22 results on '"Helmstetter, Andrew J."'
Search Results
2. Opposing effects of plant traits on diversification
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Anderson, Bruce, Pannell, John, Billiard, Sylvain, Burgarella, Concetta, de Boer, Hugo, Dufay, Mathilde, Helmstetter, Andrew J., Méndez, Marcos, Otto, Sarah P., Roze, Denis, Sauquet, Hervé, Schoen, Daniel, Schönenberger, Jürg, Vallejo-Marin, Mario, Zenil-Ferguson, Rosana, Käfer, Jos, and Glémin, Sylvain
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- 2023
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3. The demographic history of Madagascan micro-endemics : have rare species always been rare?
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Helmstetter, Andrew J., Cable, Stuart, Rakotonasolo, Franck, Rabarijaona, Romer, Rakotoarinivo, Mijoro, Eiserhardt, Wolf L., Baker, William J., and Papadopulos, Alexander S. T.
- Published
- 2021
4. Individualistic evolutionary responses of Central African rain forest plants to Pleistocene climatic fluctuations
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Helmstetter, Andrew J., Béthune, Kevin, Kamdem, Narcisse G., Sonké, Bonaventure, and Couvreur, Thomas L. P.
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- 2020
5. David versus Goliath: Early career researchers in an unethical publishing system.
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Receveur, Aurore, Bonfanti, Jonathan, D'Agata, Stephanie, Helmstetter, Andrew J., Moore, Nikki A., Oliveira, Brunno F., Petit‐Cailleux, Cathleen, Rievrs Borges, Erica, Schultz, Marieke, Sexton, Aaron N., and Veytia, Devi
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RESEARCH personnel ,CAREER changes ,BUSINESS revenue ,JOB security ,PROFIT margins - Abstract
The publish‐or‐perish culture in academia has catalysed the development of an unethical publishing system. This system is characterised by the proliferation of journals and publishers—unaffiliated with learned societies or universities—that maintain extremely large revenues and profit margins diverting funds away from the academic community. Early career researchers (ECRs) are particularly vulnerable to the consequences of this publishing system because of intersecting factors, including pressure to pursue high impact publications, rising publication costs and job insecurity. Moving towards a more ethical system requires that scientists advocate for structural change by making career choices that come with risks, many of which disproportionately impact ECRs. We illuminate major issues facing ECRs in Ecology and Evolution under the current publishing system, and propose a portfolio of actions to promote systemic change that can be implemented by ECRs and established researchers. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Phylogenomic relationships and historical biogeography in the South American vegetable ivory palms (Phytelepheae)
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Escobar, Sebastián, Helmstetter, Andrew J., Montúfar, Rommel, Couvreur, Thomas L.P., and Balslev, Henrik
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- 2022
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7. Trait‐dependent diversification in angiosperms: Patterns, models and data.
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Helmstetter, Andrew J., Zenil‐Ferguson, Rosana, Sauquet, Hervé, Otto, Sarah P., Méndez, Marcos, Vallejo‐Marin, Mario, Schönenberger, Jürg, Burgarella, Concetta, Anderson, Bruce, de Boer, Hugo, Glémin, Sylvain, and Käfer, Jos
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SPECIES diversity , *ANGIOSPERMS , *DATA modeling , *GENETICS , *FLOWERING of plants - Abstract
Variation in species richness across the tree of life, accompanied by the incredible variety of ecological and morphological characteristics found in nature, has inspired many studies to link traits with species diversification. Angiosperms are a highly diverse group that has fundamentally shaped life on earth since the Cretaceous, and illustrate how species diversification affects ecosystem functioning. Numerous traits and processes have been linked to differences in species richness within this group, but we know little about their relative importance and how they interact. Here, we synthesised data from 152 studies that used state‐dependent speciation and extinction (SSE) models on angiosperm clades. Intrinsic traits related to reproduction and morphology were often linked to diversification but a set of universal drivers did not emerge as traits did not have consistent effects across clades. Importantly, SSE model results were correlated to data set properties – trees that were larger, older or less well‐sampled tended to yield trait‐dependent outcomes. We compared these properties to recommendations for SSE model use and provide a set of best practices to follow when designing studies and reporting results. Finally, we argue that SSE model inferences should be considered in a larger context incorporating species' ecology, demography and genetics. [ABSTRACT FROM AUTHOR]
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- 2023
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8. Pulled Diversification Rates, Lineages-Through-Time Plots, and Modern Macroevolutionary Modeling.
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Helmstetter, Andrew J, Glemin, Sylvain, Käfer, Jos, Zenil-Ferguson, Rosana, Sauquet, Hervé, Boer, Hugo de, Dagallier, Léo-Paul M J, Mazet, Nathan, Reboud, Eliette L, Couvreur, Thomas L P, and Condamine, Fabien L
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BIOLOGICAL extinction , *MACROEVOLUTION , *SCIENTIFIC community , *POPULATION viability analysis , *PHYLOGENY , *GENETIC speciation - Abstract
Estimating time-dependent rates of speciation and extinction from dated phylogenetic trees of extant species (timetrees), and determining how and why they vary, is key to understanding how ecological and evolutionary processes shape biodiversity. Due to an increasing availability of phylogenetic trees, a growing number of process-based methods relying on the birth–death model have been developed in the last decade to address a variety of questions in macroevolution. However, this methodological progress has regularly been criticized such that one may wonder how reliable the estimations of speciation and extinction rates are. In particular, using lineages-through-time (LTT) plots, a recent study has shown that there are an infinite number of equally likely diversification scenarios that can generate any timetree. This has led to questioning whether or not diversification rates should be estimated at all. Here, we summarize, clarify, and highlight technical considerations on recent findings regarding the capacity of models to disentangle diversification histories. Using simulations, we illustrate the characteristics of newly proposed "pulled rates" and their utility. We recognize that the recent findings are a step forward in understanding the behavior of macroevolutionary modeling, but they in no way suggest we should abandon diversification modeling altogether. On the contrary, the study of macroevolution using phylogenetic trees has never been more exciting and promising than today. We still face important limitations in regard to data availability and methods, but by acknowledging them we can better target our joint efforts as a scientific community. [Birth–death models; extinction; phylogenetics; speciation.] [ABSTRACT FROM AUTHOR]
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- 2022
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9. Rapid Parallel Adaptation to Anthropogenic Heavy Metal Pollution.
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Papadopulos, Alexander S T, Helmstetter, Andrew J, Osborne, Owen G, Comeault, Aaron A, Wood, Daniel P, Straw, Edward A, Mason, Laurence, Fay, Michael F, Parker, Joe, Dunning, Luke T, Foote, Andrew D, Smith, Rhian J, and Lighten, Jackie
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HEAVY metals ,GLOBAL environmental change ,SILENE (Genus) ,MINES & mineral resources ,GENOMICS - Abstract
The impact of human-mediated environmental change on the evolutionary trajectories of wild organisms is poorly understood. In particular, capacity of species to adapt rapidly (in hundreds of generations or less), reproducibly and predictably to extreme environmental change is unclear. Silene uniflora is predominantly a coastal species, but it has also colonized isolated, disused mines with phytotoxic, zinc-contaminated soils. To test whether rapid, parallel adaptation to anthropogenic pollution has taken place, we used reduced representation sequencing (ddRAD) to reconstruct the evolutionary history of geographically proximate mine and coastal population pairs and found largely independent colonization of mines from different coastal sites. Furthermore, our results show that parallel evolution of zinc tolerance has occurred without gene flow spreading adaptive alleles between mine populations. In genomic regions where signatures of selection were detected across multiple mine-coast pairs, we identified genes with functions linked to physiological differences between the putative ecotypes, although genetic differentiation at specific loci is only partially shared between mine populations. Our results are consistent with a complex, polygenic genetic architecture underpinning rapid adaptation. This shows that even under a scenario of strong selection and rapid adaptation, evolutionary responses to human activities (and other environmental challenges) may be idiosyncratic at the genetic level and, therefore, difficult to predict from genomic data. [ABSTRACT FROM AUTHOR]
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- 2021
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10. Unraveling Genetic Diversity Amongst European Hazelnut (Corylus avellana L.) Varieties in Turkey.
