Morphological and molecular (RAPD) analyses confirm the hybrid origin of the diploid grassCalamagrostis longiseta var.longe-aristata (Gramineae)

• Autores: Kaku Saitou, Tatsuya Fukuda, Jun Yokoyama, Masayuki Maki
• Localización: Folia geobotánica: A journal of plant ecology and systematics, ISSN-e 1874-9348, ISSN 1211-9520, Vol. 42, Nº 1, 2007, págs. 63-76
• Idioma: inglés
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• Resumen

  • To examine the hybrid origin of the diploid grass Calamagrostis longiseta var. longe-aristata, we performed morphometric and genetic analyses of this taxon and its putative parental taxa. The morphometric analyses revealed that, in general, C longiseta var. longe-aristata is morphologically intermediate between C longiseta var. longiseta and C fauriei. Previous studies have reported that some hybrids exhibit transgressive characters but others do not; the latter is the case for C longiseta vat. longe-aristata. Their absence may be due to the ecological adaptation to environments intermediate between those inhabited by the putative parental taxa, and therefore the transgressive characters have not been selected. Nevertheless, there is no direct evidence for adaptive value of the characters examined in this study and only a small part of all characters potentially responsible for adaptation was investigated. An alternative hypothesis about the absence of transgressive characters in C longiseta vat. longe-aristata is that it is at an early stage of hybrid speciation. Random amplified polymorphic DNA (RAPD) analyses showed that individuals ofC longiseta var. longe-aristata were placed in both of the clusters formed by each putative parental taxon. Greater genetic diversity was observed in C longiseta vat. longe-aristata than in its putative parental taxa. All here reported findings support the scenario that C longiseta vat. longe-aristata is of hybrid origin, having evolved from C. longiseta var. longiseta and C fauriei.