FORTY YEARS OF QENECOLOUY
166
cline is that it is a trend of variation within a major population, namely
the species ; in recording the infraspecific variation, what is important is
to define the trends and the factors with which they are correlated, not
to seek for nameable subcategories. If the concept of ecocline in this
more abstract sense (“a variational trend”, rather than “a group of
populations”) is accepted, then Gregor’s definition of the ecotype as a
range on an ecocline loses much of its meaning.
Indeed, it may be asked whether the concept of the ecotype has outworn its usefulness and whether it might not now be discarded with
advantage. In a recent paper from Gregor’s group (Gregor and Watson,
1961), it is concluded that a better understanding “could be achieved
through the accumulation of records in which the emphasis has been
transferred from the discrete ecotype to the trends of ecotypic differentiation”. The reluctance of several authors to use the term ecotype in
recent literature reflects a rather general agreement with this view
(Heywood, 1959). Nevertheless, the abandonment of the term would be
difficult, and indeed undesirable. As an appellation for a group of populations known to have features in common adaptive to a recognizable habitat it continues to have a respectable use. It only becomes
disreputable in misuse, or when its use is taken to imply acceptance
of over-simplified conceptions of the nature of infraspecific ecological
variation.
Turesson’s efforts to elucidate patterns of ecological adaptation in
plant populations led him to propose genecological categories at and
above the level of the average Linnaean species as well as below, namely
the ecospecies and the coenospecies. The definitions of these categories
and the evolution in their use since the time of their original suggestion
have been reviewed and discussed several times (Gregor et al., 1936;
Turrill, 1938, 1946; Clausen et al., 1939, 1940, 1948; Valentine, 1949;
Baker, 1952; Heslop-Harrison, 1953b; Cab, 1954). It would be supererogatory to cover this ground again here; but it is important to pay some
attention to the relationships between genecological and taxonomic
interpretations of the species, since much of this article is concerned
with infraspecific variation, in the broad sense.
Nomenclatural taxonomy in its present form depends upon the definition of classes in a hierarchial system, the clmses at each level being
based upon an assessment of overall resemblance in the range of features
available for study. The basic unit, as defined by the “International
Code of Botanical Nomenclature” (1956) is the species, which is to be
named with a binary combination consisting of the name of the genus
followed by the specific epithet. The principal tasks of the taxonomist
concerned with formal nomenclatural taxonomy turn out to be identification and definition of variational units which may conveniently be
166
cline is that it is a trend of variation within a major population, namely
the species ; in recording the infraspecific variation, what is important is
to define the trends and the factors with which they are correlated, not
to seek for nameable subcategories. If the concept of ecocline in this
more abstract sense (“a variational trend”, rather than “a group of
populations”) is accepted, then Gregor’s definition of the ecotype as a
range on an ecocline loses much of its meaning.
Indeed, it may be asked whether the concept of the ecotype has outworn its usefulness and whether it might not now be discarded with
advantage. In a recent paper from Gregor’s group (Gregor and Watson,
1961), it is concluded that a better understanding “could be achieved
through the accumulation of records in which the emphasis has been
transferred from the discrete ecotype to the trends of ecotypic differentiation”. The reluctance of several authors to use the term ecotype in
recent literature reflects a rather general agreement with this view
(Heywood, 1959). Nevertheless, the abandonment of the term would be
difficult, and indeed undesirable. As an appellation for a group of populations known to have features in common adaptive to a recognizable habitat it continues to have a respectable use. It only becomes
disreputable in misuse, or when its use is taken to imply acceptance
of over-simplified conceptions of the nature of infraspecific ecological
variation.
Turesson’s efforts to elucidate patterns of ecological adaptation in
plant populations led him to propose genecological categories at and
above the level of the average Linnaean species as well as below, namely
the ecospecies and the coenospecies. The definitions of these categories
and the evolution in their use since the time of their original suggestion
have been reviewed and discussed several times (Gregor et al., 1936;
Turrill, 1938, 1946; Clausen et al., 1939, 1940, 1948; Valentine, 1949;
Baker, 1952; Heslop-Harrison, 1953b; Cab, 1954). It would be supererogatory to cover this ground again here; but it is important to pay some
attention to the relationships between genecological and taxonomic
interpretations of the species, since much of this article is concerned
with infraspecific variation, in the broad sense.
Nomenclatural taxonomy in its present form depends upon the definition of classes in a hierarchial system, the clmses at each level being
based upon an assessment of overall resemblance in the range of features
available for study. The basic unit, as defined by the “International
Code of Botanical Nomenclature” (1956) is the species, which is to be
named with a binary combination consisting of the name of the genus
followed by the specific epithet. The principal tasks of the taxonomist
concerned with formal nomenclatural taxonomy turn out to be identification and definition of variational units which may conveniently be