The Ecotype Concept

Abstract

In two papers, published in 1922papers, published in , Turesson (1922 introduced the ecotype concept and its importance in the study of the constitution and origin of species was almost immediately recognized. Ecologists and taxonomists alike appreciate the value of combined field observations and controlled cultural experiments. There was some criticism, in part justified, that the field studies of populations and of the conditions of their environment were insufficiently extensive and intensive and that the ecotype concept was based too much on selected individuals and not on the study of whole populations or of sufficiently large random samples of such. Nevertheless, Turesson's researches have opened up new lines of research and full recognition of his great contributions to the study of species problems must be gratefully accorded by anyone familiar with the facts.There is no intention, or need, to give details of the early investigations on ecotypes. A very useful summary is given by Barton-Wright (1932). More recently, Gregor (1944) has published a most valuable summary of much recent research and trends of thought in this subject. The present paper is concerned mainly with two matters: the full significance of changes in definition of terms first used by Turesson in 1922, and the relation between genecology and taxonomy. Gregor (1944) touched on both these problems which were also referred to by the writer in an earlier paper (Turrill, 1938) and more recently in a review (Turrill, 1942). An investigator is unavoidably impressed more by his own experiences, by the examples with which he himself has worked, and by the difficulties he meets, than by those of others, and the value of concepts, terms, definitions, and schemes of classification can only be tested pragmatically. Genecologists have often criticized taxonomists, sometimes not without reason, but sometimes from a misconception of the taxonomist's functions. Taxonomists have too often ignored these criticisms and indeed the whole experimental work of genecologists, though there is increasing improvement in this respect. The present writer again expresses his appreciation of both the methods used and the results obtained in genecological research and is confident that any criticisms he makes will be accepted in the constructive spirit in which they are offered.

The Ecospecies-Prelude to Discussion

“…Criteria involved Gregor (1944) and Turrill (1946) have pointed out that there have been several modifications of the terms ecotype, ecospecies, and coenospecies since .they were first introduced by Turesson (1922). In part, this modification has been the result of increasing precision on the part of the pioneer author himself (d. Turesson, 1929) but further definitions have been added by subsequent authors and these are reprinted in Appendix 1.…”

“…With. is discussed by Turrill (1946) and Valentine (1948Valentine ( , 1949 as one example where the opinion of most biosystematists (regarding these forms as ecotypes of one ecospecies) is at variance with the opinion of most taxonomists (who would consider them to be satisfactorily distinct species) . In fact these authors have defended admirably the case for regarding these campions as separate species in taxonomy but there is really no cause for us to alter our definitions of ecospecies to accommodate these exceptions to complete equivalence between taxonomic species and ecospecies.…”

“…Gilmour and Turrill (1941) have shown that while such a "general" classification must be maintained, there is value in experimentation with "special" classifications (based upon a limited number of kinds of attribute) for special purposes EVOLUTION 6: 61-68. March, 1952. (see also Turrill, 1938a, b;1946). "Biosystematics" (or "Experimental Taxonomy") , compounded from Turesson's originally ecological system and Danser's "fertility-sterility" system, represents such a special classification and its value is in the analysis of problems of the genetics of wild populations.…”

Mycelial growth, pathogenicity, aggressiveness and apothecial development of Sclerotinia sclerotiorum isolates from Brazil and the United States in contrasting temperature regimes

“…Reports have suggested the existence of S. sclerotiorum temperature ecotypes (9, 10, 21). Ecotypes are sub-groups of the pathogen which have different capacities to perform in different environments (22). This could be important to explain why diseases caused by this pathogen can affect susceptible host crops in certain geographic areas.…”

Variation and relationships in some rhizomatous species of Muhlenbergia

“…His sampling methods and descriptions suggest that he viewed ecotypic variation as applying to local populations (Turrill, 1946). The discontinuity demonstrated in this study is between regional types, conforming rather to the ecotypes described by Clausen, Keck, and Hiesey (1940) for Potentilia glandulosa Lindl.…”