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On the other hand, certain hemimetabolous bugs (Hemiptera) possess abdominal stretch receptors that activate secretion of PTTH (Nijhout 2003). 2005, among others) of the Drosophila Hox complex are: Ancestral arthropods possess two additional homeotic selector genes of the Hox cluster that together comprise the HOM-C, ten gene complex (see discussion in Negre et al. These additional genes are: Genomic analyses suggest that derived winged insects lost functional copies of ftz and Hox3 through disintegration of the HOM-C complex (Negre et al. Duplication of the Hox3 gene of ancestral Cyclorrhaphan flies gave rise to two maternal effect genes, bcd and zen (Stauber et al. Based upon this study it is important to include Hox3 as part of the ancestral diverging insect developmental tool kit. Possible candidates for the early divergent insect developmental tool kit might include certain homeotic selector genes of the Hox complex such as homologs and paralogs of abd-A, Abd-B, Hox3, pb, Scr (Rogers et al. 2002) are probably behind many insect body plan novelties seen in the paleontologic record of the past 400 million years of arthropod and crustacean evolution (Pavlopoulos and Akam 2011, Pavlopoulos and Averof 2002). Plant evolution occurs as variation in genetic and epigenetic developmental processes is winnowed by ecology..." The preceding quotation is from page 161 of P. Once JH circulating in the hemolymph is destroyed by juvenile hormone esterases, then PTTH secretion resumes under circadian (22-24 hour) photoperiodic control (Nijhout 2003). The importance of Ubx protein encoded by the Ubx gene in the early divergent insect developmental tool kit cannot be neglected in the present analysis since significant changes in the carboxy-terminal (C-terminal) region (Galant and Carroll 2002) and serine/threonine phosphorylation sites (Ronshaugen et al.
Some of the historical syntheses include Arber and Parkin (1907), I. Bailey (1949), Edgar Anderson (1934), Axelrod (1952, 1970), Leppik (1960, 1968), Raven and Kyhos (1965), Cronquist (1968), Thorne (1968), Melville (1969), Takhtajan (1969, 1976, 1991), Raven and Axelrod (1974), Stebbins (1958, 1974), C. Beck (1976), Hughes (1976, 1994), Meeuse (1979), Nair (1979), Krassilov (1977), Retallack and Dilcher (1981 [two papers]), Asama (1982, 1985), Melville (1983), Crane (1985), Meyen (1986, 1988), Dilcher (1986, 2000), J. Doyle and Donoghue (1986, 1987), Endress (1987), Friis et al. If the answer to the preceding question is "yes," how does this evo-devo mechanism affect arthropod antagonist body allometries and population ecology? Further, the evo-devo of flight is yet another conundrum in paleoentomology (Grimaldi and Engel 2005). Poleward migration of early angiosperm flora - angiosperms only displaced the relict Jurassic-type flora at high latitudes in late Cretaceous time.
(2017) compile particularly relevant reference lists. Flowering material of Degeneria vitiensis is shown in the right-hand image (photographed by Paddy Ryan, Ph. Fragrance of this species resembles Cananga odorata according to Professor Al Smith (A. While discussing the effects of ice-house/hot house planetary climatic switches on expansion of land plant invertebrate herbivores Labandeira (2006) states: "One possibility is that these atmospheric variables have direct physiologic consequences on the selection and turnover of particular plant clades globally, which in turn elicit an associational response from selected clades of insect herbivores." The preceding statement is quoted from page 425 of C. Labandeira (2006), The four phases of plant-arthropod associations in deep time, Geologica Acta 4(4): 409-438. Additional compilations on the origin of angiosperms and floral morphology include Krassilov (1991), Thorne (1992), Endress (1993, 2001 [a book chapter and two papers], 2004), Friedman (1992 [two papers]), Stewart and Rothwell (1993), Nixon et al. Studies on Drosophila melanogaster eggs, specifically, artificial size-selection experimentation, affects larval patterning and body allometry (Miles et al. Do host seed plant brassinolides and other hormones affect insect antagonist egg size, potentially controlling larval tissue patterning? At the very earliest, flying insects were known from the Devonian Period.
Studies of evolving allometries and body plans might help us understand a possible coevolutionary origin of angiosperms and certain clades of holometabolous phytophagous insect antagonists. Molecular control over arthropod growth varies among the major clades of insects (Grimaldi and Engel 2005).
2007) could potentially be discerned in the fossil record. (2005) review molecular evolution of homeotic genes and homeodomain TFs needed to understand regulation of body ground plan development in phytophagous arthropod antagonists.
