Chloé Galley

Origin and diversification of the Greater Cape flora: Ancient species repository, hot-bed of recent radiation, or both?

Like island-endemic taxa, whose origins are expected to postdate the appearance of the islands on which they occur, biome-endemic taxa should be younger than the biomes to which they are endemic. Accordingly, the ages of biome-endemic lineages may offer insights into biome history. In this study, we used the ages of multiple lineages to explore the origin and diversification of two southern African biomes whose remarkable floristic richness and endemism has identified them as global biodiversity hotspots (succulent karoo and fynbos). We used parsimony optimization to identify succulent karoo- and fynbos-endemic lineages across 17 groups of plants, for which dated phylogenies had been inferred using a relaxed Bayesian (BEAST) approach. All succulent karoo-endemic lineages were less than 17.5 My old, the majority being younger than 10 My. This is largely consistent with suggestions that this biome is the product of recent radiation, probably triggered by climatic deterioration since the late Miocene. In contrast, fynbos-endemic lineages showed a broader age distribution, with some lineages originating in the Oligocene, but most being more recent. Also, in groups having both succulent karoo- and fynbos-endemic lineages, there was a tendency for the latter to be older. These patterns reflect the greater antiquity of fynbos, but also indicate considerable recent speciation, probably through a combination of climatically-induced refugium fragmentation and adaptive radiation.

The Cape element in the Afrotemperate flora: from Cape to Cairo?

The build-up of biodiversity is the result of immigration and in situ speciation. We investigate these two processes for four lineages (Disa, Irideae p.p., the Pentaschistis clade and Restionaceae) that are widespread in the Afrotemperate flora. These four lineages may be representative of the numerous clades which are species rich in the Cape and also occur in the highlands of tropical Africa. It is as yet unclear in which direction the lineages spread. Three hypotheses have been proposed: (i) a tropical origin with a southward migration towards the Cape, (ii) a Cape origin with a northward migration into tropical Africa, and (iii) vicariance. None of these hypotheses has been thoroughly tested. We reconstruct the historical biogeography of the four lineages using likelihood optimization onto molecular phylogenies. We find that tropical taxa are nested within a predominantly Cape clade. There is unidirectional migration from the Cape into the Drakensberg and from there northwards into tropical Africa. The amount of in situ diversification differs between areas and clades. Dating estimates show that the migration into tropical East Africa has occurred in the last 17 Myr, consistent with the Mio-Pliocene formation of the mountains in this area.

THE PHYLOGENY OF THE PENTASCHISTIS CLADE (DANTHONIOIDEAE, POACEAE) BASED ON CHLOROPLAST DNA, AND THE EVOLUTION AND LOSS OF COMPLEX CHARACTERS

Abstract We construct a species-level phylogeny for the Pentaschistis clade based on chloroplast DNA, from the following regions: trnL-F, trnT-L, atpB-rbcL, rpL16, and trnD-psbA. The clade comprises 82 species in three genera, Pentaschistis, Pentameris, and Prionanthium. We demonstrate that Prionanthium is nested in Pentaschistis and that this clade is sister to a clade of Pentameris plus Pentaschistis tysonii. Forty-three of the species in the Pentaschistis clade have multicellular glands and we use ancestral character state reconstruction to show that they have been gained twice or possibly once, and lost several times. We suggest that the maintenance, absence, loss, and gain of glands are correlated with leaf anatomy type, and additionally that there is a difference in the degree of diversification of lineages that have these different character combinations. We propose that both glands and sclerophyllous leaves act as defense systems against herbivory, and build a cost/benefit model in which multicellular glands or sclerophyllous leaves are lost when the alternative defense system evolves. We also investigate the association between leaf anatomy type and soil nutrient type on which species grow. There is little phylogenetic constraint in soil nutrient type on members of the Pentaschistis clade, with numerous transitions between oligotrophic and eutrophic soils. However, only orthophyllous-leaved species diversify on eutrophic soils. We suggest that the presence of these glands enables the persistence of orthophyllous lineages and therefore diversification of the Pentaschistis clade on eutrophic as well as oligotrophic soils.

A Generic Classification of the Danthonioideae (Poaceae)1

Abstract We present a new generic classification of the largely Southern Hemisphere grass subfamily Danthonioideae. This classification is based on an almost completely sampled and well-resolved molecular phylogeny and on a complete morphological data set. We have attempted to delimit monophyletic genera (complicated by the presence of apparent intergeneric hybridization), which are diagnosable, as well as morphologically and ecogeographically coherent. We recognize 17 genera, including five new genera (Austroderia N. P. Barker & H. P. Linder, Capeochloa H. P. Linder & N. P. Barker, Chimaerochloa H. P. Linder, Geochloa H. P. Linder & N. P. Barker, and Tenaxia N. P. Barker & H. P. Linder), and two sections newly designated for Pentameris P. Beauv. (section Dracomontanum H. P. Linder & Galley and section Pentaschistis (Nees) H. P. Linder & Galley). Of the remaining 12 genera, the delimitations of seven are changed: Merxmuellera Conert is much reduced by the segregation of Geochloa, Capeochloa, and Tenaxia; Pentameris is expanded to include Prionanthium Desv. and Pentaschistis (Nees) Spach; Cortaderia Stapf is expanded by the inclusion of Lamprothyrsus Pilg., but reduced by the segregation of its New Zealand species into the new genus Austroderia; a large Rytidosperma Steud. is assembled out of Joycea H. P. Linder, Austrodanthonia H. P. Linder, Notodanthonia Zotov, Erythranthera Zotov, Pyrrhanthera Zotov, and Monostachya Merr.; and the species previously assigned to Karroochloa Conert & Türpe, Schismus P. Beauv., Urochlaena Nees, and Tribolium Desv. have been reassigned to only two genera. Finally, the Himalayan species of Danthonia DC. are transferred to Tenaxia and the remaining African species of Danthonia to Merxmuellera. The 281 species that we recognize in the subfamily are listed under their new genera, which are arranged in the phylogenetic sequence evident from the molecular phylogeny. The 100 necessary new combinations include: Merxmuellera grandiflora (Hochst. ex A. Rich.) H. P. Linder, Geochloa decora (Nees) N. P. Barker & H. P. Linder, G. lupulina (L. f.) N. P. Barker & H. P. Linder, G. rufa (Nees) N. P. Barker & H. P. Linder, Capeochloa arundinacea (P. J. Bergius) N. P. Barker & H. P. Linder, C. cincta (Nees) N. P. Barker & H. P. Linder, C. cincta subsp. sericea (N. P. Barker) N. P. Barker & H. P. Linder, C. setacea (N. P. Barker) N. P. Barker & H. P. Linder, Pentameris praecox (H. P. Linder) Galley & H. P. Linder, P. tysonii (Stapf) Galley & H. P. Linder, P. acinosa (Stapf) Galley & H. P. Linder, P. airoides Nees subsp. jugorum (Stapf) Galley & H. P. Linder, P. alticola (H. P. Linder) Galley & H. P. Linder, P. ampla (Nees) Galley & H. P. Linder, P. andringitrensis (A. Camus) Galley & H. P. Linder, P. argentea (Stapf) Galley & H. P. Linder, P. aristidoides (Thunb.) Galley & H. P. Linder, P. aristifolia (Schweick.) Galley & H. P. Linder, P. aspera (Thunb.) Galley & H. P. Linder, P. aurea (Steud.) Galley & H. P. Linder, P. aurea subsp. pilosogluma (McClean) Galley & H. P. Linder, P. bachmannii (McClean) Galley & H. P. Linder, P. barbata (Nees) Steud. subsp. orientalis (H. P. Linder) Galley & H. P. Linder, P. basutorum (Stapf) Galley & H. P. Linder, P. borussica (K. Schum.) Galley & H. P. Linder, P. calcicola (H. P. Linder) Galley & H. P. Linder, P. calcicola var. hirsuta (H. P. Linder) Galley & H. P. Linder, P. capensis (Nees) Galley & H. P. Linder, P. capillaris (Thunb.) Galley & H. P. Linder, P. caulescens (H. P. Linder) Galley & H. P. Linder, P. chippindalliae (H. P. Linder) Galley & H. P. Linder, P. chrysurus (K. Schum.) Galley & H. P. Linder, P. clavata (Galley) Galley & H. P. Linder, P. colorata (Steud.) Galley & H. P. Linder, P. dentata (L. f.) Galley & H. P. Linder, P. dolichochaeta (S. M. Phillips) Galley & H. P. Linder, P. ecklonii (Nees) Galley & H. P. Linder, P. exserta (H. P. Linder) Galley & H. P. Linder, P. galpinii (Stapf) Galley & H. P. Linder, P. holciformis (Nees) Galley & H. P. Linder, P. horrida (Galley) Galley & H. P. Linder, P. humbertii (A. Camus) Galley & H. P. Linder, P. insularis (Hemsl.) Galley & H. P. Linder, P. juncifolia (Stapf) Galley & H. P. Linder, P. longipes (Stapf) Galley & H. P. Linder, P. malouinensis (Steud.) Galley & H. P. Linder, P. microphylla (Nees) Galley & H. P. Linder, P. minor (Ballard & C. E. Hubb.) Galley & H. P. Linder, P. montana (H. P. Linder) Galley & H. P. Linder, P. natalensis (Stapf) Galley & H. P. Linder, P. oreodoxa (Schweick.) Galley & H. P. Linder, P. pallida (Thunb.) Galley & H. P. Linder, P. pholiuroides (Stapf) Galley & H. P. Linder, P. pictigluma (Steud.) Galley & H. P. Linder, P. pictigluma var. gracilis (S. M. Phillips) Galley & H. P. Linder, P. pictigluma var. mannii (Stapf ex C. E. Hubb.) Galley & H. P. Linder, P. pseudopallescens (H. P. Linder) Galley & H. P. Linder, P. pungens (H. P. Linder) Galley & H. P. Linder, P. pusilla (Nees) Galley & H. P. Linder, P. pyrophila (H. P. Linder) Galley & H. P. Linder, P. reflexa (H. P. Linder) Galley & H. P. Linder, P. rigidissima (Pilg. ex H. P. Linder) Galley & H. P. Linder, P. rosea (H. P. Linder) Galley & H. P. Linder, P. rosea subsp. purpurascens (H. P. Linder) Galley & H. P. Linder, P. scandens (H. P. Linder) Galley & H. P. Linder, P. setifolia (Thunb.) Galley & H. P. Linder, P. tomentella (Stapf) Galley & H. P. Linder, P. trifida (Galley) Galley & H. P. Linder, P. triseta (Thunb.) Galley & H. P. Linder, P. trisetoides (Hochst. ex Steud.) Galley & H. P. Linder, P. velutina (H. P. Linder) Galley & H. P. Linder, P. veneta (H. P. Linder) Galley & H. P. Linder, Cortaderia hieronymi (Kuntze) N. P. Barker & H. P. Linder, C. peruviana (Hitchc.) N. P. Barker & H. P. Linder, Austroderia fulvida (Buchanan) N. P. Barker & H. P. Linder, A. richardii (Endl.) N. P. Barker & H. P. Linder, A. splendens (Connor) N. P. Barker & H. P. Linder, A. toetoe (Zotov) N. P. Barker & H. P. Linder, A. turbaria (Connor) N. P. Barker & H. P. Linder, Chimaerochloa archboldii (Hitchc.) Pirie & H. P. Linder, Tenaxia aureocephala (J. G. Anderson) N. P. Barker & H. P. Linder, T. cachemyriana (Jaub. & Spach) N. P. Barker & H. P. Linder, T. cumminsii (Hook. f.) N. P. Barker & H. P. Linder, T. disticha (Nees) N. P. Barker & H. P. Linder, T. dura (Stapf) N. P. Barker & H. P. Linder, T. guillarmodiae (Conert) N. P. Barker & H. P. Linder, T. stricta (Schrad.) N. P. Barker & H. P. Linder, T. subulata (A. Rich.) N. P. Barker & H. P. Linder, Schismus schismoides (Stapf ex Conert) Verboom & H. P. Linder, Tribolium curvum (Nees) Verboom & H. P. Linder, T. pleuropogon (Stapf) Verboom & H. P. Linder, T. purpureum (L. f.) Verboom & H. P. Linder, T. tenellum (Nees) Verboom & H. P. Linder, Rytidosperma bipartitum (Kunth) A. M. Humphreys & H. P. Linder, R. diemenicum (D. I. Morris) A. M. Humphreys & H. P. Linder, R. fulvum (Vickery) A. M. Humphreys & H. P. Linder, R. lepidopodum (N. G. Walsh) A. M. Humphreys & H. P. Linder, R. pallidum (R. Br.) A. M. Humphreys & H. P. Linder, R. popinensis (D. I. Morris) A. M. Humphreys & H. P. Linder, R. remotum (D. I. Morris) A. M. Humphreys & H. P. Linder. Typifications are designated for the following names: Achneria Munro ex Benth. & Hook. f., Avena aristidoides Thunb., A. elephantina Thunb., Danthonia crispa Nees var. trunculata Nees, Danthonia sect. Himantochaete Nees, D. zeyheriana Steud. var. trichostachya Stapf, Geochloa lupulina, Pentameris aristidoides, and P. holciformis.

