Unit 1.1: Ecology. Warm-up Answers:

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1 Unit 1.1: Ecology Vocabulary Ecology: study of interactions between organisms and their environment Biodiversity: the total variety of living organisms in an ecosystem. Resource: a substance that is required for a living organism to survive; ex: food, water, space, etc Species: organisms that can interbreed to produce fertile offspring Population: all the members of a single species living in the same area at the same time Community: all the members of different populations that live together in an area 2 Herbivore: organism that only eats producers; cows, deer, vegetarians Carnivore: carn- = meat; organism that only eats other consumers; lions, dogs, sharks, spiders Omnivore: omni- = all; organism that eats both producers and consumers; pigs, raccoons, people Detritivore: organism that feeds on dead organisms or waste ( dead -tritivore); ex: worms, snails, dung beetles... Decomposer: breaks down organic matter into their basic elemental forms; ex: fungi, bacteria Biomass: amount of living material 3 I. Why Study Ecology? A. Ecology: the study of how living organisms interact with each other and with their environment. B. Interdependence: how organisms rely on each other and their environment; if you change one part of an ecosystem, it affects all other parts. 1. ex: changing water temperature affects how algae grow, which affects plankton, which affects anchovies, which affects herring, etc

2 C. Biodiversity: the total variety of living organisms in an ecosystem 1. Biodiversity depends on resources like water, food, space, temperature, salinity, etc a. Area with more resources can support more life 1) Tropical rainforest has great biodiversity because there is abundant food, water, space, and moderate temperatures 2) Arctic tundra has least biodiversity because limited food, water, cold temperatures 2. Measuring biodiversity: a. Species richness: how many different species in an area 1) Not the most numerous of a single species, but a greater number of different species 2) So an area with a million ants has less biodiversity than an area with 100 ants, 1 bird, and a cactus (extreme example ) b. Relative abundance: how many members of each species in a population 1) An area that has only one or two members of a species is not as healthy as an area that has a larger number of that species. Colors indicate the concentrations of animal species across the planet. Areas of deep red and yellow indicate the greatest density of species, while shades of blue indicate areas of less biodiversity Effects of biodiversity on an ecosystem: a. More biodiversity = greater stability b. Ex: if an area has only termites to break down dead trees and a disease kills off all termites in that area, then trees won t decay. But if an area has both termites and fungi, then if one is affected by disease, other species is still available to decompose trees. 4. Humans use compounds produced by other organisms for food, medicine, etc a. ex: rosy periwinkle only grows off African island, produces chemical used to treat cancer. b. By reducing biodiversity, we may eliminate a helpful species. 7 II. How Humans Affect Biodiversity A. Five effects include: 1. Habitat Alteration: changing the area where organisms live a. Examples of habitat alteration include: 1) Deforestation, wildfire 2) Clearing land for farming 3) Habitat fragmentation: breaks land into smaller pieces Creates biological islands Fewer species can exist, more vulnerable to changes 8 2

3 2. Invasive species: a. Non-native species out-compete native species for limited resources (food, water, space) Often have no natural predators to control their population size ex: pike introduced illegally into Lake Davis overran trout/salmon population, threatens all down-stream habitats 3. Pollution: plastics, chemicals a. Biological magnification: when plants take in DDT (a pesticide that does not biodegrade), animals that eat plants concentrate that DDT b/c eat lots of plants. Animals that eat those plant-eaters consume even more DDT b/c can t get rid of it Overharvesting: a. For meat, fur, hides b. Some people believe animal body parts have medicinal properties 5. Protect Endangered Species: a. Humans also create refuges and other protected habitats to help preserve animals in danger of extinction. b. In essence, this increases biodiversity by preventing its loss 10 III. 5 Levels of Ecological Organization: A. Less diverse systems are part of a hierarchy of more diverse systems 1. Organism, population, community, ecosystem, biosphere B. Organism/Individual the simplest level; can be a single animal, plant, or even a single cell C. Population a group of organisms of the same species living in the same area at the same time 1. Species: organisms that interbreed to produce fertile offspring 2. A population of squirrels in Grass Valley would be different than a population of squirrels in Los Angeles

