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Peter R Crane - One of the best experts on this subject based on the ideXlab platform.

  • Extinct Diversity among Early Cretaceous Angiosperms: Mesofossil Evidence of Early Magnoliales from Portugal
    International Journal of Plant Sciences, 2019
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Premise of research. Small Angiosperm fossils are diverse in Early Cretaceous mesofossil floras from Portugal and eastern North America. Investigations of these fossils have revealed an unexpectedly high diversity of extinct Angiosperms related to lineages that are now species poor, such as Austrobaileyales, Nymphaeales, and Chloranthaceae. Here we analyze Early Cretaceous fruits and seeds from Portugal that are related to eumagnoliid Angiosperms and that are also important for understanding extinct diversity in early Angiosperms.Methodology. The fossils were prepared by sieving in water; cleaned with HF, HCl, and water; and studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. The systematic conclusion based on comparative studies was tested in a phylogenetic analysis.Pivotal results. We recognize a new group of Angiosperms based on fruits and seeds united by features that are otherwise unusual among Angiosperms. Two genera, Serialis and Riaselis, are establis...

  • fossil seeds with affinities to austrobaileyales and nymphaeales from the early cretaceous early to middle albian of virginia and maryland usa new evidence for extensive extinction near the base of the Angiosperm tree
    2018
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Abstract Early Cretaceous seeds from Virginia and Maryland, USA, part of a diverse complex of exotestal seeds in Early Cretaceous mesofossil floras from North America and Europe, provide new evidence of extensive extinction among early Angiosperms. The seeds are assigned to a new genus, Nitaspermum, with six species: N. taylorii , N. hopewellense , N. crassum , N. virginiense , N. marylandense, and Nitaspermum sp. All seeds are small, anatropous, bitegmic, and exotestal, with the exotesta composed of a single layer of short, columnar sclerenchyma with strongly folded walls. Nitaspermum shows features of extant Austrobaileyales (Illiciaceae) and Nymphaeales but also critical differences precluding assignment to extant families. These discoveries are consistent with predictions from molecular phylogenetics that indicate the differentiation of Illiciaceae and Nymphaeales early in Angiosperm evolution, but the diversity of such seeds underlines the extent to which the pattern of extant Angiosperm diversity has been shaped by widespread extinction early in Angiosperm evolution.

  • Exceptional preservation of tiny embryos documents seed dormancy in early Angiosperms
    Nature, 2015
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen, Marco Stampanoni, Federica Marone
    Abstract:

    The earliest flowering plants bloomed during the Cretaceous, under the feet of the dinosaurs. They are generally thought to have been small, herbaceous plants, adapted for the quick colonization of disturbed or marginal habitats. This hypothesis is dramatically validated by this study of more than 200 Early Cretaceous Angiosperm seeds, preserved in 11 mesofossil floras from eastern North America and Portugal. The seeds were tiny, adapted for rapid dispersal and quick germination; all were preserved during a dormant phase in their development. The discovery of embryos and their associated nutrient storage tissues in exceptionally well-preserved Angiosperm seeds from the Early Cretaceous period. The rapid diversification of Angiosperms through the Early Cretaceous period, between about 130–100 million years ago, initiated fundamental changes in the composition of terrestrial vegetation and is increasingly well understood on the basis of a wealth of palaeobotanical discoveries over the past four decades^ 1 , 2 , 3 , 4 , 5 and their integration with improved knowledge of living Angiosperms^ 3 , 6 . Prevailing hypotheses, based on evidence both from living and from fossil plants, emphasize that the earliest Angiosperms were plants of small stature^ 7 , 8 , 9 , 10 , 11 , 12 with rapid life cycles^ 7 , 8 , 12 , 13 that exploited disturbed habitats^ 3 , 9 , 11 , 13 , 14 in open^ 3 , 9 , 11 , 13 , 14 , or perhaps understorey, conditions^ 15 , 16 . However, direct palaeontogical data relevant to understanding the seed biology and germination ecology of Early Cretaceous Angiosperms are sparse. Here we report the discovery of embryos and their associated nutrient storage tissues in exceptionally well-preserved Angiosperm seeds from the Early Cretaceous. Synchrotron radiation X-ray tomographic microscopy of the fossil embryos from many taxa reveals that all were tiny at the time of dispersal. These results support hypotheses based on extant plants that tiny embryos and seed dormancy are basic for Angiosperms as a whole^ 17 , 18 . The minute size of the fossil embryos, and the modest nutrient storage tissues dictated by the overall small seed size, is also consistent with the interpretation that many early Angiosperms were opportunistic, early successional colonizers of disturbance-prone habitats^ 2 , 15 , 16 .

