46
S l C I i A S U S . MILIJES
Hutchinsori ( 1 ! ~ 7 ) points out, is highly unlikely and we ordinarily
expect that there will be an optimal part of the niche with suboptimal
conditions near its boundaries. This is reflected, of course, in the law
of tolerance and is seen in the outcome of competition between T .
cnstaneum and T . confusum under different conditions of temperature
and moisture (Park, 1954). Table VI shows the percentage of replicates
for each treatment in which T . castaneum or T . confusum eventually
persisted and its competitor was eliminated (extinction of one species
was a condition of the experiment). At high temperature and moisture
T . castaneum persisted and T . confusum was eliminated in all replicates;
a t low temperature and humidity the reverse occurred. I n the latter
situation the failure of T . cnstaneum to survive was not due entirely
to competition. In single-species controls T . castaneum had a mean
life-duration of 350.0 f 34.1 days, but this was reduced to 27.15 f
18-1 days when T . confusum was present, so that the effect of the mixedspecies interaction was to hasten the elimination of T . castaneum which
would have occurred in any event. The most interesting feature of these
results is, however, the “indeterminate” outcome of competition when
temperature and moisture were between these extremes. Thus, although
T . confusum eliminated T . castaneum. in 71% of 28 replicates a t 24°C
and 70% relative humidity, T . castaneum won in 29% of the replicates.
The results were therefore “probabilistic” rather than “deterministic”
(Park, 1054).
T A B L E V I
Selective Eliminotion .f Triboliuin cavtaneum and T. confusuin in
Relation to Temperature and Moisture. (Data front Park, 1954)
Treatment
Percent of Replicates in which
Tempera,ture
Moisture
Species Persists
34
34
29
29
24
24
(Percent R.H.)
T. castaneum
70
100
3 0
10
70
86
30
13
70
29
30
0
T. coi&wrn
0
90
14
87
71
100
This interaction has been analysed in detail by Neyman, Park and
Scott (1968) and is discussed in terms of the Gause cases by Slobodkin
(1961). The patterns of competition for each set of conditions (Table VI)
can be represented by a series of empirical diagrams that effectively
S l C I i A S U S . MILIJES
Hutchinsori ( 1 ! ~ 7 ) points out, is highly unlikely and we ordinarily
expect that there will be an optimal part of the niche with suboptimal
conditions near its boundaries. This is reflected, of course, in the law
of tolerance and is seen in the outcome of competition between T .
cnstaneum and T . confusum under different conditions of temperature
and moisture (Park, 1954). Table VI shows the percentage of replicates
for each treatment in which T . castaneum or T . confusum eventually
persisted and its competitor was eliminated (extinction of one species
was a condition of the experiment). At high temperature and moisture
T . castaneum persisted and T . confusum was eliminated in all replicates;
a t low temperature and humidity the reverse occurred. I n the latter
situation the failure of T . cnstaneum to survive was not due entirely
to competition. In single-species controls T . castaneum had a mean
life-duration of 350.0 f 34.1 days, but this was reduced to 27.15 f
18-1 days when T . confusum was present, so that the effect of the mixedspecies interaction was to hasten the elimination of T . castaneum which
would have occurred in any event. The most interesting feature of these
results is, however, the “indeterminate” outcome of competition when
temperature and moisture were between these extremes. Thus, although
T . confusum eliminated T . castaneum. in 71% of 28 replicates a t 24°C
and 70% relative humidity, T . castaneum won in 29% of the replicates.
The results were therefore “probabilistic” rather than “deterministic”
(Park, 1054).
T A B L E V I
Selective Eliminotion .f Triboliuin cavtaneum and T. confusuin in
Relation to Temperature and Moisture. (Data front Park, 1954)
Treatment
Percent of Replicates in which
Tempera,ture
Moisture
Species Persists
34
34
29
29
24
24
(Percent R.H.)
T. castaneum
70
100
3 0
10
70
86
30
13
70
29
30
0
T. coi&wrn
0
90
14
87
71
100
This interaction has been analysed in detail by Neyman, Park and
Scott (1968) and is discussed in terms of the Gause cases by Slobodkin
(1961). The patterns of competition for each set of conditions (Table VI)
can be represented by a series of empirical diagrams that effectively