Biometrical features of ıntergeneric hybrid between Leuciscus cephalus (L.) and Chalcalburnus chalcoides (G.) (Osteichthyes-Cyprinidae) distributed in lake tödürge (Sivas-Turkey)

Abstract

A total of 159 (57 Leuciscus cephalus, 47 Chalcalburnus chalcoides, 55 hybrid) specimens were collected between April 1994 and November 1997 from Lake Tödürge. The identification of hybrid fish depends on the intermediacy of the suspected hybrid specimens in characteristics that serve to discriminate the parental species. For this reason, the morphometric and meristic characteristics, which are present an intermediate position in the hybrid were determined. Among the morphometric (X7: standard length/height of caudal peduncle, X19: standard length/length of anal fin, X21: standard length/length of pectoral fin, X24: standard length/ventral anal distance, X38: length of upper jaw/length of lower jaw) and meristic (X41: count of soft rays in anal, X43: count of soft rays in ventral, X49: transversal scales (upper part), X51: pharyngeal teeth) characteristics were the most effective characteristics in discrimination of both parental species and the hybrids. Two linear discriminant functions that explain 100% of the total variability of the morphometric and meristic features of hybrid and both its parents were obtained. On the basis of statistical analysis, an intergeneric hybridization was determined to occur between chub (L. cephalus) and Danube bleak (C. chalcoides) in Lake Tödürge (Sivas-Turkey), and chub and Danube bleak were really the parental species of this hybrid. Statistical analyses were also showed that there was no back-crossing with one of the parental species and therefore all hybrids were F1.

A total of 159 (57 Leuciscus cephalus, 47 Chalcalburnus chalcoides, 55 hybrid) specimens were collected between April 1994 and November 1997 from Lake Tödürge. The identification of hybrid fish depends on the intermediacy of the suspected hybrid specimens in characteristics that serve to discriminate the parental species. For this reason, the morphometric and meristic characteristics, which are present an intermediate position in the hybrid were determined. Among the morphometric (X7: standard length/height of caudal peduncle, X19: standard length/length of anal fin, X21: standard length/length of pectoral fin, X24: standard length/ventral anal distance, X38: length of upper jaw/length of lower jaw) and meristic (X41: count of soft rays in anal, X43: count of soft rays in ventral, X49: transversal scales (upper part), X51: pharyngeal teeth) characteristics were the most effective characteristics in discrimination of both parental species and the hybrids. Two linear discriminant functions that explain 100% of the total variability of the morphometric and meristic features of hybrid and both its parents were obtained. On the basis of statistical analysis, an intergeneric hybridization was determined to occur between chub (L. cephalus) and Danube bleak (C. chalcoides) in Lake Tödürge (Sivas-Turkey), and chub and Danube bleak were really the parental species of this hybrid. Statistical analyses were also showed that there was no back-crossing with one of the parental species and therefore all hybrids were F1.