Lecture 2: Fundamentals of Ecology

• Habitats are specific places in the environment where an organism is found
• Microhabitats are small areas within a larger habitat
• Niches are what an organism does in its environment
• Niches are defined by physical and biological factors that affect an organism's ability to survive and reproduce
• Fundamental niches are the broadest possible niche that an organism can occupy
• Realized niches are the part of the fundamental niche that an organism actually occupies
• Populations are a group of the same species
• Communities are populations of different species that occupy one habitat at the same time
• An ecosystem is a relatively stable system that results from the interaction of biological communities and the physical environment
• Biosphere refers to all of earth's ecosystems
• Homeostasis is the internal balance relative to external changes
• Characteristics of the physical environment include sunlight, temperature, salinity, oxygen, and pressure
• Sunlight allows for photosynthesis to occur
• Temperature is broken into ectotherms and endotherms
• Ectotherms are organisms in which their body temperature is determined by the surroundings
• Endotherms are organisms in which their body temperature is determined by metabolic heat production
• Heterotherms are animals that have a range of body temperatures, and can regulate their own body temperature

  It is broken into Inertial (large size) and Regional (countercurrent heat exchange)
• Salinity is the measured concentrated dissolved inorganic salts in the water
• Osmoconfomers are organisms whose body fluids conform with that of the surroundings
• Osmoregulators are organisms that regulate their osmotic concentration in spite of external changes
• Euryhalines are organisms that tolerate a wide range in salt concentrations
• Stenohalines are organisms that have a limited tolerance to variations in salt
• Isosmotic refers to having body fluids with the same osmotic pressure as the environment
• Hyperosmotic refers to having body fluids that are more concentrated than the surroundings
• Hypoosmotic refers to having body fluids that are less concentrated than the surroundings
• Low oxygen levels can cause increased temperature and solutes, high microbial loads and eutrophication, and lack of mixing
• Pressure increases by 1 atm per 1000 meters
• K selected species are categorized by few births, slow development, low death rate, and large size
• R selected species are categorized by many births, quick development, high death rate, and small size
• Tropic categories: autotrophs, heterotrophs
• Heterotrophs include herbivores, omnivores, carnivores, decomposers, and detritivores
• There is a 10% energy loss between trophic levels
• Three types of symbiosis: parasitism, mutualism, and commensalism