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Aim: Existing phytogeographical frameworks for tropical Africa lack either spatial completeness, unit definitions smaller than the regional scale or a quantitative approach. We investigate whether physical environmental variables can be used to interpolate floristically defined vegetation units, presenting an interpolated, hierarchical, quantitative phytogeographical framework for tropical Africa, which is compared to previously defined regions. Location: Tropical mainland Africa 24°N to 24°S. Taxon: 31,046 vascular plant species and infraspecific taxa. Methods: We calculate a betasim dissimilarity matrix from a comprehensive whole‐flora database of plant species distributions. We investigate environmental correlates of floristic turnover with local non‐metric multidimensional scaling. We derive a hierarchical biogeographical framework by clustering the dissimilarity matrix. The framework is modelled using a classification decision tree method and 12 physical environmental variables to interpolate and increase the resolution of the framework across the study region. Results: Floristic turnover is related strongly to water availability and temperature, with smaller contributions from land cover, topographic ruggedness and lithology. Region can be predicted with 90% accuracy by the model. We define 19 regions and 99 districts. We find a novel arrangement of the arid regions. Regional subdivision within the savanna biome is supported with minor variation to borders. Within the forests of west and central Africa, our whole‐flora gridded regionalization supports the divisions identified by a previous analysis of trees only. Main conclusions: Physical environmental variables can be used to predict floristically defined vegetation units with very high accuracy, and the approach could be pursued for other incompletely sampled taxa and areas outside of tropical Africa. Geographical coherence is higher than in previous quantitative phytoregional definitions. For most tropical African vascular plant species, we provide predictions of which species will occur within each mapped district and region of tropical Africa. The framework should be useful for future studies in ecology, evolution and conservation. [ABSTRACT FROM AUTHOR]

On the basis of a new phylogeny of the Detarioideae, with a particular focus on Englerodendron Harms, Anthonotha P.Beauv. and related genera, the possible options for delimiting monophyletic genera are discussed. As a result, Isomacrolobium Aubrév. & Pellegr. and Pseudomacrolobium Hauman are synonymised under Englerodendron. The following 12 new combinations are formed within the expanded Englerodendron: E. brachyrhachis (Breteler) Estrella & Ojeda, E. explicans (Baill.) Estrella & Ojeda, E. graciliflorum (Harms) Estrella & Ojeda, E. hallei (Aubrév.) Estrella & Ojeda, E. isopetalum (Harms) Breteler & Wieringa, E. lebrunii (J.Léonard) Estrella & Ojeda, E. leptorrhachis (Harms) Estrella & Ojeda, E. mengei (De Wild.) Estrella & Ojeda, E. nigericum (Baker f.) Estrella & Ojeda, E. obanense (Baker f.) Estrella & Ojeda, E. triplisomere (Pellegr.) Estrella & Ojeda and E. vignei (Hoyle) Estrella & Ojeda. A key to identification of the 17 species now recognised within Englerodendron is presented. [ABSTRACT FROM AUTHOR]

On the basis of a new phylogeny of the Detarioideae, with a particular focus on Englerodendron Harms, Anthonotha P.Beauv. and related genera, the possible options for delimiting monophyletic genera are discussed. As a result, Isomacrolobium Aubrév. & Pellegr. and Pseudomacrolobium Hauman are synonymised under Englerodendron. The following 12 new combinations are formed within the expanded Englerodendron: E. brachyrhachis (Breteler) Estrella & Ojeda, E. explicans (Baill.) Estrella & Ojeda, E. graciliflorum (Harms) Estrella & Ojeda, E. hallei (Aubrév.) Estrella & Ojeda, E. isopetalum (Harms) Breteler & Wieringa, E. lebrunii (J.Léonard) Estrella & Ojeda, E. leptorrhachis (Harms) Estrella & Ojeda, E. mengei (De Wild.) Estrella & Ojeda, E. nigericum (Baker f.) Estrella & Ojeda, E. obanense (Baker f.) Estrella & Ojeda, E. triplisomere (Pellegr.) Estrella & Ojeda and E. vignei (Hoyle) Estrella & Ojeda. A key to identification of the 17 species now recognised within Englerodendron is presented. [ABSTRACT FROM AUTHOR]

The molecular clock hypothesis is an important concept in biology. Deviations from a constant rate of nucleotide substitution have been found widely among lineages, genomes, genes and individual sites. Phylogenetic research can accommodate for these differences in applying specific models of evolution. Lineage-specific rate heterogeneity however can generate bi- or multimodal distributions of substitution rates across the branches of a tree and this may mislead phylogenetic inferences with currently available models. The plant family Annonaceae is an excellent case to study lineage-specific rate heterogeneity. The two major sister subfamilies, Annonoideae and Malmeoideae, have shown great discrepancies in branch lengths. We used high-throughput sequencing data of 72 genes, 99 spacers and 16 introns from 24 chloroplast genomes and nuclear ribosomal DNA of 23 species to study the molecular rate of evolution in Annonaceae. In all analyses, longer branch lengths and/or higher substitution rates were found for the Annonoideae compared to the Malmeoideae. The Annonaceae had wide variability in chloroplast length, ranging from minimal 175,684 bp to 201,723 for Annonoideae and minimal 152,357 to 170,985 bp in Malmeoideae, mostly reflecting variation in inverted-repeat length. The Annonoideae showed a higher GC-content in the conserved parts of the chloroplast genome and higher omega ( d N / d S )-ratios than the Malmeoideae, which could indicate less stringent purifying selection, a pattern that has been found in groups with small population sizes. This study generates new insights into the processes causing lineage-specific rate heterogeneity, which could lead to improved phylogenetic methods. [ABSTRACT FROM AUTHOR]

Summary Identifying areas of high biodiversity is an established way to prioritize areas for conservation [ 1–3 ], but global approaches have been criticized for failing to render global biodiversity value at a scale suitable for local management [ 4–6 ]. We assembled 3.1 million species distribution records for 40,401 vascular plant species of tropical Africa from sources including plot data, herbarium databases, checklists, and the Global Biodiversity Information Facility (GBIF) and cleaned the records for geographic accuracy and taxonomic consistency. We summarized the global ranges of tropical African plant species into four weighted categories of global rarity called Stars. We applied the Star weights to summaries of species distribution data at fine resolutions to map the bioquality (range-restricted global endemism) of areas [ 7 ]. We generated confidence intervals around bioquality scores to account for the remaining uncertainty in the species inventory. We confirm the broad significance of the Horn of Africa, Guinean forests, coastal forests of East Africa, and Afromontane regions for plant biodiversity but also reveal the variation in bioquality within these broad regions and others, particularly at local scales. Our framework offers practitioners a quantitative, scalable, and replicable approach for measuring the irreplaceability of particular local areas for global biodiversity conservation and comparing those areas within their global and regional context. [ABSTRACT FROM AUTHOR]

