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Organisms and the Environment • The environment of any organism includes – Abiotic, or nonliving components – Biotic, or living components – All the organisms living in the environment, the biota Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Environmental components – Affect the distribution and abundance of organisms Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Figure 50.2 Climate in northern Australia is hot and wet, with seasonal drought. Southern Australia has cool, moist winters and warm, dry summers. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year. Southeastern Australia has a wet, cool climate. Tasmania Subfields of Ecology • Organismal ecology: Adaptations – Studies how an organism’s structure, physiology, and (for animals) behavior meet the challenges posed by the environment Figure 50.3a (a) Organismal ecology. How do humpback whales select their calving areas? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Population ecology: Why we sample – Concentrates mainly on factors that affect how many individuals of a particular species live in an area (b) Population ecology. What environmental factors affect the reproductive rate of deer mice? Figure 50.3b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Community ecology – Deals with the whole array of interacting species in a community (c) Community ecology. What factors influence the diversity of species that make up a particular forest? Figure 50.3c Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Ecosystem ecology: Where do you get your energy? – Emphasizes energy flow and chemical cycling among the various biotic and abiotic components (d) Ecosystem ecology. What factors control photosynthetic productivity in a temperate grassland ecosystem? Figure 50.3d Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Landscape ecology: Biome Business – Deals with arrays of ecosystems and how they are arranged in a geographic region Figure 50.3e (e) Landscape ecology. To what extent do the trees lining the drainage channels in this landscape serve as corridors of dispersal for forest animals? Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Many naturalists – Began to identify broad patterns of distribution by naming biogeographic realms: Interactions between organisms and the environment limit the distribution of species Palearctic Nearctic Tropic of Cancer (23.5N) Oriental Ethiopian Equator Neotropical Figure 50.5 (23.5S) Tropic of Capricorn Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Australian Biotic Factors • Biotic factors that affect the distribution of organisms may include – Interactions with other species – Predation – Competition Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Interspecific interactions – Can have differing effects on the populations involved Table 53.1 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Trophic Structure: a key factor in community dynamics • Food chains – Link the trophic levels from producers to top carnivores Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Secondary consumers Carnivore Carnivore Primary consumers Zooplankton Herbivore Primary producers Plant Figure 53.12 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A terrestrial food chain Phytoplankton A marine food chain Abiotic Factors • Abiotic factors that affect the distribution of organisms may include – Temperature – Water – Sunlight – Wind – Rocks and soil Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Climates – Are determined largely by the input of solar energy and the planet’s movement in space LALITUDINAL VARIATION IN SUNLIGHT INTENSITY North Pole 60N Low angle of incoming sunlight 30N Tropic of Cancer Sunlight directly overhead 0 (equator) Tropic of Capricorn 30S Low angle of incoming sunlight 60S South pole Figure 50.10 Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Atmosphere Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms, as seen on a climograph Temperate grassland Desert Tropical forest Annual mean temperature (ºC) 30 Temperate broadleaf forest 15 Coniferous forest 0 Arctic and alpine tundra 15 100 Figure 50.18 200 300 Annual mean precipitation (cm) Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings 400 • Many aquatic biomes – Are stratified into zones or layers defined by light penetration, temperature, and depth Intertidal zone Neritic zone Littoral zone Limnetic zone 0 Oceanic zone Photic zone 200 m Continental shelf Pelagic zone Benthic zone Photic zone Aphotic zone Pelagic zone Benthic zone Aphotic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) (a) Zonation in a lake. The lake environment is generally classified on the basis of three physical criteria: light penetration (photic and aphotic zones), distance from shore and water depth (littoral and limnetic zones), and whether it is open water (pelagic zone) or bottom (benthic zone). Figure 50.16a, b Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings (b) Marine zonation. Like lakes, the marine environment is generally classified on the basis of light penetration (photic and aphotic zones), distance from shore and water depth (intertidal, neritic, and oceanic zones), and whether it is open water (pelagic zone) or bottom (benthic and abyssal zones).