[ News ]
"That's it." After working on the project for more than six years, Dr. Miller completed the essays on the origin of flowering plants, November 11, 2011.
A "Publication of the Year" will be selected and posted to Gigantopteroid Dot Org annually. I will continue posting newsworthy items, repairing broken links, and updating the "Reading List of Book Chapters and Books" based on my current research.
The massif pictured to the right is Cerro de la Encantada (Picacho del Diablo) as viewed from the crest of the Sierra San Pedro Mártir, also known as Cerro Providencia or "Hill of the Enchanted." Snow is visible in the foreground under sparse stands of Abies concolor (white fir), Pinus jeffreyi (Jeffrey pine), and Pinus lambertiana (sugar pine).
The "Mountain of Providence" or "Devil's Picacho" (elevation 3,096 meters) is the detached and uplifted grano-diorite and tonalite block of the Peninsular Mountains of westernmost North America.
High DNA Content, Karyology, and Unusual Microsporogenesis in ANA grade Hydatellaceae (September 2014):
The Botanical Society of America publishes significant findings from the Rudall Lab on the chromosome biology of Trithuria submersa (Hydatellaceae, Nymphaeales, Nymphaeanae), revealing water lily-like nuclear DNA content. Unusual microsporogenesis, a chromosome number of 2n = 56, and allopolyploidy is revealed in a study of a monocot-like, aquatic ANA-grade basal angiosperm.
"The meiotic peculiarities of simultaneous cytokinesis with traces of a successive character observed in T. submersa could be regarded as representative of the evolutionary 'experimentation' that occurred in early angiosperms before fixation of the more typical and canalized types of microspore development that characterize most flowering plants ..." (page 1453, Results and Discussion, Kynast et al. 2014).
Kynast, R. G., J. A. Joseph, J. Pellicer, M. M. Ramsay, and P. J. Rudall. 2014. Chromosome behavior at the base of the angiosperm radiation: Karyology of Trithuria submersa (Hydatellaceae, Nymphaeales). American Journal of Botany 101(9): 1447-1455.
A related paper should be read:
Friedman, W. E., J. B. Bachelier, and J. I. Hormaza. 2012. Embryology in Trithuria submersa (Hydatellaceae) and relationships between embryo, endosperm, and perisperm in early-diverging flowering plants. American Journal of Botany 99(6): 1083–1095.
Support for a Gnepine Hypothesis Builds, and Flowering Plants Are the Sister Group of Gymnosperms (June 2014):
Several reviews having bearing on the origin of flowering plants were published in the first quarter of 2014. Milestone reviews included papers written by Paul M. Barrett (2014), William L. Crepet (2014), James A. Doyle and Peter K. Endress (2014), Susana Magallón (2014), Xiao-Quan Wang and Jin-Hua Ran (2014), and Xin Wang (2014).
A detached megasporophyll of extant Cycas revoluta (Cycadaceae, Cycadales) is pictured to the left. The hairy megasporophyll bears a pair of bright-red ripened seeds and one brownish immature ovule on the lower edges of the dissected leaf.
Cycad embryos are protected by an indurate sarcotesta of the seed. Colorful seeds of Mesozoic cycads were browsed, partially digested, and dispersed by stegosaurians according to certain paleobiologists.
A coevolutionary origin and radiation of angiosperms and ornithischians has been proposed by several paleontologists. Paul M. Barrett revisits some of these ideas in his contribution to a 2014 volume of the Annual Review of Earth and Planetary Sciences:
"The most prevalent coevolutionary hypothesis proposed that changes in dinosaur browsing behavior fostered the origin and radiation of angiosperms [Bakker 1978]" (page 220, Plant-dinosaur Interactions: Coevolution or Coincidence? Barrett 2014).
Barrett, P. M. 2014. Paleobiology of Herbivorous Dinosaurs. Annual Review of Earth and Planetary Sciences 42: 207-230.
"Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions" (page 207, Abstract, Barrett 2014).
Two papers appearing this month (James A. Doyle and Endress 2014, X.-Q. Wang and J-H. Ran 2014) offer contrasting views on angiosperms, gymnosperms, and divergence[s] from the most recent common ancestor (MRCA), but coevolution is not discussed.
Wang, X.-Q. and J-H. Ran. 2014. Evolution and biogeography of gymnosperms. Molecular Phylogenetics and Evolution 75: 24-40.
Doyle, J. A. and P. K. Endress. 2014. Integrating early Cretaceous fossils into the phylogeny of living angiosperms: ANITA lines and relatives of Chloranthaceae. International Journal of Plant Sciences 175(5): 555-600 (with supplements).
Angiosperms are basal to conifers, cycads, ginkgos, and gnetophytes in several phylogenetic analyses cited and debated in these two reviews. Fossil-calibrated trees discussed by Xiao-Quan Wang and Jin-Hua Ran (2014) posit a Permo-carboniferous or Permo-triassic origin of the flowering plant stem group. Another compilation pieces together evidence from Mesozoic fossils (James A. Doyle and Endress 2014) illuminating radiation of basal angiosperms.
"Based on fossil evidence and molecular clock calibration, the divergence between gymnosperms and angiosperms could be dated to about 300–350 million years ago (MYA) ... " (Abstract, X.-Q. Wang and J-H. Ran 2014).
James A. Doyle and Endress (2014) are skeptical of some findings in the physiologic literature, and are not enthusiastic of [some] molecular-phylogenetic studies that suggest a late Paleozoic split of gymnosperms from angiosperms:
"Our results challenge this scenario [that the terrestrial ANITA lines were xerophobic, Feild et al. 2004, 2009, and that rates of angiosperm diversification were initially low and did not speed up until origin of the mesangiosperm clade, Magallón and Sanderson 2001] by showing that the ANITA lines were radiating in the Aptian-Albian, alongside Chloranthaceae and extinct relatives, magnoliids, monocots, and primitive eudicots ... This could mean that angiosperm diversification in general was being inhibited by external environmental factors before the Cretaceous, rather than by ecophysiological limitations of the first angiosperms, or that angiosperms are not as old as molecular dating implies" (page 592, Results and Discussion: Implications for Pre-Cretaceous History of the Angiosperm Line, James A. Doyle and Endress 2014).
Susana Magallón offers insight from a review of Bayesian priors, calibrations, and artifacts due to long-branch attraction in the several competing seed plant molecular-phylogenetic analyses listed in Table 1 on pages 7, 8, and 9 (Magallón 2014), which are also discussed by X.-Q. Wang and J-H. Ran (2014).
" ... studies of angiosperms depend a lot on our knowledge of gymnosperms given the sister relationship between the two groups" (page 25, X.-Q. Wang and J-H. Ran 2014).
Magallón, S. 2014. A review of the effect of relaxed clock method, long branches, genes, and calibrations in the estimation of angiosperm age. Botanical Sciences (Boletín de la Sociedad Botánica de México) 92: 1-22.
"These combined observations clearly indicate that the molecular data contain a signal congruent with an angiosperm age much older than the earliest angiosperm fossils. But I would like to argue that a very old angiosperm age is not the only possible interpretation of such molecular signal" (Discussion, page 16, Magallón 2014).
A fifth review was published early in 2014 by William L. Crepet.
Crepet, W. L. 2014. Advances in Flowering Plant Evolution. eLS (Citable Reviews in the Life Sciences [Fossils and Evolution]). Chichester: John Wiley & Sons, Ltd, 11 pp.
