Intro to Ecology What is Ecology? Ecosystems are made up of the organisms and physical environment and the interactions between the living and non-living components within them Biotic factors: living organisms Ex. Includes plants, animals, microorganisms, dead organisms. Abiotic factors: non-living factors Ex. Rocks, pH of water, amount of light, air currents, temperature

Some key terms to consider Species A group of organisms sharing common characteristics that interbreed and produce fertile offspring Population A group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding Limiting Factors Factors which slow down the growth of a population as it reaches its carrying capacity Carrying Capacity The maximum number of species or “load” that can be sustainably supported by a given area

Niche Structure Niche: Fundamental Niche Realized Niche The particular set of abiotic and biotic conditions and resources to which an organism or population responds. (The role it plays) Fundamental Niche The full range of conditions and resources in which a species could survive and reproduce. (potential) Realized Niche The actual conditions and resources in which a species exists due to biotic interactions

Can’t we all just get along? Species Interaction Can’t we all just get along?

Population Interactions: Competition Intraspecific: Between members of the same species Results: population stabilization, fittest are most successful Interspecific: Between members of different species Results: Option 1: resource partitioning (sharing) Option 2: Competitive Exclusion (Winner) Population Interactions: Competition

Population Interactions Predation: One animal eats another Herbivory: Animal eating plant Symbiosis: Living together Mutualism: Relationship between 2 or more species in which all benefit and none suffer. Commensalism: Relationship between 2 or more species in which one is helped and the other is not significantly harmed. Parasitism: One species lives in or on another gaining its food from it. Usually does not kill host, but can

Population Changes S-Curves: Starts with exponential growth, but eventually stabilizes Carrying Capacity: Maximum Population (can change) Environmental Resistance: Factors that limit population size J-Curves: Exponential followed by sudden collapse Overshoots: When the carrying capacity is exceeded before collapse Diebacks: Collapses are referred to as diebacks

(environmental resistance) POPULATION SIZE Growth factors (biotic potential) Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Abiotic Biotic High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from or defend against predators Ability to resist diseases and parasites Ability to migrate and live in other habitats Ability to adapt to environmental change Decrease factors (environmental resistance) Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend Inability to resist diseases and parasites Inability to migrate and live in other Inability to adapt to environmental