  • early flowers and Angiosperm evolution
    2011
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Preface 1. Introduction to Angiosperms 2. The nature of the Angiosperm fossil record 3. The environmental context of early Angiosperm evolution 4. Stratigraphic framework and key areas for Cretaceous Angiosperms 5. Angiosperms in context: extant and fossil seed plants 6. Origin and age of Angiosperms 7. Phylogenetic framework and the assignment of fossils to extant groups 8. Fossils near the base of the Angiosperm tree 9. Early fossil Angiosperms of uncertain relationships 10. Early fossils of eumagnoliids 11. Fossils of monocots 12. Fossils of eudicots: early diverging groups 13. Fossils of core eudicots: basal lineages 14. Fossils of core eudicots: rosids 15. Early fossils of eudicots: asterids 16. Patterns of structural diversification in Angiosperm reproductive organs 17. History and evolution of pollination in Angiosperms 18. History and evolution of dispersal in Angiosperms 19. Vegetational context of early Angiosperm diversification 20. The accumulation of Angiosperm diversity References Index.

  • Early Flowers and Angiosperm Evolution: Introduction to Angiosperms
    Early Flowers and Angiosperm Evolution, 2011
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    The phylogenetic diversification and ecological radiation of Angiosperms (flowering plants) that took place in the Early Cretaceous, between about 135 and 65 million years ago, was one of the major biotic upheavals in the history of life. It had dramatic consequences for the composition and subsequent evolution of terrestrial ecosystems. Ancient Mesozoic vegetation, which was dominated by ferns, conifers, ginkgos and cycads, as well as Bennettitales and other groups of extinct seed plants, was eventually almost entirely replaced by more modern ecosystems dominated by Angiosperms. Since the Early Cretaceous, high diversification rates have generated more than 350 000 extant Angiosperm species. Today there are more living species of Angiosperms than all other groups of land plants combined. In their rise to ecological dominance Angiosperms have exhibited extraordinary developmental and evolutionary plasticity. This has resulted in overwhelming morphological diversity and a great variety of adaptive types. Angiosperms are far more diverse in vegetative form and in the structure of their reproductive organs than any other group of land plants.

Else Marie Friis - One of the best experts on this subject based on the ideXlab platform.

  • Extinct Diversity among Early Cretaceous Angiosperms: Mesofossil Evidence of Early Magnoliales from Portugal
    International Journal of Plant Sciences, 2019
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Premise of research. Small Angiosperm fossils are diverse in Early Cretaceous mesofossil floras from Portugal and eastern North America. Investigations of these fossils have revealed an unexpectedly high diversity of extinct Angiosperms related to lineages that are now species poor, such as Austrobaileyales, Nymphaeales, and Chloranthaceae. Here we analyze Early Cretaceous fruits and seeds from Portugal that are related to eumagnoliid Angiosperms and that are also important for understanding extinct diversity in early Angiosperms.Methodology. The fossils were prepared by sieving in water; cleaned with HF, HCl, and water; and studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. The systematic conclusion based on comparative studies was tested in a phylogenetic analysis.Pivotal results. We recognize a new group of Angiosperms based on fruits and seeds united by features that are otherwise unusual among Angiosperms. Two genera, Serialis and Riaselis, are establis...

  • fossil seeds with affinities to austrobaileyales and nymphaeales from the early cretaceous early to middle albian of virginia and maryland usa new evidence for extensive extinction near the base of the Angiosperm tree
    2018
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Abstract Early Cretaceous seeds from Virginia and Maryland, USA, part of a diverse complex of exotestal seeds in Early Cretaceous mesofossil floras from North America and Europe, provide new evidence of extensive extinction among early Angiosperms. The seeds are assigned to a new genus, Nitaspermum, with six species: N. taylorii , N. hopewellense , N. crassum , N. virginiense , N. marylandense, and Nitaspermum sp. All seeds are small, anatropous, bitegmic, and exotestal, with the exotesta composed of a single layer of short, columnar sclerenchyma with strongly folded walls. Nitaspermum shows features of extant Austrobaileyales (Illiciaceae) and Nymphaeales but also critical differences precluding assignment to extant families. These discoveries are consistent with predictions from molecular phylogenetics that indicate the differentiation of Illiciaceae and Nymphaeales early in Angiosperm evolution, but the diversity of such seeds underlines the extent to which the pattern of extant Angiosperm diversity has been shaped by widespread extinction early in Angiosperm evolution.