Premise of research. Gilbertiodendron is a genus endemic to Africa with ~30 species made up of trees of primary dry-land, riverine, and gallery forests. Recently, the west and central African monotypic genus Pellegriniodendron was merged into Gilbertiodendron. Gilbertiodendron is one of 17 genera that form the exclusively African Berlinia clade, and this study presents the findings of a phylogenetic analysis designed to evaluate the generic limits of Gilbertiodendron and its relationships within the Berlinia clade. Methodology. To test the monophyly of Gilbertiodendron and its relationships with other genera, we analyzed nucleotide sequence data from the nuclear ribosomal internal transcribed spacer and the plastid trnL intron and trnL-F intergenic spacer, using parsimony and Bayesian analyses. Pivotal results. Gilbertiodendron is recovered as monophyletic, including all the samples previously recognized as Pellegriniodendron diphyllum. Conclusions. The placement of Pellegriniodendron in synonymy with Gilbertiodendron is supported by our results. Our analyses suggest that G. diphyllum is the same taxon on both sides of the Dahomey Gap. The G. ogoouense complex is a monophyletic group of species that needs a new taxonomic framework and within which several new species will be described. The phylogenetic framework presented here and the ongoing taxonomic revision should provide the baseline data required for adequate assessment of this group of tree species, of which only eight have been assessed under the International Union for Conservation of Nature's Red List criteria. [ABSTRACT FROM AUTHOR]

We have observed among the holdings of Hymenostegia (Leguminosae: Caesalpinioideae) in several major herbaria that many of the specimens determined as H. klainei Pierre ex Pellegr. are not identified correctly and instead represent undescribed taxa. We speculate that the misidentifications may be a direct consequence of the sole use of leaf characters to distinguish species in the dichotomous keys of two major regional treatments of the genus. Two such previously unrecognised taxa, both new species from Gabon, Hymenostegia elegans Wieringa and Mackinder and Hymenostegia robusta Wieringa and Mackinder are described here accompanied by a distribution map, illustrations and conservation assessments. Both species have a limited distribution area and are assessed as 'Vulnerable' and 'Endangered', respectively. This publication brings the total number of species in Hymenostegia s.s. to nine. [ABSTRACT FROM AUTHOR]

The presence or absence of hydroxypipecolic acids and hydroxyprolines in leaves of members of the former genus Monopetalanthus Harms was generally found to support the recent segregation of species into Aphanocalyx Oliver, Bikinia Wieringa and Tetraberlinia (Harms) Hauman. The species transferred to Aphanocalyx were found to lack these non-protein amino acids, like species traditionally placed in that genus, while most of the species reclassified into the new genus Bikinia accumulated hydroxypipecolic acids and hydroxyprolines (the exceptions were B. aciculifera Wieringa, B. coriacea J. Morel ex Aubre´v. and B. durandii F. Halle´ & Normand). All seven known species of Tetraberlinia, including T. longiracemosa (A. Chev.) Wieringa, which was formerly placed in Monopetalanthus, also contained one or both types of compounds. In species of Bikinia and Tetraberlinia the hydroxypipecolic acids accumulated included trans-4-hydroxypipecolic acid, trans-4-trans-5-dihydroxypipecolic acid and cis-4-cis-5-dihydroxypipecolic acid. All except T. moreliana Aubre´v. and T. korupensis Wieringa also accumulated N-methyl-trans-4-hydroxyproline and both of these species and T. bifoliolata (Harms) Hauman accumulated an epimer of N-methyl-4,5-dihydroxypipecolic acid. These chemical groupings of Tetraberlinia species are generally in accordance with those based on morphology. [Copyright &y& Elsevier]

Simplification by reduction has occurred many times independently in the floral evolution of angiosperms. These reductions have often been attributed to changes in reproductive biology. In the angiosperm plant family Annonaceae, most species have flowers with six petals, and many stamens and carpels. In the genus Monanthotaxis several deviations from this pattern have been observed, including flowers that contain three petals and three stamens only. New DNA sequences were generated for 42 specimens of Monanthotaxis. Five chloroplast markers and two nuclear markers for 72 out of 94 species of Monanthotaxis were used to reconstruct a phylogeny of the genus, which revealed several well-supported, morphologically distinct clades. The evolution of four quantitative and two qualitative floral characters was mapped onto this phylogeny, demonstrating a reduction in flower size and number of flower parts in Monanthotaxis. A large variation in stamen forms and numbers, strong correlations between petal size, stamen and carpel number, combined with a non-gradual mode of evolution and the sympatric co-occurrence of Monanthotaxis species from different clades suggest that the high diversity in the African rainforest of this genus is caused by switches in pollination systems. [ABSTRACT FROM AUTHOR]

Monodoreae (Annonaceae) is a tribe composed of 11 genera and 90 species restricted to the tropical African rain forests. All the genera are taxonomically well circumscribed except the species rich genera Uvariodendron and Uvariopsis which lack a recent taxonomic revision. Here, we used a robust phylogenomic approach, including all the 90 currently accepted species, with several specimens per species, and based on more than 300 Annonaceae-specific nuclear genes, to infer the phylogenetic tree of the Monodoreae and test the limits between the genera and species. We recover all the genera as monophyletic, except the genus Uvariopsis for which the species Uvariopsis tripetala falls outside this clade. We thus reinstate the monotypic genus Dennettia for its single species Dennettia tripetala. We also erect a new tribe, Ophrypetaleae trib. nov., to accommodate the genera Ophrypetalum and Sanrafaelia, as we recover them excluded from the Monodoreae tribe with good support. Below the genus level, the genera Isolona, Monodora, Uvariastrum, Uvariodendron and Uvariopsis show weakly supported nodes and phylogenetic conflicts, suggesting that population level processes of evolution might occur in these clades. Our results also support, at the molecular level, the description of several new species of Uvariodendron and Uvariopsis, as well as several new synonymies. Finally, we present a taxonomic revision of the genera Dennettia, Uvariodendron and Uvariopsis, which contain one, 18 and 17 species respectively. We provide a key to the 11 genera of the Monodoraeae and describe four new species to science: Uvariodendron kimbozaense Dagallier & Couvreur, sp. nov., Uvariodendron mossambicense Robson ex Dagallier & Couvreur, sp. nov., Uvariodendron pilosicarpum Dagallier & Couvreur, sp. nov. and Uvariopsis oligocarpa Dagallier & Couvreur, sp. nov., and provide provisional descriptions of three putatively new species. We also present lectotypifications and nomenclatural changes implying synonymies and new combinations (Uvariodendron citriodorum (Le Thomas) Dagallier & Couvreur, comb. et stat. nov., Uvariodendron fuscum var. magnificum (Verdc.) Dagallier & Couvreur, comb. et stat. nov., Uvariopsis congensis var. angustifolia Dagallier & Couvreur, var. nov., Uvariopsis guineensis var. globiflora (Keay) Dagallier & Couvreur, comb. et stat. nov., and Uvariopsis solheidii var. letestui (Pellegr.) Dagallier & Couvreur, comb. et stat. nov.). [ABSTRACT FROM AUTHOR]

