Transcript SPECIES INTERACTIONS

COMMUNITY ECOLOGY
OBJECTIVES:
• Describe types of relationships among organisms.
• Compare primary and secondary succession.
Community Interactions
Community = a group of populations of different species living
close enough to interact.
Types of Interactions:
• Competition,
• Predation,
• Symbiosis.
Competition
• The competitive exclusion
principle states that when two
species compete for the same
resource or niche, eventually
the one with the slight
reproductive advantage will
eliminate the other.
Predation
• A true predator kills and eats the
other animals (prey).
• A parasite spends most or all of its
life living on another organism
(host) and feeding on its tissues.
• A herbivore is an animal that eats
plants.
Symbiosis
Symbiosis = “living together”; several types:
Mutualism =
both species benefit.
Parasitism =
one organism
benefits and the
other is harmed.
Commensalism = one organism benefits; the
other is neither harmed nor benefited.
Ecological
Succession
http://www.y
outube.com/
watch?v=V4
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Succession – gradual change in the composition of species
over time; frequently following a disturbance.
1. Primary succession - succession on a new site by pioneer
species such as lichens; eventually larger plants replace the
pioneer species.
Lichen = fungus living
with algae or
cyanobacteria
(mutualism).
Example: colonization after
volcanic eruption.
Primary succession
2. Secondary
succession –
changes occurring
where soil and
vegetation already
exist.
Example: gradual
changes after a fire.
Secondary succession
• Climax community =
stable, mature community that undergoes little succession.
Hmm…
1.
Does primary or secondary succession take longer? Why?
2.
Are pioneer species r-selected or K-selected species?
3.
How do species cause changes in the habitat that will result in
different species composition?
Species Diversity
= measures the number of different species in a community and the
relative abundance of each species.
Dominant species have the highest biomass (the sum weight of all
members of a population).
Keystone species have a strong influence on the survival of other
species; their removal results in dramatic changes in the makeup of
species in a community.
Keystone species examples: sea otter, grizzly bear, wolf.
Invasive species:
http://www.youtube.com/watch?v=HAY_UsGjyZk
An introduced (non-native) species that may compete with native
species for resources such as food, space, and water.
Examples: tamarisk, zebra mussels, kudzu.
Note: Most non-native species are not invasive.
Hmm…
• How do keystone species maintain balance in ecosystems?
• How does the introduction of a non-native species influence
the balance of an ecosystem?
MATH CONNECTION
The daily caloric requirements for male versus female killer
whales (orcas) is shown below:
• Male killer whale: 308,000 kcal/day
• Female killer whale: 187,000 kcal/day
Calculate the average caloric value of a sea otter
assuming a male orca consumes five sea otters each day
to meet its caloric requirement. Give your answer to the
nearest hundredth.