I obtained a Master's degree in Biological Sciences at the University of Naples "Federico II" with full marks.
I worked on the evolution of floral epidermal micromorphology and pollen ultrastructure in the Nymphaeaceae, and on the systematic utility of cuticle characters in cycads.
I am currently working on the genetics of phloem development. Supervisors: Maria Rosaria Barone Lumaga and Peter Linder
The Gnetales are one of the most fascinating groups within seed plants. Although the advent of mo... more The Gnetales are one of the most fascinating groups within seed plants. Although the advent of molecular phylogenetics has generated some confidence in their phylogenetic placement of Gnetales within seed plants, their macroevolutionary history still presents many unknowns. Here, we review the reasons for such unknowns, and we focus the discussion on the presence of “long branches” both in their molecular and morphological history. The increased rate of molecular evolution and genome instability as well as the numerous unique traits (both reproductive and vegetative) in the Gnetales have been obstacles to a better understanding of their evolution. Moreover, the fossil record of the Gnetales, though relatively rich, has not yet been properly reviewed and investigated using a phylogenetic framework. Despite these apparent blocks to progress we identify new avenues to enable us to move forward. We suggest that a consilience approach, involving different disciplines such as developmenta...
The origin of angiosperms is a classic macroevolutionary problem, because of their rapid rise in ... more The origin of angiosperms is a classic macroevolutionary problem, because of their rapid rise in the Early Cretaceous fossil record, beginning about 139 Ma ago, and the conflict this creates with older crown-group ages based on molecular clock dating1. Silvestro et al.2 use a novel methodology to model past angiosperm diversity based on a Bayesian Brownian Bridge model of fossil finds assigned to extant families, concluding that a Cretaceous origin is vanishingly unlikely. However, their results strongly conflict with the known temporal distribution of angiosperm fossils, and, while we agree that statistical analysis aids interpretation of the fossil record, here we show the conclusions of Silvestro et al.2 are unsound.
Summary The determinants of biodiversity patterns can be understood using macroevolutionary analy... more Summary The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The integration of fossils into phylogenies offers a deeper understanding of processes underlying biodiversity patterns in deep time. Cycadales are considered a relict of a once more diverse and globally distributed group but are restricted to low latitudes today. We still know little about their origin and geographic range evolution. Combining molecular data for extant species and leaf morphological data for extant and fossil species, we study the origin of cycad global biodiversity patterns through Bayesian total‐evidence dating analyses. We assess the ancestral geographic origin and trace the historical biogeography of cycads with a time‐stratified process‐based model. Cycads originated in the Carboniferous on the Laurasian landmass and expanded in Gondwana in the Jurassic. Through now‐vanished continental connections, Antarctica and Greenland were crucial biogeographic crossroad...
The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, ... more The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, but new evidence from cuticle structure suggests that it is an angiosperm. Here we document the morphology and cuticle anatomy of Mesodescolea and explore its significance for early angiosperm evolution. We observed macrofossils and cuticles of Mesodescolea with light, scanning electron and transmission electron microscopy, and used phylogenetic methods to test its relationships among extant angiosperms. Mesodescolea has chloranthoid teeth and tertiary veins forming elongate areoles. Its cuticular morphology and ultrastructure reject cycadalean affinities, whereas its guard cell shape and stomatal ledges are angiospermous. It shares variable stomatal complexes and epidermal oil cells with angiosperm leaves from the lower Potomac Group. Phylogenetic analyses and hypothesis testing support its placement within the basal ANITA grade, most likely in Austrobaileyales, but it diverges markedly in leaf form and venation. Although many Early Cretaceous angiosperms fall within the morphological range of extant taxa, Mesodescolea reveals unexpected early morphological and ecophysiological trends. Its similarity to other Early Cretaceous lobate leaves, many identified previously as eudicots but in some cases pre-dating the appearance of tricolpate pollen, may indicate that Mesodescolea is part of a larger extinct lineage of angiosperms.