Three currently accepted Sclerosperma species appear to produce four different pollen morphologies. Sclerosperma mannii and S. walkeri pollen share the same distinct reticulate sculpture, but S. profizianum produces three different pollen types (microreticulate, fossulate, and perforate). The pollen morphology suggests that S. mannii and S. walkeri are sister taxa of the same intrageneric lineage. The pollen diversity observed in S. profizianum suggests (a) this taxon is unique regarding its pollen diversity despite being a non-heterostylous plant or (b) that circumscription of S. profizianum as a species may well be in the need of redefinition. [ABSTRACT FROM AUTHOR]

African tropical forests are generally considered less diverse than their Neotropical and Asian counterparts. By contrast, the Detarioideae is much more diverse in Africa than in South America and Asia. To better understand the evolution of this contrasting diversity pattern, we investigated the biogeographical and ecological origin of this subfamily, testing whether they originated in dry biomes surrounding the Tethys Seaway as currently hypothesized for many groups of Leguminosae., We constructed the largest time-calibrated phylogeny for the subfamily to date, reconstructed ancestral states for geography and biome/habitat, estimated diversification and extinction rates, and evaluated biome/habitat and geographic shifts in Detarioideae., The ancestral habitat of Detarioideae is postulated to be a primary forest (terra firme) originated in Africa-South America, in the early Palaeocene, after which several biome/habitat and geographic shifts occurred., The origin of Detarioideae is older than previous estimates, which postulated a dry (succulent) biome origin according to the Tethys Seaway hypothesis, and instead we reveal a post Gondwana and terra firme origin for this early branching clade of legumes. Detarioideae include some of the most dominant trees in evergreen forests and have likely played a pivotal role in shaping continental African forest diversity. [ABSTRACT FROM AUTHOR]

A comprehensively sampled reassessment of the molecular phylogeny of the genistoid legumes questions the traditional placement of Haplormosia , an African monotypic genus traditionally classified within tribe Sophoreae close to the Asian-American geographically disjunct genus Ormosia . Plastid matK sequences placed Haplormosia as sister to the American-Australian tribe Brongniartieae. Despite a superficial resemblance between Haplormosia and Ormosia , a re-examination of the morphology of Haplormosia corroborates the new phylogenetic result. The reciprocally monophyletic deep divergence of the Haplormosia stem lineage from the remaining Brongniartieae is dated to ca. 52 Mya, thus supporting a signature of an old single long-distance dispersal during the early Eocene. Conversely, we estimated a relatively recent long-distance dispersal rooted in the Early Miocene for the Australian Brongniartieae clade emerging from within a grade of American Brongniartieae. The Bayesian ancestral area reconstruction revealed the coming and going of neotropical ancestors during the diversification history of the Brongniartieae legumes in Africa and all over the Americas and Australia. [ABSTRACT FROM AUTHOR]

In conservation studies, solely widespread species are often used as indicators of diversity patterns, but narrow-ranged species can show different patterns. Here, we assess how well subsets of narrow-ranged, widespread or randomly selected plant species represent patterns of species richness and weighted endemism in Gabon, tropical Africa. Specifically, we assess the effect of using different definitions of widespread and narrow-ranged and of the information content of the subsets. Finally, we test if narrow-ranged species are overrepresented in species-rich areas. Based on distribution models of Gabonese plant species, we defined sequential subsets from narrow-ranged-to-widespread, widespread-to-narrow-ranged, and 100 randomly arranged species sequences using the range sizes of species in tropical Africa and within Gabon. Along these sequences, correlations between subsets and the total species richness and total weighted endemism patterns were computed. Random species subsets best represent the total species richness pattern, whereas subsets of narrow-ranged species best represent the total weighted endemism pattern. For species ordered according to their range sizes in tropical Africa, subsets of narrow-ranged species represented the total species richness pattern better than widespread species subsets did. However, the opposite was true when range sizes were truncated by the Gabonese national country borders. Correcting for the information content of the subset results in a skew of the sequential correlations, its direction depending on the range-size frequency distribution. Finally, we find a strong, positive, non-linear relation between weighted endemism and total species richness. Observed differences in the contribution of narrow-ranged, widespread and randomly selected species to species richness and weighted endemism patterns can be explained by the range-size frequency distribution and the use of different definitions of widespread or narrow-ranged. We call for a reconsideration of the use of widespread species as an indicator of diversity patterns, and advocate using the full ranges of species when assessing diversity patterns. [ABSTRACT FROM AUTHOR]

Species distribution models (SDMs) are widely used to predict the occurrence of species. Because SDMs generally use presence-only data, validation of the predicted distribution and assessing model accuracy is challenging. Model performance depends on both sample size and species' prevalence, being the fraction of the study area occupied by the species. Here, we present a novel method using simulated species to identify the minimum number of records required to generate accurate SDMs for taxa of different pre-defined prevalence classes. We quantified model performance as a function of sample size and prevalence and found model performance to increase with increasing sample size under constant prevalence, and to decrease with increasing prevalence under constant sample size. The area under the curve (AUC) is commonly used as a measure of model performance. However, when applied to presence-only data it is prevalence-dependent and hence not an accurate performance index. Testing the AUC of an SDM for significant deviation from random performance provides a good alternative. We assessed the minimum number of records required to obtain good model performance for species of different prevalence classes in a virtual study area and in a real African study area. The lower limit depends on the species' prevalence with absolute minimum sample sizes as low as 3 for narrow-ranged and 13 for widespread species for our virtual study area which represents an ideal, balanced, orthogonal world. The lower limit of 3, however, is flawed by statistical artefacts related to modelling species with a prevalence below 0.1. In our African study area lower limits are higher, ranging from 14 for narrow-ranged to 25 for widespread species. We advocate identifying the minimum sample size for any species distribution modelling by applying the novel method presented here, which is applicable to any taxonomic clade or group, study area or climate scenario. [ABSTRACT FROM AUTHOR]

