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Lower Paleozoic exceptional biota |
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Written by Boldone
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Wednesday, 31 October 2007 |
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The journal Geology has recently published two reports on exceptionally well-preserved fossil biotas from marginal marine sediments, one of Silurian (von Bitter et al. 2007), the other of late Ordovician age (Young et al. 2007), both from Canada. This findings are particularly important since testimonials to life in an environment that is generally little represented in the fossil record, due to the high-energy conditions met with at the shoreline, making biotic remains easily destroyed.
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Written by Boldone
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Wednesday, 12 September 2007 |
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Just as photosynthesizers form the base of food webs in sunlit communities, so do sulfide oxidizing bacteria in sulphureta (Dyer 2003 - see preceding post). One such places is the mudflat belt around the Isonzo river outlets, in the northernmost Adriatic (Italy). Phanerogam meadows provide here large quantities of food to fermenting bacteria of various types (including gram-positives and proteobacteria).
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Methane, flatulence, and the coevolution of bacteria |
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Written by Boldone
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Tuesday, 28 August 2007 |
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The book A Field Guide to Bacteria by Betsey Dexter Dyer features a mine of gold for evolutionary thinking. Easily readable, it does not require the chemical and biological background needed to approach many other textbook on prokaryotic life. Just what many ecologists and evolutionary (paleo)biologists need, in order to figure out the complexities of metabolical ways involved in energy transfer and ecosystem functioning. The qualities of this guide, a must for a nicely-stuffed bookshelf on Natural History, stem from the focus on ‘field marks’ that the author has decided to impart to her observations, and the choice to skip most aspects demanding the use of a microscope or knowledge related to this. Whatever your point of view on natural history, you can be sure there’s some type of bacteria involved in some kind of way in your work, probably many types zusammen, the afterthoughts being germane to some aspect of evolution. One example has to do with human flatulence, cited here with some indulgence, but mainly to stress how far the evolutionary mind can go when observing natural phenomena.
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From seagrass to mangrove, and back |
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Written by Boldone
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Tuesday, 24 July 2007 |
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Fishes move from seagrass to mangrove and saltmarsh during high tides, taking advantage of the abundant zooplankton, to come back at low tides (Saintilan et al. 2007). Mangrove habitat with suitable water conditions are essential to the recovery and sustainability of goliath-grouper populations, usually inhabiting coral reefs (Koenig et al. 2007). Such findings confirm that mangroves are crucial to the existence of adjacent communities, as demonstrated by earlier studies on reef fishes (Mumby et al. 2004), and that tropical species are linked in complex ways.
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Written by Boldone
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Tuesday, 10 July 2007 |
Easy: mangroves are tropical plants that grow with their roots partly or totally submerged in sea water, capable of building tidal forests. But mangrove is also said of the forest itself, or of the whole community (Tomlinson 1986). What about the past? When do you recognize something that you can call a fossil mangrove community? The mangrove plants, as presently understood, are ascertained in the fossil record from their pollen grains, whereas fruits, leaves and wood can be hardly recognized in ancient peat deposits (Plaziat 1995).  Such fossils suggest that the modern ecosystem arose at the turn of the early Eocene, during the warmest times and the largest transgressions of the Cenozoic, a fact confirmed by the record of animal associates, notably the mollusks (Ellison et al. 1999). However, the strict actualistic approach applied to mangrove plants and animals should be considered trustworthy only at the species or genus level, what hinders the identification of older “mangrove” plants adapted to sea water and their ecosystems (Plaziat et al. 2001).
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