• Background and Aims The gymnosperm order Cycadales is pivotal to our understanding of seed-plan... more • Background and Aims The gymnosperm order Cycadales is pivotal to our understanding of seed-plant phylogeny because of its phylogenetic placement close to the root node of extant spermatophytes and its combination of both derived and plesiomorphic character states. Although widely considered a 'living fossil' group, extant cycads display a high degree of morphological and anatomical variation. We investigate stomatal development in Zamiaceae to evaluate variation within the order and homologies between cycads and other seed plants. • Methods Leaflets of seven species across five genera representing all major clades of Zamiaceae were examined at various stages of development using light microscopy and confocal microscopy. • Key Results All genera examined have lateral subsidiary cells of perigenous origin that differ from other pavement cells in mature leaflets and could have a role in stomatal physiology. Early epidermal patterning in a 'quartet' arrangement occurs in Ceratozamia, Zamia and Stangeria. Distal encircling cells, which are sclerified at maturity, are present in all genera except Bowenia, which shows relatively rapid elongation and differentiation of the pavement cells during leaflet development. • Conclusions Stomatal structure and development in Zamiaceae highlights some traits that are plesiomorphic in seed plants, including the presence of perigenous encircling subsidiary cells, and reveals a clear difference between the developmental trajectories of cycads and Bennettitales. Our study also shows an unexpected degree of variation among subclades in the family, potentially linked to differences in leaflet development and suggesting convergent evolution in cycads.
The Gnetales are one of the most fascinating groups within seed plants. Although the advent of mo... more The Gnetales are one of the most fascinating groups within seed plants. Although the advent of molecular phylogenetics has generated some confidence in their phylogenetic placement of Gnetales within seed plants, their macroevolutionary history still presents many unknowns. Here, we review the reasons for such unknowns, and we focus the discussion on the presence of "long branches" both in their molecular and morphological history. The increased rate of molecular evolution and genome instability as well as the numerous unique traits (both reproductive and vegetative) in the Gnetales have been obstacles to a better understanding of their evolution. Moreover, the fossil record of the Gnetales, though relatively rich, has not yet been properly reviewed and investigated using a phylogenetic framework. Despite these apparent blocks to progress we identify new avenues to enable us to move forward. We suggest that a consilience approach, involving different disciplines such as developmental genetics, paleobotany, molecular phylogenetics, and traditional anatomy and morphology might help to "break" these long branches, leading to a deeper understanding of this mysterious group of plants.
The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The... more The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The integration of fossils into phylogenies offers a deeper understanding of processes underlying biodiversity patterns in deep time. Cycadales are considered a relict of a once more diverse and globally distributed group but are restricted to low latitudes today. We still know little about their origin and geographic range evolution. Combining molecular data for extant species and leaf morphological data for extant and fossil species, we study the origin of cycad global biodiversity patterns through Bayesian totalevidence dating analyses. We assess the ancestral geographic origin and trace the historical biogeography of cycads with a time-stratified process-based model. Cycads originated in the Carboniferous on the Laurasian landmass and expanded in Gondwana in the Jurassic. Through now-vanished continental connections, Antarctica and Greenland were crucial biogeographic crossroads for cycad biogeography. Vicariance is an essential speciation mode in the deep and recent past. Their latitudinal span increased in the Jurassic and restrained toward subtropical latitudes in the Neogene in line with biogeographic inferences of high-latitude extirpations. We show the benefits of integrating fossils into phylogenies to estimate ancestral areas of origin and to study evolutionary processes explaining the global distribution of present-day relict groups.
PremiseUnlike most flowering plants, orchid flowers have under‐developed ovules that complete dev... more PremiseUnlike most flowering plants, orchid flowers have under‐developed ovules that complete development only after pollination. Classical studies reported variation in the stage in which ovule development is arrested, but the extent of this variation and its evolutionary and ecological significance are unclear.MethodsHere, we used light microscopy to observe ovule development at anthesis for 39 species not previously studied and surveyed the literature gaining information on 94 orchid species. Tropical and temperate members of all five orchid subfamilies as well as species with contrasting pollination strategies (rewarding versus deceptive) and life forms (epiphytic versus terrestrial) were represented. We analyzed the data using statistical comparisons and a phylogenetic generalized least square (PGLS) analysis.ResultsApostasioideae, the sister to the rest of the orchids, have mature ovules similar to other Asparagales, while under‐differentiated ovules are present in the other subfamilies. Ovule developmental stages showed high variation even among closely related groups. Ovules were more developed in terrestrial than in epiphytic, in temperate than in tropical, and in rewarding than in deceptive pollination orchid species. This latter comparison was also significant in the PGLS analysis.ConclusionsThese results suggest that ovule developmental stage in orchids can be shaped by ecological factors, such as seasonality and pollination strategy, and can be selected for optimizing female reproductive investment.
