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Chapter 23 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ecology Environment - branch of biology that studies relationships between organisms and environment - factors that affect an organism during its lifetime ◦ Biotic factors Living things that affect an organism ◦ Abiotic factors Non-living things that affect an organism Organism ◦ Smallest living unit Populations Groups of organisms of same species Communities Interacting groups of populations of different species Niche - role in community for each organism Ecosystem All interacting organisms in an area and their interactions with their abiotic surroundings Sequence of organisms feeding on one another At the bottom of Food Chain: Producers • Convert sunlight into energy via photosynthesis – Produce organic material from inorganic material •Green plants, algae, some bacteria Above the Producers will be the Consumers Cannot get energy directly from sun Obtain energy in form of organic matter ◦ Animals Primary consumers (Herbivores: plant eaters) Secondary consumers (Carnivores: meat eaters) Omnivores (eat both plants and animals) At the top will be the Decomposers Organisms that decompose dead bodies into CO2, H2O, ammonia and other inorganic compounds Bacteria, fungi Trophic level – stage of energy flow through an ecosystem ◦ Trophic Levels: • First level: producers (plants) • Second level: herbivores (eat plants) • Third level: primary carnivores (eat herbivores) • Fourth level: secondary carnivores (eat primary carnivores) Two physical laws ◦ 1. Energy can neither be created or destroyed Follow energy through tropic levels ◦ 2. Natural processes lead to a disordered state (entropy) As energy passes form one trophic level to another, there is a reduction in the amount of available energy in living things and an increase in the amount of heat in the surroundings About a 90% loss in available energy from one trophic level to another Biomes: large regional ecosystems that share similar characteristics: ◦ Temperature ◦ Vegetation ◦ Animals ◦ Terrestrial ◦ Aquatic 1. Tropical Rainforest ◦ Near equator in Central and South America, Africa, parts of southern Asia and some Pacific islands ◦ Over 80 (up to 200) inches of rain ◦ Temperature has little fluctuation ◦ Greatest biodiversity in Flora and Fauna Flora: balsa, teak, ferns, orchids, vines, mosses Fauna: tree frogs, bats, lizards, snakes, birds, monkeys, insects 2. Desert ◦ Northern Africa, inland China, Australia, Antarctica ◦ Less than 10 inches of rain—nothing to do with temperature! ◦ Huge fluctuation in temperature ◦ Flora: scattered, thorny plants that lack leaves, i.e. cactus ◦ Fauna: insects, snakes, lizards, hawks, rabbits 3. Savanna ◦ Central Africa, Northern Australia and parts of South America ◦ 40 inches of rain during one period ◦ Dry and Rainy Season ◦ Grasses with a few scattered trees (Acacia) ◦ Antelope, zebra, buffalo, termites, snakes 4. Temperate Deciduous Forest ◦ Eastern North America, Europe, Japan, Korea and parts of China ◦ 30-40 inches of rainfall throughout year ◦ Cold winter, hot summer ◦ Deciduous trees – lose their leaves in the fall Maple, oak, hickory, birch, walnut, etc. ◦ Frogs, deer, owls, opossums, skunks, etc. 5. Temperate Grassland ◦ Western North America, Eurasia, Africa, Australia and South America ◦ 10-30 inches of rainfall ◦ Warm summers—cold winters ◦ Mainly grasses with a few trees along streams ◦ Prairie dog, antelope grasshopper, rattlesnake, meadowlark, etc. 6. Chaparral ◦ Mediterranean coast, southern California, southern tip of Africa, west coast of Chile and southern Australia ◦ 15 to 40 inches of rain ◦ Wet, cool winters—hot dry summers ◦ Woody shrubs ◦ Reptiles, insects, coyotes, rodents, spiders 7. Temperate Rainforest ◦ Western coastal areas of North America, southern