"What is surprising is the scale of the uncertainty surrounding our basic knowledge of angiosperms. Angiosperm relationships are only now being resolved through the application of various algorithms to the combination of molecular genetics-derived data and morphological data. Yet the relationship of the angiosperms themselves to nonangiospermous seed plants, or understanding the origin of this major group, still remains a hotly contested mystery ... " (Abstract, Crepet 2014).
The sixth and final compilation ties-in with Professor Crepet's eloquent review:
Wang, Xin. 2014. The megafossil record of early angiosperms in China since 1930s. Historical Biology: An International Journal of Paleobiology, DOI: 10.1080/08912963.2014.889695.
Evolution of a LFY Protein Homeodomain Unfolds in Streptophytes, Bryophytes, and Seed Plants (February 2014):
The American Association for the Advancement of Science (AAAS) publishes another critically important study with broad implications on the evolution the DNA-binding homeodomain of modular tool kit transcription factors (TFs) at the heart of cone and floral development.
"A highly conserved and essential TF [LFY homeodomain protein] evolved radical shifts in DNA binding specificity by a mechanism that does not require gene duplication." (page 648, Sayou et al. 2014).
Sayou, C., M. Monniaux, M. H. Nanao, E. Moyroud, S. F. Brockington, E. Thévenon, H. Chahtane, N. Warthmann, M. Melkonian, Y. Zhang, G. K.-S. Wong, D. Weigel, F. Parcy, and R. Dumas. 2014. A promiscuous intermediate underlies the evolution of LEAFY DNA binding specificity. Science 343(6171): 645-648.
Further, dimeric Leafy (LFY) protein and auxin form modules, which together with polarity networks (PINs) help determine floral primordia in SAMs of some model angiosperms.
"Its emergence [of a reproductive regulatory network] probably involved changes in cis-elements of recruited targets, to place them under LFY control, as well as the establishment of novel protein-protein interactions." (page 351, Moyroud et al. 2010).
Moyroud, E., E. Kusters, M. Monniaux, R. Koes, and F. Parcy. 2010. LEAFY blossoms. Trends in Plant Science 15: 346-352.
"Our study reveals that the LFY master regulator, which determines flower meristem fate and controls the expression of floral organ identity genes, shares structural similarity with other HTH proteins, indicating that this universal DNA-binding motif has also been adopted in plants to trigger major developmental switches."
The preceding paragraph is quoted from page 2635 of C. Hamès, D. Ptchelkine, C. Grimm, E. Thévenon, E. Moyroud, F. Gérard, J.-L. Martiel, R. Benlloch, F. Parcy, and C. W. Müller (2008), Structural basis for LEAFY floral switch function and similarity with helix-turn-helix proteins. The EMBO Journal 27: 2628-2637.
The left-hand image is reproduced from Figure 6 on page 2634 of Hamès et al. (2008), "Comparison of LFY-C with paired and homeodomain DNA binding.
(A) Two orthogonal views of LFY-C helices α1 - α3 bound to their DNA target site [red] superimposed with the three helical bundle core of the N-terminal subdomain of the paired domain of Drosophila Prd [blue, PDB-id: 1pdn]. (B) Superposition with the homeodomain of Drosophila engrailed bound to DNA [yellow, PBD-id: 1hdd], where the centre of recognition helix α3 inserts into the major groove."
Reprinted by permission from Macmillan Publishers Ltd: The European Molecular Biology Organization (EMBO) Journal, Hamès, C., D. Ptchelkine, C. Grimm, E. Thevenon, E. Moyroud, F. Gérard, J.-L. Martiel, R. Benlloch, F. Parcy, and C. W. Müller. 2008. Structural basis for LEAFY floral switch function and similarity with helix-turn-helix proteins, The EMBO Journal 27: 2628-2637, copyright ©2008.
Future research to decipher possible molecular coevolution of LFY and Engraled protein should take into account evolutionary theory on the origin and diversification of cis-regulatory modules (CRMs) and gene regulatory networks (GRNs) that orchestrate development of animal and plant organs and bodies.
Carroll, S. B. 2008. Evo-devo and an expanding evolutionary synthesis: a genetic theory of morphological evolution. Cell 134(1): 25-36.
Stomatal Guard Cell Size as Proxy for Paleopolyploidy in Vascular Plants Including Angiosperms (January 2014):
Paleogenome size in land plants is estimated from morphometric studies of stomatal guard cell length in this milestone paper that has direct bearing on evolution of seed plants and the origin of angiosperms. Data suggest a relationship between paleopolyploidy, extinction of neopolyploids, adaptive radiations, and the paleoecology of pCO2.
"Both palaeopolyploidy events [350 MYA and 200 MYA, Jiao et al. 2011] appear to coincide with relatively high, yet declining, atmospheric carbon dioxide concentration (Fig. 2c, d). However, using the fossil record rather than molecular dating techniques, the earlier event actually corresponds with the initial radiation of seed plants in the Late Devonian and Mississippian, while the latter is contemporaneous with the Triassic–Jurassic boundary and hence significantly pre-dates the earliest morphologically recognisable angiosperms (see Bateman and Hilton 2006) ..." (Page 639 and 640, Lomax et al. 2014).
Lomax, B. H., J. Hilton, R. M. Bateman, G. R. Upchurch, J. A. Lake, I. J. Leitch, A. Cromwell, and C. A. Knight. 2014. Reconstructing relative genome size of vascular plants through geological time. New Phytologist 201(2): 636–644.
Two key paleobiological papers (McElwain and Punyasena 2007, Retallack 2009) provide additional overlooked commentary on the use of stomatal indices as proxies "for past CO2 spikes."
McElwain, J. C. and S. W. Punyasena. 2007. Mass extinction events and the plant fossil record. Trends in Ecology and Evolution 22(10): 548-557.
Retallack, G. J. 2009. Greenhouse crises of the past 300 million years. GSA Bulletin 121(9-10): 1441-1455.
For purposes of future morphological phylogenetic analyses of seed plants the stomatal characters listed in Table 1 by Rudall et al. (Pages 602-603, 2013) should be employed by students, and polarity arguments posed by these authors must be discussed.
Rudall, P. J., J. Hilton, and R. M. Bateman. 2013. Several developmental and morphogenetic factors govern the evolution of stomatal patterning in land plants. New Phytologist 200(3): 598-614.
Amborella Is American Association for the Advancement of Science (AAAS) Genome of the Year (December 2013):
Volume 342, Number 6165 of Science publishes three significant papers on paleopolyploidy and the genome ecology of Amborella trichopoda, which is a specialized, root-sprouting understory endemic shrub of the high island of New Caledonia (Nouvelle Caledonie), southwest Pacific Ocean.
"The Amborella genome is a pivotal reference for understanding genome and gene family evolution throughout angiosperm history. Genome structure and phylogenomic analyses indicate that the ancestral angiosperm was a polyploid with a large constellation of both novel and ancient genes that survived to play key roles in angiosperm biology" (Structured Abstract Discussion, Amborella Genome Project 2013).
Amborella Genome Project. 2013. The Amborella genome and the evolution of flowering plants. Science 342(6165): 1467.
"Transposable elements in Amborella are ancient and highly divergent, with no recent transposon radiations" (Abstract, Amborella Genome Project 2013).
Earlier installments of this ongoing work were published in Genome Biology by D. E. Soltis et al. (2008) and Zuccolo et al. (2011).
Detailed next-generation sequencing studies by Srikar Chamala et al. (2013) report use of fluorescence probes to disentangle and decipher the large genome of Amborella trichopoda (Amborellaceae), a nonmodel basal angiosperm.
