FORTY YEARS O F GENECOLOGY
237
and photosynthetic light saturation. Thus, the southern populations revealed a clear adaptation to growth under a 15-h photoperiod, while the
northern populations reached active growth only in very long days and
were brought into a state of dormancy by 15-h days, I n respect to
temperature they point to the clear adaptive sigdcance of the lower
temperature optimum for photosynthesis evident in the high latitude
populations, which normally experience summer temperature maxima
of less than 60’ in their natural environment. The higher respiration
rate shown by the northern populations they consider also to be adaptive in permitting rapid metabolic rates to be achieved under lower
average day temperatures.
As a physiological investigation of genecological differentiation, the
work of Mooney and Billings is exemplary in asking at the outset the
essential question “How are the ecotypes related to their respective
environments?”, and in adopting field and laboratory methods and
measurements designed specifically to answer it. Their study should set
a pattern for others in this field.
IV. CONCLUSIONS
It is appropriate in conclusion to refer again to the synthetic nature of
genecology as a discipline combining ideas and methods from genetics,
taxonomy and plant physiology, and to emphasize once more the value
of this kind of concerted approach to the problems of population
differentiation and adaptation in plants.
An unfortunate trend during the post-war period has been apparent
in recurrent attempts to assimilate genecology into taxonomy. Genecological investigations of infraspecific variation naturally tend to reveal
facts of potential taxonomic significance, but taxonomic revision is not
in itself an essential part of genecology. Should it be substituted for the
original aims of analysing patterns of ecological adaptation and elucidating the means by which they are achieved, genecology becomes inseparable from the discipline commonly termed “experimental taxonomy’’ or
“biosystematics” “Experimental taxonomy” seems first to have been
used by Clausen et al. (1934), in substitution for “evolutionary taxonomy”, previously used by Clements and others of the Carnegie group.
The term was adopted by Gregor et al. (1936), and defined as the classification of evolutionary units on the basis of experimentally derived facts
relating to distribution, ecology and cytogenetics as well as to morphology. Valentine (1961) gave a slightly more dynamic version, “the study
of evolutionary processes in plants and of the bearings of this study on
their taxonomy.” “Biosystematics”, as “Biosystematy”, was introduced by Camp and Gilly (1943), with a broadly similar meaning: “(1)
to delimit the natural biotic units and (2) to apply to these units a system
237
and photosynthetic light saturation. Thus, the southern populations revealed a clear adaptation to growth under a 15-h photoperiod, while the
northern populations reached active growth only in very long days and
were brought into a state of dormancy by 15-h days, I n respect to
temperature they point to the clear adaptive sigdcance of the lower
temperature optimum for photosynthesis evident in the high latitude
populations, which normally experience summer temperature maxima
of less than 60’ in their natural environment. The higher respiration
rate shown by the northern populations they consider also to be adaptive in permitting rapid metabolic rates to be achieved under lower
average day temperatures.
As a physiological investigation of genecological differentiation, the
work of Mooney and Billings is exemplary in asking at the outset the
essential question “How are the ecotypes related to their respective
environments?”, and in adopting field and laboratory methods and
measurements designed specifically to answer it. Their study should set
a pattern for others in this field.
IV. CONCLUSIONS
It is appropriate in conclusion to refer again to the synthetic nature of
genecology as a discipline combining ideas and methods from genetics,
taxonomy and plant physiology, and to emphasize once more the value
of this kind of concerted approach to the problems of population
differentiation and adaptation in plants.
An unfortunate trend during the post-war period has been apparent
in recurrent attempts to assimilate genecology into taxonomy. Genecological investigations of infraspecific variation naturally tend to reveal
facts of potential taxonomic significance, but taxonomic revision is not
in itself an essential part of genecology. Should it be substituted for the
original aims of analysing patterns of ecological adaptation and elucidating the means by which they are achieved, genecology becomes inseparable from the discipline commonly termed “experimental taxonomy’’ or
“biosystematics” “Experimental taxonomy” seems first to have been
used by Clausen et al. (1934), in substitution for “evolutionary taxonomy”, previously used by Clements and others of the Carnegie group.
The term was adopted by Gregor et al. (1936), and defined as the classification of evolutionary units on the basis of experimentally derived facts
relating to distribution, ecology and cytogenetics as well as to morphology. Valentine (1961) gave a slightly more dynamic version, “the study
of evolutionary processes in plants and of the bearings of this study on
their taxonomy.” “Biosystematics”, as “Biosystematy”, was introduced by Camp and Gilly (1943), with a broadly similar meaning: “(1)
to delimit the natural biotic units and (2) to apply to these units a system