Nuclear and plastid markers reveal the persistence of genetic identity: A new perspective on the evolutionary history of Petunia exserta

• Published in: Molecular phylogenetics and evolution Vol. 70; pp. 504 - 512
• Main Authors: Segatto, Ana Lúcia Anversa, Cazé, Ana Luíza Ramos, Turchetto, Caroline, Klahre, Ulrich, Kuhlemeier, Cris, Bonatto, Sandro Luis, Freitas, Loreta Brandão
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-01-2014
• Subjects: Bayes Theorem; Cell Nucleus - genetics; Genetic Markers; Genetic Variation; Haplotypes; Hybridization; Hybridization, Genetic; Interspecific crossing; Introgression; Petunia; Petunia - genetics; Phylogeny; Plastids - genetics; Sequence Analysis, DNA; Speciation; Interspecific crossing; Hybridization; Introgression; Petunia; Speciation
• ISSN: 1055-7903; 1095-9513
• DOI: 10.1016/j.ympev.2013.10.011

[Display omitted]
•Nuclear and chloroplast markers produce contrasting patterns of genetic variability distribution.•Species boundaries are maintained in spite of interspecific gene flow.•Bayesian clustering, cpDNA networks, genetic diversity, coalescence analysis also suggest ancestral polymorphism sharing.
Recently divergent species that can hybridize are ideal models for investigating the genetic exchanges that can occur while preserving the species boundaries. Petunia exserta is an endemic species from a very limited and specific area that grows exclusively in rocky shelters. These shaded spots are an inhospitable habitat for all other Petunia species, including the closely related and widely distributed species P. axillaris. Individuals with intermediate morphologic characteristics have been found near the rocky shelters and were believed to be putative hybrids between P. exserta and P. axillaris, suggesting a situation where Petunia exserta is losing its genetic identity. In the current study, we analyzed the plastid intergenic spacers trnS/trnG and trnH/psbA and six nuclear CAPS markers in a large sampling design of both species to understand the evolutionary process occurring in this biological system. Bayesian clustering methods, cpDNA haplotype networks, genetic diversity statistics, and coalescence-based analyses support a scenario where hybridization occurs while two genetic clusters corresponding to two species are maintained. Our results reinforce the importance of coupling differentially inherited markers with an extensive geographic sample to assess the evolutionary dynamics of recently diverged species that can hybridize.