Chamala, S., A. S. Chanderbali, J. P. Der, T. Lan, B. Walts, V. A. Albert, C. W. dePamphilis, J. Leebens-Mack, S. Rounsley, S. C. Schuster, R. A. Wing, N. Xiao, R. Moore, P. S. Soltis, D. E. Soltis, and W. B. Barbazuk. 2013. Assembly and validation of the genome of the nonmodel basal angiosperm Amborella. Science 342(6165): 1516-1517.
This issue of Science also contains a study on horizontal transfer (HT) of mitochondrial DNA in Amborella trichopoda.
Rice, D. W., A. J. Alverson, A. O. Richardson, G. J. Young, M. V. Sanchez-Puerta, J. Munzinger, K. Berry, J. L. Boore, Y. Zhang, C. W. dePamphilis, E. B. Knox, and J. D. Palmer. 2013. Horizontal transfer of entire genomes via mitochondrial fusion in the angiosperm Amborella. Science 342(6165): 1468-1473.
Research findings by the Palmer Lab on the mitochondrial genome of Liriodendron might be relevant.
Richardson, A. O., D. W. Rice, G. J. Young, A. J. Alverson, and J. D. Palmer. 2013. The "fossilized" mitochondrial genome of Liriodendron tulipifera: ancestral gene content and order, ancestral editing sites, and extraordinarily low mutation rate. BMC Biology 11: 29.
These workers adopt the curious phrase, "throughout angiosperm history," and suggest an asymptotic age for the origin of the clade "≈200 MYA," which is the approximate date of the end-Triassic mass extinction. Yet, fossil calibration and statistical inference on origin(s) or divergence(s) of the angiosperm stem(s) awaits further genomic and tool kit studies (Bliss et al. 2013), and paleobotanical evidence of amborellas (Krassilov and Golovneva 2004) should be discussed.
Krassilov, V. A. and L. B. Golovneva. 2004. A minute mid-Cretaceous flower from Siberia and implications for the problem of basal angiosperms. Geodiversitas 26(1): 5-15.
Paleontologic data will be required to validate molecular phylogenies (Peterson et al. 2007).
"The interface of these three subject areas (Figure 1 on Page 778), molecular evolution, evolutionary developmental ('evo-devo') biology, and palaeoecology, is the theme of Molecular Palaeobiology, as it [the approach] uniquely integrates the patterns written in the two historical records, genomic and geological ... "
The preceding statement is from Page 777 of Kevin J. Peterson, R. E. Summons, and P. C. J. Donoghue (2007), Molecular palaeobiology, Palaeontology 50(4): 775-804.
Paleohexaploidy i.e. the gamma (γ)- triplication at the heart of the radiation of eudicots (Jiao et al. 2012) is apparently absent in the evolutionary history of the New Caledonian endemic species Amborella trichopoda according to the studies cited above. This begs four (4) questions, among others:
Is the single paleopolyploid event discerned from study of the Amborella genome including an epsilon (ε)- whole genome duplication (WGD), which is depicted as the asterisk in the figured Structured Abstract of Amborella Genome Project (2013), part of the ancient alpha (α)- swarm of WGDs modeled by Jiao et al. (2011)?
If angiosperms in the broad sense are fundamentally paraphyletic (and/or polyphyletic), and WGDs (including the γ-triplication) are a result of classic allopolyploidy in paleopopulations of genetically unrelated evolutionary lines, how can a single ancestral Amborella genome be manifest "throughout angiosperm history" without genetic input from unrelated seed plant populations?
Should students of evo-devo recompute a combined morphological- and molecular phylogenetic analysis of flowering plants to reflect extreme conservation of the floral tool kit and to incorporate allopolyploidy at the base of the angiosperm stem(s)?
Since the reproductive branch bauplan of Caytonia is incongruent with most models of cone and floral evo-devo, should paleobotanists dispose of Caytoniales, which are basal to the flowering plant clade in several morphological- and combined morphological-molecular phylogenetic analyses of seed plants?
Students should read a review on the interplay of evo-devo and phylogenetics with the paleobiology of evolutionary scales and probabilities by David Jablonski (2000).
"Although the macroevolutionary exploration of developmental genetics has just begun, considerable progress has been made in understanding the origin of evolutionary novelty in terms of the potential for coordinated morphological change and the potential for imposing uneven probabilities on different evolutionary directions" (Jablonski 2000).
The preceding statement is quoted from the Abstract on Page 15 of David Jablonski (2000), Micro- and macroevolution: scale and hierarchy in evolutionary biology and paleobiology, Paleobiology 26(4): 15-52.
Further, angiosperms are sister to conifers, cycads, ginkgophytes, and gnetophytes in several molecular phylogenetic analyses of seed plants, and fossil pollen studies point to several possible Triassic flowering plant populations.
Based on solid morphological evidence the reproductive male and female spur shoots of "living fossil" ginkgos are homologous with angiosperm flowers (Christianson and Jernstedt 2009).
Christianson, M. L. and J. A. Jernstedt. 2009. Reproductive short-shoots of Ginkgo biloba: a quantitative analysis of the disposition of axillary structures. American Journal of Botany 96(11): 1957-1966.
Ginkgo biloba is suggested as a prospective "model gymnosperm" on page 588 of Rachel Spicer and A. Groover (2010).
Posit morphological and molecular tool kit findings (Melzer et al. 2010) and the phylogenetics of phytochrome protein amino acid sequences (Figure 4B on page 233, Mathews 2009) and concatenated angiosperm and gymnosperm DNA data sets (see Figure 3A on page 231 and source data in the cited references, Mathews 2009), the Ancestral Angiosperm Genome Project team should adopt Ginkgo biloba as a "poster boy [or girl]."
Mathews, S. 2009. Phylogenetic relationships among seed plants: persistent questions and the limits of molecular data. American Journal of Botany 96(1): 228-236.
Melzer, R., Y.-Q. Wang, and G. Theißen. 2010. The naked and the dead: the ABCs of gymnosperm reproduction and the origin of the angiosperm flower. Seminars in Cell & Developmental Biology 21(1): 118-128.
Papaveraceae from a Gallic (Aptian) Potomac Group Member of North American Appalachia (December 2013):
Jud, N. A. and L. J. Hickey. 2013. Potomacapnos apeleutheron gen. et sp. nov., a new early Cretaceous angiosperm from the Potomac Group and its implications for the evolution of eudicot leaf architecture. American Journal of Botany 100(12): 2437-2449.
This paper should be read together with an important book chapter (D. W. Taylor and Hickey 1996), and the study by Barral et al. (2013) on the anatomy and paleophysiology of Iterophyllum lobatum (a basal eudicot) from the Neocomian (Barremian) La Huérguina Formation of the European Iberian Peninsula.
Taylor, D. W. and L. J. Hickey. 1996. Chapter 9. Evidence for and implications of an herbaceous origin for angiosperms. Pp. 232-266 In: D. W. Taylor and L. J. Hickey (eds.), Flowering Plant Origin, Evolution, and Phylogeny. London: Chapman and Hall, 403 pp.
Barral, A., B. Gomez, T. S. Feild, C. Coiffard, and V. Daviero-Gomez. 2013. Leaf architecture and ecophysiology of an early basal eudicot from the early Cretaceous of Spain. Botanical Journal of the Linnean Society 173(4): 594-605.
Holometabolous Larvae, Coleopterids, Hymenopterids, and Early Bugs from the Carboniferous (November 2013):
Nature publishes a letter by a team of entomologists and paleobiologists revealing "unexpected Pennsylvanian eumetabolan diversity."
"The data suggest that the foundations of the eventually hyperdiverse Holometabola, comprising most modern-day insect species, were already well established in the Pennsylvanian." (Letter, André Nel et al. 2013).
