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)

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

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