The Concept of Species Based on Experiment

Clausen, J.; Keck, David D.; Hiesey, William M.

doi:10.1002/j.1537-2197.1939.tb12875.x

Cited by 67 publications

(30 citation statements)

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“…For example, Gregor et al (1936: 325) provided a definition for ecotype based on reproductive isolation as 'a population distinguished by morphological and physiological characters, most frequently of a quantitative nature; interfertile with other ecotypes and ecospecies, but prevented from exchanging genes by ecological barriers'. The redefinition of the genecological terminology reflected empirical results of researchers who found that partitioning heritable genetic variation within species was more complex than Turesson (1922a) originally envisioned (Gregor, 1930;Gregor et al, 1936;Clausen et al, 1939). The classic works of Jens Clausen, David Keck, and William Hiesey at the Carnegie Institution at Stanford University further developed an experimental framework to understand the process of speciation (Hagen, 1983(Hagen, , 1984(Hagen, , 1986Núñez-Farfán & Schlichting, 2001).…”

Section: The Birth Of Ecotypementioning

confidence: 98%

“…The biosystematists that followed Turesson utilized his functional definitions and increasingly stressed the importance of reproductive isolating barriers that limited gene flow (Gregor, 1931(Gregor, , 1939Gregor, Davey & Lang, 1936;Clausen, Keck & Hiesey, 1939). For example, Gregor et al (1936: 325) provided a definition for ecotype based on reproductive isolation as 'a population distinguished by morphological and physiological characters, most frequently of a quantitative nature; interfertile with other ecotypes and ecospecies, but prevented from exchanging genes by ecological barriers'.…”

Section: The Birth Of Ecotypementioning

confidence: 99%

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Ecotypes and the controversy over stages in the formation of new species

Lowry

2012

Biological Journal of the Linnean Society

170

166

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Recent interest in the role of ecology in species formation has led to renewed discussion of the stages in the process of speciation. Although attempts to classify the stages in the process of species formation date back at least as far as Alfred Russel Wallace, one of the most intense debates on the subject occurred among botanists during the mid‐20th Century. The present review outlines the progression of the historical debate about stages in the evolution of species, which was instigated by the genecological classification scheme of Göte Turesson in the 1920s, championed in the mid‐century by Jens Clausen, and then brought under harsh scrutiny by many in the 1960s and 1970s. At the heart of the controversy is the question of whether speciation occurs rapidly on a local scale or gradually through the formation of geographically widespread ecotypes that evolve as precursors to species. A corollary to this debate is the question of whether speciation is reversible and, if so, how does it become irreversible? A third wave of interest in stages in the process of speciation is currently underway, thus making a modern historical narrative of the debate important. Both contemporary and past evolutionary biologists have argued that viewing speciation as being composed of stages can free researchers from concerns over species definitions and focus attention on the mechanisms involved in the process. How speciation becomes irreversible and whether ecogeographically isolated ecotypes are integral to this process remain as important unresolved issues. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 241–257.

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Section: The Birth Of Ecotypementioning

confidence: 98%

Section: The Birth Of Ecotypementioning

confidence: 99%

Ecotypes and the controversy over stages in the formation of new species

Lowry

2012

Biological Journal of the Linnean Society

170

166

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“…The value of this work to taxonomic theory and practice must be fully acknowledged but we are concerned here only with one aspect of it-the definition and application of terms. For this purpose we may consider two recent publications (Clausen et al 1939(Clausen et al , 1940. Clausen et al (1939) use the three terms cenospecies, ecospecies and ecotype.…”

Section: Terms and Their Definitionsmentioning

confidence: 99%

The Ecotype Concept

Turrill¹

1946

New Phytologist

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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.

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“…Common-garden experiments have been used in the adaptation research in botany since its beginning (Briggs and Walters 1997;Clausen et al 1939;Turesson 1925). Their aim is elimination or at least reducing the differences among different populations caused by environmental effects by planting individuals of different origin under equal conditions and finding out how individuals will react on the transfer in their phenotypic traits.…”

Section: Introductionmentioning

confidence: 99%

Adaptation to common optimum in different populations of Norway spruce (Picea abies Karst.)

et al. 2011

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Responses of Norway spruce populations to climatic transfer, in terms of growth and survival, were analyzed on the basis of a provenance experiment derived from the international provenance test IUFRO 1964IUFRO /1968. The experiment comprises a series of five trial plots situated at contrasting elevations ranging from 484 to 1,275 m a.s.l., with 11 provenances represented at all trial plots that were used for the analysis. Transfer rates were defined as differences in altitudes or climatic variables between the site of plantation and the site of origin. Optimal transfer rates and optimal climates for individual provenances were derived from quadratic response functions. Spruce provenances generally responded positively by height and volume growth to transfer into lower altitudes, i.e., warmer conditions with less precipitations. The analysis at the level of provenances showed that optimal transfer rates were consistently negatively correlated with the underlying environmental variables and optimal climates were consequently nearly the same for all provenances irrespective of the response traits and ecodistance variables. Stability indices based on joint regression analysis indicate that provenances from higher altitudes, colder and wetter climates tend to be more stable, whereas provenances from lower altitudes, drier and warmer sites are more responsive to site quality. However, the differences in the stability are small and stability indices were generally close to 1. The results indicate that populations in different climates remain adapted to a common optimum and the extent of local adaptation is quite limited. Possible explanations of this observation are briefly discussed.

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The Concept of Species Based on Experiment

Cited by 67 publications

References 2 publications

Ecotypes and the controversy over stages in the formation of new species

Ecotypes and the controversy over stages in the formation of new species

The Ecotype Concept

Adaptation to common optimum in different populations of Norway spruce (Picea abies Karst.)

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