Nel, A., P. Roques, P. Nel, A. A. Prokin, T. Bourgoin, J. Prokop, J. Szwedo, D. Azar, L. Desutter-Grandcolas, T. Wappler, R. Garrouste, D. Coty, D. Huang, M. S. Engel, and A. G. Kirejtshuk. 2013. The earliest known holometabolous insects. Nature 503(7475): 257-261.
"The 'key innovation' of metamorphosis, present in holometabolan larvae and some Paraneoptera, may have fostered the longevity of these taxa during the Pennsylvanian climatic oscillations and the Permian-Triassic extinction event" (Letter, André Nel et al. 2013).
Canalization of form and lability of insect body size is tied-in with arthropod brain hormone secretions and the 20E-ecdysone cascade of larval metamorphosis. Paleobiological implications of a deeply conserved holometabolan molecular tool kit should take into account the recent review on how insect larvae sense their size:
Callier, V. and H. F. Nijhout. 2013. Body size determination in insects: a review and synthesis of size- and brain-dependent and independent mechanisms. Biological Reviews 88(4): 944-954.
Further, students should pay attention to results of insect rearing studies that report larval gustatory sensing of ecdysone, sugars, and secondary plant products. Do insect larvae sense plant brassinosteroids that are structurally similar to 20E-ecdysone?
Zhang, H.-J., C. P. Faucher, A. Anderson, A. Z. Berna, S. Trowell, Q.-M. Chen, Q.-Y. Xia, and S. Chyb. 2013. Comparison of contact chemoreception and food acceptance by larvae of polyphagous Helicoverpa armigera and oligophagous Bombyx mori. Journal of Chemical Ecology 39(8): 1070-1080.
Do brassinolides effect development of beetle and thrip larvae that feed in plant tissue galleries such as crevices in massive shoot apical meristems (SAMs)?
Thummel, C. S. and J. Chory. 2002. Steroid signaling in plants and insects - common themes, different pathways. Genes and Development 16(24): 3113-3129.
Palaeo-evo-devo in Land Plants, Giant Stomata of Bennettitaleans, and Angiosperm Origins (November 2013):
A significant Tansley Review on stomatal evolutionary-development (evo-devo) with a critical reappraisal of subsidiary cell character homology has been published in the New Phytologist.
Rudall, P. J., J. Hilton, and R. M. Bateman. 2013. Several developmental and morphogenetic factors govern the evolution of stomatal patterning in land plants. New Phytologist 200(3): 598-614.
"Regarding the establishment of 'fossil fingerprints' as developmental markers for the regulation of stomatal patterning, we note that it is highly problematic to infer patterns of stomatal development based on the mere absence or presence of subsidiary cells in fossil cuticles" (page 610, Rudall et al. 2013).
This important review should be read together with three research articles on stomatal stem cell lineages, the seed plant cuticle tool kit and evolution of Class IV homeodomain leucine zipper genes in streptophytes.
Figure 1 on page 604 of Rudall et al. (2013) should be interpreted with caution as it is computed from older morphological character polarity and homology assessments, which are not supported by tool kit studies. As a class exercise to evaluate pitfalls of combined molecular and morphological phylogenies (see below), students have an opportunity to recompute seed plant evolutionary trees, and to calibrate these cladograms with fossils.
SEPALLATA Gene Expression, WGDs, and Neofunctionalization in the Monocot Floral Tool Kit (November 2013):
The Specht Lab has published a significant study of evo-devo in species of Zingiberales, which is important in understanding possible effects of paleopolyploidy on neofunctionalization of genes, gene regulatory networks (GRNs), and selection on monocotyledonous floral tool kit enzymes, polarity networks (PINs), and fertile short shoot morphologies.
Yockteng, R., A. M. R. Almeida, K. Morioka, E. R. Alvarez-Buylla, and C. D. Specht. 2013. Molecular evolution and patterns of duplication in the SEP/AGL6-like lineage of the Zingiberales: a proposed mechanism for floral diversification. Molecular Biology and Evolution 30(11): 2401-2422.
"This work contributes to a growing body of knowledge focused on understanding the role of gene duplications and the evolution of entire gene networks in the evolution of flower development" (Abstract, Yockteng et al. 2013).
Students of the evo-devo of cis-regulatory modules (CRMs), GRNs, and PINs of seed plant shoot apical meristems (SAMs) should take into account this review of theoretical approaches.
Alvarez-Buylla, E. R., E. Azpeitia, R. Barrio, M. Benítez, and P. Padilla-Longoria. 2010. From ABC genes to regulatory networks, epigenetic landscapes and flower morphogenesis: making biological sense of theoretical approaches. Seminars in Cell & Developmental Biology 21(1): 108-117.
Palynological Evidence of Flowering Plants from the Middle Triassic (Anisian) More Than 240 MYA (October 2013):
Yet another important study of pollen samples recovered from isolated sedimentary layers in [at least one] continuous stratigraphic sequence in two deep well cores, reports monosulcate, columellate palynomorphs, and Afropollis, from the Middle Triassic (Anisian) about 240 MYA.
Hochuli, P. A. and S. Feist-Burkhardt. 2013. Angiosperm-like pollen and Afropollis from the Middle Triassic (Anisian) of the Germanic Basin (Northern Switzerland). Frontiers in Plant Science, Plant Evolution and Development 4: Article 344.
The left-hand image is "PLATE I ¦ Scale bar[s] 10µm. (1), Pollen Type 1, specimen A, LM image (high focus)" (Hochuli and Feist-Burkhardt 2013): micrograph is reproduced by permission from Professor Peter A. Hochuli, Palaeontological Institute and Museum, University of Zürich, Zürich, Switzerland.
This study adds considerable weight to earlier work by these same authors (Hochuli and Feist-Burkhardt 2004), and to data reported by Bruce Cornet in the 1980s, suggesting a 100 million year old ghost lineage of enigmatic stem group angiosperms. Interestingly, the Weiach Bore Hole also yielded two types of Eucommiidites, extending the stratigraphic range of this well-known gymnosperm pollen form by more than 100 million years.
Hochuli, P. A. and S. Feist-Burkhardt. 2004. A boreal early cradle of angiosperms? Angiosperm-like pollen from the Middle Triassic of the Barents Sea (Norway). Journal of Micropalaeontology 23: 97-104.
"Whereas some authors considered it [Sanmiguelia] as an angiosperm [Brown 1956; Cornet 1986, 1989a] others suggested an attribution to ginkgophytes and rejected a possible relation to angiosperms [Crane 1987, Doyle and Donoghue 1993]" (Discussion-Cretaceous and Pre-cretaceous Records, Hochuli and Feist-Burkhardt 2013).
Definitive paleontological evidence published by Peter Hochuli and Susanne Feist-Burkhardt should be read together with a Sidney Ash and Stephen Hasiotis review of Sanmiguelia paleobiology, and their report of three new localities from the Blue Mesa Member (Norian) of the Lower Triassic Chinle Formation of southwestern North America.
Ash, S. R. and S. T. Hasiotis. 2013. New occurrences of the controversial late Triassic plant fossil Sanmiguelia Brown and associated ichnofossils in the Chinle Formation of Arizona and Utah, USA. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 268(1): 65-82.
Based on gene expression studies of extant angiosperm species does the foliar morphology, stem anatomy, and growth habit of Sanmiguelia display the fingerprint of an "ancestral developmental tool kit" (title, Floyd and Bowman 2007) of a monocotyledonous flowering plant?
Simply put, the wide-ranging and relatively abundant Norian Sanmiguelia should no longer be excluded from seed plant data sets and combined morphological- and molecular-phylogenetic analyses including possible use in calibration of tool kit phylogenies.