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Oztolan-Erol, Nihal, Helmstetter, Andrew J., İnan, Asuman, Buggs, Richard J. A., and Lucas, Stuart J.
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GENETIC variation ,HAZEL ,DNA sequencing ,NUTS ,HAZELNUTS ,POWDERY mildew diseases ,ALLELES in plants - Abstract
European hazelnut (Corylus avellana) is a diploid (2n = 22), monecious and wind-pollinated species, extensively cultivated for its nuts. Turkey is the world-leading producer of hazelnut, supplying 70–80% of the world's export capacity. Hazelnut is mostly grown in the Black Sea Region, and maintained largely through clonal propagation. Understanding the genetic variation between hazelnut varieties, and defining variety-specific and disease resistance-associated alleles, would facilitate hazelnut breeding in Turkey. Widely grown varieties 'Karafındık' (2), 'Sarıfındık' (5), and 'Yomra' (2) were collected from Akçakoca in the west, while 'Tombul' (8), 'Çakıldak' (3), 'Mincane' (2), 'Allahverdi' (2), 'Sivri' (4), and 'Palaz' (5) were collected from Ordu and Giresun provinces in the east (numbers in parentheses indicate sample sizes for each variety). Powdery mildew resistant and susceptible hazelnut genotypes were collected from the field gene bank and heavily infected orchards in Giresun. Every individual was subjected to double digest restriction enzyme-associated DNA sequencing (ddRAD-seq) and a RADtag library was created. RADtags were aligned to the 'Tombul' reference genome, and Stacks software used to identify polymorphisms. 101 private and six common alleles from nine hazelnut varieties, four private from resistants and only one from susceptible were identified for diagnosis of either a certain hazelnut variety or powdery mildew resistance. Phylogenetic analysis and population structure calculations indicated that 'Mincane', 'Sarıfındık', 'Tombul', 'Çakıldak', and 'Palaz' were genetically close to each other; however, individuals within every varietal group were found in different sub-populations. Our findings indicated that years of clonal propagation of some preferred varieties across the Black Sea Region has resulted in admixed sub-populations and great genetic diversity within each variety. This impedes the development of a true breeding variety. For example, 'Tombul' is the most favored Turkish variety because of its high quality nuts, but an elite 'Tombul' line does not yet exist. This situation continues due to the lack of a breed protection program for commercially valuable hazelnut varieties. This study provides molecular markers suitable for establishing such a program. [ABSTRACT FROM AUTHOR]
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- 2021
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11. Pleistocene climatic fluctuations promoted alternative evolutionary histories in Phytelephas aequatorialis, an endemic palm from western Ecuador.
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Escobar, Sebastián, Helmstetter, Andrew J., Jarvie, Scott, Montúfar, Rommel, Balslev, Henrik, and Couvreur, Thomas L.P.
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CLIMATE change , *RAIN forests , *PLEISTOCENE Epoch , *LAST Glacial Maximum , *IMAGINARY histories , *DATE palm - Abstract
Aim: Pleistocene (2.58 Ma–11.7 ka) climatic fluctuations have shaped intraspecific genetic patterns worldwide; however, their impact on species in many regions remains unknown. In order to determine the impact of Pleistocene climatic fluctuations on the tropical rain forests of western Ecuador, we explored the evolutionary history of the endemic palm Phytelephas aequatorialis. Location: Western Ecuador, north‐western South America. Taxon: Phytelephas aequatorialis (Arecaceae). Methods: One hundred and seventy‐six nuclear genes were sequenced in 91 individuals for phylogenomic and population structure analyses. The time of divergence between identified genetic lineages was estimated using a coalescent phylogenomic analysis. Palaeoecological niche modelling analyses were performed to determine areas of historical climatic suitability since the Last Glacial Maximum (LGM; 22 ka) that potentially acted as forest refugia during the Pleistocene. A Wilcoxon test and Pearson correlations were used to explore how current levels of genetic diversity, in terms of expected heterozygosity (Hs), have been shaped by several palaeoclimatic and geographic factors. Results: Phylogenomic and population structure analyses revealed two main genetic lineages with a north–south distribution, which diverged 1.14 Ma during the Pleistocene. Two potential Pleistocene refugia were identified, one along the Pacific coast of Ecuador and one in the Andean foothills of south‐western Ecuador. The location of these refugia agrees with the spatial location of the two genetic lineages. Within the Andean foothills, Hs was lower for the southern lineage than for the northern lineage. Hs significantly increased with decreasing latitude across the species as a whole. Main conclusions: Pleistocene climatic fluctuations promoted intraspecific divergence in P. aequatorialis within the rain forests of western Ecuador. The Andean foothills of south‐western Ecuador could be an important area for rain forest evolution because they potentially remained climatically suitable throughout the Pleistocene. Lower genetic diversity in the southern lineage, which apparently remained isolated in the Andean foothills during glacial cycles, adds evidence to the presence of a forest refugium in south‐western Ecuador. The geographic pattern in genetic diversity suggests that P. aequatorialis colonized western Ecuador from the north. This study supports the role of Pleistocene climatic fluctuations in promoting intraspecific divergence, and for the first time, we show their impact west of the Andes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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12. Introgression across evolutionary scales suggests reticulation contributes to Amazonian tree diversity.
