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Ecology
2a- Ecology & Living Relationships
Principles of Ecology
• Ecology – study of
relationships between
living and nonliving parts of
the world
• Ernst Haeckel (1866) – first
to use the word to name
the study of how organisms
fit into their environment
Interdependence
• All organisms interact with…
1. The other organisms around them
2. The nonliving parts of their environment
• Survival depends on these interactions.
Interdependence
White-tailed deer
Acorns
Humans
Deer mouse
Deer tick
Parts of the Environment
• Abiotic factors – non-living parts
of an organism’s environment
– Air currents, temperature,
moisture, light, soil
• Biotic factors – all the living
things that inhabit the
environment
Ecological Levels of Organization
Organism
Population
Community
Ecosystem
Biome
Biosphere
Niche vs. Habitat vs. Ecosystem
• Ecosystem – all the organisms in a given area and the
abiotic factors that affect them
• Habitat – the place an organism lives out its life
• Niche – role and position a species has in its environment
– Includes all biotic and abiotic interactions as an organism
meets its needs for survival
– If two species are competing for the same niche, one will
most likely drive the other out and take control of the niche.
Niche vs. Habitat vs. Ecosystem
An egret lives around Jones Pond which is part
of the Smith River Estuary. The egret and its
mate eat fish, frogs, salamanders, snakes,
crayfish, mice, aquatic insects, crickets,
grasshoppers, and a variety of other insects in
Jones Pond and build a nest in a tree along
side the pond.
• What is the egret’s habitat?
• What is the egret’s niche?
• What is the egret’s ecosystem?
Organism Interactions: Predation
• The number of
predators affects the
prey population
– More predators,
more risk to prey
• The number of prey
affects the predator
population
– More prey, more
food for predators
Organism Interactions: Competition
• Competition – Organisms within a population must
compete for resources
– When populations grow, resources are in higher demand
– If demand is greater than supply……population must
decrease
• Fight and kill each other
• Reproduce less
Relationships
• All living things form
relationships with
other living things
• Symbiotic Relationship
– a relationship
between organisms of
two different species
that live together in
direct contact
Commensalism
• One organism benefits – The other is not
affected
– Examples:
• Spanish moss on a tree
• Barnacles on a whale
• Burdock seeds on a passing animal
Mutualism
• Both organisms benefit
– Acacia tree and ants – tree provides food for the ants and
the ants protect the tree from animals that would eat the
leaves
– Lichens: algae and fungus living together.
Algae provides food (photosynthesis)
and the fungus provides protection and
attaches the lichen to the rock or
wood where it lives.
- Bacteria living in human intestines: break down nutrients
and have a safe environment
Parasitism
• One organism benefits,
the other is harmed
– Some live within the host
• Tapeworms
• Heartworms
• Bacteria
– Some feed on the external surface of the host
• Ticks
• Fleas
• Mistletoe
– Most do not kill their host
(at least not quickly)
What is this?
• Commensalism, Mutualism, or Parasitism?
Tube Worms and Hydrothermal Vents
Hydrothermal Vent Communities
• Symbiotic Relationship: Bacteria
live in Tube worms.
• Worm has no digestive tract, so it
relies on bacteria for nutrition.
• Bacteria oxidize hydrogen sulfide
that the tube worms supplies to
them.
• Both need each other to survive
so what type of relationship?
– Mutualism
Hydrothermal Vents are Pretty Rad.
Hydrothermal Vents
• https://www.youtube.com/watch?v=BXGF3XS
-yAI