  • early flowers and Angiosperm evolution
    2011
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    Preface 1. Introduction to Angiosperms 2. The nature of the Angiosperm fossil record 3. The environmental context of early Angiosperm evolution 4. Stratigraphic framework and key areas for Cretaceous Angiosperms 5. Angiosperms in context: extant and fossil seed plants 6. Origin and age of Angiosperms 7. Phylogenetic framework and the assignment of fossils to extant groups 8. Fossils near the base of the Angiosperm tree 9. Early fossil Angiosperms of uncertain relationships 10. Early fossils of eumagnoliids 11. Fossils of monocots 12. Fossils of eudicots: early diverging groups 13. Fossils of core eudicots: basal lineages 14. Fossils of core eudicots: rosids 15. Early fossils of eudicots: asterids 16. Patterns of structural diversification in Angiosperm reproductive organs 17. History and evolution of pollination in Angiosperms 18. History and evolution of dispersal in Angiosperms 19. Vegetational context of early Angiosperm diversification 20. The accumulation of Angiosperm diversity References Index.

  • Early Flowers and Angiosperm Evolution: Introduction to Angiosperms
    Early Flowers and Angiosperm Evolution, 2011
    Co-Authors: Else Marie Friis, Peter R Crane, Kaj Raunsgaard Pedersen
    Abstract:

    The phylogenetic diversification and ecological radiation of Angiosperms (flowering plants) that took place in the Early Cretaceous, between about 135 and 65 million years ago, was one of the major biotic upheavals in the history of life. It had dramatic consequences for the composition and subsequent evolution of terrestrial ecosystems. Ancient Mesozoic vegetation, which was dominated by ferns, conifers, ginkgos and cycads, as well as Bennettitales and other groups of extinct seed plants, was eventually almost entirely replaced by more modern ecosystems dominated by Angiosperms. Since the Early Cretaceous, high diversification rates have generated more than 350 000 extant Angiosperm species. Today there are more living species of Angiosperms than all other groups of land plants combined. In their rise to ecological dominance Angiosperms have exhibited extraordinary developmental and evolutionary plasticity. This has resulted in overwhelming morphological diversity and a great variety of adaptive types. Angiosperms are far more diverse in vegetative form and in the structure of their reproductive organs than any other group of land plants.

  • cretaceous Angiosperm flowers innovation and evolution in plant reproduction
    Palaeogeography Palaeoclimatology Palaeoecology, 2006
    Co-Authors: Else Marie Friis, Raunsgaard K Pedersen, Peter R Crane
    Abstract:

    Abstract Information on the fossil record of Angiosperms has expanded dramatically over the past twenty-five years, and in particular the discovery of numerous mesofossil floras with fossil flowers has added a completely new element into the study of Angiosperm history. A review of the phylogenetic diversification of Angiosperms through the Cretaceous is given based mainly on the extensive record of fossil flowers and other reproductive organs. Several major phases in the Cretaceous Angiosperm radiation can be distinguished. These are recognised primarily by structural and functional traits of the flowers and by pollen features, as well as distinct changes in the systematic composition of the floras. ANITA grade Angiosperms and Chloranthaceae, as well as other magnoliids, early monocots and early eudicots, differentiated almost simultaneously during the Early Cretaceous. There is also strong evidence for extensive diversification of core eudicots during the Late Cretaceous. In addition to patterns of phylogenetic diversification, the fossil record of Angiosperm flowers also provides insights into the timing of floral evolution in terms of the functions of the various kinds of floral organs, as well as accompanying patterns of ecological diversification.

Taylor S. Feild - One of the best experts on this subject based on the ideXlab platform.

  • Fossil evidence for low gas exchange capacities for Early Cretaceous Angiosperm leaves
    Paleobiology, 2020
    Co-Authors: Taylor S. Feild, David S. Chatelet, Kunsiri Chaw Grubbs, Marie-stéphanie Samain, Gilbert R Upchurch, Timothy J. Brodribb, Stefan Wanke
    Abstract:

    The photosynthetic gas exchange capacities of early Angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early Angiosperm success and how Angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early Angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian–early Albian Angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant Angiosperms. Gas exchange capacities for Early Cretaceous Angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later Angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal Angiosperm lineages reveals genuine signals of Early Cretaceous Angiosperm ecophysiology.