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Schley, Rowan J., Pennington, R. Toby, Pérez‐Escobar, Oscar Alejandro, Helmstetter, Andrew J., Estrella, Manuel, Larridon, Isabel, Sabino Kikuchi, Izai Alberto Bruno, Barraclough, Timothy G., Forest, Félix, and Klitgård, Bente
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SPECIES hybridization ,BOTANY ,KNOWLEDGE gap theory ,TREES ,PLANT species ,GENE flow ,PLANT diversity - Abstract
Hybridization has the potential to generate or homogenize biodiversity and is a particularly common phenomenon in plants, with an estimated 25% of plant species undergoing interspecific gene flow. However, hybridization in Amazonia's megadiverse tree flora was assumed to be extremely rare despite extensive sympatry between closely related species, and its role in diversification remains enigmatic because it has not yet been examined empirically. Using members of a dominant Amazonian tree family (Brownea, Fabaceae) as a model to address this knowledge gap, our study recovered extensive evidence of hybridization among multiple lineages across phylogenetic scales. More specifically, using targeted sequence capture our results uncovered several historical introgression events between Brownea lineages and indicated that gene tree incongruence in Brownea is best explained by reticulation, rather than solely by incomplete lineage sorting. Furthermore, investigation of recent hybridization using ~19,000 ddRAD loci recovered a high degree of shared variation between two Brownea species that co‐occur in the Ecuadorian Amazon. Our analyses also showed that these sympatric lineages exhibit homogeneous rates of introgression among loci relative to the genome‐wide average, implying a lack of selection against hybrid genotypes and persistent hybridization. Our results demonstrate that gene flow between multiple Amazonian tree species has occurred across temporal scales, and contrasts with the prevailing view of hybridization's rarity in Amazonia. Overall, our results provide novel evidence that reticulate evolution influenced diversification in part of the Amazonian tree flora, which is the most diverse on Earth. [ABSTRACT FROM AUTHOR]
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- 2020
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13. Phylogenomic approaches reveal how climate shapes patterns of genetic diversity in an African rain forest tree species.
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Helmstetter, Andrew J., Amoussou, Biowa E. N., Bethune, Kevin, Kamdem, Narcisse G., Glèlè Kakaï, Romain, Sonké, Bonaventure, and Couvreur, Thomas L. P.
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RAIN forests , *CLIMATOLOGY , *ECOLOGICAL niche , *SPECIES diversity , *TREES , *CLIMATE change , *DISPERSAL (Ecology) - Abstract
The world's second largest expanse of tropical rainforest is in Central Africa, and it harbours enormous species diversity. Population genetic studies have consistently revealed significant structure across Central African rainforest plants. In particular, previous studies have repeatedly demonstrated a north–south genetic discontinuity around the equatorial line, in a continuous expanse of rainforest where a climatic inversion is documented. Here, we took a phylogeographic approach by sequencing 351 nuclear markers in 112 individuals across the distribution of the African rainforest tree species Annickia affinis (Annonaceae). We showed for the first time that the north–south divide is the result of a single, major colonization event across the climatic inversion from an ancestral population located in Gabon. We suggested that differences in ecological niche of populations located on either side of this inversion may have contributed to this phylogenetic discontinuity. We found evidence for inland dispersal, predominantly in northern areas, and variable demographic histories among genetic clusters, indicating that populations responded differently to past climate change. We show how newly developed genomic tools can provide invaluable insights into our understanding of tropical rainforest evolutionary dynamics. [ABSTRACT FROM AUTHOR]
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- 2020
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14. Trait evolution and historical biogeography shape assemblages of annual killifish.