In 1985, Peter Crane presented an interesting idea namely, that some populations of late Paleozoic Vojnovskyales might have survived the end-Permian extinction (PTr) reappearing in the Triassic rock record as the seed plant Sanmiguelia.
"The male structures [of Sanmiguelia] appear to be strobili with sessile pairs of pollen sacs, more reminiscent of ginkgophytes than angiosperms, and the smooth monosulcate pollen has no angiosperm features" (page 319, J. A. Doyle 2012).
Doyle, J. A. 2012. Molecular and fossil evidence on the origin of angiosperms. Annual Review of Earth and Planetary Sciences 40: 301–326.
Are certain Permo-carboniferous Ginkgophyta and Vojnovskyales paraphyletic gymnosperm clades tied-in with Triassic sanmiguelias and possible stem group angiosperms?
Finally, students of a Triassic origin of angiosperms and the paleopalynology of Afropollis should read two reviews by Doyle et al. (1990 [see page 1549]). Discovery of Afropollis in stratigraphically precise layers of Triassic sediments by Hochuli and Feist-Burkhardt (2013) confounds a phylogeny of the pollen of Winteraceae proposed by James A. Doyle and coworkers (Figure 2 on page 1562), clouds serious consideration of Caytoniales as possible flowering plant antecedents, and obviates a Neocomian (mid-Hauterivian) origin of flowering plants.
Doyle, J. A., C. L. Hotton, and J. V. Ward. 1990. Early Cretaceous tetrads, zonasulculate pollen, and Winteraceae. I. Taxonomy, morphology, and ultrastructure. American Journal of Botany 77(12): 1544-1557.
Doyle, J. A., C. L. Hotton, and J. V. Ward. 1990. Early Cretaceous tetrads, zonasulculate pollen, and Winteraceae. II. Cladistic analysis and implications. American Journal of Botany 77(12): 1558-1568.
Evidence of Paleopolyploidy in Conifers: Preadaptation to Climate of the Early Triassic Hot House (October 2013):
Volume 280, Number 1768 of the Proceedings of the Royal Society of London, Series B, Biological Sciences (2013) publishes data on a Classopollis myerianus palynofloral zone of the Whitmore Point Member of the Triassic Moenave Formation of southwestern North America.
Kürschner, W. M., S. J. Batenburg, and L. Mander. 2013. Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic-Jurassic transition. Proceedings of the Royal Society of London, Series B, Biological Sciences 280(1768): 20131708.
Cheirolepidiaceae were abundant and morphologically diverse Araucaria- or Cupressus-like shrubs and trees indigenous to forests of Triassic Pangaea, which were dispersed as the supercontinent split following the eruption of the Central Atlantic Magmatic Province (CAMP) to Gondwanan and Laurasian places of later Jurassic and Cretaceous times. Classopollis (unique conifer pollen with angiosperm-like exine and tectate columellae) were shed from cones of male plants and dispersed by wind to fleshy bitegmic ovules on cone scales of mother shrubs and trees, which were indigenous to coastal terrestrial habitats (pages 831-838, T. N. Taylor et al. 2009).
Detailed paleobiological studies by Wolfram Kürschner et al. (2013) constitute the first report of unreduced gamete formation (inferred from light microscopic study of dispersed pollen) in a vascular plant, which dovetails with molecular-phylogenetic modeling by Jiao et al. (2011) documenting a swarm of whole genome duplications (WGDs) in seed plants, about 192 MYA:
Jiao, Y., N. L. Wickett, S. Ayyampalayam, A. S. Chanderbali, L. Landherr, P. E. Ralph, L. P. Tomsho, Y. Hu, H. Liang, P. S. Soltis, D. E. Soltis, S. W. Clifton, S. E. Schlarbaum, S. C. Schuster, H. Ma, J. Leebens-Mack, and C. W. dePamphilis. 2011. Ancestral polyploidy in seed plants and angiosperms. Nature 473(7345): 97-100.
Can paleobotanists find anatomical evidence of paleopolyploidy in hybridizing populations of the most recent common ancestor (MRCA) of extant seed plants, which were indigenous Euramerican cratons and island paleoenvironments of the early Carboniferous icehouse, to verify the alpha- (α-) peak of seed plant WGDs, about 319 MYA? Some allopolyploids might have been angiosperm sister groups to conifers, cycads, ginkgophytes, and gnetophytes of the Permo-Carboniferous.
Yet, some paleobotanists suggest a monophyletic origin of flowering plants in the Jurassic or Cretaceous, a hypothesis which is based on APG III analyses combined with morphological-phylogenetic data. Which hypothesis is supported by fossil-calibrated molecular- and morphological-phylogenetic analyses of seed plant homeodomain proteins including WUSCHEL and mobile transcription factors (TFs)?
Gene Expression Studies of Spruce Illuminate Conifer Cone Organ Homologies in Deep Time (October 2013):
Carlsbecker, A., J. F. Sundström, M. Englund, D. Uddenberg, L. Izquierdo, A. Kvarnheden, F. Vergara-Silva, and P. Engström. 2013. Molecular control of normal and acrocona mutant seed cone development in Norway spruce (Picea abies) and the evolution of conifer ovule-bearing organs. New Phytologist 200(1): 261-275.
"Our morphological and gene expression analyses give support to the hypothesis that the modern cone is a complex structure, and the ovuliferous scale the result of reductions and compactions of an ovule-bearing axillary short shoot in cones of Paleozoic conifers" (page 261, Carlsbecker et al. 2013).
A commentary (Ruelens and Geuten 2013) on this study by Peter Engström and coworkers, discusses spur shoot-like ovuliferous organ development in Picea abies var. acrocona mutants within the context of Permian Pseudovoltzia liebeana and Thuringiostrobus florinii cone anatomy and expression patterns of angiosperm LFY and the SEP (MIKC-type MADS-box E) gene family.
Ruelens, P. and K. Geuten. 2013. When paleontology and molecular genetics meet: a genetic context for the evolution of conifer ovuliferous scales. New Phytologist 200(1): 10-12.
"... the phylogeny of gymnosperms and their relationship to flowering plants remains debated as morphological and molecular analyses contradict each other on key relationships" (page 10, Ruelens and Geuten 2013).
Students of seed plant evolution have an opportunity to reassess character homologies and to recompute combined morphological and tool kit phylogenies calibrated by fossils, which may encourage classroom debate on the origin of flowering plants.
Contrasting Patterns of Stomatal Development in Basal Angiosperms Confirmed by Ultrastructure (October 2013):
Rudall and Knowles (page 1032, 2013) state an important caveat:
"Developmental studies of these phylogenetically pivotal taxa [Amborella, Austrobaileya, Schisandra] are essential to understand both the homologies of stomatal types and the evolution of stomatal development in angiosperms."
Rudall, P. J. and E. V. W. Knowles. 2013. Ultrastructure of stomatal development in early-divergent angiosperms reveals contrasting patterning and pre-patterning. Annals of Botany 112(6): 1031-1043.
This study confirms that some water-lilies (Nymphaeales) lost stomate developmental asymmetry while Amborella and Austrobaileya retain the putatively plesiomorphic character state, which is paracytic resulting from "... at least one asymmetric [cell] division ..."
More data from extant and fossil magnoliids and monocots are needed in order to shed light on ancestral character states of subsidiary cells and to understand stomatal evo-devo from ecophysiological and tool kit perspectives.
Major Trends in Vein Packing and Hydraulic Function in Early Angiosperms Are Evident (August 2013):
Feild, T. S. and T. J. Brodribb. 2013. Hydraulic tuning of vein cell microstructure in the evolution of angiosperm venation networks. New Phytologist 199(3): 720-726.