mcc contains the Maximum Clade Credibility tree, while posterior_sample contains the 100 random t... more mcc contains the Maximum Clade Credibility tree, while posterior_sample contains the 100 random trees from the posterior sample. <br>
This is the Occurence dataset (embargoed until October 2019) of the publictation, included in the... more This is the Occurence dataset (embargoed until October 2019) of the publictation, included in the dataset published here: https://doi.org/10.6084/m9.figshare.6668936.v1<br>"Ecophysiological strategy switch through development in heteroblastic species of mediterranean ecosystems – an example in the African Restionaceae" <br><br>by <br>Merten Ehmig, Mario Coiro, H. Peter Linder.<br>published 2018 in Annals of Botany<br><br>If you have any questions regarding scripts or data please address Merten Ehmig via mail: merten.ehmig@systbot.uzh.ch, or cropbird@ymail.com<br><br><br>if you use this script or data, pleas cite the Annals of Botany Paper
Taxonomy of the species used in this study and list of the accession numbers of the BAM sequences... more Taxonomy of the species used in this study and list of the accession numbers of the BAM sequences used for the phylogenetic analysis. (XLSX 115 kb)
Table S1. List of the species queried for the phylogenetic analysis and the corresponding sequenc... more Table S1. List of the species queried for the phylogenetic analysis and the corresponding sequences sources. (PDF 122 kb)
Protein alignment of BZR1-domain containing β-amylases from representative non-flowering plants. ... more Protein alignment of BZR1-domain containing β-amylases from representative non-flowering plants. (PDF 159 kb)
<p>(A) GBSS docks onto PTST in the stroma, and the complex binds to starch. (B) PTST dissoc... more <p>(A) GBSS docks onto PTST in the stroma, and the complex binds to starch. (B) PTST dissociates from both GBSS and the starch granule, leaving GBSS on starch to mediate amylose synthesis. (C) PTST returns to the stroma to recruit another GBSS molecule.</p
Data and script used to generate the graph in Figure 4 in Coiro, Doyle and Hilton.<br>data.... more Data and script used to generate the graph in Figure 4 in Coiro, Doyle and Hilton.<br>data.csv : Pollen data in a tabular formattree.nex: tree for analysis<br>Script.r: R scriptmagallon_tree aperture data.nex : nexus version of the data and tree including only angiosperms.<br>
The Gnetales are one of the most fascinating groups within seed plants. Although the advent of mo... more The Gnetales are one of the most fascinating groups within seed plants. Although the advent of molecular phylogenetics has generated some confidence in their phylogenetic placement of Gnetales within seed plants, their macroevolutionary history still presents many unknowns. Here, we review the reasons for such unknowns, and we focus the discussion on the presence of “long branches” both in their molecular and morphological history. The increased rate of molecular evolution and genome instability as well as the numerous unique traits (both reproductive and vegetative) in the Gnetales have been obstacles to a better understanding of their evolution. Moreover, the fossil record of the Gnetales, though relatively rich, has not yet been properly reviewed and investigated using a phylogenetic framework. Despite these apparent blocks to progress we identify new avenues to enable us to move forward. We suggest that a consilience approach, involving different disciplines such as developmenta...
The origin of angiosperms is a classic macroevolutionary problem, because of their rapid rise in ... more The origin of angiosperms is a classic macroevolutionary problem, because of their rapid rise in the Early Cretaceous fossil record, beginning about 139 Ma ago, and the conflict this creates with older crown-group ages based on molecular clock dating1. Silvestro et al.2 use a novel methodology to model past angiosperm diversity based on a Bayesian Brownian Bridge model of fossil finds assigned to extant families, concluding that a Cretaceous origin is vanishingly unlikely. However, their results strongly conflict with the known temporal distribution of angiosperm fossils, and, while we agree that statistical analysis aids interpretation of the fossil record, here we show the conclusions of Silvestro et al.2 are unsound.
Summary The determinants of biodiversity patterns can be understood using macroevolutionary analy... more Summary The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The integration of fossils into phylogenies offers a deeper understanding of processes underlying biodiversity patterns in deep time. Cycadales are considered a relict of a once more diverse and globally distributed group but are restricted to low latitudes today. We still know little about their origin and geographic range evolution. Combining molecular data for extant species and leaf morphological data for extant and fossil species, we study the origin of cycad global biodiversity patterns through Bayesian total‐evidence dating analyses. We assess the ancestral geographic origin and trace the historical biogeography of cycads with a time‐stratified process‐based model. Cycads originated in the Carboniferous on the Laurasian landmass and expanded in Gondwana in the Jurassic. Through now‐vanished continental connections, Antarctica and Greenland were crucial biogeographic crossroad...
