ECOLOGY, BYSTEMATICS AND EVOLUTION OF AUSTRALIAN FROGS 81
that the specific conditions of species such aa N. wikmorei and N. sutor,
which require high temperatures in order to breed, would be met.
Under present day conditions N. sutm and N. w i k m i are almost
entirely restricted in their east west distribution by ti: tracks of the
northern hurricanes as the? pass south-eastward across Western Australia. A typical path is shown in Fig. 3 and has been discussed earlier
(p. 43). It is uncommon for the path of the cyclones to pass east of the
area figured in Fig. 3B and it seoms clear that eastward movement of
N. sutor and N. udarnorei is only possible if the frequency of tropical
cyclones increases to the eastward of the area at present visited. It
seems unlikely that a more easterly track was followed during the
Pleistocene.
V. DISCUSSION
The position taken in this review is that biology is R singls study. A
good deal of the meaning of observations is lost if there is an arbitrary
division of the study of life into discrete self-contained disciplines.
The unit of the study has been the population which is reproductively
isolated from other populations; this entity corresponds with the
systematic entity called species. The study recognised not only that
populations occur in different places and habitats, but also that they
are of different ages and histories. Furthermore, many of the differences
between species are due to historical and evolutionary events, not to
contemporary caues. When hist'orical differences are recognised it is
immediately apparent that environmental changes will lead to different
responses in different populations simply because their genotypes, and
hence their capacity to respond, are different. These differences are well
exemplified in the wet and dry land faunas where both an old (Tertiary)
and a young (Pleistocene) element can be recognised.
All genera and most speciea are older than Pleistocene and thus agree
with the opinions expressed by Hecht (1960). A0 far as can be determined species which are of Pleistocene age have had their origin when
populations have been isolated by either:
(a) rising sea levels which cut connections between Australia and New
(b) aridity which cut connections between eastern and western
Aust'ralia lies across the Tropic of Capricorn and the sub-tropical
desert which is so well developed on the western side of the continent
is a consequence of the planetary wind circulation. In this region there
is, at present, no evidence of speciation of a Pleistocene age in frog
genera such aa Qlauertia, Notaden, Uperoleia and Cyclotana.
Guinea or Australia and Twmania; or
Aus tralia .
that the specific conditions of species such aa N. wikmorei and N. sutor,
which require high temperatures in order to breed, would be met.
Under present day conditions N. sutm and N. w i k m i are almost
entirely restricted in their east west distribution by ti: tracks of the
northern hurricanes as the? pass south-eastward across Western Australia. A typical path is shown in Fig. 3 and has been discussed earlier
(p. 43). It is uncommon for the path of the cyclones to pass east of the
area figured in Fig. 3B and it seoms clear that eastward movement of
N. sutor and N. udarnorei is only possible if the frequency of tropical
cyclones increases to the eastward of the area at present visited. It
seems unlikely that a more easterly track was followed during the
Pleistocene.
V. DISCUSSION
The position taken in this review is that biology is R singls study. A
good deal of the meaning of observations is lost if there is an arbitrary
division of the study of life into discrete self-contained disciplines.
The unit of the study has been the population which is reproductively
isolated from other populations; this entity corresponds with the
systematic entity called species. The study recognised not only that
populations occur in different places and habitats, but also that they
are of different ages and histories. Furthermore, many of the differences
between species are due to historical and evolutionary events, not to
contemporary caues. When hist'orical differences are recognised it is
immediately apparent that environmental changes will lead to different
responses in different populations simply because their genotypes, and
hence their capacity to respond, are different. These differences are well
exemplified in the wet and dry land faunas where both an old (Tertiary)
and a young (Pleistocene) element can be recognised.
All genera and most speciea are older than Pleistocene and thus agree
with the opinions expressed by Hecht (1960). A0 far as can be determined species which are of Pleistocene age have had their origin when
populations have been isolated by either:
(a) rising sea levels which cut connections between Australia and New
(b) aridity which cut connections between eastern and western
Aust'ralia lies across the Tropic of Capricorn and the sub-tropical
desert which is so well developed on the western side of the continent
is a consequence of the planetary wind circulation. In this region there
is, at present, no evidence of speciation of a Pleistocene age in frog
genera such aa Qlauertia, Notaden, Uperoleia and Cyclotana.
Guinea or Australia and Twmania; or
Aus tralia .