Age structure and growth in an isolated population of Pelodytes punctatus in northern Spain

Abstract

We studied the age structure and the growth of a breeding population of parsley frogs, Pelodytes punctatus, from a pond system in northern Spain using skeletochronological methods. This population lives in an upland area with marked seasonal differences characterized by long, cold winters and dry summers. We assessed, using the mark–recapture method, the annual periodicity of bone growth marks. Only one line of arrested growth is laid down per winter, showing, in general, a well-defined histological structure. Females are larger than males with 43.31 and 36.32 mm average body length, respectively. This sexual dimorphism in body length increases with age. Males and females reach sexual maturity when they are 1 year old. The oldest males were 8 years old while the females were 2 years older. Growth curves for both sexes were constructed based on body size and the number of lines of arrested growth found in bone sections. The growth rate of males declined abruptly after the first year. Females delayed reproduction and continued to grow at a high rate for 2 years longer than males, thus reaching a higher asymptotic size.

Keywords:

• Pelodytidae
• Pelodytes punctatus
• age structure
• northern Spain
• skeletochronology
• growth
• sexual dimorphism

Acknowledgement

We thank M. Alcobendas, M. García-París, L. Sainz de los Terreros and B. Sanchíz for constructive remarks on the manuscript. M. Tejedo helped us with the statistical analysis. The first author was supported by a postdoctoral grant in the Comunidad de Madrid project: 07M/0109/00 CAM (PI: M. García-París).