“…The Mediterranean clade was estimated to have diversified at 29.51 Ma, and the ancestors of the South East-Asian D. tentaculigera and its sister group, the Enantiophyllum clade, and the CL clade at 34.78 Ma, 28.93 Ma and 29.74 Ma, respectively.Fig. 4Beast chronogram of the African yam lineages dated using three calibrations points (● Dioscoreaceae: 80 mya [42], ★ Dioscorea Stenophora clade crown node 48.2 mya [43] and
Dioscorea dregeana - D. dumetorum clade node in Counpound Leaved clade 27.2 mya [44]). Only the four major clades are displayed in the figure.…”
Section: Resultsmentioning
confidence: 99%
“…Fritel, was used to calibrate the node of Dioscorea prazeri Prain & Burkill , (representative of the Stenophora clade). The fossil was discovered in the Cuisian stage of the Ypresian age at the Paris basin [43] and provided a minimum constraint of 48.2 ± 1.0 mya (LogNormal Prior mean = 48.2, SD 0.008) for the stem node of Stenophora . A second fossil, D. wilkinii Pan, attributed to the node of the Compound Leaved clade that comprises D. dregeana - D. dumetorum, provided a minimum constraint of 27.2 ± 0.1 mya (LogNormal Prior mean = 27.2, SD 0.002) for that node [44].…”
Background
Dioscorea is a widely distributed and highly diversified genus in tropical regions where it is represented by ten main clades, one of which diversified exclusively in Africa. In southern Africa it is characterised by a distinct group of species with a pachycaul or “elephant’s foot” structure that is partially to fully exposed above the substrate. In contrast to African representatives of the genus from other clades, occurring mainly in forest or woodland, the pachycaul taxa and their southern African relatives occur in diverse habitats ranging from woodland to open vegetation. Here we investigate patterns of diversification in the African clade, time of transition from forest to more open habitat, and morphological traits associated with each habitat and evaluate if such transitions have led to modification of reproductive organs and mode of dispersal.ResultsThe Africa clade originated in the Oligocene and comprises four subclades. The Dioscorea buchananii subclade (southeastern tropical Africa and South Africa) is sister to the East African subclade, which is respectively sister to the recently evolved sister South African (e. g., Cape and Pachycaul) subclades. The Cape and Pachycaul subclades diversified in the east of the Cape Peninsula in the mid Miocene, in an area with complex geomorphology and climate, where the fynbos, thicket, succulent karoo and forest biomes meet.ConclusionsDiversification out of forest is associated with major shifts in morphology of the perennial tuber (specifically an increase in size and orientation which presumably led them to become pachycaul) and rotation of stem (from twining to non-twining). The iconic elephant's foot morphology, observed in grasslands and thicket biomes, where its corky bark may offer protection against fire and herbivory, evolved since mid Miocene. A shift in pollination trait is observed within the forest, but entry into open habitat does not show association with reproductive morphology, except in the seed wing, which has switched from winged all round the seed margin to just at the base or at the apex of it, or has been even replaced by an elaiosome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0812-z) contains supplementary material, which is available to authorized users.