  • EVOLUTIONARY VOYAGE OF Angiosperm VESSEL STRUCTURE-FUNCTION AND ITS SIGNIFICANCE FOR EARLY Angiosperm SUCCESS
    International Journal of Plant Sciences, 2012
    Co-Authors: Taylor S. Feild, Jonathan P. Wilson
    Abstract:

    A hypothesized advantage of the building block of the Angiosperm vascular network, the vessel, is often cited as a critical innovation that elevated the competitive abilities of early Angiosperms above nonAngiosperms during the Cretaceous. Here we synthesize recent discoveries on the hydraulic functions of living basal Angiosperm lineages with evidence from the fossil record to trace the early evolutionary significance of vessels in the early ecophysiological radiation of Angiosperms. Evidence from extant comparative biology and the Early Cretaceous fossil record of leaves and wood do not support the hypotheses that vessels improved drought tolerance of Angiosperms, increased Angiosperm’s photosynthetic abilities, or provided an immediate leap in hydraulic capacity. Instead, later tuning of vessel structure for increased flow efficiency—in particular, by the evolution of simple perforation plates—enabled major increases in xylem hydraulic efficiency.

  • fossil evidence for cretaceous escalation in Angiosperm leaf vein evolution
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Taylor S. Feild, David S. Chatelet, Gilbert R Upchurch, Timothy J. Brodribb, Ari Iglesias, Andres Baresch, Bernard Gomez, Barbara A R Mohr, Clement Coiffard, Jiri Kvacek
    Abstract:

    The flowering plants that dominate modern vegetation possess leaf gas exchange potentials that far exceed those of all other living or extinct plants. The great divide in maximal ability to exchange CO2 for water between leaves of nonAngiosperms and Angiosperms forms the mechanistic foundation for speculation about how Angiosperms drove sweeping ecological and biogeochemical change during the Cretaceous. However, there is no empirical evidence that Angiosperms evolved highly photosynthetically active leaves during the Cretaceous. Using vein density (DV) measurements of fossil Angiosperm leaves, we show that the leaf hydraulic capacities of Angiosperms escalated several-fold during the Cretaceous. During the first 30 million years of Angiosperm leaf evolution, Angiosperm leaves exhibited uniformly low vein DV that overlapped the DV range of dominant Early Cretaceous ferns and gymnosperms. Fossil Angiosperm vein densities reveal a subsequent biphasic increase in DV. During the first mid-Cretaceous surge, Angiosperm DV first surpassed the upper bound of DV limits for nonAngiosperms. However, the upper limits of DV typical of modern megathermal rainforest trees first appear during a second wave of increased DV during the Cretaceous-Tertiary transition. Thus, our findings provide fossil evidence for the hypothesis that significant ecosystem change brought about by Angiosperms lagged behind the Early Cretaceous taxonomic diversification of Angiosperms.

  • leaf hydraulic evolution led a surge in leaf photosynthetic capacity during early Angiosperm diversification
    Ecology Letters, 2010
    Co-Authors: Timothy J. Brodribb, Taylor S. Feild
    Abstract:

    Angiosperm evolution transformed global ecology, and much of this impact derives from the unrivalled vegetative productivity of dominant Angiosperm clades. However, the origins of high photosynthetic capacity in Angiosperms remain unknown. In this study, we describe the steep trajectory of leaf vein density (Dv) evolution in Angiosperms, and predict that this leaf plumbing innovation enabled a major shift in the capacity of leaves to assimilate CO2. Reconstructing leaf vein evolution from an examination of 504 Angiosperm species we found a rapid three- to fourfold increase in Dv occurred during the early evolution of Angiosperms. We demonstrate how this major shift in leaf vein architecture potentially allowed the maximum photosynthetic capacity in Angiosperms to rise above competing groups 140–100 Ma. Our data suggest that early terrestrial Angiosperms produced leaves with low photosynthetic rates, but that subsequent Angiosperm success is linked to a surge in photosynthetic capacity during their early diversification.

