Maintaining genetic integrity with high promiscuity: Frequent hybridization with low introgression in multiple hybrid zones of Melocactus (Cactaceae)

Author(s)

Khan, Gulzar ^[1] ; Franco, Fernando F. ^[1] ; Silva, Gislaine A. R. ^[1] ; Bombonato, Juliana R. ^{[1, 2]} ; Machado, Marlon ^[3] ; Alonso, Diego P. ^{[4, 5]} ; Ribolla, Paulo E. M. ^{[4, 5]} ; Albach, Dirk C. ^[6] ; Moraes, Evandro M. ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Ctr Ciencias Humanas & Biol, Dept Biol, Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Programa Posgrad Biol Comparada, Sao Paulo, SP - Brazil

^[3] Univ Estadual Feira de Santana, Feira De Santana, BA - Brazil

^[4] Sao Paulo State Univ UNESP, Biotechnol Inst IBTEC, Sao Paulo, SP - Brazil

^[5] Sao Paulo State Univ UNESP, Biosci Inst Botucatu IBB, Sao Paulo, SP - Brazil

^[6] Carl von Ossietzky Univ Oldenburg, Inst Biol & Environm Sci, Oldenburg - Germany

• Document type: Journal article
• Source: Molecular Phylogenetics and Evolution; v. 142, JAN 2020.
• Web of Science Citations: 5

Abstract

Hybridization and introgression between species in contact/hybrid zones provide important insight into the genetic and ecological mechanisms of speciation. Cactaceae represents the most important radiation of true succulent angiosperms in the New World. This diversification continues to date, with species experiencing few intrinsic barriers to gene flow and the frequent occurrence of natural hybridization. Here, we used RAD-Seq single-nucleotide polymorphism (SNP) data to investigate the genetic architecture of hybridization in four hybrid zones hosting Melocactus concinnus and four congeneric species (M. ernestii, M. glaucescens, M. paucispinus, and M. zehntneri). Our results revealed that M. concinnus is highly promiscuous in sympatric areas and hybridizes with various species distributed in Morro do Chapeu (Diamantina Plateau, Bahia), eastern Brazil. However, the contemporary genomic introgression among the investigated species is very low (c. 2-5%), confirming that even in the face of hybridization, Melocactus species maintain their genetic integrity. The genomic cline approach showed a large fraction of loci deviating from a model of neutral introgression, where most of the loci are consistent with selection favoring parental genotypes. Our results suggest the occurrence of weak premating but strong postmating reproductive isolation in the analyzed cactus species. Furthermore, as most of the Melocactus species are restricted in distribution, hybridization might negatively affect their integrity if hybrids replace the parental species. (AU)

• FAPESP's process: 14/26224-5 - Hybridization and introgression in Melocactus (Cactaceae) hybrid swarms found in Diamantina Plateau, Bahia, Brazil: A genome wide approach using RAD-Sequencing
• Grantee: Gulzar Khan
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/25227-0 - Multilocus phylogenetic analysis to recover evolutionary relationships among species of genus Cereus (Cactaceae; Cereeae)
• Grantee: Fernando de Faria Franco
• Support Opportunities: Regular Research Grants