A REVIEW OF PAPER CHROMATOGRAPHY AS 

 USED IN SYSTEMATICA 



By 



David A. Farris— 



DESCRIPTION OF THE TECHNIQUE 



Chromatography, a technique for sep- 

 arating the components of a complex mixture, 

 is based on the differential adsorption and sol- 

 vation of the components. It was first described 

 by Tswett (1906) and subsequently adapted to 

 paper by Consden, Gordon and Martin (1944) . 

 A small quantity of the mixture to be separated, 

 in this case either body fluid or tissue extracts, 

 is placed on a spot not over a quarter of an inch 

 in diameter near one edge of a filter paper 

 sheet. After the spot is dry, the edge of the 

 filter paper is dipped into a solvent so that the 

 solvent flows over the spot by capillarity. As 

 the solvent front progresses over the paper, 

 the components of the mixture are spread out 

 behind the front in discrete areas. To stop the 

 process, one merely removes the solvent and 

 allows the paper to dry. By the use of indicator 

 solutions, ultra violet light, etc . , the spots are 

 located for identification . The compounds can 

 be removed from the filter paper by elution and 

 the amounts determined quantitatively . For a 

 more complete description of the technique see 

 Stein and Moore (1951); Strain (1942); Lederer 

 and Lederer (1953); Block, Durrum, and Zweig 

 (1955); and Cramer (1953). 



RATIONALE OF APPROACH 



The continuity-of-life hypothesis has 

 many corollaries among which are the hypotheses 

 of the "continuity of form" and the "continuity of 

 biochemical systems". The latter hypothesis 

 may be verified by showing the simultaneous 

 occurrence of compounds in various groups of 

 organisms thought, on the basis of other evidence, 

 to be related. It is hoped that by understanding 

 chemical relationships, it will be possible to 

 1/ Fishery Research Biologist, South Pacific 

 Fishery Investigations, U.S. Fish and Wildlife 

 Service, P.O. Box 271, La Jolla, California. 



deduce systematic relationships in cases where 

 the evidence from other disciplines is not suf- 

 ficiently strong to establish the phylogenic rank 

 of the population under question . 



Chromatography can be used for the 

 study of speciation in at least two ways. The 

 investigator may simply examine the qualitative 

 chromatographic patterns of chemical differ- 

 ences existing between populations. In this kind 

 of analysis the compounds are neither identified 

 nor the concentrations determined. This in- 

 creases the difficulty of comparing the results 

 of independent investigators. No attempt is 

 made to relate the pattern with the phylogeny of 

 the organism and one is left in doubt as to whether 

 pattern differences have any systematic signifi- 

 cance . On the other hand, quantitative methods 

 utilizing photometry, etc . , have the advantage of 

 permitting a determination of individual as well 

 as species variability . 



The lack of understanding of the "species 

 concept" has hampered both the study of evolu- 

 tion and species description. The reader is re- 

 ferred to Stebbins (1950), Mayr (1942), Simpson 

 (1953), and Myers (1952) for a discussion of the 

 mechanisms of speciation. Populations normally 

 referred to as different species (sometimes) 

 differ from each other with respect to spatial 

 and temporal separations, and the kinds and 

 numbers of genetic differences. Basically, the 

 study of speciation maybe restated as a study of 

 the change in gene pools brought about by changes 

 in the individual germ plasms within the pools 

 and selection of those changes under the influ- 

 ence of chance and environment . 



An examination of populations with 

 respect to morphological manifestations of 

 genetic differences although usually fruitful is 

 subject to some error because of the environ- 

 mental effects on gene expression . Ideally, an 



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