Comparison of age structure in two Makhmalkoh's anuran populations by means of skeletochronology

In this research age structure in populations of two anuran species: a frog R. ridibunda and a toad Bufo viridis was studied using skeletochronological method. To perform this task، 20 individuals of the frog (13 male and 7 female) and 22 individuals of the toad (13 male and 9 female) were collected during different seasons of year from their natural habitat in Khorramabad and transferred to the laboratory where they were killed and their femur bones were dissected out from their legs. The bones were then decalcified، dehydrated، cleared، embedded، cut، stained and observed under a light microscope. The age was estimated for individuals by counting the number of lines of arrested growth (LAG) in cross-sections taken from femurs. On the basis of observations، the age range was 3-11 and 1-8 for R. ridibunda and B. viridis، respectively. Moreover، to find any relation between snout-to-vent length (SVL) and age، we analyzed the data using statistical methods. Results obtained from this analysis indicated that there is no positive relation between these two characters neither in R. ridibunda nor in B. viridis. This is true for both males and females. According to these finding we can come to the conclusion that these species do not show a significant growth after puberty.