PATTERN AND PROCESS M COMPETITION
3
Volterra (1926) and Lotka (1932) used this equation system to
demonstrate that two species using the same resources cannot coexist
indefinitely in a limited environment, and Gause (1935) confkmed this
conclusion experimentally. The competitive exclusion principle that
emerged as a result of this research has become known variously as the
“Gause Hypothesis”, “Gause’s Law”, the “Volterra-Gause Principle”,
etc. The verbal statement of this principle has also taken several forms.
Crombie (1947) states, “. . . it can be demonstrated by simple argument
that species with identical needs and habits cannot survive in the same
place if they compete for limited resources - a t least if their needs
and habits remain identical.” Hardin (1960) presents the case more
simply by saying “complete competitors cannot coexist.” He defines
the principle in the following terms: (1) if two non-breeding populations
occupy the same niche, and (2) if they are sympatric, and (3) if A
multiplies faster than B, then ultimately A will replace B and B will
become extinct. Hardin notes that in practice we remove the hypothetical character of (3) because we subscribe to the “axiom of inequality” which states that “no two things or processes, in a real world, are
precisely equal.” If, for example, two populations are sufficiently distinct morphologically to be recognized as species, they differ to some
degree in their genetics, physiology and ecology as well. There is therefore an a priori assumption that no two species are ecologically identical.
This introduces a circularity, which has been discussed by Gilbert et al. ‘
(1952), such that the competitive exclusion principle can neither be
proved nor disproved. If one species excludes another we say the
principle is “proved”, but if they coexist we conclude that they differ
ecologically and therefore occupy different niches.
What importance can we assign to this axiom as a conceptual model
of competition? Can we justifiably claim that the competitive exclusion
principle is “perhaps the most important theoretical development in
general ecology”, or that it is “one of the chief foundations of modern
ecology”? (Hutchinson and Deevey, 1949). As it is usually stated, it
cannot be used to either confirm or deny the existence of competition
as a natural process and, as Cole (1960) has noted, it is in danger of
becoming dogma. He points out that the doctrine of competitive exclusion contains a device which may be used to avoid Hardin’s (1960)
admonition that “every instance of coexistence must be accounted for”,
for it is easy to dismiss observations of apparent coexistence by merely
saying “they obviously have to occupy different niches or they couldn’t
exist.”
The laboratory experiments that followed the initial research of
Volterra, Lotka and Gause have not been particularly instructive insofar as competition in natural communities is concerned. The tendency
3
Volterra (1926) and Lotka (1932) used this equation system to
demonstrate that two species using the same resources cannot coexist
indefinitely in a limited environment, and Gause (1935) confkmed this
conclusion experimentally. The competitive exclusion principle that
emerged as a result of this research has become known variously as the
“Gause Hypothesis”, “Gause’s Law”, the “Volterra-Gause Principle”,
etc. The verbal statement of this principle has also taken several forms.
Crombie (1947) states, “. . . it can be demonstrated by simple argument
that species with identical needs and habits cannot survive in the same
place if they compete for limited resources - a t least if their needs
and habits remain identical.” Hardin (1960) presents the case more
simply by saying “complete competitors cannot coexist.” He defines
the principle in the following terms: (1) if two non-breeding populations
occupy the same niche, and (2) if they are sympatric, and (3) if A
multiplies faster than B, then ultimately A will replace B and B will
become extinct. Hardin notes that in practice we remove the hypothetical character of (3) because we subscribe to the “axiom of inequality” which states that “no two things or processes, in a real world, are
precisely equal.” If, for example, two populations are sufficiently distinct morphologically to be recognized as species, they differ to some
degree in their genetics, physiology and ecology as well. There is therefore an a priori assumption that no two species are ecologically identical.
This introduces a circularity, which has been discussed by Gilbert et al. ‘
(1952), such that the competitive exclusion principle can neither be
proved nor disproved. If one species excludes another we say the
principle is “proved”, but if they coexist we conclude that they differ
ecologically and therefore occupy different niches.
What importance can we assign to this axiom as a conceptual model
of competition? Can we justifiably claim that the competitive exclusion
principle is “perhaps the most important theoretical development in
general ecology”, or that it is “one of the chief foundations of modern
ecology”? (Hutchinson and Deevey, 1949). As it is usually stated, it
cannot be used to either confirm or deny the existence of competition
as a natural process and, as Cole (1960) has noted, it is in danger of
becoming dogma. He points out that the doctrine of competitive exclusion contains a device which may be used to avoid Hardin’s (1960)
admonition that “every instance of coexistence must be accounted for”,
for it is easy to dismiss observations of apparent coexistence by merely
saying “they obviously have to occupy different niches or they couldn’t
exist.”
The laboratory experiments that followed the initial research of
Volterra, Lotka and Gause have not been particularly instructive insofar as competition in natural communities is concerned. The tendency