The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, ... more The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, but new evidence from cuticle structure suggests that it is an angiosperm. Here we document the morphology and cuticle anatomy of Mesodescolea and explore its significance for early angiosperm evolution. We observed macrofossils and cuticles of Mesodescolea with light, scanning electron and transmission electron microscopy, and used phylogenetic methods to test its relationships among extant angiosperms. Mesodescolea has chloranthoid teeth and tertiary veins forming elongate areoles. Its cuticular morphology and ultrastructure reject cycadalean affinities, whereas its guard cell shape and stomatal ledges are angiospermous. It shares variable stomatal complexes and epidermal oil cells with angiosperm leaves from the lower Potomac Group. Phylogenetic analyses and hypothesis testing support its placement within the basal ANITA grade, most likely in Austrobaileyales, but it diverges markedly in leaf form and venation. Although many Early Cretaceous angiosperms fall within the morphological range of extant taxa, Mesodescolea reveals unexpected early morphological and ecophysiological trends. Its similarity to other Early Cretaceous lobate leaves, many identified previously as eudicots but in some cases pre-dating the appearance of tricolpate pollen, may indicate that Mesodescolea is part of a larger extinct lineage of angiosperms.
• Background and Aims The gymnosperm order Cycadales is pivotal to our understanding of seed-plan... more • Background and Aims The gymnosperm order Cycadales is pivotal to our understanding of seed-plant phylogeny because of its phylogenetic placement close to the root node of extant spermatophytes and its combination of both derived and plesiomorphic character states. Although widely considered a 'living fossil' group, extant cycads display a high degree of morphological and anatomical variation. We investigate stomatal development in Zamiaceae to evaluate variation within the order and homologies between cycads and other seed plants. • Methods Leaflets of seven species across five genera representing all major clades of Zamiaceae were examined at various stages of development using light microscopy and confocal microscopy. • Key Results All genera examined have lateral subsidiary cells of perigenous origin that differ from other pavement cells in mature leaflets and could have a role in stomatal physiology. Early epidermal patterning in a 'quartet' arrangement occurs in Ceratozamia, Zamia and Stangeria. Distal encircling cells, which are sclerified at maturity, are present in all genera except Bowenia, which shows relatively rapid elongation and differentiation of the pavement cells during leaflet development. • Conclusions Stomatal structure and development in Zamiaceae highlights some traits that are plesiomorphic in seed plants, including the presence of perigenous encircling subsidiary cells, and reveals a clear difference between the developmental trajectories of cycads and Bennettitales. Our study also shows an unexpected degree of variation among subclades in the family, potentially linked to differences in leaflet development and suggesting convergent evolution in cycads.
The Gnetales are one of the most fascinating groups within seed plants. Although the advent of mo... more The Gnetales are one of the most fascinating groups within seed plants. Although the advent of molecular phylogenetics has generated some confidence in their phylogenetic placement of Gnetales within seed plants, their macroevolutionary history still presents many unknowns. Here, we review the reasons for such unknowns, and we focus the discussion on the presence of "long branches" both in their molecular and morphological history. The increased rate of molecular evolution and genome instability as well as the numerous unique traits (both reproductive and vegetative) in the Gnetales have been obstacles to a better understanding of their evolution. Moreover, the fossil record of the Gnetales, though relatively rich, has not yet been properly reviewed and investigated using a phylogenetic framework. Despite these apparent blocks to progress we identify new avenues to enable us to move forward. We suggest that a consilience approach, involving different disciplines such as developmental genetics, paleobotany, molecular phylogenetics, and traditional anatomy and morphology might help to "break" these long branches, leading to a deeper understanding of this mysterious group of plants.