“…The Mediterranean clade was estimated to have diversified at 29.51 Ma, and the ancestors of the South East-Asian D. tentaculigera and its sister group, the Enantiophyllum clade, and the CL clade at 34.78 Ma, 28.93 Ma and 29.74 Ma, respectively.Fig. 4Beast chronogram of the African yam lineages dated using three calibrations points (● Dioscoreaceae: 80 mya [42], ★ Dioscorea Stenophora clade crown node 48.2 mya [43] and
Dioscorea dregeana - D. dumetorum clade node in Counpound Leaved clade 27.2 mya [44]). Only the four major clades are displayed in the figure.…”
Section: Resultsmentioning
confidence: 99%
“…Fritel, was used to calibrate the node of Dioscorea prazeri Prain & Burkill , (representative of the Stenophora clade). The fossil was discovered in the Cuisian stage of the Ypresian age at the Paris basin [43] and provided a minimum constraint of 48.2 ± 1.0 mya (LogNormal Prior mean = 48.2, SD 0.008) for the stem node of Stenophora . A second fossil, D. wilkinii Pan, attributed to the node of the Compound Leaved clade that comprises D. dregeana - D. dumetorum, provided a minimum constraint of 27.2 ± 0.1 mya (LogNormal Prior mean = 27.2, SD 0.002) for that node [44].…”
Background
Dioscorea is a widely distributed and highly diversified genus in tropical regions where it is represented by ten main clades, one of which diversified exclusively in Africa. In southern Africa it is characterised by a distinct group of species with a pachycaul or “elephant’s foot” structure that is partially to fully exposed above the substrate. In contrast to African representatives of the genus from other clades, occurring mainly in forest or woodland, the pachycaul taxa and their southern African relatives occur in diverse habitats ranging from woodland to open vegetation. Here we investigate patterns of diversification in the African clade, time of transition from forest to more open habitat, and morphological traits associated with each habitat and evaluate if such transitions have led to modification of reproductive organs and mode of dispersal.ResultsThe Africa clade originated in the Oligocene and comprises four subclades. The Dioscorea buchananii subclade (southeastern tropical Africa and South Africa) is sister to the East African subclade, which is respectively sister to the recently evolved sister South African (e. g., Cape and Pachycaul) subclades. The Cape and Pachycaul subclades diversified in the east of the Cape Peninsula in the mid Miocene, in an area with complex geomorphology and climate, where the fynbos, thicket, succulent karoo and forest biomes meet.ConclusionsDiversification out of forest is associated with major shifts in morphology of the perennial tuber (specifically an increase in size and orientation which presumably led them to become pachycaul) and rotation of stem (from twining to non-twining). The iconic elephant's foot morphology, observed in grasslands and thicket biomes, where its corky bark may offer protection against fire and herbivory, evolved since mid Miocene. A shift in pollination trait is observed within the forest, but entry into open habitat does not show association with reproductive morphology, except in the seed wing, which has switched from winged all round the seed margin to just at the base or at the apex of it, or has been even replaced by an elaiosome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0812-z) contains supplementary material, which is available to authorized users.
“…Vessel elements are also present in various non-angiosperms, such as Selaginella , Equisetum , Pteridium [1], Gigantopteriales [51], and Gnetales [1,4,31,32]. Reticulate venation has been reported in non-angiosperms, including Dipteridaceae [52-55], Gigantopteriales [56,57], Caytoniales [33,58], Glossopteridales [5,40,46,58], Bennettitales [32], and Gnetales [31,32]. Pollen grains with an angiosperm-like wall structure have been reported in many pre-Cretaceous plants [59-61] that are regarded as non-angiosperms by others [62].…”
Background: The origin of angiosperms has been under debate since the time of Darwin. While there has been much speculation in past decades about pre-Cretaceous angiosperms, including Archaefructus, these reports are controversial. The earliest reliable fossil record of angiosperms remains restricted to the Cretaceous, even though recent molecular phylogenetic studies suggest an origin for angiosperms much earlier than the current fossil record.
“…The holotype of "Rhacopteris" subpetiolata, MB.Pb. 2003/960, sampled in 1887 and published by Potonié (1899), originated from the "Fürstlicher Tiefbau" near Waldenburg (Wałbrzych). Specimen MB.…”
Section: Methodsmentioning
confidence: 99%
“…Comparison of studied species with other plants of similar pinnule-type Potonié (1889Potonié ( , 1899 placed this species (Rh. subpetiolatum) in Rhacopteris Schimper based on the similarity of pinnules which are differentiated into deep and sharp lobes that correspond with veins.…”
Section: Comparison Of Rhodeites Gutbieri and Rhodeopteridium Subpetimentioning
The paper deals with two Pennsylvanian species Rhodeites gutbieri (Ettingshausen) Němejc and Rhodeopteridium subpetiolatum (Potonié) comb. nov. which are mostly mistakenly placed into one species Rhodea subpetiolata (Potonié) Zeiller. The clear differences between the two species are given. This paper focuses on their morphological details (including cuticle), as well as stratigraphical and geographical distributions. The genus Rhodeites is emended. Only sterile specimens of Rhodeites are known up till now and so the systematic position is still unknown. This paper also discusses their ecological status in nature.•
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