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TURTLE, AN EXOTIC AND INTRODUCED SPECIES IN FRANCE: FIRST RESULTS
CONCERNING THEIR COLONIZING CAPACITIES
Abstract
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The red-eared slider turtle (Trachemys scripta elagans) is an aquatic species native to North
America. Since the early 1970s, thousands of juvenile slider turtles, so-called “dwarf-turtles”,
have been sold worldwide as pets. In the European Community, importation of red-eared
sliders has been forbidden since 1997. Turtles rapidly became cumbersome when they
reached adult size and well-intentioned people released them in natural ponds. Today, in
France, this species is observed in many aquatic ecosystems and in all French administrative
departments. This species seems to be well acclimated to local conditions and is already
designated as an invasive species, without any scientific evidence.
During my PhD, I investigated the capacity of red-eared slider turtle populations to establish
themselves in French natural environments. Establishment of an introduced species, a key
step inherent to the invasion process, underlies that this turtle must be able to successfully
breed to enable population turn-over. Particularly, I studied environmental influences,
especially the influence of climatic conditions, on different factors that may limit
establishment of these introduced populations. Thus, I developed a new mechanistic model to
predict sex-ratios of clutches in natural conditions (i.e. the sex of the embryo is influenced by
incubation temperature in this turtle species). I also studied, through experimental approaches,
the influence of temperature and water potential within the nest on hatching success,
incubation length of the eggs and quality of juveniles. My first results showed that the redeared
slider turtle might be a good candidate to colonize natural environments in France.
However, the pattern of the release of these turtles and their reproduction might be strong
barriers to invasion of this species.
Key-words: introduced species; biological invasion; red-eared slider; TSD
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Address of laboratory
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Ecologie, Systématique et Evolution
Département Ecologie des Populations et des Communautés
UMR 8079, bât. 362
Université Paris-Sud XI (Orsay)
91405 ORSAY CEDEX