Resource Partitioning
Resources in an environment are limited. Some species have evolved to “share”
a specific resource. This sharing may take several forms: ■ TEMPORAL
PARTITIONING occurs when two species eliminate direct competition by utilizing
the same resource at different times (e.g., one species of spiny mouse feeds on
insects during the day while a second species of spiny mouse feeds on the same
insects at night).
■ SPATIAL PARTITIONING occurs when competing species use the same
resource by occupying different areas or habitats within the range of
occurrence of the resource (e.g, different species of fish feeding at
different depths in a lake or different species of monkeys feeding at
different heights in a tree).
■ MORPHOLOGICAL PARTITIONING occurs when two species share the same
resource but have evolved slightly different structures to utilize the same
resource (e.g., two different species of bees have evolved different
proboscis lengths to utilize various size flowers of the same species).Interactions Among Species
Various types of interactions occur among species. They can benefit one or both
species, harm one or both species, or not affect one of the species involved.
Interactions Among Species
Interaction Description
Amensalism The interaction between two species whereby
one species suffers and the other species is not
affected. Usually this occurs when one organism
releases a chemical compound that is detrimental
to another organism. Examples: The bread mold
Penicillium secretes penicillin, which is a
chemical that kills bacteria. The black walnut
tree releases a chemical that kills neighboring
plants. Amensalism is common in chaparral and
desert communities as it stabilizes the
community by reducing competition for scarce
nutrients in the water. This chemical interaction
is known as allelopathy.Commensalism The interaction between two species whereby