Phylogenetic relationships in Opuntia (Cactaceae, Opuntioideae) from southern South America

Abstract

The patterns of relationships between species of Opuntia from southern South America are scarcely known in spite of the importance of this region as a diversification center for the Cactaceae. This paper contributes to the better understanding of the genetic and phylogenetic relationships of 15 Opuntia species from Argentina, Bolivia, Brazil, Paraguay, and Uruguay by generating new genetic data through Inter-Simple Sequence Repeat (ISSR) genotyping and the sequencing of plastid intergenic spacers trnL-trnF and psbJ-petA. The species surveyed are: O. anacantha, O. arechavaletae, O. aurantiaca, O. bonaerensis, O. colubrina, O. discolor, O. elata, O. megapotamica, O. monacantha, O. penicilligera, O. quimilo, O. salmiana, O. schickendantzii, O. sulphurea, and O. ventanensis. The genetic distance-based analysis of 110 ISSR bands, applying the Neighbor-Joining and NeighborNet algorithms, evidenced considerable intraspecific variation in O. aurantiaca, O. elata, O. discolor, and O. salmiana. The emergent clustering pattern and the species assignment to taxonomic series show a general agreement for Armatae and Aurantiacae. The phylogenetic relationships were investigated via haplotype network and maximum likelihood approaches, within a broader sampling that involves most species currently accepted for South America, and samples from throughout the American continent. Hence, 15 haplotypes are recognized for southern South American opuntias whereas eight haplotypes are established for Northern Hemisphere opuntias. Biparentally and maternally inherited genetic data yield partially consistent results, giving genetic support for morphologically defined taxonomic series.