title: Turtle carapace anomalies: the roles of genetic diversity and environment.
abstract: BACKGROUND
  Phenotypic anomalies are common in wild populations and multiple genetic, biotic and abiotic factors might contribute to their formation. Turtles are excellent models for the study of developmental instability because anomalies are easily detected in the form of malformations, additions, or reductions in the number of scutes or scales.
  
  
  RESULTS
  In this study, we integrated field observations, manipulative experiments, and climatic and genetic approaches to investigate the origin of carapace scute anomalies across Iberian populations of the European pond turtle, Emys orbicularis. The proportion of anomalous individuals varied from 3% to 69% in local populations, with increasing frequency of anomalies in northern regions. We found no significant effect of climatic and soil moisture, or climatic temperature on the occurrence of anomalies. However, lower genetic diversity and inbreeding were good predictors of the prevalence of scute anomalies among populations. Both decreasing genetic diversity and increasing proportion of anomalous individuals in northern parts of the Iberian distribution may be linked to recolonization events from the Southern Pleistocene refugium.
  
  
  CONCLUSIONS
  Overall, our results suggest that developmental instability in turtle carapace formation might be caused, at least in part, by genetic factors, although the influence of environmental factors affecting the developmental stability of turtle carapace cannot be ruled out. Further studies of the effects of environmental factors, pollutants and heritability of anomalies would be useful to better understand the complex origin of anomalies in natural populations.
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, United States of America. gv47@cornell.edu
authors.forename: Guillermo
authors.initials: G
authors.lastname: Velo-Antón
authors.forename: C Guilherme
authors.initials: CG
authors.lastname: Becker
authors.forename: Adolfo
authors.initials: A
authors.lastname: Cordero-Rivera
mesh_terms: D000818:Animals; D014644:Genetic Variation; D014426:Turtles / Q000002:abnormalities / Q000235:genetics*