80
A. R. MAIN
but not the most recent, the climate improved so much that both wet
land (but not forest) frogs and those of the semi-arid country invaded.
These wet land frogs (Neobatracha.8 peEobakrides, Heleiopus burycragus, Crinia glauerti, Limnodynmtes dorsalis and Hylu nzoorek) are
listed under the second migration in Table VII. The position of
C. glauerti in relation to the supposed migrations has been so interpreted
because its call is more distinctive compared with C. signifera than
C. subimignifera is compared with C. parinsignifera (Littlejohn, 1959,
1961). Divergence in call is related to length of isolation so presumably
C. glauerti has been isolated from the east longer than has C. subinsignifera and therefore must be older than the last migration in
which C. subinsignifera entered Western Australia (Littlejohn, 1961).
A somewhat similar case to that of C. glauerti - C. sigBifera species
pair is provided by the pair Neobatrachus pelubatoides - N . pictus
whose calls (Littlejohn and Main, 1959; Littlejohn, 1965) and genotypes
are distinctive. Lee (1965,1967) has shown that Hebiopmu australkcus
from eastern Australia is readily distinguished from the western form,
Heleioporue burycragus, in morphology and s e w n of breeding. Moore
(1954) has shown that H y h moorei is genetically distinct fkom H. aurea
of eastern Australia. The relationship of the western Limnodynastes
dorsalis to its eastern countkrpart is as yet unanalysed. However, all
the foregoing species are frogs depending on reliable winter rainfall, all
have a rehtively long larval life and are forms which can be grouped
together, when interpreting the speciation pattern, as representing a
single poat-Tertiary migration. On the reasoning developed in relation
to the call of C. glauerti this migration cannot have been at the same
time aa the arrival of Crinia subinsignifera and NeoWrmhus centralis.
In Table V I I it is placed as the second of the three postulated invasions.
This is the most recent migration possible; it could have been earlier,
i.e. the first migration of Table VII, in which case Hekioporus inornatus
would be regarded as a Tertiary species.
Since the wet land frogs invaded, they have persisted in minor wetter
habitats. This modified hypothesis obviates the problem of extinction
of Bassian elements in Western Australia while such wet forest elements
as Metucrinia persisted (Main et al., 1958), but leaves unexplained the
absence from Western Australia of the widespread eastern species
Limnodynustes tasmaniensb.
In a general way one would expect that the migration route between
east and west would be open for traffic both ways. However, the supposed earlier migrants among the western species of Crinia, Neobatrmhw and Hekioporus are more specialised in their ecology than
their eastern counterparts and since pluvials are periods of low temperatume and times of general non-seasonal rainfall it seems unlikely
A. R. MAIN
but not the most recent, the climate improved so much that both wet
land (but not forest) frogs and those of the semi-arid country invaded.
These wet land frogs (Neobatracha.8 peEobakrides, Heleiopus burycragus, Crinia glauerti, Limnodynmtes dorsalis and Hylu nzoorek) are
listed under the second migration in Table VII. The position of
C. glauerti in relation to the supposed migrations has been so interpreted
because its call is more distinctive compared with C. signifera than
C. subimignifera is compared with C. parinsignifera (Littlejohn, 1959,
1961). Divergence in call is related to length of isolation so presumably
C. glauerti has been isolated from the east longer than has C. subinsignifera and therefore must be older than the last migration in
which C. subinsignifera entered Western Australia (Littlejohn, 1961).
A somewhat similar case to that of C. glauerti - C. sigBifera species
pair is provided by the pair Neobatrachus pelubatoides - N . pictus
whose calls (Littlejohn and Main, 1959; Littlejohn, 1965) and genotypes
are distinctive. Lee (1965,1967) has shown that Hebiopmu australkcus
from eastern Australia is readily distinguished from the western form,
Heleioporue burycragus, in morphology and s e w n of breeding. Moore
(1954) has shown that H y h moorei is genetically distinct fkom H. aurea
of eastern Australia. The relationship of the western Limnodynastes
dorsalis to its eastern countkrpart is as yet unanalysed. However, all
the foregoing species are frogs depending on reliable winter rainfall, all
have a rehtively long larval life and are forms which can be grouped
together, when interpreting the speciation pattern, as representing a
single poat-Tertiary migration. On the reasoning developed in relation
to the call of C. glauerti this migration cannot have been at the same
time aa the arrival of Crinia subinsignifera and NeoWrmhus centralis.
In Table V I I it is placed as the second of the three postulated invasions.
This is the most recent migration possible; it could have been earlier,
i.e. the first migration of Table VII, in which case Hekioporus inornatus
would be regarded as a Tertiary species.
Since the wet land frogs invaded, they have persisted in minor wetter
habitats. This modified hypothesis obviates the problem of extinction
of Bassian elements in Western Australia while such wet forest elements
as Metucrinia persisted (Main et al., 1958), but leaves unexplained the
absence from Western Australia of the widespread eastern species
Limnodynustes tasmaniensb.
In a general way one would expect that the migration route between
east and west would be open for traffic both ways. However, the supposed earlier migrants among the western species of Crinia, Neobatrmhw and Hekioporus are more specialised in their ecology than
their eastern counterparts and since pluvials are periods of low temperatume and times of general non-seasonal rainfall it seems unlikely