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Amat M.E.,Real Jardin Botanico de Madrid | Silvertown J.,Open University Milton Keynes | Vargas P.,Real Jardin Botanico de Madrid
Journal of Heredity | Year: 2013

Clonal growth can be a double-edged sword for endangered species, because the short-term insurance against extinction may incur a longer-term hazard of creating small inbred populations with low fecundity. In the present study, we quantify the advantages and disadvantages of clonal growth regarding the fitness of the central Iberian monotypic endangered genus Pseudomisopates. Preliminary studies showed that the species is self-incompatible and exhibits extensive clonal growth with plants flowering profusely. However, seeds at many sites seemed to be unviable, and no seedlings have been observed in the field. A fully replicated nested sampling design (n = 100) was conducted to explore genetic (using seven SSR loci) and environmental factors potentially affecting seed viability, such as: 1) clonal and genetic diversity, 2) spatial genetic structure, and 3) environmental factors (shrub cover and grazing). Generalized Linear Mixed Models were fitted relating genetic and environmental variables to reproductive variables (seed viability and flower display). Our results indicate that the relatively low genotypic diversity of the population (PD = 0.23), as quantified by SSRs, and the strong spatial genetic structure observed are congruent with intense clonal growth. This clonal growth is enhanced by unfavorable environmental conditions, such as canopy closure and grazing. Under these circumstances, both flower display and mate availability decrease, thus hindering sexual reproduction. Indeed, a mixed reproductive system (clonal and sexual) to escape environmental stochasticity is crucial for the survival of Pseudomisopates, a species inhabiting a disturbance-prone ecosystem. © The American Genetic Association. 2013. All rights reserved.


Balao F.,University of Seville | Valente L.M.,Real Jardin Botanico de Madrid | Vargas P.,Real Jardin Botanico de Madrid | Herrera J.,University of Seville | Talavera S.,University of Seville
New Phytologist | Year: 2010

Summary: •The micro-evolutionary mechanisms that drive large-scale radiations are not completely understood, partly because of a shortage of population-level studies aimed at identifying putative causes of rapid evolutionary change. The Dianthus broteri complex, representing the largest polyploid series known to date for any species in the genus (2×, 4×, 6× and 12× cytotypes), belongs to a lineage that was recently found to have diversified at unusually rapid rates.•We used a combination of genome sequencing (internal transcribed spacer (ITS), plus chloroplast DNA (cpDNA) regions trnH-psbA, psbA-trnK and trnK-matK) and amplified fragment length polymorphism (AFLP) fingerprinting in 25 populations to infer the evolutionary history of extant polyploid races.•The haplotype, ribotype and AFLP reconstructions showed a star-shaped arrangement suggesting a pattern of radiative evolution. The major, widespread haplotype occurred at all ploidy levels, whereas 20 minor haplotypes were restricted to single populations and cytotypes. In addition, AFLP analyses retrieved well-supported cytogeographic groups: six clades were clearly differentiated in terms of ploidy level and geography. Molecular data indicate that gene flow among different cytotypes is rare or nonexistent.•Our study supports a scenario of rapid diversification in carnations in which autopolyploidy and allopolyploidy, in interaction with geography and/or isolation, have played prominent roles. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).


Garcia-Verdugo C.,University of California at Berkeley | Calleja J.A.,Autonomous University of Madrid | Vargas P.,Real Jardin Botanico de Madrid | Silva L.,University of The Azores | And 2 more authors.
Molecular Ecology | Year: 2013