  • The ecophysiology of early Angiosperms.
    Plant Cell and Environment, 2007
    Co-Authors: Taylor S. Feild, Nan Crystal Arens
    Abstract:

    Angiosperms first appeared during the Early Cretaceous, and within 30 million years they reigned over many floras worldwide. Associated with this rise to prominence, Angiosperms produced a spectrum of reproductive and vegetative innovations, which produced a cascade of ecological consequences that altered the ecology and biogeochemistry of the planet. The pace, pattern and phylogenetic systematics of the Cretaceous Angiosperm diversification are broadly sketched out. However, the ecophysiology and environmental interactions that energized the early Angiosperm radiation remain unresolved. This constrains our ability to diagnose the selective pressures and habitat contexts responsible for the evolution of fundamental Angiosperm features, such as flowers, rapid growth, xylem vessels and net-veined leaves, which in association with environmental opportunities, drove waves of phylogenetic and ecological diversification. Here, we consider our current understanding of early Angiosperm ecophysiology. We focus on comparative patterns of ecophysiological evolution, emphasizing carbon- and water-use traits, by merging recent molecular phylogenetic studies with physiological studies focused on extant basal Angiosperms. In doing so, we discuss how early Angiosperms established a roothold in pre-existing Mesozoic plant communities, and how these events canalized subsequent bursts of Angiosperm diversification during the Aptian–Albian.

Susana Magallón - One of the best experts on this subject based on the ideXlab platform.

  • Using fossils to break long branches in molecular dating: A comparison of relaxed clocks applied to the origin of Angiosperms
    Systematic Biology, 2010
    Co-Authors: Susana Magallón
    Abstract:

    Long branches are potentially problematic in molecular dating because they can encompass a vast number of combinations of substitution rate and time. A long branch is suspected to have biased molecular clock estimates of the age of flowering plants (Angiosperms) to be much older than their earliest fossils. This study explores the effect of the long branch subtending Angiosperms in molecular dating and how different relaxed clocks react to it. Fossil Angiosperm relatives, identified through a combined morphological and molecular phylogenetic analysis for living and fossil seed plants, were used to break the long Angiosperm stem branch. Nucleotide sequences of Angiosperm fossil relatives were simulated using a phylogeny and model parameters from living taxa and incorporated in molecular dating. Three relaxed clocks, which implement among-lineage rate heterogeneity differently, were used: penalized likelihood (using 2 different rate smoothing optimization criteria), a Bayesian rate-autocorrelated method, and a Bayesian uncorrelated method. Different clocks provided highly correlated ages across the tree. Breaking the Angiosperm stem branch did not result in major age differences, except for a few sensitive nodes. Breaking the Angiosperm stem branch resulted in a substantially younger age for crown Angiosperms only with 1 of the 4 methods, but, nevertheless, the obtained age is considerably older than the oldest Angiosperm fossils. The origin of crown Angiosperms is estimated between the Upper Triassic and the early Permian. The difficulty in estimating crown Angiosperm age probably lies in a combination of intrinsic and extrinsic complicating factors, including substantial molecular rate heterogeneity among lineages and through time. A more adequate molecular dating approach might combine moderate background rate heterogeneity with large changes in rate at particular points in the tree.

  • Angiosperm diversification through time
    American Journal of Botany, 2009
    Co-Authors: Susana Magallón, Amanda Castillo
    Abstract:

    : The extraordinary diversity of Angiosperms is the ultimate outcome of the interplay of speciation and extinction, which determine the net diversification of different lineages. We document the temporal trends of Angiosperm diversification rates during their early history. Absolute diversification rates were estimated for order-level clades using ages derived from relaxed molecular clock analyses that included or excluded a maximal constraint to Angiosperm age. Diversification rates for Angiosperms as a whole ranged from 0.0781 to 0.0909 net speciation events per million years, with dates from the constrained analysis. Diversification through time plots show an inverse relationship between clade age and rate, where the younger clades tend to have the highest rates. Angiosperm diversity is found to have mixed origins: slightly less than half of the living species belong to lineages with low to moderate diversification rates, which appeared between 130 and 102 Mya (Barremian-uppermost Albian; Lower Cretaceous). Slightly over half of the living species belong to lineages with moderate to high diversification rates, which appeared between 102 and 77 Mya (Cenomanian-mid Campanian; Upper Cretaceous). Terminal lineages leading to living Angiosperm species, however, may have originated soon or long after the phylogenetic differentiation of the clade to which they belong.

