Bio 161 Ecology and Evolution Community Ecology Competition
Bio 161 Ecology and Evolution Community Ecology: Competition. Spec A Spec B name Competition
Competition: definition
(Ecological) NICHE: concept.
Two modes of competition: (a) Exploitative competition: (b) Interference competition:
Two levels of competition: (a) Inter-specific competition: (b) Intra-specific competition:
Based on field observations, Joseph Grinell formulated the principle of competitive exclusion in 1904: "Two species of approximately the same food habits are not likely to remain long evenly balanced in numbers in the same region. One will crowd out the other".
Grinnell’s hypothesis.
Georgy Framtsevich Gause (1910 -1986)
Gause’s experiment:
Gause’s conclusion:
What if more than one species seem to occupy the Same niche? :
What if more than one species seem to occupy the Same niche? :
Thomas Park (1954).
Thomas Park (1954). Tribolium confusum Hot - wet Cool - dry Tribolium castaneum
A. C. Crombie (1946): Oryzaephilus sp. Tribolium sp.
A. C. Crombie (1946): Environment Simple Complex Oryzaephilus sp. Tribolium sp.
Gause (again):
Resource partitioning. Robert Mac. Arthur:
Resource partitioning. African vultures:
Resource partitioning. African grazers:
Resource partitioning. Caribbean Anoles sp. Lizards:
Corolla length of the flowers visited by bumble bees (Bombus sp. ) Bees with the same proboscis length occur at different altitudes.
Resource partitioning. Distribution of bumblebees along mountain slope: Corolla length of flowers Altitude Long Short High B. appositus B. bifarius Low B. kibyellus B. frigidus
Resource partitioning. Darwin’s finches of the Galapagos Islands:
Resource partitioning. Darwin’s finches of the Galapagos Islands:
Resource partitioning. Darwin’s finches: Natural Experiment.
Fundamental and Realized Niche.
Fundamental vs. realized niche competitor Balanus sp. = dominant Chthamalus sp. >
Realized vs Fundamental Niche. Chipmunks of the Sierra Nevada mountains:
Realized vs Fundamental Niche. Chipmunks of the Sierra Nevada mountains:
Realized vs Fundamental Niche. Chipmunks of the Sierra Nevada mountains: Fundamental vs Realized Niche Competitor = dominant >
Establishing the nature of symbiotic relationship. Ex. Rodent and ants in desert.
Symbiotic relationships. Species A Species B Neutralism 0 0 Commensalism + 0 Amensalism 0 - Mutualism + + Competition - Antagonism + -
Establishing the nature of symbiotic relationship.
Establishing the nature of symbiotic relationship. Ex. Rodent and ants in desert. Experiment:
THE END.
Q 2. Why is interference competition dependent on resource abundance?
Q 2. How many species are there in an (ecological niche)? Why?
Q 1. What form of competition is most intense?
Q 2. Two species can share a habitat if: a: b:
Q 3. What relationships are mutualistic?
Q 5. Why are the piggy-back ants present on the leaf fragments?
Q 5. (a) SD and SE are measures of _______ Q 5. (b) Express the SE in function of the variance: SE = Variance
Q 1. What did Thomas Park demonstrate using work with Tribolium (flour beetle) species?
Q 2. What did A. C. Crombie’s work (using Oryzaephilus and Tribolium) suggest about survival in the environment?
Q 3. Single trees of the tropical rainforest are heavily infested by a large number of leaf-eating insects. List three reasons.
Q 4. Why can the Lappet-faced, Ruppell’s, and Egyptian vultures feed on the same carcass?
Q 5. How do you summarize: 22, 21, 23, 25, 22, 33, 24, 20, 22, 21, 25, and 25?
Q 1. What two phenomena are illustrated by the observations on the slide?
Q 2. What does the following graph tell you about the ants and rodents of the southern desert?
Q 3. Based on the results of the table what is the symbiosis between ants and rodents in the sonoran desert?
Q 4. If the Lodge pole ground squirrel aggressively removes the Alpine ground squirrel from the lodge pole forest then for the Alpine ground squirrel: fundamental niche realized niche, for the Lodge pole squirrel: fundamental niche realized niche (Fill in: < or > or =)
Q 5. What is the relationship between Milkweed and Monarch butterfly? Positive, negative, or no effect on population size of symbiosis. Milkweed Monarch A 0 0 B 0 C + - + + + D E
Q 3. What is the function of the yellow dots at the base of the Passion flower leaves?
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