L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Gubányi, A.: Biometrical investigation of water frogs in the Szigetköz Landscape Protection Area

For biometrical analysis 1326 frogs were tested. Measurements were taken with a vernier calliper on the left side of the living animals. Four morphometric characters were measured: BL - body length; TB - tibia length; FTL - first toe length; IMTL - inner metatarsal tubercle length. From the above measurements the following two additional ratios were computed: BL/FTL and TL/IMTL. In the beginning of the study identification and ploidy level of water frog forms were based on electrophoretic phenotype of LDH-B isozyme. Afterwards an identification function key was computed based on the comparison of morphometric indices and electrophoretic phenotypes of LDH isozyme (see Gubányi 1992 for review). Blood samples were taken from the hind limb of the frogs using a micropipette and diluted with amphibian Ringer-solution. Finally, samples were centrifuged (5 min, 4500 rpm) and stored at 25 °C until processing. Lactate dehydrogenase (LDH, EC 1.1.1.27) was studied by the method of vertical polyacrilamid gel electrophoresis after Maurer (1971). The isozymes were localized by a standard procedure (cf. Gubányi & Pekli 1991). Calculations of descriptive statistics, significance of differences (Mann-Whitney U-test), frequency distributions, allometric properties, correlations and discriminant analysis were performed by using SPSS/PC + programme package (Norusis 1990). Results After comparing the electrophoretic phenotypes of LDH-B isozyme and morphometrical indices by using the Fisher's linear discriminant function, the following identification function key was calculated for the two water frog forms: Rana lessonae 0.094LC/DP + 2.866 LT/CIL < 20.44* Rana kl. esculenta 0.094LC/DP + 2.866 LT/CIL > 20.44 As shown in Table 2 applying discriminant analysis to LC/DP and LT/CIL indices gave correct classification percentage of the two water frog forms. The classification result of the discriminant analysis was correct at a high level for Rana lessonae specimens (more than 90 Table 2. Classification results on the basis of discriminant analysis applied to ratios body length / first toe length and tibia length / inner metatarsal tubercle length (actual groups were identified by the means of electrophoretic phenotypes of LDH-B isozyme, percentage is given in parenthesis) Predicted group Actual group R. lessonae R. esculenta Rana lessonae 67 (91,8) 6 (8.2) Rana esculenta 11 (22.9) 37 (77.1) Percent of frogs correctly classified (%) 85.95 values of indices are in mm