  • Angiosperm divergence times the effect of genes codon positions and time constraints
    Evolution, 2005
    Co-Authors: Susana Magallón, Michael J Sanderson
    Abstract:

    An understanding of the evolution of modern terrestrial ecosystems requires an understanding of the dynamics associated with Angiosperm evolution, including the timing of their origin and diversification into their extraordinary present-day diversity. Molecular estimates of Angiosperm age have varied widely, and many substantially predate the Early Cretaceous fossil appearance of the group. In this study, the effect of different genes, codon positions, and chronological constraints on node ages are examined on divergence time estimates across seed plants, with a special focus on Angiosperms. Penalized likelihood was used to estimate divergence times on a phylogenetic hypothesis for seed plants derived from Bayesian analysis, with branch lengths estimated with maximum likelihood. The plastid genes atpB, psaA, psbB, and rbcL were used individually and in combination, using first and second, third, and the three codon positions, including and excluding age constraints on 20 nodes derived from a critical examination of the land-plant fossil record. The optimal level of rate smoothing according to each unconstrained and constrained dataset was obtained with penalized likelihood. Tests for a molecular clock revealed significantly unclocklike rates in all datasets. Addition of fossil constraints resulted in even greater departures from constancy. Consistently with significant deviations from a clock, estimated optimal smoothing values were low, but a strict correlation between rate heterogeneity and optimal smoothing value was not found. Age estimates for nodes across the phylogeny varied, sometimes substantially, with gene and codon position. Nevertheless, estimates based on the four concatenated genes are very similar to the mean of the four individual gene estimates. For any given node, unconstrained age estimates are more variable than constrained estimates and are frequently younger than well-substantiated fossil members of the clade. Constrained estimates of ages of clades are older than unconstrained estimates and oldest fossil representatives, sometimes substantially so. Angiosperm age estimates decreased as rate smoothing increased. Whereas the range of unconstrained Angiosperm age estimates spans the fossil age of the clade, the range of constrained estimates is narrower (and older) than the earliest Angiosperm fossils. Results unambiguously indicate the relevance of constraints in reducing the variability of ages derived from different partitions of the data and diminishing the effect of the smoothing parameter. Constrained optimizations of divergence times and substitution rates across the phylogeny suggest appreciably different evolutionary dynamics for Angiosperms and for gymnosperms. Whereas the gymnosperm crown group originated shortly after the origin of seed plants, a long time elapsed before the origin of crown group Angiosperms. Although absolute age estimates of Angiosperms and Angiosperm clades are older than their earliest fossils, the estimated pace of phylogenetic diversification largely agrees with the rapid appearance of Angiosperm lineages in stratigraphic sequences.

  • absolute diversification rates in Angiosperm clades
    Evolution, 2001
    Co-Authors: Susana Magallón, Michael J Sanderson
    Abstract:

    The extraordinary contemporary species richness and ecological predominance of flowering plants (angio- sperms) are even more remarkable when considering the relatively recent onset of their evolutionary diversification. We examine the evolutionary diversification of Angiosperms and the observed differential distribution of species in Angiosperm clades by estimating the rate of diversification for Angiosperms as a whole and for a large set of Angiosperm clades. We also identify Angiosperm clades with a standing diversity that is either much higher or lower than expected, given the estimated background diversification rate. Recognition of Angiosperm clades, the phylogenetic relationships among them, and their taxonomic composition are based on an empirical compilation of primary phylogenetic studies. By making an integrative and critical use of the paleobotanical record, we obtain reasonably secure approximations for the age of a large set of Angiosperm clades. Diversification was modeled as a stochastic, time-homogeneous birth- and-death process that depends on the diversification rate (r) and the relative extinction rate ( e). A statistical analysis of the birth and death process was then used to obtain 95% confidence intervals for the expected number of species through time in a clade that diversifies at a rate equal to that of Angiosperms as a whole. Confidence intervals were obtained for stem group and for crown group ages in the absence of extinction ( e5 0.0) and under a high relative extinction rate ( e5 0.9). The standing diversity of Angiosperm clades was then compared to expected species diversity according to the background rate of diversification, and, depending on their placement with respect to the calculated confidence intervals, exceedingly species-rich or exceedingly species-poor clades were identified. The rate of diver- sification for Angiosperms as a whole ranges from 0.077 ( e5 0.9) to 0.089 ( e5 0.0) net speciation events per million years. Ten clades fall above the confidence intervals of expected species diversity, and 13 clades were found to be unexpectedly species poor. The phylogenetic distribution of clades with an exceedingly high number of species suggests that traits that confer high rates of diversification evolved independently in different instances and do not characterize the Angiosperms as a whole.