4 D. Community different populations that live together in an area 1. Ex: squirrels, trees, bacteria, bugs, etc all living in Yosemite 2. Communities only include living organisms biotic factors E. Ecosystem a community of organisms interacting with their physical environment 1. Include organisms and nonliving components abiotic factors 2. Ex: freshwater or salt water, amount of sunlight, temperature 3. Includes habitats and niches for different communities F. Biosphere includes all ecosystems on Earth 1. Most biodiverse of the hierarchy 2. Three parts of the biosphere: a. Lithosphere: litho- = rock b. Hydrosphere: hydro- = water c. Atmosphere: atmos- = vapor IV. Energy Production in Ecosystems *Most energy for life comes from the Sun* A. Autotrophs produce food: auto- = self; troph- = feeder, so self-feeders, called producers 1. Use photosynthesis: convert energy from sunlight to produce food. a. Plants, algae, cyanobacteria 2. Or chemosynthesis: using energy from chemicals to produce food a. Bacteria on ocean bottom - no sunlight so must use chemicals that spew from hydrothermal sea vents. b. Or thermophiles next to volcanoes, hot springs 15 B. Heterotrophs consume food: hetero = other; troph- = feeder, so feed on others, called consumers 1. Cannot make their own food, so get energy by consuming other organisms 2. All animals and fungi are heterotrophs! a. Herbivore: eats only producers Ex: deer, cow, vegetarians b. Carnivore: eats only consumers Ex: spiders, lions, dogs c. Omnivore: eats producers and consumers Ex: humans, raccoons, bears, pigs d. Detritivore: eats remains of dead things Ex: worms, flies, vultures, scavengers e. Decomposer: break down dead organisms into elements; ex: bacteria, fungi 16 4

5 C. Producers = life 1. If no producers, then no food, so no life! D. Decomposers = life (almost) 1. Producers need minerals (nitrogen, phosphorus, magnesium) to make organic materials 2. Decomposers generate, recycle these minerals when breaking down dead, decaying matter 3. If no decomposers, then no minerals for plants to assimilate; (and lots of dead bodies just laying around!) 17 V. Feeding Relationships: A. Food Chain: show a one-way flow of energy 1. Ex: grass antelope lion B. Food Web: links many food chains 1. Shows more complex feeding relationships 2. Ex: mouse and rabbit both eat plants, and are eaten in turn by owls, jackals, etc 18 C. Ecological Pyramids: 1. Trophic pyramid: each step in a food web can be represented in a trophic pyramid a. Bottom level: autotrophs that produce food 1) Plants, algae, phytoplankton, some bacteria b. 2 nd level: herbivores/omnivores that eat the producers 1) Primary (1 ) consumers: deer, mice, zooplankton 19 c. 3 rd level: carnivores/omnivores that eat herbivores 1) Secondary (2 ) consumers 2) Usually smaller carnivores: raccoons, cats, spiders d. 4 th level: carnivores/omnivores that eat other carnivores 1) Tertiary (3 ) consumers 2) Usually larger carnivores: lions, orcas, eagles e. Detritivores/Decomposers exist at every level 1) Detritivores: scavengers that eat dead organisms 2) Decomposers: bacteria, fungi break down organic matter further 20 5

6 2. Energy Pyramids: show amount of energy that is transferred from one trophic level to the next a. 90% of energy is lost at each level why? b. Some energy used to grow/build up body systems c. Most energy is given off as heat during respiration d. *Heat is lost, cannot be recycled!* 3. Biomass Pyramid: shows amount of living organic matter (biomass) at each trophic level a. Less biomass at each level why? b. Less energy available so less biomass Pyramid of Numbers: shows relative # s of organisms at each trophic level a. Fewer organisms at the top of the pyramid b/c energy is limited b. Supply-and-demand: if more field mice, then more foxes b/c greater supply 23 6