Transcript Ecology
Ecology Ecology • Scientific study of the interactions between organisms and their environment Levels of Study • Organism – Individual – 1 turtle Levels of Study • Population • Individuals of the same species living in the same area • All the turtles of the same species Levels of Study • Community • All the organisms living in an area • All the turtles, plants, insects, algae, bacteria Levels of Study • Ecosystem • All the organisms and all the abiotic factors • All the organisms & the soil, water, gases, minerals Levels of Study • Biosphere • All the organisms & all the abiotic factors on Earth • Earth Abiotic Factors • Nonliving • Temperature • Climate • Soil type • Rainfall • Gases • Minerals Biotic Factors • Living • Predators • Parasites • Herbivores • Carnivores • Decomposers Biomes • Tropical rainforest • Tall trees • High temperature • Heavy rainfall Biomes • • • • • • Savannas Tropical Grasslands Scattered trees High temperature Less rainfall than tropical rain forest Biomes • Temperate grasslands • Grasses • Seasonal droughts • Occasional fires • Lower temperature & less rainfall than savannas Biomes • Deciduous forests • Deciduous trees • Oak, maple • Warm summers • Cold winters • Moderate rainfall Biomes • Taiga • Coniferous forests • Pines & firs • Cold winters • Heavy snowfall Biomes • Tundra • Grasses & sedges • Very cold winters • Permafrost • High winds • Little rain Population Characteristics • Density • Number of individuals per unit area or volume Population Characteristics • Dispersal Patterns • Spacing between individuals • Clumped • Uniform • Random Population Characteristics • Dispersal Patterns • Clumped Population Characteristics • Dispersal Patterns • Uniform Population Characteristics • Dispersal Patterns • Random (ferns) Population Characteristics • Demographics • Study of vital statistics • Age structure – Groupings by age – Graphed • Sex ratio – % of females compared to males Population Characteristics Survivorship Curves • Graph of # of survivors vs. relative age Survivorship Curves • Type I • Most survive to middle age • Humans Survivorship Curves • Type II • Likelihood of death same at any age • Squirrel Survivorship Curves • Type III • Most die young • Oyster Limiting Factors • Prevent population from reaching biotic potential • Types – Density dependent – Density independent Limiting Factors • Density dependent • Effect becomes more intense with increased density • Examples – – – – Parasites & diseases Competition for resources Toxic effect of waste products Predation Limiting Factors • Density independent • Occur independently of density • Examples: – Natural disasters – Climate extremes Population Growth Models • Exponential Growth • Change in # of individuals (N) over time (t) is equal to the growth rate (r) times the number of individuals (N) N rN t Population Growth Models • Exponential Growth • J-shaped curve Population Growth Models • Logistic Growth • When limiting factors restrict size of population to carrying capacity • Carrying capacity (K) = max. # of individuals of a population that can be sustained by the habitat N KN rN t K Population Growth Models • Logistic Growth • Sigmoid (S) shaped curve Life-History Strategies • • • • r-selected species Exhibit rapid growth (J-curve) Examples – grasses, insects Characterized by opportunistic species – Quickly invade habitat – Quickly reproduce – Then die • Produce many offspring that are small, mature quickly, require little parental care Life-History Strategies • k-selected species • Population size remains relatively constant • Example - humans • Produce small number of relatively large offspring that require extensive parental care • Reproduction occurs repeatedly during lifetime Community Interactions • Interspecific Competition • Competition between different species • When 2 species compete for same resources one will be more successful • To survive, the less successful species – Must use slightly different resources – Must use resources during different time of day Community Interactions • Predation • Any animal that totally or partly consumes a plant or animal • True predator kills and eats another animal • Parasite lives in and off a host • Herbivore is an animal that eats plants Community Interactions • Symbiosis • Two species that live together in close contact • Types – Mutualism – Commensalism – Parasitism Community Interactions • Mutualism • Both species benefit from relationship • Examples – Bacteria in root nodules – Lichens – algae & fungus living together Community Interactions • Commensalism • One species benefits while the other is neither harmed nor helped • Examples – Birds building nests in trees – Egrets that eat insects around cattle Community Interactions • Parasitism • One species benefits while the other is harmed • Examples – Tapeworm inside animal – Ticks on dog Ecosystems – Trophic Levels • Primary producers • Plants • Photosynthetic bacteria • Algae Ecosystems – Trophic Levels • Primary consumers • Herbivores • Eat producers Ecosystems – Trophic Levels • Secondary consumers • Carnivores • Eat primary consumers (herbivores) Ecosystems – Trophic Levels • Tertiary consumers • Secondary carnivores • Eat secondary consumers Ecosystems – Pyramids • Pyramid of numbers • Most = producers • Least = top level consumers Ecosystems – Pyramids • Pyramid of energy • Most = producers • Least = top level consumers Ecosystems – Pyramids • 10% rule • Only 10% of energy available at each trophic level is converted into new biomass at the next level Ecosystems – Food Chain Ecosystems – Food Web Nitrogen Cycle Water Cycle Carbon Cycle Human Impact • Greenhouse effect • Ozone depletion • Acid rain • Deforestation • Pollution • Species extinction