Abstract
Four populations of Dacus tryoni collected from widely separated regions on the
east coast of Australia (Cairns, Brisbane, Sydney, and East Gippsland) were compared
in the laboratory to determine how they differed in their adaptations to temperature, and
what adaptations have enabled the species to spread into colder areas.
The main criteria used for the comparisons were the innate capacity for increase
(rm) and its components : speed of development, survival rate, and fecundity. The races
were compared at three different temperatures and in two successive years.
Differences between the races from Cairns, Brisbane, and Sydney were often
large and consistent, and in general they correlated well with differences in the climates
of the respective geographic areas. At the lowest temperature the Sydney strain had the
highest (rm), while the Cairns strain had the lowest. At the intermediate temperature
there were no significant differences between the strains. At the highest temperature
the Cairns strain had the highest (rm), while the Sydney strain had the lowest. The strain
from East Gippsland behaved in an unpredictable way in most of the experiments,
and rarely fitted into the trends set by the other three strains.
The major differences appear to have been due primarily to adaptations affecting
fecundity. There were also significant differences in the longevity of adults and the
survival rates of immature stages, but not in speeds of development. The differences
in fecundity may have been related to differences in the proportions of females fertilized
in the experimental cages.
Subject
Animal Science and Zoology,Ecology, Evolution, Behavior and Systematics
Cited by
108 articles.
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