FORTY YEARS O F QENECOLOGY
239
logical work is being published that reveals a lack of appreciation of
some highly relevant facets of population genetics theory. This is
reflected in deficiences in technique, particularly in respect to surveying
and sampling methods. In this connection, critiques such as those of
Wilkins (1959) and Harberd (1957, 1958), discussed at some length
above, are of special note. Morley (1959), discusses the general limitation
of survey methods as an approach to understanding genecological variation. Studiee of population differentiation, he states, “should attempt
not only to demonstrate the existence of selection pressure, but also to
evaluate selection intensities, to specify mechanisms of adaptation, and
to determine the effect of natural selection on population, distribution,
structure and number.” Genecological surveys “may disclose relationships between features of the habitat and characteristics of the plants,
which hint at, or clearly propose, mechanisms of adaptation. Since
selection coefficients cannot be measured by scch relationships, characters of major importance cannot be distinguished from those of minor,
though real, significance”. Morley urges the value of the study of natural
or artificial populations exposed to selective forces under experimental
conditions for the measurement of selection intensities, and refers to
work on cultivated plants and man-managed plant communities which
has yielded evidence directly relevant to adaptation and population
differentiation in wild species. That limitations of space have prevented
any consideration of this work in the present review is not to be interpreted as implying that it is not significant for the main theme. Particularly in respect to biotic influences, work on agricultural plants has
provided data unmatched as yet from wild populations, and there is
every reason to suppose that agricultural experimentation will continue
to supply a significant proportion of the evidence relating to selective
processes in general.
The experimental study of selection in plant populations should
obviously be complemented, where feasible, with investigations of
mechanisms of adaptation, and we may expect to see much more effort
in this field in the next decade or so. This is ensured, if by nothing else,
by the increasing availability of controlled environment equipment, and
by the steady improvement of the instrumentation necessary to study
plant environment and plant responses. If the effort is to be rewarded by
commensurate results in the improved understanding of adaptation and
adaptive processes, there is no avoiding the necessity for a careful
appraisal of the aims of physiological study of genecologically differentiated populations, and of the appropriateness of the techniques
adopted.
This illustrates again the importance of an understanding of genecology as a synthetic discipline. It will be all too easy to deploy sophisti-
239
logical work is being published that reveals a lack of appreciation of
some highly relevant facets of population genetics theory. This is
reflected in deficiences in technique, particularly in respect to surveying
and sampling methods. In this connection, critiques such as those of
Wilkins (1959) and Harberd (1957, 1958), discussed at some length
above, are of special note. Morley (1959), discusses the general limitation
of survey methods as an approach to understanding genecological variation. Studiee of population differentiation, he states, “should attempt
not only to demonstrate the existence of selection pressure, but also to
evaluate selection intensities, to specify mechanisms of adaptation, and
to determine the effect of natural selection on population, distribution,
structure and number.” Genecological surveys “may disclose relationships between features of the habitat and characteristics of the plants,
which hint at, or clearly propose, mechanisms of adaptation. Since
selection coefficients cannot be measured by scch relationships, characters of major importance cannot be distinguished from those of minor,
though real, significance”. Morley urges the value of the study of natural
or artificial populations exposed to selective forces under experimental
conditions for the measurement of selection intensities, and refers to
work on cultivated plants and man-managed plant communities which
has yielded evidence directly relevant to adaptation and population
differentiation in wild species. That limitations of space have prevented
any consideration of this work in the present review is not to be interpreted as implying that it is not significant for the main theme. Particularly in respect to biotic influences, work on agricultural plants has
provided data unmatched as yet from wild populations, and there is
every reason to suppose that agricultural experimentation will continue
to supply a significant proportion of the evidence relating to selective
processes in general.
The experimental study of selection in plant populations should
obviously be complemented, where feasible, with investigations of
mechanisms of adaptation, and we may expect to see much more effort
in this field in the next decade or so. This is ensured, if by nothing else,
by the increasing availability of controlled environment equipment, and
by the steady improvement of the instrumentation necessary to study
plant environment and plant responses. If the effort is to be rewarded by
commensurate results in the improved understanding of adaptation and
adaptive processes, there is no avoiding the necessity for a careful
appraisal of the aims of physiological study of genecologically differentiated populations, and of the appropriateness of the techniques
adopted.
This illustrates again the importance of an understanding of genecology as a synthetic discipline. It will be all too easy to deploy sophisti-