G.E.P. at the XIV Iberian Congress of Herpetology

A. Rotger presented part of his Ph.D. thesis at the XIV Iberian Congress of Herpetology

with a contribution titled "Contrasting size-dependent life history strategies in female Balearic Wall lizards (Podarcis lilfordi) from insular close populations".

He will defend his work the 30th of November at the University of Barcelona

Spring 2016 campaign on Lilford's lizard ended!

The 2016 spring campaign on Lilford's lizard ended last week. It has been a difficult one, with many days of bad weather and several unexpected problems with boat and logisitc....but hey, this is job. Populations reached a very low level, but it seems there will be many new recruits in October. Thank to the many people from the GEP who gave their help.

New Publication on Lilford's wall lizard !!

Rotger, A., Smith, J.J., Igual, J.-M. and Tavecchia, G., 2016: Relative role of population density and climatic factors in shaping the body growth rate of Lilford’s Wall Lizard (Podarcis lilfordi). Canadian Journal of Zoology. doi: 10.1139/cjz-2015-0188

 Abstract: The growth rate in small reptiles is modulated by per-capita food resources and recent evidence suggested that this constraint is the mechanism underlying differences between cohorts. Per-capita food resources depend on population size and climatic factors, but their relative role in explaining the variations in growth rate is unclear.

Photo: G. Tavecchia

We used morphological data collected over 6 years to model the body growth of an insular lizard (Lilford’s Wall Lizard, Podarcis lilfordi (Günther, 1874)). We used nonlinear equations to describe the appropriate length-at-age relationship. For each sex, seasonal growth was observed and the oscillatory von Bertalanffy curve was fitted to the data. Three age classes were recognized, and we investigated the relative role of density, spring rainfall, and temperature in explaining the variation of the growth rate in each sex-by-age class. Results showed that the relative role of density and climatic factors varied according to the age considered. While population size and temperature had a negative effect on the growth rate of juveniles, rainfall had a positive influence on the growth of subadults. Adult growth was near zero and constant over time. The different role of density-dependent and climatic factors in explaining age-dependent growth rate provides an important insight in understanding lizard population dynamics and life-history tactics.