Unit 9 - Ecology

B-6.1 Explain how the interrelationships among organisms (including predation, competition, parasitism, mutualism, and commensalism) generate stability within ecosystems. Summarize how a stable ecosystem is obtained Identify/illustrate roles of various organisms in an ecosystem (predator, prey, parasite, host) using pictures, diagrams, or words Interpret a graph of predator/prey numbers over time Explain how the numbers of various organisms fluctuate in an ecosystem to maintain stability Exemplify biological relationships Explain how a significant change in the numbers of a particular organism will affect the stability of the ecosystem Classify a symbiotic relationship as mutualism, parasitism or commensalism Summarize each of the types of biological relationships Compare how various types of biological relationships affect the organisms involved

Ecology Scientific Study of interactions among organisms and how they interact with their environment

Levels of Organization

Levels of Organization Species – group of organisms similar to one another Can breed & produce fertile offspring Populations – groups of individuals belonging to the same species, live in the same area

Levels of Organization Community – different populations living together in a defined area Includes many species Ecosystem – collection of all organisms living in a particular place together Community and the factors that affect them Biotic and abiotic factors

Levels of Organization Biome – group of ecosystems having the same climate & similar dominant communities Biosphere - the portion of the earth that supports life - composed of living and non-living things

Biotic factors All living components of an ecosystem Examples: Bacteria Fungi Plants Animals

Abiotic factors Chemical or physical Examples: Water Nitrogen Oxygen (non-living factors) Chemical or physical Examples: Water Nitrogen Oxygen Salinity (salt) pH Soil nutrients & composition Temperature Amount of sunlight Precipitation

In a stable ecosystem: Population #’s of each organism fluctuate at a predictable rate 2. Supply of resources in physical environment fluctuates at a predictable rate 3. Energy flows through ecosystem at a fairly constant rate over time Constant interaction within an ecosystem generates stability

Community Interactions Predation Predator Prey Competition Niche Symbiotic relationships Parasitism Mutualism Commensalism

Predation Interaction between species One species (predator) eats the other (prey) Helps regulate population within ecosystem Causes stability

Predation Fluctuations in predator-prey populations are predictable At some point, prey population grows so numerous that they are easy to find

As prey population increases, predator population decreases As predator population increases, prey population decreases

Competition Relationship that occurs when 2 or more organisms need the same resources at the same time Can be same or different species Usually with organisms sharing the same niche

Competition - niche Niche: role of an organism in its environment Includes: Type of food it eats How it obtains its food How it interacts with other organisms 2 species with identical ecological niches cannot coexist in the same habitat

Competition - results decrease in the population of a species less adapted to compete for resource

Symbiotic Relationships Exists between organisms of 2 different species that live together in direct contact If a population of symbiotic organisms becomes unbalanced, all organisms fluctuate 3 types: Parasitism Mutualism Commensalism

Parasitism One organism (parasite) benefits at the expense of the other (host) Parasite does not kill the host

Parasitism Some parasites live within the host Examples: Tape worms Heartworms Bacteria

Parasitism Some parasites feed on the external surface of a host Examples: Aphids Fleas Mistletoe

Parasitism Survival of parasite-host populations: Neither has a devastating effect on the other Death of parasite-host populations: Devastating to both parasite & host It’s important that the host survive & thrive long enough for the parasite to reproduce & spread

Mutualism Both organisms benefit 2 organisms work closely together Help each other survive Example: Bacteria: can digest wood, live within digestive tracts of termites Plant roots: provide food for fungi that break down nutrients the plant needs

Commensalism One organism benefits & the host organism is not affected Host not helped or harmed Examples: Barnacles: attach to whales, dispersed to different environments where they obtain food & reproduce Burdock seeds: attach to organisms & carried to locations where they can germinate