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Systematics, hybridization, and character evolution within the southern African genus, Zaluzianskya (Scrophulariaceae s.s., tribe Manuleeae)
| Title: | Systematics, hybridization, and character evolution within the southern African genus, Zaluzianskya (Scrophulariaceae s.s., tribe Manuleeae) |
| Author: | Archibald, Jenny Kay |
| Description: | Zaluzianskya (Scrophulariaceae s.s., tribe Manuleeae) is a southern African genus with four sections, whose floral diversity is particularly evident. This work examines Zaluzianskya at population and genus-wide levels. Sympatric and allopatric populations of Z. microsiphon (day-flowering) and Z. natalensis (night-flowering) were examined using ISSR markers in combination with ordination analyses of morphology. Although unexpected due to differences in flowering time between these species, putative hybrids have been found. The high genetic similarity between these species made it difficult to recover patterns of gene flow. However, it appears that genetic material from Z. microsiphon may be introgressing into Z. natalensis. The first broad phylogenies for Zaluzianskya were resolved using nuclear (ITS) and chloroplast (rpl16 and trnL-trnF) sequences. Analyses of separate and combined data sets were largely congruent, resolving three main clades. The only significant incongruence involved the single species included from section Macrocalyx. This species is placed sister to section Nycterinia by ITS but within that section by cpDNA. Consequently, the monophyly of section Nycterinia is undecided. It is certain, however, that sections Zaluzianskya and Holomeria are not monophyletic. Additionally, one of the purported outgroups (Reyemia) was nested within Zaluzianskya with strong support. Based on this and morphological affinity, this ditypic genus should be submerged within Zaluzianskya. Finally, the status of Z. microsiphon is uncertain, with three populations clearly separated in the phylogeny. Potentially this represents three lineages with convergent morphology due to pollinator selection. Alternatively, hybridization may have distorted Z. microsiphons placement on the phylogeny. Character evolution was also examined, to find morphological synapomorphies for the new infrageneric groups and to consider the evolution of floral diversity within Zaluzianskya. Several traits support various levels in the phylogeny, including petal shape, stamen placement, tube length, nectary adnation, stem indumentum, and calyx lobing. Reconstruction of some traits was complicated by the uncertain status of Z. microsiphon. For example, the evolution of flowering time, floral symmetry, and throat indumentum is more labile if Z. microsiphon is divided. The evolution of habit (annual vs. perennial) and distribution (within relatively arid vs. mesic regions) appear associated although concentrated-changes tests did not reveal a significant correlation. |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1068675610
http://hdl.handle.net/2374.OX/4240 |
| Date: | 2003 |
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