Objectives: Species Distribution Models (SDMs) are used to produce predictions of potential Leguminosae diversity in West Central Africa. Those predictions are evaluated subsequently using expert opinion. The established methodology of combining all SDMs is refined to assess species diversity within five defined vegetation types. Potential species diversity is thus predicted for each vegetation type respectively. The primary aim of the new methodology is to define, in more detail, areas of species richness for conservation planning. Methodology: Using Maxent, SDMs based on a suite of 14 environmental predictors were generated for 185 West Central African Leguminosae species, each categorised according to one of five vegetation types: Afromontane, coastal, nonflooded forest, open formations, or riverine forest. The relative contribution of each environmental variable was compared between different vegetation types using a nonparametric Kruskal-Wallis analysis followed by a post-hoc Kruskal-Wallis Paired Comparison contrast. Legume species diversity patterns were explored initially using the typical method of stacking all SDMs. Subsequently, five different ensemble models were generated by partitioning SDMs according to vegetation category. Ecological modelers worked with legume specialists to improve data integrity and integrate expert opinion in the interpretation of individual species models and potential species richness predictions for different vegetation types. Results/Conclusions: Of the 14 environmental predictors used, five showed no difference in their relative contribution to the different vegetation models. Of the nine discriminating variables, the majority were related to temperature variation. The set of variables that played a major role in the Afromontane species diversity model differed significantly from the sets of variables of greatest relative important in other vegetation categories. The traditional approach of stacking all SDMs indicated overall centers of diversity in the region but the maps indicating potential species richness by vegetation type offered more detailed information on which conservation efforts can be focused. [ABSTRACT FROM AUTHOR]

Malvaceae s.l., the most diverse family within Malvales, includes well-known species of great economic importance like cotton, cacao, and durian. Despite numerous phylogenetic analyses employing multiple markers, relationships between several of its nine subfamilies, particularly within the largest lineage/Malvadendrina, remain unclear. In this study, we attempted to resolve the relationships within the major clades of Malvaceae s.l. using plastid genomes of 48 accessions representing all subfamilies. Maximum likelihood and Bayesian analyses recovered a fully resolved and well-supported topology confirming the split of the family into/Byttneriina (/Grewioideae þ/Byttnerioideae) and/Malvadendrina. Within/Malvadendrina,/Helicteroideae occupied the earliest branching position, followed by/Sterculioideae, / Brownlowioideae,/Tiliodeae, and/Dombeyoideae formed a clade sister to/Malvatheca (/Malvoideae þ/Bombacoideae), a grouping morphologically supported by the lack of androgynophore. Results from dating analyses suggest that all subfamilies originated during hot or warm phases in the Late Cretaceous to Paleocene. This study presents a well-supported phylogenetic framework for Malvaceae s.l. that will aid downstream revisions and evolutionary studies of this economically important plant family. [ABSTRACT FROM AUTHOR]

The consequences of the Cretaceous–Paleogene (K–Pg) boundary (KPB) mass extinction for the evolution of plant diversity remain poorly understood, even though evolutionary turnover of plant lineages at the KPB is central to understanding assembly of the Cenozoic biota. The apparent concentration of whole genome duplication (WGD) events around the KPB may have played a role in survival and subsequent diversification of plant lineages. To gain new insights into the origins of Cenozoic biodiversity, we examine the origin and early evolution of the globally diverse legume family (Leguminosae or Fabaceae). Legumes are ecologically (co-)dominant across many vegetation types, and the fossil record suggests that they rose to such prominence after the KPB in parallel with several well-studied animal clades including Placentalia and Neoaves. Furthermore, multiple WGD events are hypothesized to have occurred early in legume evolution. Using a recently inferred phylogenomic framework, we investigate the placement of WGDs during early legume evolution using gene tree reconciliation methods, gene count data and phylogenetic supernetwork reconstruction. Using 20 fossil calibrations we estimate a revised timeline of legume evolution based on 36 nuclear genes selected as informative and evolving in an approximately clock-like fashion. To establish the timing of WGDs we also date duplication nodes in gene trees. Results suggest either a pan-legume WGD event on the stem lineage of the family, or an allopolyploid event involving (some of) the earliest lineages within the crown group, with additional nested WGDs subtending subfamilies Papilionoideae and Detarioideae. Gene tree reconciliation methods that do not account for allopolyploidy may be misleading in inferring an earlier WGD event at the time of divergence of the two parental lineages of the polyploid, suggesting that the allopolyploid scenario is more likely. We show that the crown age of the legumes dates to the Maastrichtian or early Paleocene and that, apart from the Detarioideae WGD, paleopolyploidy occurred close to the KPB. We conclude that the early evolution of the legumes followed a complex history, in which multiple auto- and/or allopolyploidy events coincided with rapid diversification and in association with the mass extinction event at the KPB, ultimately underpinning the evolutionary success of the Leguminosae in the Cenozoic. [Allopolyploidy; Cretaceous–Paleogene (K–Pg) boundary; Fabaceae, Leguminosae; paleopolyploidy; phylogenomics; whole genome duplication events] [ABSTRACT FROM AUTHOR]

