[ Publication of the Year ]
Each year I will select a scientific paper, book chapter, or book as being of paramount importance toward finding a solution to the enigmatic origin of angiosperms. My annual selection is stated and discussed in the section that follows this geologic and biogeographic note.
Spectacular outcrops of the 40 million year old Sespe Formation are composed of purplish conglomerate rock exposures. Rounded cobbles, lenticular gravels, and water-worn pebbles and sands of the conglomerate, probably owe their shapes to scouring from the Colorado Paleoriver.
Sandstone cliffs have kept the incidence of catastrophic wildfire to a minimum allowing three pinids to survive on ledges and crevices of rock formations in this area. Abies concolor (white fir), Pinus lambertiana (sugar pine), and Pseudotsuga macrocarpa (big cone Douglas fir) constitute the indigenous coniferous populations of the Sespe Sandstone Block of the Topa Topa Mountains.
The Topa Topa Mountains support a population of the Santa Ynez false lupine. A relict fabid population of Thermopsis macrophylla (Fabaceae, Fabales, Rosanae) occurring on the sandstone shelves of Bear Heaven northeast of Santa Paula Peak is of possible interest to students of botany and ecology.
The Outstanding Scientific Paper of 2013:
Four significant conclusions from a study of molecular phylogenies of the WOX family of homeodomain proteins shed light on stem cell niches and vegetative leaf morphologies of the last common ancestor of angiosperms and gymnosperms. Phylogenies were computed from inferred amino acid sequences of the DNA-binding homeodomain by genome walking of the WUSCHEL and WUS/WOX5 homeobox genes by plant biologists from the Institute of Developmental Biology, University of Cologne:
Nardmann, J. and W. Werr. 2013. Symplesiomorphies in the WUSCHEL clade suggest that the last common ancestor of seed plants contained at least four independent stem cell niches. New Phytologist 199(4): 1081-1092.
Critically important research by Nardmann and Werr (2013) discussing eudicot and Gnetum foliar tool kit process homology and deeply conserved angiosperm and gymnosperm shoot apical meristem (SAM) transcription factors (TFs), is a clear choice for outstanding publication of the year. An earlier installment of this work is relevant:
Nardmann, J., P. Reisewitz, and W. Werr. 2009. Discrete shoot and root stem cell-promoting WUS/WOX5 functions are an evolutionary innovation of angiosperms. Molecular Biology and Evolution 26(8): 1745-1755.
Angiosperms are sister to Gnetales, Ginkgo, cycads, Pinaceae, and Cupressaceae in Figure 5 (Nardmann and Werr 2013). Expression patterns, and a WOX cladistic analysis, suggesting eudicot and Gnetum process homology, were not calibrated by late Paleozoic fossils (Discussion, Nardmann and Werr 2013).
Yet, Permian Gnetum-like seed plant permineralized leaves have been anatomically studied by Mamay et al. (1988), and venation patterns of these Leonardian fossils are identical to Figure 5a on page 1088 (Nardmann and Werr 2013) and Figure 3 on page 346 ("character 5-7" ["110"] in text, J. A. Doyle and Donoghue 1986).
"We also placed leaves of angiosperms and Gnetum in the 110 category, since their derivation from taeniopteroid ancestors would involve no change in major venation, only origin of reticulations and interpolation of new vein orders [coded as characters 9 and 10], whereas derivation from pinnately compound would require at least one additional step, simplification" (page 347, J. A. Doyle and Donoghue 1986).
Doyle, J. A. and M. J. Donoghue. 1986. Seed plant phylogeny and the origin of angiosperms: an experimental cladistic approach. Botanical Review (Lancaster) 52(4): 321-431.
Previous Publication of the Year:
Mathews, S. and E. M. Kramer. 2012. The evolution of reproductive structures in seed plants: a re-examination based on insights from developmental genetics. New Phytologist 194(4): 910-923.
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.
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.
Taylor, T. N., E. L. Taylor, and M. Krings. 2009. Paleobotany: The Biology and Evolution of Fossil Plants, Second Edition. Burlington: Elsevier Academic Press, 1230 pages.
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.
Theißen, G. and R. Melzer. 2007. Molecular mechanisms underlying origin and diversification of the angiosperm flower. Annals of Botany 100(3): 1-17.
Baum, D. A. and L. C. Hileman. 2006. A developmental genetic model for the origin of the flower. Pp. 3-27 In: C. Ainsworth (ed.), Volume 20, Annual Plant Reviews, Flowering and Its Manipulation. Sheffield: Blackwell Publishing Ltd., 304 pp.
Soltis, D. E., P. S. Soltis, P. K. Endress, and M. W. Chase. 2005. Phylogeny and Evolution of Angiosperms. Sunderland: Sinauer, 370 pp.
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.
The image was captured by the author in 1970 using Kodak ASA 25 film as part of a biome project conducted by Allen Cattel, Richard May, John Miller, and Bernie Rios for a Moorpark College biology class taught by the late Clinton Schoenberger. Two of these community college students (Cattel and Miller) went on to earn their doctorate degrees from The University of British Columbia and Oregon State University, respectively.
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