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Helmstetter, Andrew J., Papadopulos, Alexander S. T., Igea, Javier, and Van Dooren, Tom J. M.
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BIOGEOGRAPHY , *BODY size , *ENDEMIC animals , *ENVIRONMENTAL sampling , *SUBSET selection , *KILLIFISHES - Abstract
Aim: Different species assemblages of annual killifish possess replicated body size distributions yet have unique sets of species in each area of endemism. Here, we use models of trait evolution and historical biogeography to discover how size variation originated and has been restructured. Location: South America. Taxon: Austrolebias (Cyprinodontiformes). Methods: We sampled 63 individuals from 26 Austrolebias species. Using phylogenetic trees (BEAST2), data on environmental variables at sampling locations and size data, we compare different models for trait evolution (SURFACE, l1OU) of body size and niche traits. We model the historical biogeography of the areas of endemism (BioGeoBEARS) and use both analyses in combination to reconstruct the history of four species assemblages. Results: We present new phylogenetic trees for Austrolebias and use them to show that large size principally arose within a single area driven by a shifted selection optimum for a subset of the species in that area. We suggest that ecological interactions triggered size divergence and that this large‐bodied lineage subsequently spread to two other areas. A second assemblage may have been shaped by adaptation to a new environment without an associated increase in size divergence. A third assemblage, which has the smallest size range and the most recent origin, is phylogenetically clustered, and we found no evidence of environmental filtering. Main conclusions: Assemblage similarity in Austrolebias is the result of contrasting ecological, evolutionary and historical processes. Modelling trait evolution together with historical biogeography can help to disentangle the complex histories of multispecies assemblages. This approach provides context to commonly used tests investigating the role of ecological processes from phylogenetic data and generates new testable hypotheses on the processes that generated trait diversity and assemblage similarity. [ABSTRACT FROM AUTHOR]
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- 2020
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15. Genetic diversity and domestication of hazelnut (Corylus avellana L.) in Turkey.
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Helmstetter, Andrew J., Oztolan‐Erol, Nihal, Lucas, Stuart J., and Buggs, Richard J. A.
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HAZELNUTS , *CLIMATE change , *AGRICULTURAL productivity , *CROP yields , *SINGLE nucleotide polymorphisms - Abstract
Societal Impact Statement: Hazelnut is consumed worldwide and is of critical economic importance to the rural communities of Turkey's northern coast. A new disease outbreak has drastically decreased yields across Turkey and climate change is emerging as a new threat to cultivation. Our study is the first to provide a genomic perspective on diversity in this vulnerable crop, which will prove valuable for future breeding efforts. Such research into perennial crops like hazelnut can help to improve farmer livelihoods and ensure the sustainability of crop production in a changing world. SummaryAssessing and describing genetic diversity in crop plants is a crucial first step toward their improvement. The European hazelnut, Corylus avellana L., is one of the most economically important tree nut crops worldwide. It is primarily produced in Turkey where rural communities depend on it for their livelihoods. Despite this, we know little about its domestication history and the genetic diversity it holds.We use double digest restriction‐site associated DNA (ddRAD) sequencing to produce a genome‐wide dataset containing wild and domesticated hazelnut. We uncover patterns of population structure and diversity, determine levels of crop‐wild gene flow, and estimate the relationships among different genetic clusters.We use a dataset of over 60k single nucleotide polymorphisms to find that genetic clusters of cultivars do not reflect their given names and that there is limited evidence for a reduction in genetic diversity in domesticated individuals. We find evidence that hazelnut may have been domesticated more than once and that admixture has likely occurred multiple times between wild and domesticated hazelnut.We provide the first genomic assessment of Turkish hazelnut diversity and suggest that there has not been an extreme bottleneck during the domestication of this crop, leading to cultivars at different stages of domestication. Our study provides a platform for further research that will protect hazelnut from the threats of climate change and an emerging fungal disease. [ABSTRACT FROM AUTHOR]
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- 2020
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16. Phylogenomics of the Major Tropical Plant Family Annonaceae Using Targeted Enrichment of Nuclear Genes.