Tropical Africa is home to an astonishing biodiversity occurring in a variety of ecosystems. Past climatic change and geological events have impacted the evolution and diversification of this biodiversity. During the last two decades, around 90 dated molecular phylogenies of different clades across animals and plants have been published leading to an increased understanding of the diversification and speciation processes generating tropical African biodiversity. In parallel, extended geological and palaeoclimatic records together with detailed numerical simulations have refined our understanding of past geological and climatic changes in Africa. To date, these important advances have not been reviewed within a common framework. Here, we critically review and synthesize African climate, tectonics and terrestrial biodiversity evolution throughout the Cenozoic to the mid‐Pleistocene, drawing on recent advances in Earth and life sciences. We first review six major geo‐climatic periods defining tropical African biodiversity diversification by synthesizing 89 dated molecular phylogeny studies. Two major geo‐climatic factors impacting the diversification of the sub‐Saharan biota are highlighted. First, Africa underwent numerous climatic fluctuations at ancient and more recent timescales, with tectonic, greenhouse gas, and orbital forcing stimulating diversification. Second, increased aridification since the Late Eocene led to important extinction events, but also provided unique diversification opportunities shaping the current tropical African biodiversity landscape. We then review diversification studies of tropical terrestrial animal and plant clades and discuss three major models of speciation: (i) geographic speciation via vicariance (allopatry); (ii) ecological speciation impacted by climate and geological changes, and (iii) genomic speciation via genome duplication. Geographic speciation has been the most widely documented to date and is a common speciation model across tropical Africa. We conclude with four important challenges faced by tropical African biodiversity research: (i) to increase knowledge by gathering basic and fundamental biodiversity information; (ii) to improve modelling of African geophysical evolution throughout the Cenozoic via better constraints and downscaling approaches; (iii) to increase the precision of phylogenetic reconstruction and molecular dating of tropical African clades by using next generation sequencing approaches together with better fossil calibrations; (iv) finally, as done here, to integrate data better from Earth and life sciences by focusing on the interdisciplinary study of the evolution of tropical African biodiversity in a wider geodiversity context. [ABSTRACT FROM AUTHOR]

Island disharmony refers to the biased representation of higher taxa on islands compared to their mainland source regions and represents a central concept in island biology. Here, we develop a generalizable framework for approximating these source regions and conduct the first global assessment of island disharmony and its underlying drivers. We compiled vascular plant species lists for 178 oceanic islands and 735 mainland regions. Using mainland data only, we modelled species turnover as a function of environmental and geographic distance and predicted the proportion of shared species between each island and mainland region. We then quantified the over‐ or under‐representation of families on individual islands (representational disharmony) by contrasting the observed number of species against a null model of random colonization from the mainland source pool, and analysed the effects of six family‐level functional traits on the resulting measure. Furthermore, we aggregated the values of representational disharmony per island to characterize overall taxonomic bias of a given flora (compositional disharmony), and analysed this second measure as a function of four island biogeographical variables. Our results indicate considerable variation in representational disharmony both within and among plant families. Examples of generally over‐represented families include Urticaceae, Convolvulaceae and almost all pteridophyte families. Other families such as Asteraceae and Orchidaceae were generally under‐represented, with local peaks of over‐representation in known radiation hotspots. Abiotic pollination and a lack of dispersal specialization were most strongly associated with an insular over‐representation of families, whereas other family‐level traits showed minor effects. With respect to compositional disharmony, large, high‐elevation islands tended to have the most disharmonic floras. Our results provide important insights into the taxon‐ and island‐specific drivers of disharmony. The proposed framework allows overcoming the limitations of previous approaches and provides a quantitative basis for incorporating functional and phylogenetic approaches into future studies of island disharmony. [ABSTRACT FROM AUTHOR]

• The Daniellia clade emerged during the Early Eocene from North African rainforests. • A dry-climate-adapted lineage dispersed to Madagascar to form the Madagascan clade. • The genus Daniellia had a rainforest origin and diversified in the Middle Miocene. • Two savannah species of Daniellia arose from separate rainforest ancestors. • Eight of 14 species in the clade are threatened or near-threatened with extinction. The legume subfamily Detarioideae is exceptionally diverse in tropical Africa and Madagascar, compared to South America or Asia, a trend contrary to that shown by most other pantropical plant groups. We aim to elucidate the process of diversification giving rise to these high diversity levels by focussing our investigations on the Daniellia clade, which is present in both Africa and Madagascar. The Daniellia clade is an early-diverging lineage of subfamily Detarioideae (Leguminosae; pea family) and consists of three genera: Daniellia , Brandzeia and Neoapaloxylon. The species belonging to this group exhibit a wide range of habitat types. The Madagascar endemics Brandzeia (1 species) and Neoapaloxylon (3 species) occupy dry woodlands and arid succulent habitats respectively. Daniellia alsteeniana and D. oliveri are found in savannahs while the remaining eight species within Daniellia all occupy rainforest habitats. Phylogenetic analyses were generated from a dense, multi-individual species level sampling of the clade. Divergence time estimates were carried out using a molecular clock method to investigate biogeographical patterns and shifts in habitat types within the Daniellia clade, and conservation assessments were conducted to determine the levels of extinction risks these species are facing. We estimate that the Daniellia clade first emerged during the Early Eocene from an ancestor present in the rainforests of North Africa at that time, reflecting an ancestral habitat preference. There was a first major split over the course of the Eocene, giving rise to both African rainforest and Madagascan savannah lineages. With the emergence of a drier climate and vegetation type in Africa during the Eocene, it is likely that a dry-climate adapted lineage from the Daniellia clade ancestor could have dispersed through suitable savannah or woodland regions to reach Madagascar, subsequently giving rise to the savannah-adapted ancestor of Brandzeia and Neoapaloxylon in the Early Miocene. The African rainforest lineage gave rise to the genus Daniellia , which is postulated to have first diversified in the Middle Miocene, while savannah species of Daniellia emerged independently during the Pliocene, coinciding with the global rise of C4-dominated grasslands. More than half of the species in the Daniellia clade are near threatened or threatened, which highlights the need to understand the threats of anthropogenic pressures and climate change these species are facing to prioritise their conservation. [ABSTRACT FROM AUTHOR]

Natural history collections and tropical tree diversity are both treasure troves of biological and evolutionary information, but their accessibility for scientific study is impeded by a number of properties. DNA in historical specimens is generally highly fragmented, complicating the recovery of high-grade genetic material. Furthermore, our understanding of hyperdiverse, wide-spread tree assemblages is obstructed by extensive species ranges, fragmented knowledge of tropical tree diversity and phenology, and a widespread lack of species-level diagnostic characters, prohibiting the collecting of readily identifiable specimens which can be used to build, revise or strengthen taxonomic frameworks. This, in turn, delays the application of downstream conservation action. A sizable component of botanical collections are sterile—thus eluding identification and are slowing down progress in systematic treatments of tropical biodiversity. With rapid advances in genomics and bioinformatic approaches to biodiversity research, museomics is emerging as a new field breathing life into natural collections that have been built up over centuries. Using MIGseq (multiplexed ISSR genotyping by sequencing), we generated 10,000s of short loci, for both freshly collected materials and museum specimens (aged >100 years) of Lithocarpus—a widespread tropical tree genus endemic to the Asian tropics. Loci recovery from historical and recently collected samples was not affected by sample age and preservation history of the study material, underscoring the reliability and flexibility of the MIGseq approach. Phylogenomic inference and biogeographic reconstruction across insular Asia, highlights repeated migration and diversification patterns between continental regions and islands. Results indicate that co-occurring insular species at the extremity of the distribution range are not monophyletic, raising the possibility of multiple independent dispersals along the outer edge of Wallacea. This suggests that dispersal of large seeded tree genera throughout Malesia and across Wallacea may have been less affected by large geographic distances and the presence of marine barriers than generally assumed. We demonstrate the utility of MIGseq in museomic studies using non-model taxa, presenting the first range-wide genomic assessment of Lithocarpus and tropical Fagaceae as a proof-of-concept. Our study shows the potential for developing innovative genomic approaches to improve the capture of novel evolutionary signals using valuable natural history collections of hyperdiverse taxa. [ABSTRACT FROM AUTHOR]

