ECOSPHERE

Definition of Ecosphere

• domain of life on Earth
• the thin layer of Earth where life exists
• the intersection of the hydrosphere, lithosphere, and atmosphere where life exists
• ecosphere = biosphere
  
• The biosphere is the sum total of all places in which organisms live. It includes:
  • hydrosphere
  • lithosphere
  • atmosphere
    

System for Classifying Life on Earth

• Kingdom (Monera, Protoctista, Fungi, Platae, Animalia)
• Phyla
• Classes
• Order
• Families
• Genera
• Species
  

Requirements For Life

• all forms of life (that we know of) require energy and liquid water
  
• the ultimate source of energy for all life (except some bacteria) is solar radiation
  
• Earth's unique position
  • Mercury and Venus (closer to the sun) receive so much energy that their water has been vaporized
    
  • The planets further from the sun than Earth receive such low levels of energy any water present is frozen and unable to sustain life
    
  • The two planets closest to the Earth
    • Venus: the surface temperature is high enough to melt lead due to runaway "Greenhouse Effect"
      
    • Mars: surface temperature is

• Solar energy is converted to chemical energy by Earth's green plants through photosynthesis
  • Photosynthesis is the process plants use to convert inorganic material into organic matter, using the assistance of light energy
    • Light energy enables the smaller inorganic molecules (water and CO₂) into organic sugar molecules
      
    • Process releases oxygen
      
    • Sugar is used as a source of energy by plants and animals that eat the plants
      
  • Respiration
    

Ecological Concepts

• Environment - everything that affects an organism in its lifetime
  • Abiotic factors of the environment
    • flow of energy
      
    • physical factors
      • climate
      • temperature
      • precipitation
      • soil, etc..
        
  • Biotic
    • all forms of life that an organism interacts with
      
• Limiting Factors - a shortage or absence of a key factor that restricts the success of an organism
  • Range of tolerance
    
• Habitat and Niche
  • Habitat - the space that an organism inhabits
    • soil type
    • availability of water
    • climate
    • plant species, etc..
      
  • Niche - the functional role that an organism has in its surroundings
    
    
• Natural Selection - process of more successful individuals surviving and reproducing larger number of offspring than those that are less successful
  • Species - a population of organisms in which the individuals are potentially able to interbreed and produce fertile offspring
    
    
  • Mechanisms of Natural Selection
    • Charles Darwin (1859) "On the Origin of Species by Means of Natural Selection"
      • Individuals within a species showed variation
        
      • Organisms within a species typically produce many more offspring than can survive
        
      • The excess number of individuals results in a struggle for survival
        
      • Because of the variation among individuals, some have a greater chance of surviving and reproducing than others
        
      • As time passes and each generation is subjected to the same process, the percentage of individuals showing favorable variations will increase and those having unfavorable variations will decrease

• Kinds of Organism Interactions
  • Predation
    
  • Competition
    • intraspecific competition
    • interspecific competition
      
  • Symbiotic Relationships: a close, long-lasting, physical relationship between two species in which at least one species derives nourishment from the other
    • Parasitism
      
    • Commensalism
      
    • Mutualism