7A Ecology Basics Subtitle

Levels of Ecological Organization Individual Population Community Ecosystem Biosphere

Habitat VS Niche Habitat NICHE WHERE an organism lives What an organism DOES and how it INTERACTS with the environment

Partitioning Sharing resources Competitive Exclusion Principle No two species can occupy the exact same niche Partitioning Sharing resources

What affects living organisms? Biotic Factors Relationships between living organisms Humans pick flowers Coyotes eat chickens Abiotic Factors Physical or nonliving factors that affect living organisms Oxygen, water, sunlight, temperature, rocks, climate, buildings

Biotic Factors Competition Competing for resources Living space, food, water, mates, etc

Biotic Factors Predation One organism kills and eats the other Herbivory – herbivores eating plants Similar to predation Mimicry – mimic a dangerous animal so that others stay away

Biotic Factors Parasitism One organism feed on another (typically does not kill the host)

Biotic Factors Mutualism Commensalism Both organisms benefit One organism benefits and the other is neither helped nor harmed Crocodile and plover

Other Biotic Factors Disease Spread of pathogens or disease causing agents Bacterial or viral

Abiotic Factors Oxygen Water Sunlight Temperature Rocks Climate

Populations Both biotic and abiotic factors can affect population size (+) Number of births (-) Number of deaths Number of organisms that (+) move in (immigration) or (-) out (emigration) of a population

Exponential Growth Population under IDEAL conditions with UNLIMITED resources can grow EXPONENTIALLY J Shaped graph

In The Real World… Most population do NOT have unlimited resources Biotic factors: competition, predation, disease Abiotic Factors: drought, temperature, water, light All affect the growth of a population

Logistic Growth Populations may experience growth, but eventually reach carrying capacity Carrying Capacity Maximum number of individuals a particular environment can support at a given time

Logistic Growth S-Shaped Graph

Limiting Factor Anything that can limit population size Density Dependent Limiting Factors Any limiting factor that affects dense populations MORE Disease Overcrowding Predators

Limiting Factor Density Independent Limiting Factor Any limiting factor that affects all population equally Flood Tornado Drought Natural disasters

Non-Native Species Invasive Species Zebra Mussels

Stability For the most part, ecosystems are relatively stable Most population sizes remain relatively the same over time Only when there are changes to the ecosystem does the population sizes change

Stability If a small change occurs in an ecosystem, the population may change slightly If a dramatic change occurs in an ecosystem, the population size may change a lot