When "Baileyan trends," are revealed from future analyses of innovative third and fourth order venation patterns, high DV, and complex hydraulic conduit microstructure (including protoxylem, metaxylem, and a 2° vascular cambium) documented in thin-sectioned, permineralized Gnetum-like Permian leaves, does Figure 2 on page 723 of Feild and Brodribb (2013) become more intriguing?
Angiosperm-like fossilized leaves, midribs, and wood of Permian gigantopterids (seed plants incertae cedis), which were not studied by Feild and Brodribb (2013), have been discussed in the paleophysiologic literature (page 350, Wilson and Knoll 2010).
"... vegetative features of gigantopterids suggest that they may resemble medullosans and angiosperms in functional [morpho] space, rather than conifers."
Wilson, J. P. and A. H. Knoll. 2010. A physiologically explicit morphospace for tracheid-based water transport in modern and extinct seed plants. Paleobiology 36: 335-355.
Further, Wilson and Knoll (page 344, 2010) state an important point in the introductory paragraph of the discussion on wood evolution and their analyses of hydraulic morphospaces:
"Molecular phylogenies suggest that angiosperms are sister to all other living seed plants."
Feild and Brodribb data (page 723, 2013) apparently motivated these workers to hypothesize that "... angiosperms represent the only clade that evolved a xylem conduit anatomy sufficiently conductive to permit miniature vessels to maintain water supply ..."
Why not execute a paleobiological project to assess documented examples of anatomical, hydraulic, and foliar innovations in seed plants that were indigenous to Permian terrestrial paleoenvironments, and to conduct phylogenetic tests of possible xylem heterochronies, calibrated by fossils?
MADS-box B Sister TFs in Bitegmic Ovules of Ginkgo Function in Development of a Fruit-like Organ (August 2013):
Lovisetto, A., Guzzo, F., Busatto, N., and G. Casadoro. 2013. Gymnosperm B-sister genes may be involved in ovule/seed development and, in some species, in growth of fleshy fruit-like structures. Annals of Botany 112(3): 535-544.
According this genetic study ... "a strong level of [MADS-box B sister] expression was maintained throughout the ovule [of Ginkgo biloba] also in later stages of development, when a layered organization of the integument had clearly developed, and both the inner and the outer integuments could be distinguished [Fig. 2H]" (page 537, Lovisetto et al. 2013).
Conversely, can ategmic ovules develop by fusion of integuments? Yes, according to R. H. Brown et al. (2010).
Brown, R. H., Nickrent, D. L. and C. S. Gasser. 2010. Expression of ovule and integument-associated genes in reduced ovules of Santalales. Evolution and Development 12(2): 231-240.
Is the bitegmic ovule an angiosperm-specific character? No.
Based on gene expression data and studies of plant development in extant model plant species, should paleobotanists reconsider homologies of angiosperm and ginkgoalean integuments and a common evo-devo of ovules attached to megasporophylls of reproductive spur shoots?
RAM Organization in Nymphaeales Is Similar to Acorales While Amborella Roots Are Eudicot-like (July 2013):
Oxford Journals publishes a review on root apical meristem (RAM) evo-devo in angiosperms.
Seago, J. L., Jr. and D. D. Fernando. 2013. Anatomical aspects of angiosperm root evolution. Annals of Botany 112(2): 223-238.
What is the putative relationship of mycorrhizal fungi to strigolactones and the RAM tool kit when placed in an ecological and phylogenetic context? Students can mine more information in this same issue of the Annals of Botany, and from a related book chapter:
Koltai, H. L. 2013. Strigolactones activate different hormonal pathways for regulation of root development in response to phosphate growth conditions. Annals of Botany 112(2): 409-415.
Koltai, H., R. Matusova, and Y. Kapulnik. 2012. Strigolactones in root exudates as a signal in symbiotic and parasitic interactions. Pp. 49-73 In: J. M. Vivanco and F. Baluška (eds.), Secretions and Exudates in Biological Systems, Signaling and Communication in Plants Volume 12. New York: Springer, 283 pp.
DNA-binding LFY Protein and Auxin Comprise Modules Determining Floral Primordia in Malvid SAMs (May 2013):
The Society of Experimental Biology publishes another important study on the evo-devo of SAM primordia and the floral tool kit.
Chahtane, H., G. Vachon, M. Le Masson, E. Thévenon, S. Périgon, N. Mihajlovic, A. Kalinina, R. Michard, E. Moyroud, M. Monniaux, C. Sayou, V. Grbic, F. Parcy, and G. Tichtinsky. 2013. A variant of LEAFY reveals its capacity to stimulate meristem development by inducing RAX1. The Plant Journal 74(4): 678-689.
A related paper from the recent archives of Cell Press sheds light on the biochemistry of LEAFY genes, auxins, and TFs in malvids:
Yamaguchi, N., M.-F. Wu, C. M. Winter, M. C. Berns, S. Nole-Wilson, A. Yamaguchi, G. Coupland, B. A. Krizek, and D. Wagner. 2013. A molecular framework for auxin-mediated initiation of flower primordia. Developmental Cell 24(3): 271-282.
A growing body of biochemical and morphological evidence suggests that cones and flowers are reproductive short shoots. Fertile spur shoots are demonstrably ancient organs known from Permo-carboniferous seed plant fossils. Further, numerous molecular phylogenetic studies of homeodomain proteins and TFs posit deep conservation of cone and floral CRMs, GRNs and PINs.
Can we compute a molecular phylogeny of LFY enzyme and its DNA-binding homeodomain, which is calibrated by fossils of cones and protoflowers, to better understand starting points of floral tool kit function and to discern evolutionary patterns in deep time?
Annual Review of Earth and Planetary Sciences Discusses Late Paleozoic Insect-Plant Associations (May 2013):
Labandeira, C. C. and E. D. Currano. 2013. The fossil record of plant-insect dynamics. Annual Review of Earth and Planetary Sciences 41: 287-311.
The most recent review on paleoherbivory and recovery of Permian landscapes following global biotic crises is published by Annual Reviews.
A second review in this volume by Montañez and Poulsen on the demise of the Upper Devonian and Lower Carboniferous icehouse should set a stage for interacting arthropods and seed plants of the Permo-triassic hothouse.
Montañez, I. P. and C. J. Poulsen. 2013. The late Paleozoic ice age: an evolving paradigm. Annual Review of Earth and Planetary Sciences 41: 629-656.
Evolutionarily Advanced Magnoliales and Nymphaeales from a Gondwanan Crato Paleoflora (February 2013):
Clément Coiffard and co-workers report a definitive fossil find of crown group Nymphaeales from the early Cretaceous South American Crato Formation.
Coiffard, C., B. A. Mohr, and M. E. C. Bernardes-de-Oliveira. 2013. Jaguariba wiersemana gen. nov. et sp. nov., an early Cretaceous member of crown group Nymphaeales (Nymphaeaceae) from northern Gondwana. Taxon 62(1): 141-151.
The left-hand image is Figure 1B on page 144 of Coiffard et al. (2013), "Jaguariba wiersemana gen. nov. et sp. nov.: morphology. B, complete plant, paratype (1999/615)." The scale bar at the lower right of the image is 1 cm.
Figure 1B is reproduced by permission from the International Association for Plant Taxonomy, Bratislava, Slovak Republic through Professor Joachim W. Kadereit, Editor-in-chief of Taxon, International Journal of Taxonomy, Phylogeny and Evolution, copyright ©2013.