Refugia are expected to preserve genetic variation of relict taxa, especially in polyploids, because high gene dosages could prevent genetic erosion in small isolated populations. However, other attributes linked to polyploidy, such as asexual reproduction, may strongly limit the levels of genetic variability in relict populations. Here, ploidy levels and patterns of genetic variation at nuclear microsatellite loci were analysed in Prunus lusitanica, a polyploid species with clonal reproduction that is considered a paradigmatic example of a Tertiary relict. Sampling in this study considered a total of 20 populations of three subspecies: mainland lusitanica (Iberian Peninsula and Morocco), and island azorica (Azores) and hixa (Canary Islands and Madeira). Flow cytometry results supported an octoploid genome for lusitanica and hixa, whereas a 16-ploid level was inferred for azorica. Fixed heterozygosity of a few allele variants at most microsatellite loci resulted in levels of allelic diversity much lower than those expected for a high-order polyploid. Islands as a whole did not contain higher levels of genetic variation (allelic or genotypic) than mainland refuges, but island populations displayed more private alleles and higher genotypic diversity in old volcanic areas. Patterns of microsatellite variation were compatible with the occurrence of clonal individuals in all but two island populations, and the incidence of clonality within populations negatively correlated with the estimated timing of colonization. Our results also suggest that gene flow has been very rare among populations, and thus population growth following founder events was apparently mediated by clonality rather than seed recruitment, especially in mainland areas. This study extends to clonal taxa the idea of oceanic islands as important refugia for biodiversity, since the conditions for generation and maintenance of clonal diversity (i.e. occasional events of sexual reproduction, mutation and/or seed immigration) appear to have been more frequent in these enclaves than in mainland areas. © 2013 Blackwell Publishing Ltd.


Valente L.M.,Real Jardin Botanico de Madrid | Valente L.M.,Imperial College London | Manning J.C.,South African National Biodiversity Institute | Manning J.C.,University of KwaZulu - Natal | And 2 more authors.
American Naturalist | Year: 2012

The pollinator-driven ecological speciation model has frequently been invoked to explain plant richness in biodiversity hotspots. Here, by focusing on Gladiolus (260 species), a flagship example of a clade with diverse pollination biology, we test the hypothesis that high species diversity in southern Africa, one of the world's most floristically rich regions, has primarily been driven by ecological shifts in pollination systems.We use phylogenetic methods to estimate rates of transition between the seven highly specialized pollination strategies in Gladiolus. We find that pollination systems have evolved multiple times and that some pollination strategies arose by a variety of evolutionary pathways. Pollination shifts account for up to one-third of all lineage splitting events in the genus, providing partial support for the pollinator-driven speciation model. Transitions from the ancestral pollination mode to derived systems have also resulted in increased rates of diversification, suggesting that certain pollination systems may speed up speciation processes, independently of pollination shifts per se. This study suggests that frequent pollination shifts have played a role in driving high phenotypic and species diversity but indicates that additional factors need to be invoked to account for the spectacular diversification in southern African Gladiolus. © 2012 by The University of Chicago.


Lado C.,Real Jardin Botanico de Madrid | Wrigley De Basanta D.,Real Jardin Botanico de Madrid | Estrada-Torres A.,University of Tlaxcala | Stephenson S.L.,University of Arkansas
Fungal Diversity | Year: 2013

The results obtained from two expeditions to survey the biodiversity of myxomycetes in Central Chile are reported in this paper. The surveys were carried out as part of Global Biodiversity of Eumycetozoans project funded by the National Science Foundation (USA) and the Myxotropic project funded by the Spanish Government. The expeditions were made to the temperate zone of the central part of the country between 23 and 39 South latitudes, which is characterized by Mediterranean vegetation, as well as to the transition areas between the arid and semi-arid regions of northern Chile, and the humid, cold Valdivian and Andean-Patagonian forests of the far South. Eight of the fifteen regions of the country, from Antofagasta to Araucanía, in selected areas where the native vegetation is well preserved, were included in these surveys. Over 600 collections were obtained, and a total of 110 species of myxomycetes representing 29 genera have been identified. Two of these (Dianema succulenticola, Didymium chilense) are species new to science and are described in this paper, 12 species (Collaria nigricapillitia, Comatricha alta, Cribraria oregana, Dianema depressum, Didymium eximium, D. nivicolum, Enerthenema melanospermum, Lepidoderma chailletii, Macbrideola ovoidea, Physarum clavisporum, Ph. newtonii and Trichia alpina) were previously unknown for either the Neotropics or South America, and 49 additional species are new records for Chile. Comments are provided on the morphology, distribution and ecology of selected species and light and SEM micrographs of the most significant species are included. An evaluation of the biodiversity of myxomycetes in Chile, with special emphasis on the endemic plants that provided the substrates with which they were associated, and a comparative analysis of our results with those from other countries of South America is presented. © 2012 The Mushroom Research Foundation.


