent opportunity to study speciation because of its association with pollinators and unique microenvironments. This study evaluated the phylogenetic relationships among a Petunia clade species with different floral syndromes that inhabit several environments. We based our work on multiple individuals per lineage and employed nuclear and plastid phylogenetic markers and nuclear microsatellites. The phylogenetic tree revealed two main groups regarding the elevation of the distribution range, whereas microsatellites showed high polymorphism-sharing splitting lineages into three clusters. Isolation by distance, migration followed by new environment colonization, and shifts in floral syndrome were the motors for lineage differentiation, including infraspecific structuring, which suggests the need for taxonomic revision in the genus.

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“…Petunia can be considered a well-studied genus of Solanaceae due to several articles published on its systematics, taxonomy, reproductive biology and evolution in last decades (e.g., Ando et al 2001;Gübitz et al 2009;Kulcheski et al 2006;Stehmann et al 2009;Stehmann & Greppi 2013;Reck-Kortmann et al 2014;Segatto et al 2014a;b;Teixeira et al 2019;2021;Turchetto et al 2015a;b;. Most species of Petunia have showy and large flowers, making them easy to collect by attracting the attention of botanists, with the exception of the narrow endemic ones.…”

Section: Introductionmentioning

confidence: 99%

Petunia toropiensis (Solanaceae): A surprising new species endemic from Toropi river basin in southern Brazil

Stehmann

Larocca²

2023

Acta Bot. Bras.

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A new species of Petunia (Solanaceae) is described and illustrated for the Brazilian flora. Petunia toropiensis Stehmann & Larocca is known only from a few sites along the middle Toropi river basin, in the central region of the Rio Grande do Sul state. The new species is easily recognizable by its erect or ascending habit, infundibuliform corolla with yellow tube and purple limb, yellow pollen, and erect peduncle in fruiting. The species was assessed as Critically Endangered due to the narrow geographic distribution, the few populations known, and the loss of habitat quality.A key for identification of Petunia species from Rio Grande do Sul is given. We also discuss the impact of the dams on the populations of the new species and the conservation efforts needed.

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Morphological and genetic perspectives of hybridization in two contact zones of closely related species of Petunia (Solanaceae) in southern Brazil

Cited by 7 publications

References 39 publications

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

Shades of white: The Petunia long corolla tube clade evolutionary history

Petunia toropiensis (Solanaceae): A surprising new species endemic from Toropi river basin in southern Brazil

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