Interspecific hybridization in North American Polygala (Polygalaceae)
DOI:
https://doi.org/10.17348/jbrit.v14.i1.895Keywords:
interspecific hybrid, nrITS, Polygala balduinii, Polygala lutea, Polygala ramosa, Polygala rugelii, Polygalaceae, trnL-FAbstract
As a part of ongoing systematic and phylogenetic studies in Polygalaceae, field collections of two pairs of North American species (Polygala balduinii and P. ramosa, and P. lutea and P. rugelii) had morphologically intermediate forms and grew sympatrically, and so were suspected to be interspecific hybrids. Although hybrids among plants are often invoked in taxonomic and floristic literature based on morphologic intermediacy, they are rarely documented and substantiated using molecular tools. We found that the morphologically intermediate individuals within intermixed populations of both species pairs did indeed share all of the variable nucleotide sites in nrITS among the parent species. Likewise, using plastid sequence data (trnL-F), we determined that in both species pairs, the parentage was bidirectional. Although some DNA inheritance phenomena (e.g. incomplete lineage sorting) can result in similar polymorphic DNA sequence data, the intermediacy in both morphology and sequence data within sympatric populations is more indicative of interspecific hybridization.
References
Abbott, J.R. 2009. Phylogeny of Polygalaceae and a revision of Badiera. Ph.D., University of Florida, Gainesville, U.S.A.
Abbott, J.R. 2011. Notes on the disintegration of Polygala (Polygalaceae), with four new genera for the flora of North America. J. Bot. Res. Inst. Texas 5:125–137.
Abbott, J.R. & J.F.B. Pastore. 2015. Preliminary synopsis of the genus Hebecarpa (Polygalaceae). Kew Bull. 70:39.
Arnold, M.L. & N.H. Martin. 2010. Hybrid fitness across time and habitats. Trends Ecol. Evol. 25:530–536.
Azhagiri, A.K. & P. Maliga. 2007. Exceptional paternal inheritance of plastids in Arabidopsis suggests that low-frequency leakage of plastids via pollen may be universal in plants. Plant J. 52:817–823.
Castro, S., P. Silveira, A.P. Coutinho, & J. Paiva. 2007. Heterosamara sect. Villososperma comb. nov. (Polygalaceae) from eastern Asia. Nordic J. Bot. 25:286–293.
Chase, M.W. & H.G. Hills. 1991. Silica gel: An ideal material for field preservation of leaf samples for DNA studies. Taxon 40:215–220.
Doyle, J.J. & J.L. Doyle. 1987. A rapid DNA isolation procedure for small quantities of fresh leaf tissue. Phytochem. Bull. 19:11–15.
Ellstrand, N.C. & K.A. Schierenbeck. 2000. Hybridization as a stimulus for the evolution of invasiveness in plants? Proc. Natl. Acad. Sci. U.S.A. 97:7043–7050.
Ellstrand, N.C., R. Whitkus, & L.H. Rieseberg. 1996. Distribution of spontaneous plant hybrids. Proc. Natl. Acad. Sci. U.S.A. 93:5090–5093.
Felsenstein, J. 1985. Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39:783–791.
Fitch, W.M. 1971. Toward defining the course of evolution: minimum change for a specific tree topology. Syst. Zool. 20:406–416.
Forest, F., M.W. Chase, C. Persson, P.R. Crane, & J.A. Hawkins. 2007. The role of biotic and abiotic actors in evolution of ant dispersal in the milkwort family (Polygalaceae). Evolution 61:1675–1694.
Hansen, A.K., L.K. Escobar, L.E. Gilbert, & R.K. Jansen. 2007. Paternal, maternal, and biparental inheritance of the chloroplast genome in Passiflora (Passifloraceae): Implications for phylogenetic studies. Amer. J. Bot. 94:42–46.
Hoshi, Y., J. Shirakawa, M. Hasebe, K. Fukushima, & K. Kondo. 2008. Tandem repeat rDNA sequence derived from parents were stably maintained in hexaploids of Drosera spathulata complex (Droseraceae). Cytologia 73:313–325.
Ionta, G.M., W.S. Judd, N.H. Williams, & W.M. Whitten. 2007. Phylogenetic relationships in Rhexia (Melastomataceae): Evidence from DNA sequence data and morphology. Int. J. Pl. Sci. 168:1055–1066.