Valente L.M.,Real Jardin Botanico de Madrid | Valente L.M.,Imperial College London | Savolainen V.,Imperial College London | Manning J.C.,South African National Biodiversity Institute | And 2 more authors.
Global Ecology and Biogeography | Year: 2011

Aim The causes of geographical variation in species richness in clades that do not follow the latitudinal diversity gradient have rarely been investigated. Here, we examine spatial asymmetries of diversity in Gladiolus (Iridaceae), a large genus (>260 species) that is present in two mediterranean climate biomes: the Cape of southern Africa (106 species) and the Mediterranean Basin (7 species). Despite convergence of climatic conditions between the two regions, the species density of Gladiolus is over one order of magnitude higher in the Cape than in the Mediterranean Basin. We investigate whether the diversity disparities observed in the genus are better explained by recent colonization of species-poor areas (temporal hypothesis) or by differential rates of diversification (evolutionary hypothesis). Location Africa, Madagascar and Eurasia Methods We employ a recently developed Bayesian method for the estimation of diversification rates and a biogeographical optimization approach within a phylogenetic framework. Results In Gladiolus, the 'diversity anomaly' between the two Mediterranean climate regions cannot be explained solely by the time available for speciation in the Cape, but is also due to locally reduced rates of diversification in the Mediterranean Basin. Furthermore, high overall diversity in southern Africa stems from an ancient origin in the Cape allied with high rates of diversification in the summer-rainfall region of the subcontinent. Main conclusions Both evolutionary and temporal hypotheses must be taken into account in order to explain the diversity anomaly between the Mediterranean Basin and the Cape. Our results suggest that regions at comparable latitudes and/or with similar climate may not converge in diversity levels due to heterogeneity of diversification rates and contrasting biogeographical histories. © 2011 Blackwell Publishing Ltd.


Escudero M.,Pablo De Olavide University | Vargas P.,Real Jardin Botanico de Madrid | Arens P.,Wageningen University | Ouborg N.J.,Radboud University Nijmegen | LuceNo M.,Pablo De Olavide University
Molecular Ecology | Year: 2010

Coastal plants are ideal models for studying the colonization routes of species because of the simple linear distributions of these species. Carex extensa occurs mainly in salt marshes along the Mediterranean and European coasts. Variation in cpDNA sequences, amplified fragment length polymorphisms (AFLPs) and simple sequence repeats (SSRs) of 24 populations were analysed to reconstruct its colonization history. Phylogenetic relationships indicate that C. extensa together with the South American Carex vixdentata and the southern African Carex ecklonii form a monophyletic group of halophilic species. Analyses of divergence times suggest that early lineage diversification may have occurred between the late Miocene and the late Pliocene (Messinian crisis). Phylogenetic and network analyses of cpDNA variation revealed the monophyly of the species and an ancestral haplotype contained in populations of the eastern Mediterranean. The AFLP and SSR analyses support a pattern of variation compatible with these two lineages. These analyses also show higher levels of genetic diversity and differentiation in the eastern population group, which underwent an east-to-west Mediterranean colonization. Quaternary climatic oscillations appear to have been responsible for the split between these two lineages. Secondary contacts may have taken place in areas near the Ligurian Sea in agreement with the gene flow detected in Corsican populations. The AFLP and SSR data accord with the 'tabula rasa' hypothesis in which a recent and rapid colonization of northern Europe took place from the western Mediterranean after the Last Glacial Maximum. The unbalanced west-east vs. west-north colonization may be as a result of 'high density blocking' effect. © 2009 Blackwell Publishing Ltd.


