24
RICHARD S. MILLER
is now negligible if it occurs at all. If the tremex larvae are uniformly
or randomly distributed at different depths in the logs and do not alter
their distributions as a result of the relative effects of the three species
of parasite upon their numbers, each species of Megurhyssa will continue to utilize a separate portion of the total resource regardless of the
activities or effects of the other two species, and changes in the abundance of tremex larvae at different depths will not lead to inter-specific
interactions between the wasps. Thus, three apparently sympatric
species which use the same habitat in the same ways are in fact allopatric
at the level of their larval distributions and therefore do not compete.
+
t
u:13
N-SO
N:18
0
atrata
macrurus
greenei
FIG. 4. Ovipositor lengths of Megarhyssa atrata, M . macrurus and M . greenei. Horizontal
line, mean length; vertical line, range; rectangle, fS.D. (After Heat,wole and Davis,
19661.
Contiguous allopatry is a particularly interesting phenomenon which
has received very little attention from ecologists, in spite of the fact
that it seems by its nature to indicate a strong element of competition.
It is unlikely that the fundamental niches of two species would be
entirely separate but contiguous (Fig. 3 D) over any appreciable area.
Nevertheless, such a'distribution pattern could be produced by a sharp
environmental discontinuity, and there is nothing in the pattern itself
which immediately reveals whether it is controlled by environmental
factors or competitive exclusion.
The geographic and habitat distributions of the four species of pocket
gopher (Beomyidae) that occur in Colorado show a pattern of contiguous
RICHARD S. MILLER
is now negligible if it occurs at all. If the tremex larvae are uniformly
or randomly distributed at different depths in the logs and do not alter
their distributions as a result of the relative effects of the three species
of parasite upon their numbers, each species of Megurhyssa will continue to utilize a separate portion of the total resource regardless of the
activities or effects of the other two species, and changes in the abundance of tremex larvae at different depths will not lead to inter-specific
interactions between the wasps. Thus, three apparently sympatric
species which use the same habitat in the same ways are in fact allopatric
at the level of their larval distributions and therefore do not compete.
+
t
u:13
N-SO
N:18
0
atrata
macrurus
greenei
FIG. 4. Ovipositor lengths of Megarhyssa atrata, M . macrurus and M . greenei. Horizontal
line, mean length; vertical line, range; rectangle, fS.D. (After Heat,wole and Davis,
19661.
Contiguous allopatry is a particularly interesting phenomenon which
has received very little attention from ecologists, in spite of the fact
that it seems by its nature to indicate a strong element of competition.
It is unlikely that the fundamental niches of two species would be
entirely separate but contiguous (Fig. 3 D) over any appreciable area.
Nevertheless, such a'distribution pattern could be produced by a sharp
environmental discontinuity, and there is nothing in the pattern itself
which immediately reveals whether it is controlled by environmental
factors or competitive exclusion.
The geographic and habitat distributions of the four species of pocket
gopher (Beomyidae) that occur in Colorado show a pattern of contiguous