Ecology

• 1. Species richness and relative abundance of different species.
• 2. Dominant species
• 3. Response to disturbances
• 2. Trophic structure-the feeding relationships among the various species

• Competition
• Predation
• Symbiosis
• Herbivory

between species

within a species

This is the concept that two species competing for the same limiting resources cannot coexist in the same community. One will use resources more efficiently, thus reproduce more rapidly and eliminate the inferior competitor.

Or one species may evolve to use a different set of resources

When a nonpoisonous species mimics a poisonous species

When two poisonous species mimic each other

A keystone species is a species that plays a critical role in maintaining the structure of an ecological community and whose impact on the community is greater than would be expected based on its relative abundance or total biomass.

One organism harmed and the other helped.

One organism is helped and the other is neither harmed nor helped.

Both organisms benefit

A predictable and orderly changes in the composition or structure of an ecological community.

• begins in a virtually lifeless area with no soil. New volcanic islands rubble left by a retreating
• glacier.

When a disturbance destroys an existing community.

1

# of individuals of a species per unit area or volume

the way individuals are spaced within their area.

Clumped pattern.

Plot the proportion of individuals alive at any given at each age

• •I – fewer offspring but live longer
• •II – mortality is more constant over the life span.
• •III – high death rates for very young and then a period when death rates are lower for those who survive.

Growth idealized. J curve

S curve

• Occur with some regularity
• –ex: lynx & hare cycles every 10 years
• –food shortages, predator-prey interactions, or combinations of both

• Age at which reproduction first occurs
• The frequency of reproduction
• The number of offspring
• Amount of parental care given.

Smaller organisms. They reproduce quickly

Bigger organisms. In stable and predictable environments. Longer life expectancy.