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Ecology WHAT IS ECOLOGY? Ecology- the scientific study of interactions between organisms and their environments, focusing on energy transfer Ecology is a science of relationships The environment is made up of two factors: • Biotic factors- all living organisms inhabiting the Earth – plants, animals, bacteria, etc. • Abiotic factors- nonliving parts of the environment – temperature, soil, light, moisture, air currents Nutrient Cycles • Abiotic factors are often nutrients needed by plants and animals and they must be cycled within the biomes and ecosystems. • Cycling maintains homeostasis (balance) in the environment. • 3 cycles: 1. Water cycle 2. Carbon cycle 3. Nitrogen cycle Water Cycle • Evaporation – liquid to gas • Transpiration – loss of water from plant leaves • Condensation – gas to liquid in the clouds • Precipitation – rain, sleet, snow Water Cycle Carbon Cycle • Photosynthesis and respiration cycle carbon and oxygen through the environment. • Carbon dioxide (CO2) is removed from the atmosphere by the ocean and plants during photosynthesis • Carbon dioxide (CO2) is returned to the atmosphere by volcanic activity, burning of fossil fuels and cellular respiration by plants and animals. Carbon cycle Nitrogen Cycle Atmospheric nitrogen (N2) makes up nearly 78%-80% of air. Organisms can not use it in that form. Lightning and bacteria convert nitrogen into usable forms. Nitrogen Cycle Nitrogen-fixing bacteria • Some live in a symbiotic relationship with plants of the legume family (e.g., soybeans, clover, peanuts). • Some nitrogen-fixing bacteria live free in the soil. Nitrogen Cycle Nitrogen fixation – convert atmospheric nitrogen (N2) into ammonia (NH3) and nitrates (NO3) N2 NH4+ Denitrification – other bacteria change ammonia and nitrates back into nitrogen gas (N2) Biosphere Levels of Organization Biome Ecosystem Community Population Organism Organism - any unicellular or multicellular form exhibiting all of the characteristics of life, an individual. •The lowest level of organization POPULATION - a group of organisms of one species living in the same place at the same time that interbreed • Produce fertile offspring • Compete with each other for resources (food, mates, shelter, etc.) Community - several interacting populations that inhabit a common environment and are interdependent. Ecosystem - populations in a community and the abiotic factors with which they interact (ex. marine, terrestrial) Biome – a group of ecosystems that have the same climate and similar dominant communities • Each biome contains distinctive plant and animal groups, which are adapted to that particular environment Biosphere - life supporting portions of Earth composed of air, land, fresh water, and salt water. •The highest level of organization Major Land Biomes • Biome- complex of terrestrial communities that cover a large area; characterized by soil, climate, plants, and animals • Plants and animals vary by tolerance to temperature and precipitation • 8 Major Biomes Tropical Rain Forest • Hot and Wet Boa constrictor – close to equator so warm temperatures year round – Over 250 cm rain per year Toucan Black Jaguar Sloth Jaguar Orchids Tapir Tropical Rain Forest • Most species of plants & animals (species diversity) • Soil lacks nutrients • Plants: broad leaved evergreen trees, large woody vines, climbing plants, orchids, bromeliads • Animals (photos) Tapir Boa constrictor Toucan Black Jaguar Sloth Jaguar Tropical Rain Forest • Adaptations of Plants and Animals – Toucans and parrots have large, strong beaks to crack open nuts. – Animals have camouflage to blend in to the surroundings of the rain forest. • Example: Insects may be shaped like leaves or twigs – Some animals have very bright colors to warn predators that they are poisonous. • Example: Poison arrow frogs Tropical Savanna • Seasonal rainfall: 100-150 cm per year • Warm year round • Frequent fires Giraffe Storks Aardvark Hyena Lion Tropical Savanna • Plants: Tall perennial grasses, small trees and shrubs that are often drought-tolerant and fireresistant • Animals: (photos) Giraffe Storks Aardvark Hyena Lion Tropical Savanna • Adaptations of Plants and Animals – Drought tolerant and fire resistant plants can retain water or survive the frequent fires of this biome Kangaroo