Valente L.M.,Real Jardin Botanico de Madrid | Valente L.M.,Imperial College London | Valente L.M.,Jodrell Laboratory | Savolainen V.,Imperial College London | And 2 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2010

The most rapid species radiations have been reported from 'evolutionary laboratories', such as the Andes and the Cape of South Africa, leading to the prevailing view that diversification elsewhere has not been as dramatic. However, few studies have explicitly assessed rates of diversification in northern regions such as Europe. Here, we show that carnations (Dianthus, Caryophyllaceae), a well-known group of plants from temperate Eurasia, have diversified at the most rapid rate ever reported in plants or terrestrial vertebrates. Using phylogenetic methods, we found that the majority of species of carnations belong to a lineage that is remarkably species-rich in Europe, and arose at the rate of 2.2-7.6 species per million years. Unlike most previous studies that have inferred rates of diversification in young diverse groups, we use a conservative approach throughout that explicitly incorporates the uncertainties associated with phylogenetic inference, molecular dating and incomplete taxon sampling. We detected a shift in diversification rates of carnations coinciding with a period of increase in climatic aridity in the Pleistocene, suggesting a link between climate and biodiversity. This explosive radiation suggests that Europe, the continent with the world's best-studied flora, has been underestimated as a cradle of recent and rapid speciation. © 2010 The Royal Society.


Valcarcel V.,Pablo De Olavide University | Vargas P.,Real Jardin Botanico de Madrid
American Journal of Botany | Year: 2010

Premise of the study: The use of continuous morphological characters in taxonomy is traditionally contingent on the existence of discrete diagnostic characters. When plant species are the result of recent divergence and gene flow and/or hybridization occur, the use of continuous morphological characters may help in species identification and delimitation. Between nine and 15 species have been recognized in the last treatments of Hedera. The recent divergence of the species and the involvement of allopolyploidization as the main force in this process may have greatly impeded the establishment of clear limits and contributed to multiple taxonomic proposals. Methods: A multivariate statistical decision-making procedure was applied to 56 quantitative morphological characters and 602 specimens to identify and delimit Hedera species under the general lineage concept. Species' exclusive genetic ancestry was evaluated with the genealogical sorting index from the Bayesian inference trees of 30 Hedera ITS sequences. Key results: The decision-making procedure allowed recognizing 12 species and two groups (stellate and scale-like trichome groups) in Hedera and provided statistical support for making decisions about long-standing taxonomic controversies. Common ancestry was detected for the populations of three species even in the absence of the species monophyly. Conclusions: Quantitative variation supports discrete variation and provides statistical support for the taxa recognized in some recent proposals of Hedera. The need of explicit analysis of quantitative data are claimed to reduce taxonomic subjectivity and ease decision-making when qualitative data fail. © 2010 Botanical Society of America.


Valente L.M.,Imperial College London | Vargas P.,Real Jardin Botanico de Madrid
Journal of Biogeography | Year: 2013

Aim: The Cape of southern Africa and the Mediterranean Basin, two of the world's five mediterranean-climate biodiversity hotspots, are exceptionally species-rich and constitute a well-described example of ecological convergence. However, the area-adjusted plant species diversity of the Cape is on average more than double that of the Mediterranean Basin. Here, we investigate the causes of this diversity asymmetry by drawing on phylogenetic information from a variety of plant groups and focusing on three competing hypotheses: diversity disparities arising from differential clade ages, diversification rates or diversity limits. Location: Cape of southern Africa and the Mediterranean Basin. Methods: We reviewed a variety of studies in order to contrast the geography, geomorphic history, biogeographical connectivity and ecological context in the two hotspots. We also tested the relationship between clade age and species richness in both regions based on phylogenetic information from 39 clades. Results: Clades are on average older in the Cape than in the Mediterranean Basin. Clade age is a strong predictor of species diversity in the Cape, suggesting that diversity-dependent regulatory mechanisms may be weak. In contrast, we failed to find a relationship between age and diversity in the Mediterranean Basin, indicating that a diversity limit may have been achieved in multiple clades. Main conclusions: The Cape has a higher species density than the Mediterranean Basin owing to a combination of older clade ages, high rates of diversification in certain lineages and an exceptionally high upper limit to diversity. High richness in the Cape is linked to long-term lineage persistence in a heterogeneous but stable evolutionary context. In contrast, the climatically unstable Mediterranean Basin has offered fewer opportunities for diversity accumulation in the long term (owing to high extinction rates), but appears to be a hotspot of recent rapid speciation. © 2013 John Wiley & Sons Ltd.

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