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Couvreur, Thomas L. P., Helmstetter, Andrew J., Koenen, Erik J. M., Bethune, Kevin, Brandão, Rita D., Little, Stefan A., Sauquet, Hervé, and Erkens, Roy H. J.
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ANNONACEAE ,PLANT evolution ,TRANSCRIPTOMES - Abstract
Targeted enrichment and sequencing of hundreds of nuclear loci for phylogenetic reconstruction is becoming an important tool for plant systematics and evolution. Annonaceae is a major pantropical plant family with 110 genera and ca. 2,450 species, occurring across all major and minor tropical forests of the world. Baits were designed by sequencing the transcriptomes of five species from two of the largest Annonaceae subfamilies. Orthologous loci were identified. The resulting baiting kit was used to reconstruct phylogenetic relationships at two different levels using concatenated and gene tree approaches: a family wide Annonaceae analysis sampling 65 genera and a species level analysis of tribe Piptostigmateae sampling 29 species with multiple individuals per species. DNA extraction was undertaken mainly on silicagel dried leaves, with two samples from herbarium dried leaves. Our kit targets 469 exons (364,653 bp of sequence data), successfully capturing sequences from across Annonaceae. Silicagel dried and herbarium DNA worked equally well. We present for the first time a nuclear gene-based phylogenetic tree at the generic level based on 317 supercontigs. Results mainly confirm previous chloroplast based studies. However, several new relationships are found and discussed. We show significant differences in branch lengths between the two large subfamilies Annonoideae and Malmeoideae. A new tribe, Annickieae, is erected containing a single African genus Annickia. We also reconstructed a well-resolved species-level phylogenetic tree of the Piptostigmteae tribe. Our baiting kit is useful for reconstructing well-supported phylogenetic relationships within Annonaceae at different taxonomic levels. The nuclear genome is mainly concordant with plastome information with a few exceptions. Moreover, we find that substitution rate heterogeneity between the two subfamilies is also found within the nuclear compartment, and not just plastomes and ribosomal DNA as previously shown. Our results have implications for understanding the biogeography, molecular dating and evolution of Annonaceae. [ABSTRACT FROM AUTHOR]
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- 2019
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17. Diversification of African Rainforest Restricted Clades: Piptostigmateae and Annickieae (Annonaceae).
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Brée, Baptiste, Helmstetter, Andrew J., Bethune, Kévin, Ghogue, Jean-Paul, Sonké, Bonaventure, and Couvreur, Thomas L. P.
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ANNONACEAE , *MOLECULAR phylogeny , *MASS extinctions , *CLIMATE change , *VICARIANCE - Abstract
African rainforests (ARFs) are species rich and occur in two main rainforest blocks: West/Central and East Africa. This diversity is suggested to be the result of recent diversification, high extinction rates and multiple vicariance events between west/central and East African forests. We reconstructed the diversification history of two subtribes (Annickieae and Piptostigmateae) from the ecologically dominant and diverse tropical rainforest plant family Annonaceae. Both tribes contain endemic taxa in the rainforests of West/Central and East Africa. Using a dated molecular phylogeny based on 32 nuclear markers, we estimated the timing of the origin of East African species. We then undertook several diversification analyses focusing on Piptostigmateae to infer variation in speciation and extinction rates, and test the impact of extinction events. Speciation in both tribes dated to the Pliocene and Pleistocene. In particular, Piptostigma (13 species) diversified mainly during the Pleistocene, representing one of the few examples of Pleistocene speciation in an African tree genus. Our results also provide evidence of an ARF fragmentation at the mid-Miocene linked to climatic changes across the region. Overall, our results suggest that continental-wide forest fragmentation during the Neogene (23.03–2.58 Myr), and potentially during the Pliocene, led to one or possibly two vicariance events within the ARF clade Piptostigmateae, in line with other studies. Among those tested, the best fitting diversification model was the one with an exponential speciation rate and no extinction. We did not detect any evidence of mass extinction events. This study gives weight to the idea that the ARF might not have been so negatively impacted by extinction during the Neogene, and that speciation mainly took place during the Pliocene and Pleistocene. [ABSTRACT FROM AUTHOR]
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- 2020
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18. Unraveling the Phylogenomic Relationships of the Most Diverse African Palm Genus Raphia (Calamoideae, Arecaceae).