The phylogeny of the austral grass subfamily Danthonioideae: Evidence from multiple data sets

The grass subfamily Danthonioideae is one of the smaller in the family. We utilize DNA sequence data from three chloroplast regions (trnL, rpoC2 and rbcL) and one nuclear region (Internal Transcribed Spacer; ITS) both singly and in combination to elucidate the relationships of the genera in the subfamily. The topology retrieved by the ITS region is not congruent with that of the plastid data, but this conflict is not strongly supported. Nine well-supported clades are retrieved by all data sets. The relationships at the base of the subfamily are clearly established, comprising a series of three clades of Merxmuellera species. The earliest diverging clade probably does not belong in Danthonioideae. The other two clades are centered in the tropical African mountains and Cape mountains respectively. A clade of predominantly North and South American Danthonia species as well as D. archboldii from New Guinea is retrieved, but the African and Asian species of Danthonia are related to African species of Merxmuellera, thus rendering Danthonia polyphyletic. The relationships of the Danthonia clade remain equivocal, as do those of the two Cortaderia clades, the Pseudopentameris and Rytidosperma clades.

The Migration of the Palaeotropical Arid Flora: Zygophylloideae as an Example

Abstract The rate and direction of biotic exchange between the Palaeotropical arid floras of Asia, Africa, and Australia is poorly understood because of a lack of phylogenetic hypotheses for relevant plant groups. Periodic aridification may have facilitated migrations of arid-adapted plants between southwestern Africa and the Horn of Africa as recently as the last glacial maximum, allowing further exchange with the arid floras of Asia. However, no conclusive evidence of the age and direction of such migrations have been documented. We use a molecular phylogeny of the Zygophylloideae to infer a biogeographic scenario for the arid Palaeotropics, using relaxed clock dating and likelihood and parsimony based ancestral area reconstruction methods. We infer up to five migrations across the African continent (in contrast to just one each to Australia and Asia from Africa). The three most recent were in the Pliocene/Pleistocene and from southern to northern Africa, while the oldest dates to the Oligoccene to Miocene. For the recruitment of the arid Palaeotropical flora, the preponderance of migrations across the African continent points to a repeated pattern of dispersal mediated by periodically more contiguous habitat, the so called ‘African arid corridor,’ with rarer long distance dispersal events between other disjunct areas.

Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora

BackgroundThe best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africas biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years.ResultsForty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology.ConclusionsAdaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the floras extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record.