Erbar (2007) summarizes past ideas on a supposed Mesozoic origin of angiosperms from the research perspective of evolutionary-development (evo-devo). Retallack and Dilcher (1981) presented in-depth discussion of Melville's ideas on a glossopterid ancestry of the angiosperms including a reanalysis of glossopterid fructifications. Others suggest that flowering plants evolved from multiple, unrelated seed plant lineages (Edgar Anderson 1934). 2002) and Nair's Triphyletic Theory (Nair 1979) are best placed in this paragraph. Eichler (1976) proposed that unisexual gymnosperms may be the ancestors of angiosperms. Finally the column labeled "Paraphyly or Polyphyly" denotes whether the scientific paper in question attributes the origin of flowering plants to a natural, intergeneric hybridization event, allopolyploidy, or events that brought together two or more distinct lines of seed plant evolution. Doyle and Donoghue 1986, 1987) and classic research by Arber and Parkin (1907), Edgar Anderson (1934), Axelrod (1952), Ehrlich and Raven (1964), Raven and Kyhos (1965), Takhtajan (1969, 1976), and Raven (1977), dovetail with- and potentially support a coevolutionary hypothesis on the origin of flowering plants, which is developed on the following pages of the web site for purposes of classroom and seminar debate and discussion. Doyle 2008) of perianth parts, microsporophylls, and megasporophylls to form a flower was an improbable and unnecessarily complicated saltational event punctuating a long and gradual evolutionary history of angiosperms. Simply put, massive, shortened bisexual cone axes bearing megasporophylls, laminar microsporophylls, and spirally-arranged foliar tepals, probably existed in populations of poorly understood Paleozoic seed plants described as gigantopteroids and Vojnovskyales, groups omitted by J. Doyle and others in their many published phylogenetic analyses.
Studies of wood paedomorphosis may offer new clues on a possible Mesozoic origin of angiosperms (Carlquist 2009), but studies of potentially neotenous gymnosperm secondary xylem development in deep (Paleozoic) time are lacking. Additional discussion is available in several papers that reinvestigate conifer cone abnormalities (Flores-Rentería et al. A "No" response (the box is uncolored) indicates that the paper or book chapter in question favors a younger Jurassic or Cretaceous origin of flowering plants. The picture of the rock slab on the left is of an indeterminate pentamerous fossil rosid flower (Celastrales, Rosanae) collected by Professor David L. Three of the largest islands (Viti Levu, Vanua Levu, and Taveuni) support harmonic "continental" floras (A. A common gnetophyte (Gnetum gnemon) and a narrowly distributed cycad (Cycas rumphii) occur in the archipelago. as intractable a mystery today as it was to Darwin 130 years ago" (page 318, Rothwell et al. Simply put, the origin of angiosperms is a conundrum. Another important reason for students of insect-seed plant coevolution to be conversant with arthropod tool kits is that evo-devo of the anterior (head) segment is linked to feeding, pollinating, and sensory perception. According to the discussion in Chapter 6 of Grimaldi and Engel (page 158-159, Insects Take to the Skies, 2005) a "plethora of ideas" on the evo-devo of insect flight "can be distilled into two current but contrasting theories." Studies of pterygote and polyneopteran nymphs suggest that wing pad development evolved independently several times over the past 400 million years (Haug et al. Respiratory enzymes, specifically hemocyanins and hemoglobins, and moulting storage proteins (hexamerins) are key elements of the early divergent arthropod developmental tool kit that tie-in with the evolution of insect legs and wings from bilaterian gills. Interestingly, hexamerins are also implicated as silencers of JH signaling in neotenous castes of hemimetabolous termites (X. Certain details of the Frasnian-famennian boundary extinction (De CARB) are discussed in a later section. New occurrences of the controversial late Triassic plant fossil Sanmiguelia Brown and associated ichnofossils in the Chinle Formation of Arizona and Utah, USA. Dilcher from the Lower Cretaceous Dakota Formation of North America. Tropical forests of the larger islands yield ten genera of monocotyledonous palms including the monotypic Alsmithia longipes, and the enigmatic magnoliid flowering plant family, Degeneriaceae. Historical Context: Many bibliographies on angiosperm floral diversity and the origin and evolution of flowering plants are available. Labandeira (2010) states: The aforementioned passage is from page 471 of C. Labandeira (2010), The pollination of mid-Mesozoic seed plants and the early history of long-proboscid insects, Annals of the Missouri Botanical Garden 97(4): 469-513. Ancient insect wings probably functioned as respiratory organs. Molecular model systems used as tools in beetle genomic research and phylogenetic studies include proteins central to development (JH esterases), diapause proteins, heat shock proteins, ultraspiracle (an ecdysone nuclear receptor protein), cuticle proteins, hexamerins, genes encoding vitellogenin, and apolipophorins, among others (see review by Gómez-Zurita and Galián 2005). Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 268(1): 65-82. Taylor (2009), Xin Wang (2009), Dilcher (2010), Magallón (2010), Stephen A. Stewart and Rothwell (1993) recapitulated the main steps needed to form the conduplicate carpel using glossopterid-, other seed fern-, and early angiosperm fossils as examples. Cambridge: Cambridge University Press, 521 pp., with additional comments distilled from E. Further, White proposed that the glossopterid Megafructi were a second basal group upon which ranalian angiosperms, monocotyledonous flowering plants including Pandanus (Pandanaceae, Pandanales, Arecidae), Williamsonia (a bennettitalean), additional cycads, and certain other angiosperms evolved (M. Principal morphologic innovations in angiosperms and gymnosperms according to Krassilov (1997) are: Paleoherb hypothesis. Burger published a paper in 1981 suggesting that the earliest angiosperms were monocotyledonous plants. Molecular tracers include naturally occurring but fossilized triterpenoids known as oleanone triterpanes (oleananes). These TSBs are a stratigraphically-important but "inconvenient truth," which is often buried or ignored in modern syntheses on the origin and evolution of flowering plants. Flowers and simple cones are reproductive short- (spur-) shoots according to Christianson and Jernstedt (2009). A novel "Mosaic Theory for the Evolution of the Dimorphic Perianth" proposed by Warner et al. Melville develops his earlier ideas on a Gonophyll Theory (1969) in a review published in 1983 that proposes a Permian origin of angiosperms from glossopterids. Rothwell (1993), Paleobotany and the Evolution of Plants (second edition). Mary White (1986) proposes that glossopterid Microfructi were basal to several parallel but sometimes branching and reticulate lines of evolution leading to the Caytoniales, angiosperms, Cycas (Cycadaceae, Cycadales), Podocarpaceae (Podocarpales), Araucariaceae (Araucariales), and certain catkin-bearing angiosperms including the Casuarinaceae. The polyphyletic-polychromic-polytopic hypothesis (Z.-Y. Cyclic angiospermization is reviewed by Krassilov (1997) and Ponomarenko (1998) within the context of a polyphyletic origin of angiosperms. Clifford (1982), The Monocotyledons: A Comparative Study. A discussion of this theory and how it links to the anthophyte hypothesis is presented by T. A few elements of ideas proposed by Cascales-Miñana et al. Armen Takhtajan's often criticized proposal on a "neotenous" origin of flowering plants (1969, 1976, and previous papers) is my starting place. Equally puzzling is that despite intense interest in the origins of seed plants and angiosperms throughout the entire last century, few have looked at the problems from a life cycle evo-devo perspective, with perhaps one exception (Takhtajan 1976), who alluded to neoteny as one of the possible mechanisms contributing to the origin of angiosperms." "Some authors seem curiously determined to prove that pre-Cretaceous fossils are crown-group angiosperms, but for understanding most aspects of the origin of angiosperms [other than their age], close stem relatives would be far more significant ..." (page 318, J. Doyle 2012) Based on four decades of study of the problem by Professor Emeritus J. Doyle, where on the Pangaean continent (and when) do students of angio-ovuly and the origin of flowering plants focus the search for "close stem relatives" of the group? Surprising and often ignored clues shedding light on the shadowy origin of flowering plants originate from oil and gas exploration data and the geochemistry of taxon-specific biomarkers (TSBs) and molecular traces, which are recoverable from mud logs of well boreholes, or from coal balls, compressions, and permineralizations (Moldowan and Jacobson 2002). Mud-loggers are able to ascertain higher plant input into a core segment of a stratigraphic horizon pulled-up from the well-site gas chromatography and mass spectrometry, and microscopic analysis of animal and plant microfossils including pollen and vascular plant fragments in core samples. Rudall (2006), Morphological and molecular phylogenetic context of the angiosperms: contrasting the 'top-down' and 'bottom-up' approaches used to infer the likely characteristics of the first flowers, Journal of Experimental Botany 57(13): 3471-3503. Flowering plants probably did not appear "suddenly," and the concept of a so-called "first flower" including proposals published by Albert et al. The reproductive short- (spur-) shoots of these Permo-carboniferous seed plants were equivalent to theoretical constructs of the protoflower proposed by Leppik (1960, 1968). Could paleoecologists benefit by studying experimental, 3-D printed artificial constructs of shoots and protoflowers in theoretical morphospace? By measuring and scaling detached and shed foliar and cone- floral-organs, and by combining these data with studies of permineralizations, "fingerprints of developmental regulation" (quoted from page 723, Sanders et al.