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ECOLOGY The scientific discipline that is concerned with the relationships between organisms and their environments. • How they interact with other living things • How they interact with the nonliving factors of the environment Ecology These interactions determine the distribution and abundance of organisms 2 main themes in ecology: Where do organisms live & why? How many organisms are present & why? Ecological research ranges from individuals to the entire biosphere Ecology Population A group of individuals of the same species that lives in a particular area & can interbreed The black-veined white butterfly (Aporia crataegi) mating the lake whitefish (Coregonus clupeaformis) http://www.maine.gov/ifw/fishing/species/identification/lakewhitefish.htm Species A group of organisms that can breed to produce fully fertile offspring A species usually consists of multiple populations… Great White Pelican Pelecanus onocrotalus Community All the populations in an area. i.e., populations of all the plant species & fungi species & bacterial species & archaea species & protist species & animal species = all the living parts 7-spotted ladybug (Adephagia septempunctata) Bean aphids (Aphis fabae) Red ant (Myrmica rubra) Broom plant (Cytisus scoparius) Plus... Ecosystem community + abiotic environment Biosphere The entire portion of the Earth that supports life biosphere Bio = life, sphere = sphere Compare with the lithosphere (litho = stone) hydrosphere (hydro = water) atmosphere ( atmos = vapor) http://www.ucar.edu/learn/1.htm Interactions The biosphere is the portion of earth in which all known life forms exist. It occupies a thin layer of air (atmosphere), water (hydrosphere), and land (lithosphere). biosphere Term was first coined by geologist Eduard Suess (1875) as A place on earth’s surface where life dwells. Interrelates and interacts with the other spheres; living things have a great impact on the other spheres The biosphere only occupies about 0.0007% of the volume of the planet (Margulis & Sagan, 2002) Ecological Factors Abiotic factors The non-living parts of the environment sand buildings pollutants water rocks temperature wind sunlight Biotic factors The living parts of the environment Geese Plankton People Trees Grass Fish Bacteria fungi Biodiversity Biological diversity (biodiversity, for short) is all of the species found in an area AND the interactions between those species. Worcester City Museums Habitat The characteristics of the type of environment where an organism normally lives. (e.g. a stony stream, a deciduous temperate woodland, a mixedgrass prairie) Biotic and abiotic factors determine the survival and growth of an organism & the productivity of the ecosystem in which the organism lives This area where the critter lives is its habitat Ecosystem Processes Energy flow—energy moves through the ecosystem Nutrient cycling—chemical elements (matter) recycled in the ecosystem IT’S ALL ABOUT MATTER AND ENERGY!!! Energy Flow 1st law of thermodynamics Energy cannot be created or destroyed, it can only be converted in form 2nd law of thermodynamics When energy changes form, some energy is always lost in the form of heat Energy Flow The SUN!!! = solar energy Of incoming solar radiation, Of the solar radiation absorbed, 66% absorbed 34% reflected (albedo) ~22% water cycle Nearly all transforms to heat & radiates Tiny amount of solar energy goes into photosynthesis (<0.1%) Trophic Levels Producers/autotrophs Heterotrophs Primary consumer/herbivore Secondary consumer/1st level carnivore Tertiary, quaternary, etc. consumers/carnivores Detritivores/decomposers Energy in Ecosystems Energy from the Sun is the major source of energy for MOST of the living things we know about The process of photosynthesis traps sunlight so it can be used by living things Energy is NOT recycled throughout the ecosystem Energy and organisms Autotrophs Plants are considered primary producers because they make their own food from inorganic molecules Inorganic molecules autotrophs complex organic molecules Energy and organisms Are there any non-photosynthetic autotrophs? Chemosynthesis and chemosynthetic organisms!! Chemosynthesis Heterotrophs Heterotrophs obtain their energy from eating/consuming other organisms Herbivores Heterotrophic organisms who eat primarily plant material Carnivores Heterotrophic organisms who eat other animals 1st level carnivores 2nd level carnivores etc. Omnivores Heterotrophs, like us, that eat both producers (plants) and other consumers Detritivores Heterotrophic organisms who ingest dead organic matter. (e.g. earthworms, woodlice, millipedes) Earth worm (Lumbricus terrestris) Saprotrophs Heterotrophic organisms who secrete digestive enzymes onto dead organism matter and absorb the digested material. (e.g. fungi, bacteria) Chanterelle (Cantherellus cibarius) Heterotroph specialists Fruit-eating = fructivores Insect-eating = insectivores Detritus-eating = detritivores &c. Feeding relationships Predators & prey Herbivory Parasite & host Mutualism Competition Large blue butterfly (Maculinea arion) Energy Flow in Ecosystems Food chains/webs—organisms linked by energy and nutrient flow Trophic level—the feeding level of an organism in a food chain/web Energy Flow Between Trophic Levels Does 100% of energy transfer from 1 trophic level to another? No. Remember 2nd Law of Thermodynamics Energy Flow Between Trophic Levels Range 5-20% transference (usually ~10%) SO…only about 10% of the total energy is transferred to this level to be used by these consumers. = 10% RULE Graphical representation of energy transference in food web = energy pyramid Energy Flow Between Trophic Levels Why such low efficiency? three reasons: 1) not everything gets eaten! 2) indigestible material 3) metabolic processes—energy lost as ___________ Biogeochemical Cycles Elements, Chemical compounds and other forms of matter are passed from one organism to another and from one part of the biosphere to another. Pass the same molecules around again and again within the biosphere. Matter is always recycled! Bioaccumulation = Biomagnification Nutrient Cycles What does the Law of Conservation of Matter state? • circular flow of chemicals = recycling • • • • • Water (H2O) Carbon (C) Nitrogen (N) Phosphorus (P) Sulfur (S) Water Cycle Movement of water (l, s, g) through biological, geological, and atmospheric processes Precipitation Evaporation Transpiration Percolation Surface waters Groundwater Water vapor respiration Sublimation Condensation Desublimation Surface water flow Ground water flow Storage in cells Photosynthesis Cellular processes &c… Water Cycle http://ga.water.usgs.gov Carbon Cycle • Carbon = building block of life • Reservoirs = atmosphere, ocean, organisms • High rate of exchange in/out reserves • Any relation to global warming? Carbon cycle Nitrogen Fixation Types 1) atmospheric fixation via lightening or sunlight; NO3 as precipitation (ppt) 2) biological fixation* via soil & water bacteria (blue-green algae); NH3; legumes & root nodules Water Quality & Nitrates Soil Condition & Fertilizers Nitrogen Cycle Phosphorus Cycle • Water Quality & Phosphorus • Eutrophication: increase in nutrient content of lakes Phosphorus Cycle Nutrient cycling Ecosystems can be sources, sinks, or transformers of chemicals Source = supplier of nutrients to other habitats Sink = “holder” of nutrients from other habitats Transformer = takes nutrients in one form and gives them up as another form Food Chain Energy flow can be represented by a food chain. Arrows show the direction the energy is flowing. Food Chain Series of steps in an ecosystem in which organisms transfer energy by eating and by being eaten. Energy flows in one direction from sun or inorganic compounds to autotrophs to various heterotrophs Food Webs Many food chains combined together. Ecological Pyramids Is a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. 3 types: biomass, energy, or numbers What is a trophic level? Trophic levels First level = Second level = Third level = Fourth level = Biomass Pyramid The total mass of living tissue at each trophic level. Represents the amount of potential food available for each trophic level in an ecosystem Biomass Pyramid The first level includes producers. Here we find the most abundant amount of biomass. Energy Pyramid About 10% of the total energy is transferred to this level to be used by these consumers. This is the 10% Rule 10 cal 100 cal 1000 cal 10,000 calories Ecological pyramids Numbers pyramid Pyramid of numbers The number of organisms at each trophic level. NICHE All the roles that an organism plays in its environment; the way in which an organism fits into an ecological community or ecosystem. Niche The niche of a species consists of: What it eats What eats it Where it lives Shelter All interrelationships How activities affect the habitat & benefit/harm other critters &c. Niche—an example Sunflower Absorbs light, water, nutrients Converts electromagnetic energy into chemical energy Produces food Plant tissues Nectar Pollen &c. Loosens soil w/roots Provides shade and shelter (homes) Niche—an example Leafcutter ants Niche—an example Leafcutter ants Largest herbivore—harvest huge amounts of leaf material (15-20% of fresh vegetation) Excavate large underground nests Cultivate a fungus, Lepiotaceae Fungus fixes Nitrogen—transformed to ammonium Extra nitrogen to surrounding soil Escovopsis mold—potential parasite Support Actinomycete bacteria (antibiotic) Support fungus, black yeast (anti-fungal) Ant eaten by various critters Compete with other arthropods Community interactions Competition Intra-species Inter-species Predation Symbiosis Mutualism Commensalism parasitism Mutualism • Two organisms living together and both benefiting from each other. Lichens are fungus and algae living together. Algae produces the food and the fungus absorbs the nutrients. More Mutualistic Relationships Bee gets food and the flower gets pollinated. The ant benefits by receiving honeydew from the aphid, while the aphid benefits by being protected by the ant. Commensalism The relationships between two kinds of organisms in which one benefits and the other is not affected. Examples: •hummingbirds hitchhike rides with other birds •Barnacles, ghost shrimp, &c. live on sea turtle shells Parasitism two organisms live together, one drawing its nourishment at the expense of the other The lamprey eel gets energy from the fish. Parasites rarely kill the host but will leave wounds What are some other Parasites? • Viruses • Flukes (liver parasites) • Tape worms (intestinal parasites) • Fungus (athletes foot) • Trypanasoma (malaria) • Bacteria Summary Mutualism Commensalism parasitism NICHE All the roles that an organism plays in its environment; the way in which an organism fits into an ecological community or ecosystem. THE COMPETITIVE EXCLUSION PRINCIPLE G.F. Gause (1934) If two species, with the same niche, coexist in the same ecosystem, then one will be excluded from the community due to intense competition The niche as a two-dimensional shape Species A Niche represented by a 2-dimensional area Separate niches Species B Species A No overlap of niches. So coexistence is possible Overlapping niches Species B Species C Interspecific competition occurs where the niches overlap Specialization avoids competition Species C Species B Evolution by natural selection towards separate niches Species B’ Species C’ Specialization into two separate niches This niche is not big enough for the both of us! Species A Species D Very heavy competition leads to competitive exclusion One species must go Total exclusion Species A has a bigger niche it is more generalist Species E has a smaller niche it is more specialist Specialists do tend to avoid competition Example: Squirrels in Britain The Red Squirrel (Sciurus vulgaris) is native to Britain Its population has declined due to: Competitive exclusion Disease Disappearance of hazel coppices and mature conifer forests in lowland Britain © 2008 Paul Billiet ODWS Isle of Wight Tourist Guide The Alien The Grey Squirrel (Sciurus carolinensis) is an alien species Introduced to Britain in about 30 sites between 1876 and 1929 It has easily adapted to parks and gardens replacing the red squirrel © 2008 Paul Billiet ODWS Today’s distribution Red squirrel © 2008 Paul Billiet ODWS Grey squirrel