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Helmstetter, Andrew J., Kamga, Suzanne Mogue, Bethune, Kevin, Lautenschläger, Thea, Zizka, Alexander, Bacon, Christine D., Wieringa, Jan J., Stauffer, Fred, Antonelli, Alexandre, Sonké, Bonaventure, and Couvreur, Thomas L. P.
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PALMS ,CONSTRUCTION materials ,RAIN forests ,DATE palm - Abstract
Palms are conspicuous floristic elements across the tropics. In continental Africa, even though there are less than 70 documented species, they are omnipresent across the tropical landscape. The genus Raphia has 20 accepted species in Africa and one species endemic to the Neotropics. It is the most economically important genus of African palms with most of its species producing food and construction material. Raphia is divided into five sections based on inflorescence morphology. Nevertheless, the taxonomy of Raphia is problematic with no intra-generic phylogenetic study available. We present a phylogenetic study of the genus using a targeted exon capture approach sequencing of 56 individuals representing 18 out of the 21 species. Our results recovered five well supported clades within the genus. Three sections correspond to those based on inflorescence morphology. R. regalis is strongly supported as sister to all other Raphia species and is placed into a newly described section: Erectae. Overall, morphological based identifications agreed well with our phylogenetic analyses, with 12 species recovered as monophyletic based on our sampling. Species delimitation analyses recovered 17 or 23 species depending on the confidence level used. Species delimitation is especially problematic in the Raphiate and Temulentae sections. In addition, our clustering analysis using SNP data suggested that individual clusters matched geographic distribution. The Neotropical species R. taedigera is supported as a distinct species, rejecting the hypothesis of a recent introduction into South America. Our analyses support the hypothesis that the Raphia individuals from Madagascar are potentially a distinct species different from the widely distributed R. farinifera. In conclusion, our results support the infra generic classification of Raphia based on inflorescence morphology, which is shown to be phylogenetically useful. Classification and species delimitation within sections remains problematic even with our phylogenomic approach. Certain widely distributed species could potentially contain cryptic species. More in-depth studies should be undertaken using morphometrics, increased sampling, and more variable markers. Our study provides a robust phylogenomic framework that enables further investigation on the biogeographic history, morphological evolution, and other eco-evolutionary aspects of this charismatic, socially, and economically important palm genus. [ABSTRACT FROM AUTHOR]
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- 2020
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19. Repeated long-distance dispersal and convergent evolution in hazel.
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Helmstetter, Andrew J., Buggs, Richard J. A., and Lucas, Stuart J.
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CONVERGENT evolution , *HAZEL , *BIOLOGICAL evolution , *CHLOROPLASTS , *PHYLOGENY - Abstract
Closely related species with a worldwide distribution provide an opportunity to understand evolutionary and biogeographic processes at a global scale. Hazel (Corylus) is an economically important genus of tree and shrub species found in temperate regions of Asia, North America and Europe. Here we use multiple nuclear and chloroplast loci to estimate a time-calibrated phylogenetic tree of the genus Corylus. We model the biogeographic history of this group and the evolutionary history of tree and shrub form. We estimate that multiple Corylus lineages dispersed long distances between Europe and Asia and colonised North America from Asia in multiple independent events. The geographic distribution of tree versus shrub form of species appears to be the result of 4–5 instances of convergent evolution in the past 25 million years. We find extensive discordance between our nuclear and chloroplast trees and potential evidence for chloroplast capture in species with overlapping ranges, suggestive of past introgression. The important crop species C. avellana is estimated to be closely related to C. maxima, C. heterophylla var. thunbergii and the Colurnae subsection. Our study provides a new phylogenetic hypothesis or Corylus and reveals how long-distance dispersal can shape the distribution of biodiversity in temperate plants. [ABSTRACT FROM AUTHOR]
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- 2019
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20. Viviparity stimulates diversification in an order of fish.