Summary: Determining where species diversify (cradles) and persist (museums) over evolutionary time is fundamental to understanding the distribution of biodiversity and for conservation prioritization. Here, we identify cradles and museums of angiosperm generic diversity across tropical Africa, one of the most biodiverse regions on Earth.Regions containing nonrandom concentrations of young (neo‐) and old (paleo‐) endemic taxa were identified using distribution data of 1719 genera combined with a newly generated time‐calibrated mega‐phylogenetic tree. We then compared the identified regions with the current network of African protected areas (PAs).At the generic level, phylogenetic diversity and endemism are mainly concentrated in the biogeographically complex region of Eastern Africa. We show that mountainous areas are centres of both neo‐ and paleo‐endemism. By contrast, the Guineo‐Congolian lowland rain forest region is characterized by widespread and old lineages. We found that the overlap between centres of phylogenetic endemism and PAs is high (> 85%).We show the vital role played by mountains acting simultaneously as cradles and museums of tropical African plant biodiversity. By contrast, lowland rainforests act mainly as museums for generic diversity. Our study shows that incorporating large‐scale taxonomically verified distribution datasets and mega‐phylogenies lead to an improved understanding of tropical plant biodiversity evolution. [ABSTRACT FROM AUTHOR]

Summary: Phylogenomics is increasingly used to infer deep‐branching relationships while revealing the complexity of evolutionary processes such as incomplete lineage sorting, hybridization/introgression and polyploidization. We investigate the deep‐branching relationships among subfamilies of the Leguminosae (or Fabaceae), the third largest angiosperm family. Despite their ecological and economic importance, a robust phylogenetic framework for legumes based on genome‐scale sequence data is lacking.We generated alignments of 72 chloroplast genes and 7621 homologous nuclear‐encoded proteins, for 157 and 76 taxa, respectively. We analysed these with maximum likelihood, Bayesian inference, and a multispecies coalescent summary method, and evaluated support for alternative topologies across gene trees.We resolve the deepest divergences in the legume phylogeny despite lack of phylogenetic signal across all chloroplast genes and the majority of nuclear genes. Strongly supported conflict in the remainder of nuclear genes is suggestive of incomplete lineage sorting.All six subfamilies originated nearly simultaneously, suggesting that the prevailing view of some subfamilies as 'basal' or 'early‐diverging' with respect to others should be abandoned, which has important implications for understanding the evolution of legume diversity and traits. Our study highlights the limits of phylogenetic resolution in relation to rapid successive speciation. [ABSTRACT FROM AUTHOR]

The palm family, Arecaceae, is notoriously depauperate in Africa today, and its evolutionary, paleobiogeographic, and extinction history there are not well documented by fossils. In this article we report the pollen of two new extinct species of the small genus, Sclerosperma (Arecoideae), from a late Oligocene (27-28 Ma) stratum exposed along the Guang River in Chilga Wereda of north-western Ethiopia. The pollen are triporate, and the two taxa can be distinguished from each other and from modern species using a combination of light and scanning electron microscopy, which reveals variations in the finer details of their reticulate to perforate exine sculpture. We also report a palm leaf fragment from a stratum higher in the same section that is in the Arecoideae subfamily, and most likely belongs to Sclerosperma. The implications of these discoveries for the evolutionary history of this clade of African arecoid palms is that their diversification was well underway by the middle to late Oligocene, and they were much more widespread in Africa at that time than they are now, limited to West and Central Africa. Sclerosperma exhibits ecological conservatism, as today it occurs primarily in swamps and flooded forests, and the sedimentology of the Guang River deposits at Chilga indicate a heterogeneous landscape with a high water table. The matrix containing the fossil pollen is lignite, which itself indicates standing water, and a variety of plant macrofossils from higher in the section have been interpreted as representing moist tropical forest or seasonally inundated forest communities. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To delineate bioregions in tropical Africa and determine whether different plant growth forms (trees, terrestrial herbs, lianas and shrubs) display the same pattern of regionalization, diversity and endemism as the whole flora. Location: Tropical Africa (excl. Madagascar), from 20° N to 25° S. Taxon: Vascular plants. Methods: Analyses were based on occurrences of 24,719 vascular plant species distributed across tropical Africa extracted from the RAINBIO database. The majority of species (93%) were classified into four growth forms: terrestrial herbs, trees, shrubs and lianas. Biogeographical regions (bioregions) were delimited using a bipartite network clustering approach on the whole dataset and then separately for each growth form. Relationships among bioregions were investigated using non‐metric multidimensional scaling ordination, flora nestedness and endemism patterns. Results: Analyses of the whole dataset identified 16 bioregions and 11 transition zones. These were congruent with most of the currently recognized phytogeographical classifications, and also highlighted previously under‐recognized bioregions. Bioregion endemism rates were lower and species richness higher when compared to estimates from the White/Association pour l'Etude Taxonomique de la Flore d'Afrique Tropicale (AETFAT) classification. Analysed separately, plant growth forms showed contrasting geographical patterns. Bioregionalization was better resolved for closed forest types using trees and lianas and for open vegetation types using terrestrial herbs, while shrubs showed good discriminative power in all vegetation types. Main conclusions: We show that distribution patterns based on solely trees are not sufficient to define floristic bioregions in tropical Africa. Analyses of spatial patterns using different growth forms are complementary, likely reflecting different evolutionary processes and ecological relationships. The contribution of growth forms to delimit geographical floristic patterns across tropical Africa is of critical importance for land use planning and management, and for selecting priority conservation areas. [ABSTRACT FROM AUTHOR]

