The Experts below are selected from a list of 420 Experts worldwide ranked by ideXlab platform
Mark W Chase - One of the best experts on this subject based on the ideXlab platform.
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biogeography and genome size evolution of the oldest extant vascular plant genus equisetum Equisetaceae
Annals of Botany, 2021Co-Authors: Maarten J. M. Christenhusz, Mark W Chase, Michael F Fay, Oriane Hidalgo, Ilia J Leitch, Jaume PellicerAbstract:Background and aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.
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trends and concepts in fern classification
Annals of Botany, 2014Co-Authors: Maarten J. M. Christenhusz, Mark W ChaseAbstract:†BackgroundandAimsThroughoutthehistoryoffernclassification,familialandgenericconceptshavebeenhighly labile. Many classifications and evolutionary schemes have been proposed during the last two centuries, reflecting different interpretations of the available evidence. Knowledge of fern structure and life histories has increased through time, providing more evidence on which to base ideas of possible relationships, and classification has changed accordingly. This paper reviews previous classifications of ferns and presents ideas on how to achieve a more stable consensus. †Scope An historical overview is provided from the first to the most recent fern classifications, from which conclusions are drawn on past changes and future trends. The problematic concept of family in ferns is discussed, with a particular focus on how this has changed over time. The history of molecular studies and the most recent findings are also presented. †Key Results Fern classification generally shows a trend from highly artificial, based on an interpretation of a few extrinsic characters, via natural classifications derived from a multitude of intrinsic characters, towards more evolutionarycircumscriptionsofgroupsthatdonotingeneralalignwellwiththedistributionofthesepreviouslyusedcharacters.Italsoshowsaprogressionfromafewbroadfamilyconceptstosystemsthatrecognizedmanymorenarrowly andhighlycontroversiallycircumscribedfamilies;currently,thenumberoffamiliesrecognizedisstabilizingsomewherebetweentheseextremes.Placementofmanygenerawasuncertainuntilthearrivalofmolecularphylogenetics, which has rapidly been improving our understanding of fern relationships. As a collective category, the so-called ‘fern allies’ (e.g. Lycopodiales, Psilotaceae, Equisetaceae) were unsurprisingly found to be polyphyletic, and the
Maarten J. M. Christenhusz - One of the best experts on this subject based on the ideXlab platform.
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biogeography and genome size evolution of the oldest extant vascular plant genus equisetum Equisetaceae
Annals of Botany, 2021Co-Authors: Maarten J. M. Christenhusz, Mark W Chase, Michael F Fay, Oriane Hidalgo, Ilia J Leitch, Jaume PellicerAbstract:Background and aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.
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trends and concepts in fern classification
Annals of Botany, 2014Co-Authors: Maarten J. M. Christenhusz, Mark W ChaseAbstract:†BackgroundandAimsThroughoutthehistoryoffernclassification,familialandgenericconceptshavebeenhighly labile. Many classifications and evolutionary schemes have been proposed during the last two centuries, reflecting different interpretations of the available evidence. Knowledge of fern structure and life histories has increased through time, providing more evidence on which to base ideas of possible relationships, and classification has changed accordingly. This paper reviews previous classifications of ferns and presents ideas on how to achieve a more stable consensus. †Scope An historical overview is provided from the first to the most recent fern classifications, from which conclusions are drawn on past changes and future trends. The problematic concept of family in ferns is discussed, with a particular focus on how this has changed over time. The history of molecular studies and the most recent findings are also presented. †Key Results Fern classification generally shows a trend from highly artificial, based on an interpretation of a few extrinsic characters, via natural classifications derived from a multitude of intrinsic characters, towards more evolutionarycircumscriptionsofgroupsthatdonotingeneralalignwellwiththedistributionofthesepreviouslyusedcharacters.Italsoshowsaprogressionfromafewbroadfamilyconceptstosystemsthatrecognizedmanymorenarrowly andhighlycontroversiallycircumscribedfamilies;currently,thenumberoffamiliesrecognizedisstabilizingsomewherebetweentheseextremes.Placementofmanygenerawasuncertainuntilthearrivalofmolecularphylogenetics, which has rapidly been improving our understanding of fern relationships. As a collective category, the so-called ‘fern allies’ (e.g. Lycopodiales, Psilotaceae, Equisetaceae) were unsurprisingly found to be polyphyletic, and the
Jaume Pellicer - One of the best experts on this subject based on the ideXlab platform.
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biogeography and genome size evolution of the oldest extant vascular plant genus equisetum Equisetaceae
Annals of Botany, 2021Co-Authors: Maarten J. M. Christenhusz, Mark W Chase, Michael F Fay, Oriane Hidalgo, Ilia J Leitch, Jaume PellicerAbstract:Background and aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.
Oriane Hidalgo - One of the best experts on this subject based on the ideXlab platform.
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biogeography and genome size evolution of the oldest extant vascular plant genus equisetum Equisetaceae
Annals of Botany, 2021Co-Authors: Maarten J. M. Christenhusz, Mark W Chase, Michael F Fay, Oriane Hidalgo, Ilia J Leitch, Jaume PellicerAbstract:Background and aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.
Michael F Fay - One of the best experts on this subject based on the ideXlab platform.
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biogeography and genome size evolution of the oldest extant vascular plant genus equisetum Equisetaceae
Annals of Botany, 2021Co-Authors: Maarten J. M. Christenhusz, Mark W Chase, Michael F Fay, Oriane Hidalgo, Ilia J Leitch, Jaume PellicerAbstract:Background and aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum, Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum, despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae.