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“We must consider our planet to be on loan from our children, rather than being a gift from our ancestors”, G.H. Brundtland (former Prime Minister of Norway) QuickTime™ and a TIFF (U ncompressed) decompressor are needed to see this picture. Ecology (Unit 2: Chap 3, 4, 5, and 6) • Ecology is the study of how living things interact with their environment - it’s niche! What biotic (living) and abiotic (nonliving) factors does this Cheetah need in order to survive? Organismal Ecology - learning (imprinting, maturation, innate, habituation, conditioning, etc.) Population Ecology - cohorts, fecundity,carrying capacity, density, generation time Community Ecology LE 52-21 120 9 Lynx 80 6 40 3 0 1850 1875 1900 Year 1925 0 Lynx population size (thousands) Hare population size (thousands) Snow shoe hare 160 Landscape Ecology Community Ecology (Part I) LE 54-2 Tertiary consumers Microorganisms and other detritivores Detritus Secondary consumers Primary consumers Primary producers Heat Key Chemical cycling Energy flow Sun LE 53-12 Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Carnivore Primary consumers Herbivore Zooplankton Primary producers Plant A terrestrial food chain Phytoplankton A marine food chain Pyramids of Production • This loss of energy with each transfer in a food chain – Can be represented by a pyramid of net production Tertiary consumers Secondary consumers Primary consumers Primary producers Figure 54.11 10 J 100 J 1,000 J 10,000 J 1,000,000 J of sunlight Food Web: network of feeding relationships • In biological magnification – Toxins concentrate at higher trophic levels because at these levels biomass tends to be lower Concentration of PCBs Herring gull eggs 124 ppm Figure 54.23 Lake trout 4.83 ppm Smelt 1.04 ppm Zooplankton 0.123 ppm Phytoplankton 0.025 ppm Production Efficiency • When a caterpillar feeds on a plant leaf – Only about one-sixth of the energy in the leaf is used for secondary production Plant material eaten by caterpillar 200 J 67 J Feces 100 J 33 J Figure 54.10 Growth (new biomass) Cellular respiration • Density is the result of a dynamic interplay – Between processes that add individuals to a population and those that remove individuals from it Births and immigration add individuals to a population. Births Immigration PopuIation size Emigration Deaths Figure 52.2 Deaths and emigration remove individuals from a population. Population Ecology • A clumped dispersion – Is one in which individuals aggregate in patches – May be influenced by resource availability and behavior (a) Clumped. For many animals, such as these wolves, living in groups increases the effectiveness of hunting, spreads the work of protecting and caring for young, and helps exclude other individuals from their territory. Figure 52.3a • A uniform dispersion – Is one in which individuals are evenly distributed – May be influenced by social interactions such as territoriality (b) Uniform. Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors. Figure 52.3b • A random dispersion – Is one in which the position of each individual is independent of other individuals (c) Random. Dandelions grow from windblown seeds that land at random and later germinate. Figure 52.3c • Carrying capacity (K) – Is the maximum population size the environment can support • K-selection, or density-dependent selection – Selects for life history traits that are sensitive to population density (large animals - elephants) • r-selection, or density-independent selection – Selects for life history traits that maximize reproduction (small animals - minnows) • Some populations overshoot K Number of Daphnia/50 ml – Before settling down to a relatively stable density 180 150 120 90 60 30 0 0 20 40 60 80 100 120 140 160 Time (days) Figure 52.13b (b) A Daphnia population in the lab. The growth of a population of Daphnia in a small laboratory culture (black dots) does not correspond well to the logistic model (red curve). This population overshoots the carrying capacity of its artificial environment and then settles down to an approximately stable population size. The Global Human Population • The human population – Increased relatively slowly until about 1650 and then began to grow exponentially 5 4 3 2 The Plague 1 Figure 52.22 8000 B.C. 4000 3000 2000 1000 B.C. B.C. B.C. B.C. 0 0 1000 2000 A.D. A.D. Human population (billions) 6 • Age structure – Is commonly represented in pyramids Rapid growth Afghanistan Male Female 8 6 4 2 0 2 4 6 8 Percent of population Figure 52.25 Age 85 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Slow growth United States Female Male 8 6 4 2 0 2 4 6 8 Percent of population Age 85 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Decrease Italy Female Male 8 6 4 2 0 2 4 6 8 Percent of population Community Ecology (Part II) Ecological succession in Massachusetts . . . • • • • Ferns and Grasses Shrubs White pine Hardwoods (maple, oak, hickory, and some birches) • Hemlock and Beech Resource Partitioning • Resource partitioning is the differentiation of niches – That enables similar species to coexist in a community A. insolitus usually perches on shady branches. A. ricordii A. distichus perches on fence posts and other sunny surfaces. A. insolitus A. alinigar A. distichus A. christophei A. cybotes A. etheridgei Figure 53.3 Community Interactions • • • • • • • • Mimicry Parasitism Commensalism Coevolution Predator/prey Mutualism Symbiosis Exotic species • Cryptic coloration, or camouflage – Makes prey difficult to spot Figure 53.5 • Aposematic coloration – Warns predators to stay away from prey Figure 53.6 • In Batesian mimicry – A palatable or harmless species mimics an unpalatable or harmful model (b) Green parrot snake Figure 53.7a, b (a) Hawkmoth larva • In Müllerian mimicry – Two or more unpalatable species resemble each other (a) Cuckoo bee Figure 53.8a, b (b) Yellow jacket • In commensalism – One species benefits and the other is not affected Figure 53.10 Keystone Species • Keystone species – Are not necessarily abundant in a community – Exert strong control on a community by their ecological roles, or niches • Field studies of sea stars Number of species present – Exhibit their role as a keystone species in intertidal communities 20 With Pisaster (control) 15 10 Without Pisaster (experimental) 5 0 1963 ´64 ´65 ´66 ´67 ´68 ´69 ´70 ´71 ´72 ´73 (a) The sea star Pisaster ochraceous feeds preferentially on mussels but will consume other invertebrates. Figure 53.16a,b (b) When Pisaster was removed from an intertidal zone, mussels eventually took over the rock face and eliminated most other invertebrates and algae. In a control area from which Pisaster was not removed, there was little change in species diversity. Biogeochemical Cycles THE CARBON CYCLE THE WATER CYCLE • The water cycle and the carbon cycle CO2 in atmosphere Transport over land Photosynthesis Solar energy Cellular respiration Net movement of water vapor by wind Precipitation over ocean Evaporation from ocean Precipitation over land Burning of fossil fuels and wood Evapotranspiration from land Percolation through soil Runoff and groundwater Figure 54.17 Carbon compounds in water Higher-level Primary consumers consumers Detritus Decomposition THE PHOSPHORUS CYCLE THE NITROGEN CYCLE • The nitrogen cycle and the phosphorous cycle N2 in atmosphere Rain Geologic uplift Runoff Assimilation NO3 Nitrogen-fixing bacteria in root nodules of legumes Denitrifying bacteria Consumption Sedimentation Decomposers NH3 Nitrogen-fixing soil bacteria Nitrifying bacteria Nitrification Ammonification Figure 54.17 Plants Weathering of rocks Soil Plant uptake of PO43 Leaching NO2 NH4+ Nitrifying bacteria Decomposition