Aim Pleistocene climatic oscillations induced range fluctuations in African rain forest organisms and may have shaped species diversification through allopatric speciation events. We compared the spatial genetic structure of two forest species that live in obligate symbiosis and thus must have experienced the same range fluctuations, as a means to discriminate incipient speciation from transient differentiation simply resulting from past divergence. Location Western central Africa. Methods We genotyped 765 individuals of the tree Barteria fistulosa and 605 colonies of its symbiotic ant Tetraponera aethiops at 12 and 13 microsatellite loci, respectively. We compared the spatial genetic structure of the two symbionts by using Bayesian clustering algorithms, isolation-by-distance analyses and clines of synthetic alleles. We used species niche modelling (climatic and soil variables) to investigate ecological variables associated with genetic discontinuities in tree populations. Results The trees and the ants showed congruent patterns of spatial genetic structure. However, the trees showed a very steep genetic discontinuity between groups north and south of latitude 1° N, which was much weaker in the ants. There was no evidence for effective gene flow between the two tree lineages in contact at the transition zone, despite the presence of a few hybrids. Niche modelling did not predict the occurrence of northern trees south of this genetic transition, and vice versa. Main conclusions The genetic discontinuity near latitude 1° N is inferred to be a tension zone resulting from reproductive incompatibilities between previously allopatric tree lineages. This tension zone may have stabilized at a climatic transition (between boreal and austral seasonal regimes), and matches patterns of genetic structure previously observed in other forest plant species. Our results illustrate independent speciation between two species that live in specific and obligate symbiosis and suggest that a tension zone may separate lineages of several central African forest plants near the thermal equator. [ABSTRACT FROM AUTHOR]

Polyploidy has rarely been documented in rain forest trees but it has recently been found in African species of the genus Afzelia (Leguminosae), which is composed of four tetraploid rain forest species and two diploid dry forest species. The genus Afzelia thus provides an opportunity to examine how and when polyploidy and habitat shift occurred in Africa, and whether they are associated. In this study, we combined three plastid markers ( psbA , trnL , ndhF ), two nuclear markers (ribosomal ITS and the single-copy PEPC E7 gene), plastomes (obtained by High Throughput Sequencing) and morphological traits, with an extensive taxonomic and geographic sampling to explore the evolutionary history of Afzelia . Both nuclear DNA and morphological vegetative characters separated diploid from tetraploid lineages. Although the two African diploid species were well differentiated genetically and morphologically, the relationships among the tetraploid species were not resolved. In contrast to the nuclear markers, plastid markers revealed that one of the diploid species forms a well-supported clade with the tetraploids, suggesting historical hybridisation, possibly in relation with genome duplication (polyploidization) and habitat shift from dry to rain forests. Molecular dating based on fossil-anchored gene phylogenies indicates that extant Afzelia started diverging c. 14.5 or 20 Ma while extant tetraploid species started diverging c. 7.0 or 9.4 Ma according to plastid and nuclear DNA, respectively. Additional studies of tropical polyploid plants are needed to assess whether the ploidy-habitat association observed in African Afzelia would reflect a role of polyploidization in niche divergence in the tropics. [ABSTRACT FROM AUTHOR]

Recent deep-level phylogenies of the basal papilionoid legumes (Leguminosae, Papilionoideae) have resolved many clades, yet left the phylogenetic placement of several genera unassessed. The phylogenetically enigmatic Amazonian monospecific genus Petaladenium had been believed to be close to the genera of the Genistoid Ormosieae clade. In this paper we provide the first DNA phylogenetic study of Petaladenium and show it is not part of the large Genistoid clade, but is a new branch of the Amburaneae clade, one of the first-diverging lineages of the Papilionoideae phylogeny. This result is supported by the chemical observation that the quinolizidine alkaloids, a chemical synapomorphy of the Genistoids, are absent in Petaladenium . Parsimony and Bayesian phylogenetic analysis of nuclear ITS/5.8S and plastid matK and trnL intron agree with a new interpretation of morphology that Petaladenium is sister to Dussia , a genus comprising ∼18 species of trees largely confined to rainforests in Central America and northern South America. Petaladenium , Dussia , and Myrospermum have papilionate flowers in a clade otherwise with radial floral symmetry, loss of petals or incompletely differentiated petals. Our phylogenetic analyses also revealed well-supported resolution within the three main lineages of the ADA clade (Angylocalyceae, Dipterygeae, and Amburaneae). We also discuss further molecular phylogenetic evidence for the undersampled Amazonian genera Aldina and Monopteryx , and the tropical African Amphimas , Cordyla , Leucomphalos , and Mildbraediodendron . [ABSTRACT FROM AUTHOR]

Unlocking the vast genomic diversity stored in natural history collections would create unprecedented opportunities for genome-scale evolutionary, phylogenetic, domestication and population genomic studies. Many researchers have been discouraged from using historical specimens in molecular studies because of both generally limited success of DNA extraction and the challenges associated with PCR-amplifying highly degraded DNA. In today's next-generation sequencing (NGS) world, opportunities and prospects for historical DNA have changed dramatically, as most NGS methods are actually designed for taking short fragmented DNA molecules as templates. Here we show that using a standard multiplex and paired-end Illumina sequencing approach, genome-scale sequence data can be generated reliably from dry-preserved plant, fungal and insect specimens collected up to 115 years ago, and with minimal destructive sampling. Using a reference-based assembly approach, we were able to produce the entire nuclear genome of a 43-year-old Arabidopsis thaliana (Brassicaceae) herbarium specimen with high and uniform sequence coverage. Nuclear genome sequences of three fungal specimens of 22–82 years of age (Agaricus bisporus, Laccaria bicolor, Pleurotus ostreatus) were generated with 81.4–97.9% exome coverage. Complete organellar genome sequences were assembled for all specimens. Using de novo assembly we retrieved between 16.2–71.0% of coding sequence regions, and hence remain somewhat cautious about prospects for de novo genome assembly from historical specimens. Non-target sequence contaminations were observed in 2 of our insect museum specimens. We anticipate that future museum genomics projects will perhaps not generate entire genome sequences in all cases (our specimens contained relatively small and low-complexity genomes), but at least generating vital comparative genomic data for testing (phylo)genetic, demographic and genetic hypotheses, that become increasingly more horizontal. Furthermore, NGS of historical DNA enables recovering crucial genetic information from old type specimens that to date have remained mostly unutilized and, thus, opens up a new frontier for taxonomic research as well. [ABSTRACT FROM AUTHOR]

