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Section I: General Principles of Ecology ECOLOGY – how organisms interact with one another and with their environment ENVIRONMENT – living and non-living components • ABIOTIC – non-living component or physical factors as soil, rainfall, sunlight, temperatures • BIOTIC – living component are other organisms. Environment of an Organism ABIOTIC components BIOTIC components Heat Light Water Substrate physical chemical Atmosphere Four elements of ancient Greek philosophy: Earth, air, fire, water Conspecifics Food (prey) Predators Symbionts parasites commensals mutualists Competitors Modifiers of the Abiotic Environment ECOLOGICAL ORGANIZATION INDIVIDUAL – individual organisms POPULATION – organisms of same species in same area (biotic factors) COMMUNITY – several populations in same area (biotic factors) ECOSYSTEM – community plus abiotic factors BIOSPHERE – all ecosystems on earth ECOLOGY OF INDIVIDUALS Homeostasis – delicate balance of a stable state Components Physiological Ecology Temperature and Water Balance Light and Biological Cycles Physiological Ecology and Conservation INTERACTIONS AMONG SPECIES Interactions Interspecific competition Predation Exploitation Symbiosis Niches and Habitats The place where an animal lives is called its habitat. An animal lives where it can find food, water, shelter and a mate. Combined, these characteristics are called the organism’s “niche” The Niche is the organisms way of life within an ecosystem. Niche The niche of a species consists of: Its role in the ecosystem (herbivore, carnivore, producer etc) Its tolerance limits (e.g. soil pH, humidity) Its requirements for shelter, nesting sites etc etc, all varying through time The niche as a two-dimensional shape Species A Niche represented by a 2-dimensional area Separate niches Species A Species B No overlap of niches. So coexistence is possible Overlapping niches Species B Species C Interspecific competition occurs where the niches overlap Specialisation avoids competition Species C Species B Evolution by natural selection towards separate niches Species B’ Species C’ Specialisation into two separate niches This niche is not big enough for the both of us! Species A Species D Very heavy competition leads to competitive exclusion One species must go Total exclusion Species A has a bigger niche it is more generalist Species E has a smaller niche it is more specialist Specialists, however, do tend to avoid competition Here it is total swamped by Species A Example: Squirrels in Britain The Red Squirrel (Sciurus vulgaris) is native to Britain Its population has declined due to: Competitive exclusion Disease Disappearance of hazel coppices and mature conifer forests in lowland Britain The Alien The Grey Squirrel (Sciurus carolinensis) is an alien species Introduced to Britain in about 30 sites between 1876 and 1929 It has easily adapted to parks and gardens replacing the red squirrel Today’s distribution Red squirrel Grey squirrel Carnivores Some animals, like the kingfisher, eat only other animals. These animals are called “carnivores”. Herbivores Some animals do not eat other animals. They survive on plants and are known as “herbivores”. Omnivores Some animals, like us, eat both plants and animals. These animals are called “omnivores”. Consumers “Consume” means “eat”. Animals are consumers because they “eat” (consume) food provided by plants or other animals. Producers Plants are living organisms. They need nourishment to survive. But… Plants do not eat other plants or animals. Plants are called producers, because they make their own food inside themselves. Predator A predator eats other animals. Cats eat fish. So do bears! Prey Any animal which is hunted and killed by another animal for food is prey. Predator Prey Types of Species Interactions Neutral – two species do not interact Mutualism – both benefit Commensalism – one benefits, other neutral Parasitism – one benefits, one harmed but not killed Predation – one benefits, other killed Predator - Prey Relationship Biogeochemical Cycles Hydrologic Cycle Phosphorus Cycle Nitrogen Cycle Carbon Cycle Hydrologic (Water) Cycle Phosphorus Cycle Nitrogen Cycle Carbon Cycle Food Chain rose plant aphids beetle chameleon hawk Producer 1st order Consumer or Herbivore 2nd order Consumer or 1st order Carnivore 3rd order Consumer or 2nd order Carnivore 4th order Consumer or 3rd order Carnivore Decomposers – consume dead and decaying matter Food Web ECOLOGY OF ECOSYSTEMS Energy Flow Energy Flow Pyramids Bio-mass Pyramids Community Succession and Stability Nutrient Recycling – nutrient cycles Energy vs Nutrient Nutrients – cyclic (Biogeochemical Cycles) Energy flow – one way Ecologic Pyramids Ecological pyramid - a graph representing trophic level numbers within an ecosystem. The primary producer level is at the base of the pyramid with the consumer levels above. Numbers pyramid - compares the number of individuals in each trophic level. Biomass pyramid - compares the total dry weight of the organisms in each trophic level. Energy pyramid - compares the total amount of energy available in each trophic level. This energy is usually measured in kilocalories. Numbers Pyramid Biomass & Energy Flow Pyramids Limiting Factor Any factor which limits a population’s growth Growth Curves Human Population An Introduction to Biomes Aquatic and terrestrial biomes (Biome = major ecosystem type) Climate Four abiotic factors determine climate Macroclimate Sunlight Temperature Wind and Ocean currents Precipitation Global, regional, local climate Microclimate Details of environmental conditions in small spaces Forest floor Under rock or log Climate Temperature Affected by sunlight But much more so by: Ocean currents Climate Precipitation Warm moist air carried by winds Condensation Biomes Distribution of major habitat types strongly influenced by climate Aquatic biomes cover about 75% of the earth’s surface - Wetlands - Lakes - Rivers, streams - Intertidal zones - Oceanic pelagic biome - Coral reefs - Benthos Wetlands: includes marshes, bogs, swamps, seasonal ponds. Among richest biomes with respect to biodiversity and productivity. Very few now exist as they are thought of often as wastelands. Marine environment with zonation. Coral Reefs occur in neritic zones of warm, tropical water, dominated by cnidarians (corals); very productive, protect land from storms; most are now dying from rise in global temperatures Deep-sea vent: Occurs in benthic zone; diverse, unusual organisms; energy comes not from light but from chemicals released from the magma. Terrestrial biomes - Tropical forest - Savanna - Desert - Chaparral - Temperate grassland - Temperate deciduous forest - Coniferous forest - Tundra Tropical Forest: Vertical stratification with trees in canopy blocking light to bottom strata. Many trees covered by epiphytes (plants that grow on other plants). Example of Tropical, Dry Forest Savannah: exotic grassland with larger animal species more common than a temperate grassland (more energy coming in = more energy going up the food chain) Desert: Sparse rainfall (< 30 cm per year), plants and animals adapted for water storage and conservation. Can be either very, very hot, or very cold (e.g. Antarctica) Chaparral: Dense, spiny, evergreen shrubs, mild rainy winters; long, hot, dry summers. Periodic fires, some plants require fire for seeds to germinate. Temperate Grassland: Marked by seasonal drought and fires, and grazing by large animals. Rich habitat for agriculture, very little prairie exists in US today. Temperate Deciduous Forest: Mid-latitudes with moderate amounts of moisture, distinct vertical strata: trees, understory shrubs, herbaceous sub-stratum. Loss of leaves in cold, many animals hibernate or migrate then. Original forests lost from North America by logging and clearing. Coniferous forest: Largest terrestial biome on earth, old growth forests rapidly disappearing, usually receives lots of moisture as rain or snow. Tundra: Permafrost (Permanent frozen ground), bitter cold, high winds and thus no trees. Has 20% of land surface on earth.