ECOLOGY, SYSTEMATICS AND EVOLUTION OF AUSTRALIAN FROGS 73
either of the call races of Crinia insignifera, wbch occurs to the west.
In vitro crosses gave very inconclusive results and Phv was regarded
M a spcierJ (Crinia pseudimignifera Main) on the basis of the distinctive
male breeding call (Main, 1957).
Subsequently Littlejohn (1959) questioned the specific status of this
form because, in an area disturbed by soil excavation, near Bullsbmk,
he recorded what he regarded as hybrid calla in a two-species breeding
congress. A whole array of calls ranging from unpulsed through 2 and
3 pulses to typical four-pulsed calls of C. pedinsignifera was recorded
(Littlejohn, 1959, Fig, 9). In retrospect it seems that these calls were
those of C. pseudimignifera males when the temperature was not that
under which normal full breeding and calling takes place (see ecological
section).
Subsequently, in 1959 and 1960, soil waa again removed from this
site which was then watched closely each winter until 1963. The characteristics of the Bullsbrook site are as follows: it is an area of laterite
and clay soils on which water lies during winter. At other times the
area is completely dry. From time to time soil is removed from the
study area as needed for construction work on the nearby Royal
Australian Air Force base. Following such removal, extensive areas of
bare soil are left and in the following winter the ponds which form are
occupied by breeding congresses of both C. insignifera and C. pseudinsignifera. Mixed breeding choruses are oommon if the excavation has
been in typical C. insignifera habitat. Littlejohn’s work (1959) was done
following such a disturbance. However, as the area was kept under
observation, while the vegetation regenerated during 1959 and 1960 it
became clear that C. insignifera tended to remain in any area where
the vegetation was high, 80 producing good cover. On the other hand
Crinia peudinsignifera withdrew to exposed areas where vegetation
wag low and sparse. By 1963 there was good habitat separation of the
two species.
While the plant regeneration was being observed, study of the breeding of both species was also undertaken. The 1962 observations are
typical; ponds first formed in late May and from 29 May until 29 June
C. insignifera called and bred. However, C. peudinsignifera did not
commence calling until this last date. The temperature and season of
male call for these two species are shown in Fig. 4.
C. peudinsignifera in the area of overlap has been crossed a number
of times with C. insignifera from the same locality. A total of 144 eggs
has been used in control crosses and 131 in experimental crosses.
Significantly fewer larvae hatch from the experimental crosses compared with control crosses (p < 0.001). When all results from experimental crosses between allopatric populations of the two species are
either of the call races of Crinia insignifera, wbch occurs to the west.
In vitro crosses gave very inconclusive results and Phv was regarded
M a spcierJ (Crinia pseudimignifera Main) on the basis of the distinctive
male breeding call (Main, 1957).
Subsequently Littlejohn (1959) questioned the specific status of this
form because, in an area disturbed by soil excavation, near Bullsbmk,
he recorded what he regarded as hybrid calla in a two-species breeding
congress. A whole array of calls ranging from unpulsed through 2 and
3 pulses to typical four-pulsed calls of C. pedinsignifera was recorded
(Littlejohn, 1959, Fig, 9). In retrospect it seems that these calls were
those of C. pseudimignifera males when the temperature was not that
under which normal full breeding and calling takes place (see ecological
section).
Subsequently, in 1959 and 1960, soil waa again removed from this
site which was then watched closely each winter until 1963. The characteristics of the Bullsbrook site are as follows: it is an area of laterite
and clay soils on which water lies during winter. At other times the
area is completely dry. From time to time soil is removed from the
study area as needed for construction work on the nearby Royal
Australian Air Force base. Following such removal, extensive areas of
bare soil are left and in the following winter the ponds which form are
occupied by breeding congresses of both C. insignifera and C. pseudinsignifera. Mixed breeding choruses are oommon if the excavation has
been in typical C. insignifera habitat. Littlejohn’s work (1959) was done
following such a disturbance. However, as the area was kept under
observation, while the vegetation regenerated during 1959 and 1960 it
became clear that C. insignifera tended to remain in any area where
the vegetation was high, 80 producing good cover. On the other hand
Crinia peudinsignifera withdrew to exposed areas where vegetation
wag low and sparse. By 1963 there was good habitat separation of the
two species.
While the plant regeneration was being observed, study of the breeding of both species was also undertaken. The 1962 observations are
typical; ponds first formed in late May and from 29 May until 29 June
C. insignifera called and bred. However, C. peudinsignifera did not
commence calling until this last date. The temperature and season of
male call for these two species are shown in Fig. 4.
C. peudinsignifera in the area of overlap has been crossed a number
of times with C. insignifera from the same locality. A total of 144 eggs
has been used in control crosses and 131 in experimental crosses.
Significantly fewer larvae hatch from the experimental crosses compared with control crosses (p < 0.001). When all results from experimental crosses between allopatric populations of the two species are