rat Desert • Dry, less than 25 cm of rain a year • Extreme changes in temperature throughout the day Roadrunner – Extremely hot during the day and cold at night Desert big horned sheep Golden eagle Mule deer Mountain lion Creosote bush Desert Kangaroo rat • Plants with short growth cycles that Roadrunner can retain water: cacti, succulents, creosote bush • Animals with high tolerance to temperature changes Desert big horned sheep Golden eagle Mule deer Mountain lion Creosote bush Desert • Adaptations of Plants and Animals – Reptiles have thick, waterproof skin to hold in water – Cacti and other succulents have thick fleshy leaves that can hold large amounts of water for a long time – Many animals are nocturnal. They sleep in shade or underground during the day and are active at night when it is cool. Pronghorn antelope Temperate Grassland • Moderate precipitation: Polecat 25-75 cm per year • Hot summers & Cold Bison winters • Periodic fires Black-tailed prairie dog Blazing stars sunflowers Coyotes Badgers Pronghorn antelope Temperate Grassland Polecat • Plants: lush grasses and herbs, drought and fire-resistant plants Bison • Animals: many herbivores and carnivorous predators (photos) Black-tailed prairie dog Blazing stars sunflowers Coyotes Badgers Temperate Grassland • Adaptations of Plants and Animals – Drought and fire-resistant plants – Rich soil allows many lush grasses to grow and makes this biome excellent for farming. Temperate Woodland and Shrubland • Also called the CHAPPARAL • Hot, dry summer with cool, moist winter • Rainfall: 25-45 cm per year, mostly during winter Squirrel Fox Warbler California quail Black-tailed deer Temperate Woodland and Shrubland • Plants: Woody, evergreen shrubs with small leathery leaves, oily herbs • Animals (photos) Squirrel Fox Coyotes Warbler California quail Black-tailed deer Raccoon Temperate Forest • Warm summer with cold, moderate winters • Year around rain: 200-350 cm per year Skunk Bobcat Turkey Black bear Raccoon Temperate Forest • Plants: Deciduous and coniferous trees, mosses, and ferns • Animals (photos) Squirrel Skunk Deer Bobcat Turkey Black bear Temperate Forest • Adaptations of Plants and Animals – Deciduous trees lose their leaves when winter approaches to keep them from freezing. – Some animals migrate during cold seasons to a warmer climate. Boreal Forest • Also known as TAIGA • Northern hemisphere • Long, cold winter, short summers • Moderate precipitation: 20-200 cm per year, mostly snow Spruce Snowshoe hare Boreal Forest • Plants: Needle leaf coniferous trees, broad leaf deciduous trees, small berry bearing shrubs • Animals: migratory animals and large herbivores (photos) Timber wolves Lynx Moose Boreal Forest • Adaptations of Plants and Animals – Waxy coating on conifers to retain water. – Animals such as bears hibernate during the coldest months. Tundra • Northern hemisphere • Characterized by permafrost, permanently frozen snow • Cold & windy • Little precipitation: 15-25 cm per year (almost as little as desert) Bearberry Artic fox Artic willow Caribou Polar bear Caribou Tundra • Plants: small with short roots because of permafrost, no trees • Animals: Migratory animals or animals with high tolerances for harsh conditions (photos) Polar bear Snowy owl Artic fox Tundra • Adaptations of Plants and Animals – Animals such as the arctic fox have white fur to camouflage themselves in the snow. – Plants have adapted to grow with short roots because they cannot grow deep roots in the permafrost. Habitat vs. Niche Habitat- the place in which an organism lives out its life Niche - the functional role a species plays in a community; how it fits in to its particular community and ecosystem Habitat vs. Niche A niche is determined by the tolerance limitations of an organism, or a limiting factor. Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment. Limiting Factors Examples of limiting factors •Amount of water •Amount of food •Temperature •Amount of space •Availability of mates Limiting Factors Density dependent factors – depend on the number of organisms in a population •Ex: Available food & water Density independent factors – do not depend on the number of organisms in a population •Ex: Weather, natural disasters & human activities Interrelationships of Organisms • There are 3 main types of feeding relationships 1. Producer – Consumer 2. Predator – Prey 3. Parasite - Host Feeding Relationships Producers (Autotrophs) • Make their own food through photosynthesis or chemosynthesis – Ex: plants, algae • Bottom of the food chain Feeding Relationships Consumers (Heterotrophs) • Must eat other organisms to obtain energy Herbivores Carnivores Omnivores Decomposers Feeding Relationships • Herbivores • Primary consumers • Eat plants • Carnivores • Secondary & Tertiary consumers • Eat animals Feeding Relationships Carnivores • Meat eaters • Predators – Hunt prey animals for food. Feeding Relationships • Omnivores – Eat both plants and animals – Ex: humans Feeding Relationships • Detritivores • Scavengers • Feed on carrion, dead animals Feeding Relationships • Decomposers – Breakdown the complex compounds of dead and decaying plants and animals into simpler molecules that can be absorbed Symbiotic Relationships Symbiosis- two organisms living closely together 3 Types of symbiosis: 1. Commensalism 2. Parasitism 3. Mutualism Symbiotic Relationships • Commensalism – one species benefits and the other is neither harmed nor helped – Ex. orchids on a tree Symbiotic Relationships • Parasitism – one species benefits (parasite) and the other is harmed (host) – Ex. lampreys, leeches, fleas, ticks, tapeworm Symbiotic Relationships • Mutualism – beneficial to both species – Ex. cleaning birds and cleaner shrimp Energy Flow in Ecosystems • All living organisms require energy to function. • Energy is used up and lost as heat as it moves through ecosystems • Each step in the energy transfer from one organism to another is called a trophic level Energy Flow in Ecosystems • Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem. • Producers (Autotrophs) are at the lowest level • Consumers (Heterotrophs) are at the higher levels Energy Flow in Ecosystems • 10% Law – Approx. only 10% of the energy from one trophic level is transferred to the next Heat Heat Heat Producers Consumers Decomposers 100 Units of Energy 10 Units of Energy 1 Unit of Energy Energy Flow in Ecosystems Food chain- simple model that shows how matter and energy move through an ecosystem The arrows show the direction of energy flow Energy Flow in Ecosystems • Food web- shows all possible feeding relationships in a community at each trophic level • Represents a more complex network of interconnected food chains Energy Flow in Ecosystems • An ecological pyramid shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web. • Three types of ecological pyramids: • energy pyramids • biomass pyramids • pyramids of numbers Energy Pyramid: Shows the relative amount of energy available at each trophic level. 0.1% Third-level consumers 1% Second-level consumers 10% First-level consumers 100% Producers Only 10% of the energy that is stored in one trophic level is passed on to the next level. Biomass - The total amount of living tissue within a given trophic level 50 grams of human tissue 500 grams of chicken 5000 grams of grain Biomass Pyramid: Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid. Pyramid of Numbers: Shows the relative number of individual organisms at each trophic level. Biological Magnification While energy decreases as it moves up the food chain, toxins increase in potency (concentration). •This is called biological magnification Example: DDT used in pesticides in the mid 50’s and 60’s contributed to the near extinction of bald eagles before it was banned Biological Magnification Ecological Succession Succession – the series of predictable changes that occurs in a community over time Primary Succession – occurs on surfaces where no soil exists – Ex: On rock surfaces formed after volcanoes erupt Ecological Succession Pioneer species – the first species to populate the area Ecological Succession Secondary Succession – occurs when a community experiences a disturbance such as a fire, plowing a field for farming, or clearing a field for construction – Occurs on pre-existing soil Ecological Succession Climax community– the final community of organisms in a ecosystem once it becomes stable Human Impact on Ecosystems Biodiversity – the variety of life in an area Biodiversity my be decreased by human activities such as: – Using pesticides and chemical fertilizers – Clearing land for construction – Introducing non-native species