WEINSTEIN and YERGER: PROTEIN TAXONOMY OF CYNOSCION 



ences were almost wholly quantitative rather 

 than qualitative. Data from other studies indicate 

 two further conclusions. First, lens proteins on the 

 whole express a high degree of conservatism. 

 Secondly, in cases where evidence of polymor- 

 phisms have been obtained, fishes have been most 

 often implicated. Smith and Goldstein (1967), 

 Smith (1969, 1971), and Smith and Clemens (1973) 

 reported intraspecific variations in the lens pat- 

 terns of numerous species. Barrett and Williams 

 (1967) detected a polymorphism in the lens pro- 

 teins of the bonito Sarda cluliensis. Eckroat and 

 Wright (1969) and Eckroat (1973) provided direct 

 evidence of polymorphisms in the eye lens of the 

 brook trout, Salvelinus fontinalis, and demon- 

 strated simple Mendelian inheritance for several 

 characters. 



Previous observations for eye lens proteins and 

 the conclusions stated above are reflected in our 

 work on the patterns derived from the genus 

 Cijnoscion. Lens protein patterns displayed con- 

 siderable convervatism among the four seatrouts. 

 Four bands from a total of eight occur in all taxa 

 and are probably high molecular weight a- and 

 /8-crystallins. Only a single band (E in C. nebulo- 

 sus, Figure 3) is unique and is found in either very 

 low frequency or not at all in four of the seven 

 estuaries sampled. Its relatively high frequencies 

 in Corpus Christi, Galveston, and Florida Bay (36, 

 39, and 50%, respectively) indicate a possible 

 relationship to high turbidity and low light inten- 

 sities characteristic of these three areas. 



Although intensity patterns did not vary sig- 

 nificantly within a species (with the exception of 

 two bands involved in a suspected polymorphism 

 in C. nebulosus), the quantities of protein in bands 

 with the same mobility were quite different and 

 species-specific (Figure 3). The selective forces 

 which control the quantity of protein present in a 

 given band are not easily recognized. The geogra- 

 phic ranges of these four species overlap con- 

 siderably althouth their centers of abundance are 

 quite different. Cijnoscion nothus is found farther 

 offshore than its congeners; C. nebulosus is 

 primarily restricted to the estuarine habitat. All 

 seatrouts probably experience a similar range of 

 water color and turbidities in their respective 

 habitats. None is considered to be more diurnal or 

 nocturnal than the others. Their temperature 

 ranges overlap considerably. Therefore, it is 

 somewhat puzzling as to the cause of the common 

 observation that variations in patterns both with- 



in a species and between them is restricted mainly 

 to intensity differences. Presently the advantages 

 of difTerent proportions of crystallins and other 

 eye lens protein in a particular species are poorly 

 known. 



Myogen Proteins 



The general application of myogen proteins to 

 systematic studies has been reviewed by Tsuyuki 

 (1974). Perhaps no other tissue investigated has 

 displayed such an overall lack of intraspecific 

 variations. Only a few species of fishes have 

 exhibited detectable polymorphisms (e.g., Nyman 

 1967; Tsuyuki et al. 1968; Gray and McKenzie 

 1970), and it is noteworthy that most of these are 

 "tetraploid" species. The majority of investiga- 

 tions on other forms reveal virtually no intra- 

 specific variation, an observation in direct contrast 

 with other protein systems which generally dis- 

 play polymorphisms. Various estimates of propor- 

 tions of polymorphic alleles in vertebrate species 

 are placed at from 10 to 20% (Selander and Kauf- 

 man 1973). The constancy maintained in myogen 

 proteins in the presence of selective forces is 

 indeed remarkable. 



The general conservatism displayed in myogen 

 patterns was observed in our own work, but with 

 several important differences. As previously de- 

 scribed, C. nothus and C. nebulosus differed in the 

 presence or absence of one or more major (by 

 staining intensity) bands. Band J (Figure 5), 

 unique in C. nebulosus, is found in all samples, and 

 produces a large characteristic peak on densi- 

 tometer tracings. The absence of several bands, 

 notably B and C (Figure 5), characterizes C. 

 nothus. 



On the basis of myogen patterns, we suggest 

 that C. arenarius and C. regalis are more closely 

 related to each other than are any other combina- 

 tion of species under consideration and should be 

 treated as conspecific. Thus, we reject the 

 phylogeny based on slight osteological differences 

 proposed by Mohsin (1973). The gulf form (C. are- 

 narius) should be recognized as a subspecies of C. 

 regalis, a conclusion strengthened by recent 

 confirmation of specimens of C. regalis from the 

 Gulf of Mexico. 



Earlier reports of C. regalis in the gulf generally 

 lacked documentation, or were misidentifications 

 of C. arenarius. The report of Jordan and Eigen- 

 mann (1889) from Mobile Bay, Ala., was based on 

 specimens of C. arenarius, a form not recognized 



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