The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The... more The determinants of biodiversity patterns can be understood using macroevolutionary analyses. The integration of fossils into phylogenies offers a deeper understanding of processes underlying biodiversity patterns in deep time. Cycadales are considered a relict of a once more diverse and globally distributed group but are restricted to low latitudes today. We still know little about their origin and geographic range evolution. Combining molecular data for extant species and leaf morphological data for extant and fossil species, we study the origin of cycad global biodiversity patterns through Bayesian totalevidence dating analyses. We assess the ancestral geographic origin and trace the historical biogeography of cycads with a time-stratified process-based model. Cycads originated in the Carboniferous on the Laurasian landmass and expanded in Gondwana in the Jurassic. Through now-vanished continental connections, Antarctica and Greenland were crucial biogeographic crossroads for cycad biogeography. Vicariance is an essential speciation mode in the deep and recent past. Their latitudinal span increased in the Jurassic and restrained toward subtropical latitudes in the Neogene in line with biogeographic inferences of high-latitude extirpations. We show the benefits of integrating fossils into phylogenies to estimate ancestral areas of origin and to study evolutionary processes explaining the global distribution of present-day relict groups.
PremiseUnlike most flowering plants, orchid flowers have under‐developed ovules that complete dev... more PremiseUnlike most flowering plants, orchid flowers have under‐developed ovules that complete development only after pollination. Classical studies reported variation in the stage in which ovule development is arrested, but the extent of this variation and its evolutionary and ecological significance are unclear.MethodsHere, we used light microscopy to observe ovule development at anthesis for 39 species not previously studied and surveyed the literature gaining information on 94 orchid species. Tropical and temperate members of all five orchid subfamilies as well as species with contrasting pollination strategies (rewarding versus deceptive) and life forms (epiphytic versus terrestrial) were represented. We analyzed the data using statistical comparisons and a phylogenetic generalized least square (PGLS) analysis.ResultsApostasioideae, the sister to the rest of the orchids, have mature ovules similar to other Asparagales, while under‐differentiated ovules are present in the other subfamilies. Ovule developmental stages showed high variation even among closely related groups. Ovules were more developed in terrestrial than in epiphytic, in temperate than in tropical, and in rewarding than in deceptive pollination orchid species. This latter comparison was also significant in the PGLS analysis.ConclusionsThese results suggest that ovule developmental stage in orchids can be shaped by ecological factors, such as seasonality and pollination strategy, and can be selected for optimizing female reproductive investment.
mcc contains the Maximum Clade Credibility tree, while posterior_sample contains the 100 random t... more mcc contains the Maximum Clade Credibility tree, while posterior_sample contains the 100 random trees from the posterior sample. <br>
This is the Occurence dataset (embargoed until October 2019) of the publictation, included in the... more This is the Occurence dataset (embargoed until October 2019) of the publictation, included in the dataset published here: https://doi.org/10.6084/m9.figshare.6668936.v1<br>"Ecophysiological strategy switch through development in heteroblastic species of mediterranean ecosystems – an example in the African Restionaceae" <br><br>by <br>Merten Ehmig, Mario Coiro, H. Peter Linder.<br>published 2018 in Annals of Botany<br><br>If you have any questions regarding scripts or data please address Merten Ehmig via mail: merten.ehmig@systbot.uzh.ch, or cropbird@ymail.com<br><br><br>if you use this script or data, pleas cite the Annals of Botany Paper
Taxonomy of the species used in this study and list of the accession numbers of the BAM sequences... more Taxonomy of the species used in this study and list of the accession numbers of the BAM sequences used for the phylogenetic analysis. (XLSX 115 kb)
Table S1. List of the species queried for the phylogenetic analysis and the corresponding sequenc... more Table S1. List of the species queried for the phylogenetic analysis and the corresponding sequences sources. (PDF 122 kb)
Protein alignment of BZR1-domain containing β-amylases from representative non-flowering plants. ... more Protein alignment of BZR1-domain containing β-amylases from representative non-flowering plants. (PDF 159 kb)
<p>(A) GBSS docks onto PTST in the stroma, and the complex binds to starch. (B) PTST dissoc... more <p>(A) GBSS docks onto PTST in the stroma, and the complex binds to starch. (B) PTST dissociates from both GBSS and the starch granule, leaving GBSS on starch to mediate amylose synthesis. (C) PTST returns to the stroma to recruit another GBSS molecule.</p
Data and script used to generate the graph in Figure 4 in Coiro, Doyle and Hilton.<br>data.... more Data and script used to generate the graph in Figure 4 in Coiro, Doyle and Hilton.<br>data.csv : Pollen data in a tabular formattree.nex: tree for analysis<br>Script.r: R scriptmagallon_tree aperture data.nex : nexus version of the data and tree including only angiosperms.<br>
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