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Evolutionary relationships in Thunbergioideae and other early branching lineages of Acanthaceae
Stockholm University, Faculty of Science, Department of Botany.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Acanthaceae as circumscribed today consists of the three subfamilies Acanthoideae (Acanthaceae sensu stricto), Thunbergioideae and Nelsoniodieae, plus the genus Avicennia. Due to the morphological dissimilarities of Thunbergioideae and Nelsonioideae, the delimitation of the family has been controversial. The mangrove genus Avicennia was only recently associated with Acanthaceae for the first time, based on molecular evidence, but without morphological support. In this thesis, phylogenetic analyses of nuclear and chloroplast DNA sequences were used to test the monophyly and exact positions of Thunbergioideae and Nelsonioideae, and to infer detailed phylogenetic relationships within these subfamilies and among major lineages of Acanthaceae. Floral structure and development were comparatively studied in Avicennia and other Acanthaceae using scanning electron microscopy and stereo microscopy. Phylogenetic analyses strongly support monophyly of Thunbergioideae and Nelsonioideae, and place the latter clade with strong support as sister to all other plants treated as Acanthaceae. Thunbergioideae and Avicennia are moderately supported as sister taxa, and together they are sister to Acanthoideae. The general morphology of Avicennia can be easily accommodated in the Acanthaceae, and three synapomorphies support the suggested sister group relationship of Avicennia and Thunbergioideae: (1) collateral ovule arrangement, (2) vertical orientation of ovule curvature, and (3) an exposed nucellus that is contiguous with the ovary wall. Within Thunbergioideae and Nelsonioideae, support values for major lineages are generally high. With some exceptions, the constituent genera are supported as monophyletic. Evolutionary relationships among and within genera are discussed in a morphological and biogeographical context.

Place, publisher, year, edition, pages
Department of Botany, Stockholm University , 2012. , 29 p.
National Category
Botany
Research subject
Plant Systematics
Identifiers
URN: urn:nbn:se:su:diva-71080ISBN: 978-91-7447-445-9 (print)OAI: oai:DiVA.org:su-71080DiVA: diva2:483792
Public defence
2012-03-02, föreläsningssalen, Botanicum, Lilla Frescativägen 5, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
At the time of doctoral defence, the following papers were unpublished and had a status as follows: Papers 2 & 3: ManuscriptsAvailable from: 2012-02-08 Created: 2012-01-25 Last updated: 2012-02-17Bibliographically approved
List of papers
1. Molecular phylogenetics and morphological evolution of Thunbergioideae (Acanthaceae)
Open this publication in new window or tab >>Molecular phylogenetics and morphological evolution of Thunbergioideae (Acanthaceae)
2008 (English)In: Taxon, Vol. 57, no 3, 811-822 p.Article in journal (Refereed) Published
National Category
Biological Systematics
Identifiers
urn:nbn:se:su:diva-16121 (URN)000258974600012 ()
Available from: 2008-12-15 Created: 2008-12-15 Last updated: 2012-01-26Bibliographically approved
2. Comparative floral development and structure of the black mangrove genus Avicennia L. and related taxa in the Acanthaceae
Open this publication in new window or tab >>Comparative floral development and structure of the black mangrove genus Avicennia L. and related taxa in the Acanthaceae
2011 (English)In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 172, no 3, 330-344 p.Article in journal (Refereed) Published
Abstract [en]

Phylogenetic relationships of Avicennia have been difficult to trace because of the presence of convergent characters related to the mangrove environment. Recent molecular data suggest a close relationship to Thunbergioideae, a subfamily within Acanthaceae (Lamiales), but morphological support for the new findings has been equivocal. Floral structure and development are comparatively studied here in three species of Avicennia, with special attention given to the ovary and the ovules, which are also studied in Thunbergioideae. The suggested sister group relationship of Avicennia and Thunbergioideae is supported by three synapomorphies: (1) collateral ovule arrangement, (2) vertical orientation of ovule curvature, and (3) an exposed nucellus that is contiguous with the ovary wall, at least during early stages of ovule development. We interpret the latter character as a neotenic feature that is retained in the anthetic ovules of Avicennia. We confirm that the apparently tetramerous flowers of Avicennia have a basically pentamerous floral ground plan. Additional floral characters shared between Avicennia and Thunbergioideae include left contort corolla aestivation, thickened filament bases with glandular hairs, presence of pollen sac placentoids, and various aspects of fruit morphology and embryology. However, these features are either symplesiomorphic or are not known well enough to allow for unequivocal conclusion on character evolution in Acanthaceae.