Douglas E Soltis - One of the best experts on this subject based on the ideXlab platform.

  • Angiosperm phylogeny based on matK sequence information
    American Journal of Botany, 2020
    Co-Authors: Khidir W. Hilu, Martyn P. Powell, Lawrence A. Alice, Thomas Borsch, Douglas E Soltis, Pamela S Soltis, Vincent Savolainen, Mark W Chase, Kai F Muller, Rodger C. Evans
    Abstract:

    Plastid matK gene sequences for 374 genera representing all Angiosperm orders and 12 genera of gymnosperms were analyzed using parsimony (MP) and Bayesian inference (BI) approaches. Traditionally, slowly evolving genomic regions have been preferred for deep-level phylogenetic inference in Angiosperms. The matK gene evolves approximately three times faster than the widely used plastid genes rbcL and atpB. The MP and BI trees are highly congruent. The robustness of the strict consensus tree supercedes all individual gene analyses and is comparable only to multigene-based phylogenies. Of the 385 nodes resolved, 79% are supported by high jackknife values, averaging 88%. Amborella is sister to the remaining Angiosperms, followed by a grade of Nymphaeaceae and Austrobaileyales. Bayesian inference resolves Amborella 1 Nymphaeaceae as sister to the rest, but with weak (0.42) posterior probability. The MP analysis shows a trichotomy sister to the Austrobaileyales representing eumagnoliids, monocots 1 Chloranthales, and Ceratophyllum 1 eudicots. The matK gene produces the highest internal support yet for basal eudicots and, within core eudicots, resolves a crown group comprising Berberidopsidaceae/Aextoxicaceae, Santalales, and Caryophyllales 1 asterids. Moreover, matK sequences provide good resolution within many Angiosperm orders. Combined analyses of matK and other rapidly evolving DNA regions with available multigene data sets have strong potential to enhance resolution and internal support in deep level Angiosperm phylogenetics and provide additional insights into Angiosperm evolution.

  • The origin and diversification of Angiosperms.
    American Journal of Botany, 2020
    Co-Authors: Pamela S Soltis, Douglas E Soltis
    Abstract:

    The Angiosperms, one of five groups of extant seed plants, are the largest group of land plants. Despite their relatively recent origin, this clade is extremely diverse morphologically and ecologically. However, Angiosperms are clearly united by several synapomorphies. During the past 10 years, higher-level relationships of the Angiosperms have been resolved. For example, most analyses are consistent in identifying Amborella, Nymphaeaceae, and Austrobaileyales as the basalmost branches of the Angiosperm tree. Other basal lineages include Chloranthaceae, magnoliids, and monocots. Approximately three quarters of all Angiosperm species belong to the eudicot clade, which is strongly supported by molecular data but united morphologically by a single synapomorphy-triaperturate pollen. Major clades of eudicots include Ranunculales, which are sister to all other eudicots, and a Glade of core eudicots, the largest members of which are Saxifragales, Caryophyllales, rosids, and asterids. Despite rapid progress in resolving Angiosperm relationships, several significant problems remain: (1) relationships among the monocots, Chloranthaceae, magnoliids, and eudicots, (2) branching order among basal eudicots, (3) relationships among the major clades of core eudicots, (4) relationships within rosids, (5) relationships of the many lineages of parasitic plants, and (6) integration of fossils with extant taxa into a comprehensive tree of Angiosperm phylogeny.

  • Angiosperm phylogeny: 17 genes, 640 taxa
    American Journal of Botany, 2011
    Co-Authors: Douglas E Soltis, Samuel F. Brockington, Nico Cellinese, Kenneth J. Wurdack, David C. Tank, Nancy F. Refulio-rodriguez, Jay B. Walker, Stephen A Smith, Michael J. Moore, Barbara S. Carlsward
    Abstract:

    Recent analyses employing up to five genes have provided numerous insights into Angiosperm phylogeny, but many relationships have remained unresolved or poorly supported. In the hope of improving our understanding of Angiosperm phylogeny, we expanded sampling of taxa and genes beyond previous analyses. We conducted two primary analyses based on 640 species representing 330 families. The first included 25260 aligned base pairs (bp) from 17 genes (representing all three plant genomes, i.e., nucleus, plastid, and mitochondrion). The second included 19846 aligned bp from 13 genes (representing only the nucleus and plastid). Many important questions of deep-level relationships in the nonmonocot Angiosperms have now been resolved with strong support. Amborellaceae, Nymphaeales, and Austrobaileyales are successive sisters to the remaining Angiosperms (MesAngiospermae), which are resolved into Chloranthales + Magnoliidae as sister to Monocotyledoneae + [Ceratophyllaceae + Eudicotyledoneae]. Eudicotyledoneae contains a basal grade subtending Gunneridae. Within Gunneridae, Gunnerales are sister to the remainder (Pentapetalae), which comprises (1) Superrosidae, consisting of Rosidae (including Vitaceae) and Saxifragales; and (2) Superasteridae, comprising Berberidopsidales, Santalales, Caryophyllales, Asteridae, and, based on this study, Dilleniaceae (although other recent analyses disagree with this placement). Within the major subclades of Pentapetalae, most deep-level relationships are resolved with strong support. Our analyses confirm that with large amounts of sequence data, most deep-level relationships within the Angiosperms can be resolved. We anticipate that this well-resolved Angiosperm tree will be of broad utility for many areas of biology, including physiology, ecology, paleobiology, and genomics.

  • The age and diversification of the Angiosperms re-revisited
    American Journal of Botany, 2010
    Co-Authors: Charles D. Bell, Douglas E Soltis, Pamela S Soltis
    Abstract:

     Premise of the study : It has been 8 years since the last comprehensive analysis of divergence times across the Angiosperms. Given recent methodological improvements in estimating divergence times, refi ned understanding of relationships among major Angiosperm lineages, and the immense interest in using large Angiosperm phylogenies to investigate questions in ecology and comparative biology, new estimates of the ages of the major clades are badly needed. Improved estimations of divergence times will concomitantly improve our understanding of both the evolutionary history of the Angiosperms and the patterns and processes that have led to this highly diverse clade.  Methods : We simultaneously estimated the age of the Angiosperms and the divergence times of key Angiosperm lineages, using 36 calibration points for 567 taxa and a “ relaxed clock ” methodology that does not assume any correlation between rates, thus allowing for lineage-specifi c rate heterogeneity.  Key results : Based on the analysis for which we set fossils to fipriors, we obtained an estimated age of the Angiosperms of 167 – 199 Ma and the following age estimates for major Angiosperm clades: MesAngiospermae (139 – 156 Ma); Gunneridae (109 – 139 Ma); Rosidae (108 – 121 Ma); Asteridae (101 – 119 Ma).  Conclusions : With the exception of the age of the Angiosperms themselves, these age estimates are generally younger than other recent molecular estimates and very close to dates inferred from the fossil record. We also provide dates for all major Angiosperm clades (including 45 orders and 335 families [208 stem group age only, 127 both stem and crown group ages], sensu APG III). Our analyses provide a new comprehensive source of reference dates for major Angiosperm clades that we hope will be of broad utility.

  • polyploidy and Angiosperm diversification
    American Journal of Botany, 2009
    Co-Authors: Douglas E Soltis, Charles D. Bell, Victor A Albert, Jim Leebensmack, Andrew H Paterson, Chunfang Zheng, David Sankoff, Claude W De Pamphilis, Kerr P Wall
    Abstract:

    : Polyploidy has long been recognized as a major force in Angiosperm evolution. Recent genomic investigations not only indicate that polyploidy is ubiquitous among Angiosperms, but also suggest several ancient genome-doubling events. These include ancient whole genome duplication (WGD) events in basal Angiosperm lineages, as well as a proposed paleohexaploid event that may have occurred close to the eudicot divergence. However, there is currently no evidence for WGD in Amborella, the putative sister species to other extant Angiosperms. The question is no longer "What proportion of Angiosperms are polyploid?", but "How many episodes of polyploidy characterize any given lineage?" New algorithms provide promise that ancestral genomes can be reconstructed for deep divergences (e.g., it may be possible to reconstruct the ancestral eudicot or even the ancestral Angiosperm genome). Comparisons of diversification rates suggest that genome doubling may have led to a dramatic increase in species richness in several Angiosperm lineages, including Poaceae, Solanaceae, Fabaceae, and Brassicaceae. However, additional genomic studies are needed to pinpoint the exact phylogenetic placement of the ancient polyploidy events within these lineages and to determine when novel genes resulting from polyploidy have enabled adaptive radiations.