Lewis, W.H. & S.A. Davis. 1962. Cytological observations of Polygala in eastern North America. Rhodora 64:102–109.
Majure, L., W.S. Judd, P.S. Soltis, & D.E. Soltis. 2012. Phylogeny of Opuntia s.s. (Cactaceae): Clade delineation, geographic origin, and reticulate evolution. Amer. J. Bot. 99:847–864.
Mallet, J. 2007. Hybrid speciation. Nature 336:279–283.
Mallet, J. 2008. Hybridization, ecological races and the nature of species: Empirical evidence for the ease of speciation. Phil. Trans., Ser. B 363:2971–2986.
Paiva, J.A.R. 1998. Polygalarum Africanarum et Madagascariensium prodromus atque gerontogaei generis Heterosamara Kuntze, a genere Polygala L. segregati et a nobis denuo recepti, synopsis monographica. Fontqueria 50:1–346.
Pastore, J.F.B. 2012. Caamembeca: Generic status and new name for Polygala subgenus Ligustrina (Polygalaceae). Kew Bull. 67:435–442.
Pastore, J.F.B. & J.R. Abbott. 2012. Taxonomic notes and new combinations for Asemeia (Polygalaceae). Kew Bull. 67:801–813.
Pastore, J.F.B. & P.L.R. de Moraes. 2013. Generic status and lectotypifications for Gymnospora (Polygalaceae). Novon 22:304–306.
Pastore, J.F.B., D.B.O.S. Cardoso, & G.A. Aymard. 2010. A synopsis, new combinations, and synonyms in Acanthocladus (Polygalaceae). Novon 20:317–324.
Pastore, J.F.B., J.R. Abbott, K.M. Neubig, W.M. Whitten, R. Mascarenhas, M.C.A. Mota, & C. van den Berg. 2017. A molecular phylogeny and taxonomic notes in Caamembeca (Polygalaceae). Syst. Bot. 42:54-62.
Persson, C. 2001. Phylogenetic relationships in Polygalaceae based on plastid sequences from the trnL-F region. Taxon 50:763–779.
Rambaut, A. 1996. Se-Al: Sequence alignment editor, v2.0a11. http://evolve.zoo.ox.ac.uk/. Accessed 8 Aug 2002.
Reboud, X. & C. Zeyl. 1994. Organelle inheritance in plants. Heredity 72:132–140.
Rieseberg, L.H., T.E. Wood, & E.J. Baack. 2006. The nature of plant species. Nature 440:524–527.
Smith, R.R. & D.B. Ward. 1976. Taxonomy of the genus Polygala series Decurrentes (Polygalaceae). Sida 6:284–310.
Soltis, D.E., E.V. Mavrodiev, J.J. Doyle, J. Rauscher, & P.S. Soltis. 2008. ITS and ETS sequence data and phylogeny reconstruction in allopolyploids and hybrids. Syst. Bot. 33:7–20.
Swofford, D.L. 1999. PAUP*: Phylogenetic analysis using parsimony (*and other methods), version 4.0b10. Sinauer Associates, Sunderland, Massachusettts, U.S.A.
Taberlet, P., L. Gielly, G. Pautou, & J. Bouvet. 1991. Universal primers for amplification of three non-coding regions of chloroplast DNA. Pl. Molec. Biol. 17:1105–1109.
Tate, J.A., Z. Ni, A.-C. Scheen, J. Koh, C.A. Gilbert, D. Lefkowitz, Z.J. Chen, P.S. Soltis, & D.E. Soltis. 2006. Evolution and expression of homeologous loci in Tragopogon miscellus (Asteraceae), a recent and reciprocally formed allopolyploid. Genetics 173:1599–1611.
Wang, X.-R., A.E. Szmidt, & O. Savolainen. 2001. Genetic composition and diploid hybrid speciation of a high mountain pine, Pinus densata, native to the Tibetan Plateau. Genetics 159:337–346.
Zuccarello, G.C., J.A. West, M. Kamiya, & R.J. King. 1999. A rapid method to score plastid haplotypes in red seaweeds and its use in determining parental inheritance of plastids in the red alga Bostrychia (Ceramiales). Hydrobiologia 401:207–214.