Keyword
asterids, floral anatomy, Lamiales, neoteny, ovule development, Thunbergioideae
National Category
Botany
Identifiers
urn:nbn:se:su:diva-69430 (URN)10.1086/658159 (DOI)000292654700003 ()
Note
authorCount :2Available from: 2012-01-16 Created: 2012-01-12 Last updated: 2017-12-08Bibliographically approved
3. Phylogenetic placement, delineation, and relationships among genera of the enigmatic Nelsonioideae (Lamiales: Acanthaceae)
Open this publication in new window or tab >>Phylogenetic placement, delineation, and relationships among genera of the enigmatic Nelsonioideae (Lamiales: Acanthaceae)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We took a two-tiered approach to test monophyly of Nelsonioideae and place the group within Lamiales, and to determine relationships among taxa within the group. Phylogenetic analysis of a molecular data set (ndhF + trnLF) for a broad sample of Lamiales supports monophyly of Nelsonioideae and places the clade with strong support as sister to a lineage composed of all other plants treated as Acanthaceae (i.e., Avicennia, Thunbergioideae, Acanthoideae). We propose to treat this entire group as Acanthaceae s.l. and advance indurate, explosively dehiscent capsules as a synapomorphy for the family, albeit with autapomorphic fruit types in Avicennia and Mendoncia. These results further support monophyly of family level groups that have emerged from recent studies of Lamiales but are largely not successful in resolving relationships among these groups, as also encountered by other workers. In fact, our results contradict some aspects of relationships that have seemed resolved by earlier studies, notably among Byblidaceae, Scrophulariaceae, Thomandersia, and other Lamiales. Among Nelsonioideae, analysis of sequence data from more rapidly evolving genic regions (i.e., trnS-G, ndhF-rpl32 + rpl32-trnL(UAG), nrITS) and a larger sample of nelsonioids (i.e., all genera and multiple taxa to represent the diversity of species-rich genera) indicates that Nelsonia and Elytraria are monophyletic with strong support but with only moderate support for Nelsonia as the first branching clade and Elytraria sister to the remaining nelsonioids. An African clade comprising monospecific Saintpauliopsis sister to Anisosepalum (2 of 3 species sampled) is sister to a clade that includes all sampled members of pantropical Staurogyne plus New World Gynocraterium and Asian Ophiorrhiziphyllon. Gynocraterium is sister to all sampled members of New World Staurogyne; this last clade is sister to a clade comprising the other sampled Staurogyne plus Ophiorrhiziphyllon which is nested among Asian Staurogyne. The taxonomic implications of these patterns of relationship are discussed. Our results suggest that Nelsonioideae have a complex history of inter-continental dispersals compared to other acanth lineages of similar to much larger size in terms of number of species, making it an interesting group for biogeographic study.

Keyword
Acanthaceae, Bayesian analysis, Lamiales, Nelsonioideae, parsimony, phylogenetic relationships
National Category
Biological Systematics
Research subject
Systematic Botany; Plant Systematics
Identifiers
urn:nbn:se:su:diva-71075 (URN)
Available from: 2012-01-25 Created: 2012-01-25 Last updated: 2012-01-26Bibliographically approved
4. Phylogenetic relationships in Acanthaceae based on nuclear and chloroplast sequences with particular focus on the Thunbergioideae
Open this publication in new window or tab >>Phylogenetic relationships in Acanthaceae based on nuclear and chloroplast sequences with particular focus on the Thunbergioideae
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Phylogenetic analyses using maximum parsimony and Bayesian inference of one nuclear (ETS) and three chloroplast DNA regions (rpl16, rps16, trnT-trnL) were used to infer detailed phylogenetic relationships within the tropical and subtropical subfamily Thunbergioideae and among major lineages of Acanthaceae. For the first time, sequencing of the monotypic genus Anomacanthus is reported and its position as sister to Mendoncia gains strong support. Relationships among South and Central American Mendoncia species are poorly resolved, most likely reflecting an earlier rapid radiation. The clade with Anomacanthus and Mendoncia is sister to the clade comprising Pseudocalyx and Thunbergia. Relationships within the larger genus Thunbergia are generally well resolved. Two species (Thunbergia heterochondros and T. colpifera) appear morphologically intermediate between Pseudocalyx and Thunbergia. We discuss evolutionary relationships, including unclear species boundaries revealed by the molecular data, in a morphological context. Relationships among and within the four genera shed light on the biogeographic history of the group. All four genera are represented in Africa, from where Mendoncia appears to have dispersed to South and Central America and subsequently diversified into a large number of closely related species. The geographic origin of Thunbergia is uncertain, and the data point to interesting biogeographical patterns in this genus.

Keyword
Anomacanthus, biogeography, Lamiales, morphology, Nelsonia, Pseudocalyx
National Category
Biological Systematics
Research subject
Plant Systematics; Plant Morphology; Systematic Botany
Identifiers
urn:nbn:se:su:diva-71076 (URN)
Available from: 2012-01-25 Created: 2012-01-25 Last updated: 2012-01-26Bibliographically approved

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