This original research work should be read together with Barbara Mohr et al. (2013) on the discovery of the novel magnolialean species, Schenkeriphyllum glanduliferum from the Crato beds, to include revisiting important earlier discussions on biogeography, character evolution, and paleobotany of magnoliids by Bernhardt, Dilcher, J. A. Doyle, Endress, R. M. K. Saunders, Thien, and others (citations and discussion in the links to articles and the essay):
Mohr, B. A., C. Coiffard, and M. E. C. Bernardes-de-Oliveira. 2013. Schenkeriphyllum glanduliferum, a new magnolialean angiosperm from the early Cretaceous of northern Gondwana and its relationships to fossil and modern Magnoliales. Review of Paleobotany and Palynology 189: 57-72.
Together with Endressinia brasiliana these magnoliids possess putatively secreting staminodia not unlike extant Calycanthaceae, Degeneriaceae, and Eupomatiaceae. Many questions surface from morphological-phylogenetic, paleobotanical, and stratigraphic studies of South American sedimentary deposits of Gondwana by Clément Coiffard, Barbara Mohr, and others:
Can the Mohr et al. morphological-phylogenetic analysis (page 66-68, plate IX, 2013) of South American Crato Endressinia and Schenkeriphyllum, including Australasian Galbulimima (Himantandraceae, Magnoliales, Magnolianae) and Fijian Degeneria allow for a phylogeographic understanding of the paleobiology of common ancestors of these four Gondwanan genera with Laurasian magnoliids?
Do discoveries of fossilized remains from the Lower Cretaceous Crato Formation, which are referable to modern Nymphaeanae and core Magnolianae open a window to better understand origins and paraphyletic lines of evolution in basal flowering plants and magnoliids? Does the discovery of early Cretaceous fossil aroids including Spixiarum kipea from the Crato Paleolake complicate APG III after calibrating the basal angiosperm-monocot split?
Coiffard, C., B. A. Mohr, and M. E. C. Bernardes-de-Oliveira. 2013. The early Cretaceous aroid, Spixiarum kipea gen. et sp. nov., and implications on early dispersal and ecology of basal monocots. Taxon 62(5): 997-1008.
Further, does a supposed monophyletic origin of these geographically widespread, harmonic flowering plant groups with a derived (phenotypically specialized and genomically miniaturized) New Caledonian endemic Amborella trichopoda make evolutionary and phylogeographic sense, taking into account Loren Kroenke's neglected review of the complex and intriguing Mesozoic tectonic history of the southwest Pacific Basin with blocks of ancient, buried continental crust and shifting systems of ocean basins, island arcs, and subduction zones?
Kroenke, L. W. 1984. Chapter 2. New Caledonia: the Norfolk and Loyalty ridges; the New Caledonia and Loyalty Basins. Pp. 15-28 In: Cenozoic Tectonic Development of the Southwest Pacific. United Nations ESCAP, CCOP/SOPAC Technical Bulletin No. 6.
Cytochrome P450 Theme Issue Is Published by The Royal Society (February 2013):
Volume 368, Number 1612 of the Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences (2013), edited by David R. Nelson, is devoted to a discussion of the ancient protein family of cytochrome P450 enzymes.
Animals, fungi, microbes, and plants contain more than 18,000 molecular configurations of these fascinating enzymes, which are involved in the biosynthesis of anthocyanins, cutin, lignin, sporopollenin, steroids, suberin, and terpenoids, including compounds at the heart of the "chemical arms race."
These enzymes often act in concert with R2R3 MYB transcription factors (TFs) involved in the catalysis of flavonoid biosynthesis. Flavonoids are important signaling molecules in seed plants, which interact with the PIN proteins of auxin regulation. Anthocyanins and flavonols are localized in epidermal cone cells and nectar guides of flower petals acting as optical cues for insect and bird pollinators.
Based on extreme conservation of R2R3 myeloblastosis (MYB) homeodomain oncoproteins and some cytochrome P450s, were Paleozoic protoflowers colored and visualized by flying insects such as paleodictyopterans?
Cold Spring Harbor Symposium Book Volume on The Biology of Plants Is Available (January 2013):
The Cold Spring Harbor Laboratory held a symposium from May 30 to June 4, 2012 titled, "The Biology of Plants." Four of the workshop contributions, among others, are important toward a better understanding of the evo-devo of seed plant organs, ecophysiology and character homologies of the stomatal apparatus, and paleobiology of the pollination mutualism.
Bolduc, N., D. O'Connor, J. Moon, M. Lewis, and S. Hake. 2012. How to pattern a leaf. Cold Spring Harbor Symposia on Quantitative Biology 77: 47-51.
Plavskin, Y. and M. C. P. Timmermans. 2012. Small RNA-regulated networks and the evolution of novel structures in plants. Cold Spring Harbor Symposia on Quantitative Biology 77: 221-233.
Sheehan, H., K. Hermann, and C. Kuhlemeier. 2012. Color and scent: how single genes influence pollinator attraction. Cold Spring Harbor Symposia on Quantitative Biology 77: 117-133.
Wengler, D. L. and D. C. Bergmann. 2012. On fate and flexibility in stomatal development. Cold Spring Harbor Symposia on Quantitative Biology 77: 53-62.
Macmillan Publishers News of a Preserved Arthropod Brain from Cambrian Rocks (October 2012):
Nature publishes a letter by a team of entomologists and paleobiologists having a bearing on the evo-devo of neuropils associated with the brain, and homologies with sensory organs of advanced crustaceans and insects:
Ma, Xiaoya, X. Hou, G. D. Edgecombe, and N. J. Strausfeld. 2012. Complex brain and optic lobes in an early Cambrian arthropod. Nature 490(7419): 258-262.
A fossilized brain from a Cambrian stem group arthropod is evidence of the early existence of an extremely conserved and sophisticated olfactory and visual sensory system in these animals ... Did evo-devo of insect eyes, mushroom bodies, neuropils, and trichromatic vision predate late Paleozoic pollen phytophagy and flying predatory behaviors of paleodictyopterans and wasps?
The left-hand image is reproduced from Figure 1 on page 258 of X. Ma et al. (2012), "Fuxianhuia protensa from the Chengjiang Lagerstätte. Dorsal view of complete specimen, YKLP 11321. A1, antenna; Ab, abdomen; Es, eye stalk; Ey, eye; Hs, head shield; Oc, optic capsule; Th, thorax. Scale bar, 1 cm." Figure 1 is licensed and reprinted by permission from Macmillan Publishers Ltd and the journal Nature, copyright ©2012.
Ecologists should compare this paleobiological study with earlier work by Chittka (1996), Briscoe and Chittka (2001), and Chittka et al. (2001). Implications of these three studies toward an understanding of the deep time evolution of pollination mutualisms and color and scent perception by species of the "Big Five" holometabolous insect orders and late Paleozoic seed plants, when taking into account the paleobiology of the arthropod brain, are absolutely profound.
"It is likely that trichromacy existed prior to the advent of angiosperm flowers" (page 138, Chittka 1996).
Chittka, L. 1996. Does bee color vision predate the evolution of flower color? Naturwissenschaften 83: 136-138.
Briscoe, A. D. and L. Chittka. 2001. The evolution of color vision in insects. Annual Review of Entomology 46: 471–510.
Chittka, L., J. Spaethe, A. Schmidt, and A. Hickelsberger. 2001. 6. Adaptation, constraint, and chance in the evolution of flower color and pollinator color vision. Pp. 106-126 In: L. Chittka and J. D. Thomson (eds.), Cognitive Ecology of Pollination, Animal Behaviour and Floral Evolution. Cambridge: Cambridge University Press, 344 pp.
