Transcript Continue competition - Powerpoint for Oct. 14.

Competition
Species can compete for two resources and can
coexist when 2 conditions are met:
1) The habitat must be such that one species is
more limited by one resource and the other
species is more limited by the other resource.
2) Each species must consume more of the
resource that more limits its own growth.
Another look at plant strategies
– from Peter Grime
Grime’s C-S-R strategies
• Competitive - plants such as perennial herbs, shrubs
and trees typically have dense leaf canopies, high
growth rates, low seed production and relatively long
life spans
• Stressful -stress-tolerant plants that often have small
evergreen leaves, low growth rates, low seed
production and long life spans
• Disturbed environments - the plants are primarily
Ruderals – plants which are usually small, grow
rapidly, short life spans and produce many seeds
Grime’s C-S-R strategies
Fynbos – South African
Mediterranean shrubland
Fynbos burning
Fynbos recovery
Competition in Nature –
the Birth of Experimental Ecology
Joe Connell
Acorn barnacles growing on an old car tire
Acorn barnacles on the rocky coast
Sceloporus – Fence lizard
Urosaurus – long tailed brush lizard
aka tree lizard
Competitive Release
• Competitive Release is a prediction from
examining the competitive exclusion principle
that in the absence of competition a species
should expand its niche
Chalcophaps indica – Emerald Dove
Chalcophaps
stephani –
Stephen’s
Dove
Gallicolumba rufigula
Character Displacement
• Character displacement is a measurable
physical difference between two species which
has arisen by natural selection as a result of the
selection pressure on one or both to avoid
competition with each other - here we assume
that environment is the same at all locations
Hydrobia ulvae
Hydrobia ventrosa
Hydrobia ulvae – note size
The Ghost of Competition Past
Joe Connell
Patterns like character displacement or competitive
release can be caused by several things:
1. the pressure of current competition causes the pattern
2. competition which occurred in the past may have driven
natural selection to cause the pattern we see today - "the
ghost of competition past"
3. competition in the past eliminated a number of other species,
leaving behind only those that were different in the use of
habitat
4. the species may have evolved independently and in different
ways and have never competed with each other
5. the species may differ in their niches, but not enough to
coexist in a stable environment, however the environment
varies and thus prevents competition from reaching its
predicted end result
Blackburnian warbler
Cape May warbler
Black-throated green
warbler
Bay-breasted warbler
Yellow-rumped
warbler
Ghost of Competition Past in
Israeli Rodents
Gerbillus allenbyi
Meriones tristami