Chile and west coast of New Zealand ◦ 80 inches of rain ◦ Mild temperatures throughout year ◦ Sitka spruce, Douglas fir, western hemlock, redwoods, red alder, maple, cottonwood. Mosses, ferns ◦ Deer, skunks, frogs, opossums, owls, beetles, mosquitos 8. Boreal Coniferous Forest (Taiga) ◦ Southern Canada, mountains of U.S., Northern Europe and Asia ◦ 10-40 inches of rain (lots of snow) ◦ Short, cool, humid summers—long, cold winters ◦ Small lakes and bogs ◦ Spruce and fir ◦ Bears, mice, wolves, moose, squirrels, midges, flies 9. Tundra ◦ Extreme northern North America, northern Europe and Asia (Artic circle) ◦ Less than 10 inches of rain (snow) ◦ Permafrost ◦ Freezing temps most of the year (summer nights) ◦ Dwarf willow, shrubs, moss, lichen ◦ Caribou, wolves, musk oxen, fox, snowy owls, mice, insects Environmental Factors in Aquatic Ecosystems • • • • • Ability of sunlight to penetrate water Depth of water Nature of bottom substrate Water temperature Salinity Marine ◦ High salt content Freshwater ◦ Low salt content ◦ Standing water (lakes, ponds, reservoirs) ◦ Running water (streams, rivers) Estuaries ◦ Shallow partially enclosed area where freshwater enters ocean ◦ Salinity varies with tide and water flow from river ◦ Productive ecosystem Sunlight penetrates Nutrients collect from river flow Pelagic - organisms that float or swim in open ocean ◦ Larger, active swimmers ◦ Smaller, weaker swimmers Plankton: very small, very weak swimmers, carried by current Phytoplankton Common in euphotic zone (where sunlight penetrates) Carry on photosynthesis (plant like) Zooplankton Feed on phytoplankton (animal like) Benthic ◦ Organisms that live on bottom Seaweed, clams, crustaceans, etc. (lobsters, shrimps) Coral reefs 1. Stationary water (lakes, ponds) Deep lake Similar to ocean Euphotic zone- top Plankton Littoral zone- along sides Rooted vegetation, algae Limnetic Zone- inner, deeper water No rooted vegetation 2. 3. Water running downhill (streams and rivers) Moving water Light reaches bottom But most streams not productive Major nutrients from terrestrial sources (Leaves, vegetation, insects) Estuaries Freshwater enters the ocean more salt tides Lots of nutrients Shallow water so light reaches to bottom Major nursery sites for a number of fish and crustaceans Habitat – place or part of an ecosystem occupied by an organism Niche – specific functional role of an organism Predation Parasitism Commensalism Mutualism Competition ◦ One animal (predator) captures, kills and eats another (prey) ◦ One organism (parasite) derives nourishment by living in or on another organism (host) ◦ One organism benefits while the other is not affected ◦ Two species live in close association and both benefit ◦ Interaction between organisms in which both are harmed to some extent Both organisms require a resource in short supply Environmental resistance- all limiting factors affecting a population Carrying capacity - maximum sustainable population of an area Limiting factors include: • • • • • • • Food Space Oxygen supply Climate variations Disease Environmental changes Predators World population ~ 7 billion ◦ Expected to grow to ~8 billion by 2025 (25% increase in 20 years) ◦ Divided into two distinct segments: Developed 2010 1.237 B 2025 1.290 B Fertility 1.7 Infant m 6/1000 Death 10/1000 % Over 65 17 GNI $31,200 Less Developed 5.656 B 6.819 B 2.7 50/1000 8/1000 6 $4,760 Almost all earth’s surface affected by humans ◦ More than 80% of land modified Habitat Destruction ◦ Other species displaced ◦ More resources diverted or destroyed by humans Global Climate Change (?) ◦ Increased amounts of greenhouse gases (CO2, Methane) Pollutants (organics, mercury, DDT, etc.) Consumption of the developed world ◦ Less than 20% of population consumes ~60% of energy US has <5% world’s population but consumes ~25% of its energy ◦ Food