Presentation on theme: "The Real Scoop on Dirt "More organization and complexity exist in a handful of soil than on the surface of all the other planets combined.”"— Presentation transcript:
1 The Real Scoop on Dirt"More organization and complexity exist in a handful of soil than on the surface of all the other planets combined.” *************************************Edwin O. Wilson Harvard UniversitySAFS
2 So what lives in soils?“The soil is alive and the diversity is enormous. One square foot of soil has an array of small invertebrates, mites, arachnids... hundreds, or even thousands of species, many of which are still unknown to science.” E.O.Wilson
3 Nematodes (round worms) Protozoafeed on bacteria and fungi10 million /m2 (3 to 20 g/m2)Nematodes (round worms)feed on bacteria, fungi, protozoa and plant roots10 million /m2 in grassland soils, 30 million /m2 in woodland soilsEnchytraeids (pot worms)feed on dead plant material/m2 in grassland (50-35 g/m2)Tardigrades (water bears)50 to 500 /m2Pauropoda20 to /m2Molluscs (Slugs and Snails)feed on rotting vegetation (+ a few carnivorous species which eat other molluscs)approx. 15 /m2 in grassland soils, 450 /m2 in woodland soils
4 Diplopoda (Millipedes) Symphylafeed on fungiup to 1000 /m2 in grassland soils, 3000 /m2 in woodland soilsIsopoda (Woodlice)feed on fungi, and dead plant material500 to 1500 /m2 in grassland soils, 3000 /m2 in woodland soilsDiplopoda (Millipedes)approx. 20 /m2 in grazed grassland, 100 /m2 in ungrazed grassland, 100+ /m2 in woodlandsChilopoda (Centipedes)feed on insects an other soil arthropodsapprox. 120 /m2 in grassland, 150+ in woodlandsAranaea (Spiders)feed on other arthropods480 /m2 in Moorlands, 200 /m2 in pasture
5 Acari (Mites)feed on everything100,000 to 600,000 /m2 woodland soilsCollembola (Springtails)feed on fungi and bacteria40,000 to 70,000 /m2 in grassland soils, /m2 in coniferous woodlandColeoptera (Beetles)up to 2000 to 3000 /m2 in ungrazed grasslands, considerably lower in arable soils.Hymenoptera (Ants)feed on other arthropods and plants secretionsimportant soil movers
6 Today’s topics Taxonomy The n-dimensional ecological niche Aravalli, She and Garrett Archaea & the new age of microorganisms.The n-dimensional ecological nicheSilvertown, J Plant coexistence and the niche.Soil food webs and crazy soil critters!
7 Taxonomy = naming and classifying organisms into groups that share similar characteristics Taxon = a taxonomic group or levelTaxa = plural of taxonLinneaus ( )Systema NaturaePhysician - studied medicinal plantsFather of taxonomyLinneaus - check this for more info on Linneaus
8 Linneaus’ hierarchy Imperium ("Empire") - the phenomenal world Regnum ("Kingdom") - the three great divisions of nature at the time - animal, vegetable, and mineralClassis ("Class") - subdivisions of the above, in the animal kingdom six were recognized (mammals, birds, amphibians, fish, insects, and worms)Ordo ("Order") - further subdivision of the above - the class Mammalia has eightGenus - further subdivisions of the order - in the mammalian order Primates there are four. e.g. HomoSpecies - subdivisions of genus, e.g. Homo sapiens.Varietas ("Variety") - species variant, e.g. Homo sapiens europaeus.
9 King Philip Came Over For Games Saturday Binomial nomenclatureGenus speciesKingdomClassOrderGenusSpeciesTaxonomy of FidoPhylumNote additionFamilyKing Philip Came Over For Games Saturday
10 The problem of common names - this fish is a: Look ma, I think I caught a snake …Northern pikeCommon PikeGreat Northern PikeJackJackfishNorthernPickerelPikeSnakeG嚇da (Swedish)tika obecn� (Czech)kinoje (Ojibwe)Esox lucius
11 Oh, naaaa …. its just a squirrel This is for you, Joey and John!I couldn’t resist!!
12 Back to taxonomy … what were those groupings anyway Back to taxonomy … what were those groupings anyway? It depends on who you ask …Linnaeus ’s2 kingdomsPlantae, AnimaliaErnst Haeckel - early 1900’s3 kingdomsPlantae, Animalia, ProtistaRobert Whitaker5 kingdomsPlantae, Animalia, Protista, Fungi, MoneraKarl Woese3 domainsBacteria, Archea, Eukarya
13 The 5 Kingdoms Based on morphology, reproduction, metabolism, etc. In general, the height up the “tree” represents time
14 The 3 DomainsBacteriaEucaryaArcheaBased on molecular structure of 16S or 18s subunits of ribosomal RNAFungiPlantaeAnimaliaProteobacteriaCyanoobacteriaEuryarchaeotaCrenarchaeotaAnimaliaChloroplastsMitochondriaAdapted from McGraw-Hill Pub.
15 X-ray crystallography image of ribosome structure University of California, Santa Cruz16s rRNA of 3 spp.UniversalSimilar functionChanges slowlyCan be compared between organismsMcGraw Hill Pub.
16 Dendrogram of 3 domainsBacteriaArcheaEucaryaMcGraw-Hill Pub.And this brings us back to Aravalli, She and Garrett, Archaea & the new age of microorganisms
17 Why were these authors so excited? Archea are no longer just extremeophiles!!!They’re ubiquitous!!!Will this change our thinking on:how food webs work?how organisms are related?how microbial communities are organized?how soil communities are organized?IUPUI Dept. of Biology
18 And this brings us to the concept of an ecological niche Grinnell (1917) - the sites where organisms of a species can liveElton (1927) - the function performed by the species in the communityGause (1934) - intensity of competition determines overlap of nicheHutchinson (1957) - a region (n-dimensional hypervolume) in a multi-dimensional space of environmental factors that affect the welfare of a species
19 Species that need the same resources must compete They either coexist or one will die out
20 General theory has been - to coexist, spp General theory has been - to coexist, spp. must use resources in slightly different wayTime of resource useDiurnal, crepuscular, or nocturnal feedingEarly or late spring nesting for owls/hawksParticular part of resource usedSeeds versus nectar versus leaves of a plantLarge versus small seedsArea of tree canopy used by bird spp. (MacArthur)More or less efficient use of same resourceBoth maples and paw paw need sunlight, but paw paw need less
21 So how do so many spp. of plants coexist? (Silvertown) If plants all use same few resources, why so many spp.?Two possibilities:Niche model is wrongPlant niches ARE different (we just don’t know enough to know HOW they differ)Conclusion --> differences have not been studied sufficientlyNot asking the right questions (4 tests of niche separation)Studies should test all 4 of these when determining how plants use resources to see if niche model applies equally to plantsOne difference = mycorrhizaeAnd that takes us right back to ……soil communities
23 Communities rule!The amount of decomposition was greater with soil macrofauna than withoutHättenschwiler and Gasser 2005Fig. 3. Total remaining litter mass of entire microcosms as a function of total predicted litter mass remaining. Data points represent individual microcosms either without macrofauna (open circles) or with macrofauna (i.e., millipedes, earthworms or both; solid diamonds).
24 And diversity matters for tough biodegrabables! Fig. 1. Litter mass of individual species predicted from monocultures of the respective species and animal treatments. (Left) Data from the three more slowly decomposing species are shown. (Right) Data from the more rapidly decomposing species.Hättenschwiler and Gasser 2005
25 Roles of soil critters: DecompositionNitrogen fixationMineralizationPrimary production
27 Thanks to Dr. Nancy Nicholson for the following images and fun facts!
28 Nematodes and fungi - an “inversion of the animal-eat- plant relationship” BackgroundNitrogen is inert in the atmosphere, so doesn’t mix with soilNitrogen in soils is a limiting factor for plant growthNematodes and fungi abound in healthy soils - both are essential for healthy plants because they retain nitrogen (and other nutrients) in soils once it has been captured by nitrogen-fixing bacteriaThe nematode - fungus relationship keeps nitrogen from going back to the atmosphere as a gas (methane)
38 Phragmospores of some nemtode-trapping fungi germinate as constricting rings if nematodes are present
39 And yes, there is the usual relationship of animal-eat-plant And yes, there is the usual relationship of animal-eat-plant. Above right, a nematode avoids the paralytic toxin of the oyster mushroom and feeds on fungal tissue