Indian snakeroot ( Rauvolfia serpentina) is a valuable forest product, root extracts of which are used as an antihypertensive drug. Increasing demand led to overharvesting in the wild. Control of international trade is hampered by the inability to identify root samples to the species level. We therefore evaluated the potential of molecular identification by searching for species-specific DNA polymorphisms. We found two species-specific indels in the rps16 intron region for R. serpentina. Our DNA barcoding method was tested for its specificity, reproducibility, sensitivity and stability. We included samples of various tissues and ages, which had been treated differently for preservation. DNA extractions were tested in a range of amplification settings and dilutions. Species-specific rps16 intron sequences were obtained from 79 herbarium accessions and one confiscated root, encompassing 39 different species. Our results demonstrate that molecular analysis provides new perspectives for forensic identification of Indian snakeroot. [ABSTRACT FROM AUTHOR]

Abstract: The four species of the central African genus Barteria show variation in habitat and in degree of association with ants. Whereas B. solida, restricted to submontane forests, attracts opportunistic ants to extrafloral nectar, the three other species, found in lowland rainforests (B. fistulosa, B. dewevrei) and in littoral scrub (B. nigritana), possess stem domatia of varying shapes and degrees of specialisation, hosting either non-specific arboreal ants (B. nigritana, some B. dewevrei) or two large species of ants of the genus Tetraponera Smith, 1852 that are specific to some species of Barteria (B. fistulosa, some B. dewevrei). We aimed to investigate whether this variation represents an evolutionary trend toward increasing specialisation of mutualism or the reduction or loss of myrmecophytic traits. For this, we determined phylogenetic relationships within the genus using DNA sequences (primarily nuclear ITS) and microsatellite genotypes (11 loci) on a large sample of individuals, mostly from Cameroon and Gabon. The two types of markers support an initial dichotomy that groups B. dewevrei with B. nigritana and B. fistulosa with B. solida respectively. Within these pairs, species do not appear reciprocally monophyletic. At microsatellite loci, B. nigritana forms a clade embedded within B. dewevrei; and within both B. solida and B. fistulosa, geographical populations show levels of differentiation similar to that observed between populations of B. solida and B. fistulosa. Geographic distance alone does not account for genetic differentiation between species, which indicates reproductive isolation. Divergence in each of the two pairs implies evolutionary transitions in habitat and in myrmecophytism. Specialised mutualism with specific ant species of the genus Tetraponera has been lost in species found in more marginal habitats. [Copyright &y& Elsevier]

1. It has been proposed that, across broad spatial scales, climatic factors are the main drivers of ecological patterns, while biotic factors are mainly important at local spatial scales. However, few tests of the effect of biotic interactions on broad-scale patterns have been conducted; conclusions about the scale-dependence of the importance of biotic interactions thus seem premature. 2. We developed an extensive database of locality records of one of Africa's most conspicuous groups, the acacias (the genera Senegalia and Vachellia), and used species distribution models (SDMs) to estimate the distribution of all African acacias. 3. African acacias are particularly well adapted against mammalian herbivory; therefore, we hypothesized that browser diversity could be an important driver of acacia richness. Species richness maps for the two genera were created from SDM-generated maps. Ordinary least square (OLS) regressions and, to consider spatial autocorrelation, simultaneous autoregressive (SAR) analyses were used to model richness of the two genera in relation to mammalian browser richness, current environment (including climate), and climate history since the Last Glacial Maximum (LGM). We used variation partitioning to determine what percentage of variation could be explained by these three groups of factors. 4. Both genera showed centres of richness in East Africa and the Limpopo Basin of southern Africa. Browser richness was the best explanatory variable for richness of both genera. Environmental factors explained negligible variation in the richness of Senegalia, but some variation in Vachellia. For both genera, the residuals of the species richness model of one genus also explained much variation in the richness of the other genus, indicating that common factors not considered in the richness analyses here may additionally be driving the richness of both genera. 5. Mechanisms that could generate a correlation between browser and acacia richness are proposed, and differences in the determinants of richness patterns of Senegalia and Vachellia discussed in the light of the two genera's history of colonization of Africa. 6. Synthesis. This is the first study that demonstrates that consumer diversity can influence richness patterns at continental scales and demonstrates that biotic factors can drive richness even at broad spatial scales. [ABSTRACT FROM AUTHOR]

• Whole plastome sequencing elucidates the demographic history of two African trees. • The two species exhibit congruent phylogeographic patterns. • However, they show very contrasted timing of population divergence. • The Cameroon Volcanic Line was a refuge at the origin of Dahomey Gap populations. • Similar phylogeographic patterns can be generated over contrasted timescales. Paleo-environmental data show that the distribution of African rain forests was affected by Quaternary climate changes. In particular, the Dahomey Gap (DG) – a 200 km wide savanna corridor currently separating the West African and Central African rain forest blocks and containing relict rain forest fragments – was forested during the mid-Holocene and possibly during previous interglacial periods, whereas it was dominated by open vegetation (savanna) during glacial periods. Genetic signatures of past population fragmentation and demographic changes have been found in some African forest plant species using nuclear markers, but such events appear not to have been synchronous or shared across species. To better understand the colonization history of the DG by rain forest trees through seed dispersal, the plastid genomes of two widespread African forest legume trees, Anthonotha macrophylla and Distemonanthus benthamianus , were sequenced in 47 individuals for each species, providing unprecedented phylogenetic resolution of their maternal lineages (857 and 115 SNPs, respectively). Both species exhibit distinct lineages separating three regions: 1. Upper Guinea (UG, i.e. the West African forest block), 2. the area ranging from the DG to the Cameroon volcanic line (CVL), and 3. Lower Guinea (LG, the western part of the Central African forest block) where three lineages co-occur. In both species, the DG populations (including southern Nigeria west of Cross River) exhibit much lower genetic diversity than UG and LG populations, and their plastid lineages originate from the CVL, confirming the role of the CVL as an ancient forest refuge. Despite the similar phylogeographic structures displayed by A. macrophylla and D. benthamianus , molecular dating indicates very contrasting ages of lineage divergence (UG diverged from LG since c. 7 Ma and 0.7 Ma, respectively) and DG colonization (probably following the Mid Pleistocene Transition and the Last Glacial Maximum, respectively). The stability of forest refuge areas and repeated similar forest shrinking/expanding events during successive glacial periods might explain why similar phylogeographic patterns can be generated over contrasting timescales. [ABSTRACT FROM AUTHOR]