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Helmstetter, Andrew J., Papadopulos, Alexander S. T., Igea, Javier, Van Dooren, Tom J. M., Leroi, Armand M., and Savolainen, Vincent
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- 2016
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21. Toward a phylogenomic classification of magnoliids.
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Helmstetter AJ, Ezedin Z, de Lírio EJ, de Oliveira SM, Chatrou LW, Erkens RHJ, Larridon I, Leempoel K, Maurin O, Roy S, Zuntini AR, Baker WJ, Couvreur TLP, Forest F, and Sauquet H
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- Genome, Plant, Phylogeny, Magnoliopsida genetics, Magnoliopsida classification
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Premise: Magnoliids are a strongly supported clade of angiosperms. Previous phylogenetic studies based primarily on analyses of a limited number of mostly plastid markers have led to the current classification of magnoliids into four orders and 18 families. However, uncertainty remains regarding the placement of several families., Methods: For the first comprehensive phylogenomic analysis of magnoliids as a whole, we sampled 235 species from 199 (74%) genera and representing all families and most subfamilies and tribes. We analyzed newly generated data from the Angiosperms353 probe set using both coalescent and concatenation analyses and testing the impact of multiple filtering and alignment strategies., Results: While our results generally provide further support for previously established phylogenetic relationships in both magnoliids as a whole and large families including Annonaceae and Lauraceae, they also provide new evidence for previously ambiguous relationships. In particular, we found support for the position of Hydnoraceae as sister to the remainder of Piperales, though evidence was conflicting, and resolved the backbone of relationships among most genera of Myristicaceae. Different analytical strategies tended to have rather small effects on branch support and topology., Conclusions: Although some of our results are limited by low gene recovery for a number of taxa and significant gene tree conflict for some relationships, this study represents a significant step toward reconstructing the evolutionary history of a major lineage of angiosperms. Based on these results, we present an updated phylogenetic classification for magnoliids, recognizing 21 families, summarizing previously established subfamilies and tribes, and describing new tribes for Myristicaceae., (© 2025 The Author(s). American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)
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- 2025
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22. Field-based species identification of closely-related plants using real-time nanopore sequencing.
- Author
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Parker J, Helmstetter AJ, Devey D, Wilkinson T, and Papadopulos AST
- Subjects
- DNA, Plant analysis, DNA, Plant genetics, Sequence Analysis, DNA methods, Arabidopsis classification, Arabidopsis genetics, Arabidopsis Proteins metabolism, Computational Biology methods, Genome, Plant, High-Throughput Nucleotide Sequencing methods, Nanopores
- Abstract
Advances in DNA sequencing and informatics have revolutionised biology over the past four decades, but technological limitations have left many applications unexplored. Recently, portable, real-time, nanopore sequencing (RTnS) has become available. This offers opportunities to rapidly collect and analyse genomic data anywhere. However, generation of datasets from large, complex genomes has been constrained to laboratories. The portability and long DNA sequences of RTnS offer great potential for field-based species identification, but the feasibility and accuracy of these technologies for this purpose have not been assessed. Here, we show that a field-based RTnS analysis of closely-related plant species (Arabidopsis spp.) has many advantages over laboratory-based high-throughput sequencing (HTS) methods for species level identification and phylogenomics. Samples were collected and sequenced in a single day by RTnS using a portable, "al fresco" laboratory. Our analyses demonstrate that correctly identifying unknown reads from matches to a reference database with RTnS reads enables rapid and confident species identification. Individually annotated RTnS reads can be used to infer the evolutionary relationships of A. thaliana. Furthermore, hybrid genome assembly with RTnS and HTS reads substantially improved upon a genome assembled from HTS reads alone. Field-based RTnS makes real-time, rapid specimen identification and genome wide analyses possible.
- Published
- 2017
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