Protoflowers known only from fragments and detached megasporophylls were probably modifications of developmentally plastic bisexual cone axes representing divergent clades of several Permian gymnosperms that survived the end-Permian apocalypse. When supported by paleobotanical evidence, were anthocyanic, pinwheel shaped fertile short (spur) shoots of Permo-carboniferous seed plants visually discernable to pollinivores, paleodictyopterans, and predatory wasps?
"Hence, a flower that stands out against green foliage can be predicted to be equally conspicuous against brown soil, grey stones and other inorganic backgrounds" (page 1505, Chittka et al. 1994).
Chittka, L., A. Schmidt, N. Troje, and R. Menzel. 1994. Ultraviolet as a component of flower reflections, and the colour perception of Hymenoptera. Vision Research 34: 1489-1508.
Annals of Botany Publication on Secondary Pollen Receptive Surfaces (August 2012):
Transferential stigmatic tool kit function to a foliar organ of an angiosperm flower ... can petals act as male-receptive female organs? Oxford Journals publishes a paper by a team of entomologists and plant biologists having a bearing on the evo-devo of the carpel and evolution of a pollination mutualism with the foliar organ of a monocot flower.
Johnson, S. D., A. Jürgens, and M. Kuhlmann. 2012. Pollination function transferred: modified tepals of Albuca (Hyacinthaceae) serve as secondary stigmas. Annals of Botany 110(3): 565-572.
Annual Review of Earth and Planetary Sciences Publishes Research on the Origin of Flowering Plants (May 2012):
Doyle, J. A. 2012. Molecular and fossil evidence on the origin of angiosperms. Annual Review of Earth and Planetary Sciences 40: 301–326.
The most recent review to date on the origin of flowering plants is published by Annual Reviews. The review is the latest installment of Professor Doyle's more than 35 years of research on the origin of angiosperms.
Annual Review of Ecology, Evolution, and Systematics Revisits Ehrlich and Raven (December 2011):
Annual Reviews, a non-profit scientific organization, publishes a paper by Niklas Janz that critiques Paul Ehrlich and Peter Raven’s classic 1964 article on plant and lepidopteran mutualisms:
Janz, N. 2011. Ehrlich and Raven revisited: mechanisms underlying codiversification of plants and enemies. Annual Review of Ecology, Evolution, and Systematics 42: 71-89.
Yale University Research on the Triassic Origin of Flowering Plants (March 2010):
Molecular phylogenetic studies by Yale University colleagues suggest a late Triassic age for the flowering plant crown group (March 2010).
Contrary to assertions reported in the Science Daily, Stephen A. Smith et al. (2010) are not the first scientists to propose a Triassic origin of angiosperms. Bruce Cornet, Ph.D. should receive credit for his quite correct and detailed arguments in support of a Triassic origin of flowering plants, which appear in two papers published in 1986 and 1989.
Students have ample opportunities to compare and contrast relaxed-clock methods and to discuss Bayesian priors when comparing angiosperm and seed plant phylogenies computed by Bell et al. (2010) with Stephen A. Smith et al. (2010) and Magallón (2010).
Bell, C. D., D. E. Soltis, and P. S. Soltis. 2010. The age and diversification of the angiosperms revisited. American Journal of Botany 97: 1296-1303.
Magallón, S. 2010. Using fossils to break long branches in molecular dating: a comparison of relaxed clocks applied to the origin of angiosperms. Systematic Biology 59(4): 384-399.
Discussion Meeting Issue "Darwin and the Evolution of Flowers" (February 2010):
Volume 365, Number 1539 of the Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences (2010), edited by Peter R. Crane, Else Marie Friis, and William G. Chaloner is devoted to a discussion of Charles Darwin and the origin of flowers.
Fifteen articles are devoted to the topic including papers by:
Endress, P. A. 2010. The evolution of floral biology in basal angiosperms. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 365(1539): 411-421.
Friis, E. M., K. R. Pedersen, and P. R. Crane. 2010. Diversity in obscurity: fossil flowers and the early history of angiosperms. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 365(1539): 369-382.
Jasinski, S., A. C. M. Vialette-Guiraud, and C. P. Scutt. 2010. The evolutionary-developmental analysis of plant microRNAs. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 365(1539): 469-476.
Mathews, S., M. D. Clements, and M. A. Beilstein. 2010. A duplicate gene rooting of seed plants and the phylogenetic position of flowering plants. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 365(1539): 383-395.
Rudall, P. J. and R. M. Bateman. 2010. Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili. Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences 365(1539): 397-409.
Charles Darwin Bicentennial issue of the American Journal of Botany (January 2009). The January 2009 issue of the American Journal of Botany explores the origin, evolution, and radiation of flowering plants. More than twenty articles are devoted to the topic.
Contributions to the revised Jepson Manual (July 2008). John and the original authors of The Jepson Manual: Higher Plants of California (Hickman 1993) have revised and submitted treatments of Anacardiaceae (Malosma, Pistacia, Rhus, Schinus, and Searsia), Cucurbitaceae (Brandegea, Citrullus, Cucumis, Cucurbita, and Marah), Lamiaceae (Acanthomintha, Glechoma, Hedeoma, Lycopus, Marrubium, Melissa, Moluccella, Nepeta, Poliomintha, Prunella, Salazaria, Satureja, and Teucrium), and Montiaceae (Calandrinia, Calyptridium [with C. Matt Guilliams], Cistanthe [with C. Matt Guilliams], Claytonia, Lewisia, and Montia), for The Jepson Manual: Vascular Plants of California, Second Edition.
Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken (eds.). 2012. The Jepson Manual: Vascular Plants of California, Second Edition. Berkeley: University of California Press, 1568 pp.
Systematics of Claytonia [Portulacaceae] (July 2006). John M. Miller, Ph.D. and Kenton L. Chambers, Ph.D. have published a taxonomic monograph titled, Systematics of Claytonia (Portulacaceae), culminating more than 40 years of research on a biogeographically significant group of flowering plants, which are indigenous to the mountain chains of Asia and North America.
The image to the right consists of several tetraploid plants of Claytonia parviflora subsp. parviflora from the Greenhorn Mountains of western North America.
Interested persons may order a copy of the hardbound Volume 78 of this serial through the American Society of Plant Taxonomists Business Manager. Booksellers, botanists, and buyers should also consult the home page of Systematic Botany Monographs.
Death Valley desert blooms (April 2005). The 2005 bloom season was extraordinary on the floor and alluvial debris fans of Death Valley, a graben located east of the Panamint Mountains, Death Valley National Park, Inyo County, California, USA. The author and his associates visited the region in April 2005 and captured these images, among others.
To the left is an image of a Holocene debris fan of the Amargosa Mountains (the Panamint Mountains are to the right): the yellow color is a population of Geraea canescens (Asteraceae, Asterales, Asteranae). To the right is a close-up of Eremalche rotundiflora (Malvaceae, Malvales, Rosanae) photographed by Homer Hobi (who accompanied John together with Ed Dipesa, now deceased).
Fairy lantern field biology (April 2004). Together with Tim Armstrong, the author discovered a previously undocumented population of Calochortus pulchellus (Liliaceae, Liliales, Lilianae) from a volcanic plateau in southern Solano County, California, which is not far from the Willis Linn Jepson Ranch.
The Mount Diablo fairy lantern was previously known from Contra Costa County on Mount Diablo, a prominent mountain peak of the Diablo Range rising above the foothills south of the Carquinez Straits and Suisun Bay of western North America.
Students may wish to read about Calochortus pulchellus in recent biosystematic studies of some Calochortus species published by Bryan Ness in 1989 (Systematic Botany 14:495-505).
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