The European pond turtle Emys orbicularis is a small freshwater turtle native to Central Europe. It relies on both aquatic and terrestrial environments for ensuring its physiological and reproductive needs. As an ectotherm, its activity is highly dependent on the ambient temperature making this species directly impacted by climate change. Additionally, global changes, including climate and human activities, have been dramatically impacting its habitats and natural populations. Nowadays, the European pond turtle is considered as the reptile that has suffered the most dramatic decline in Europe. The species is of conservation concern and benefits from conservation initiatives, including reintroductions. The success of reintroduction depends on both intrinsic (individual quality, population genetics) and extrinsic (environmental conditions, habitat quality, food resource availability) factors.
The monitoring of Emys orbicularis behavior and ecology in the wild through traditional capture-mark-recapture methods is challenging mainly due to its cryptic, discrete, and mostly aquatic lifestyle and nocturnal nesting behavior. Furthermore, the polygamous mating strategy of E. orbicularis makes it difficult to assess the actual drivers of a populations' genetic structure.
A good understanding of the turtles' behavior, habitat use and reproductive strategies (including nesting site selection and mating selection) is the basis for effective land management and conservation initiatives as well as for assessing their capacity to adapt to global and climatic changes. In this project we aim to expand this knowledge by incorporating data from advanced biologgers and genomic pedigree analysis.
1) Analysis of biologger data to reveal individual behavior, habitat use, social interactions and nesting sites
Advanced data loggers have become small and lightweight enough to be attached to small sized freshwater turtles: these devices offer access to a wide range of environmental and behavioral data, including temperature, light, pressure, accelerometry, geolocation and proximity to other congeners. For instance, novel inter-individual proximity data loggers can help to reveal social interactions between turtle individuals within the group and to understand the social structure of the population, but also to identify potential mating partners which cannot be done through direct observation. These tools make it possible to uncover fine-scale patterns, both on individual and population levels, that would otherwise remain hidden. At the same time, the analysis of such data introduces new challenges that we will address through custom bioinformatic pipelines.
We will analyze data that already exists from the DE-FR cross-bordering Long Term Study in Ecology and Evolution (SEE-Life) site of Neu-Woerr, and complement it with original data collected during this project. Through that, we aim to describe, from a fundamental point of view, the fine-scale behavior and the habitat use of Emys orbicularis in relation to individual (e.g., phenological traits, reproductive status) and environmental conditions (e.g., landscape features, habitat types), and from a more operational point of view, to identify breeding phenology and nesting site locations for providing scientific-based knowledge to stakeholders in charge of the land management and reintroduction actions.
2) Genomic pedigree analysis
European pond turtles potentially have, as shown for other turtle species, a complex mating system including multiple paternity and sperm storage capacity of females, making it difficult to study it through observation alone. The underlying mating behavior strongly influences the genetic diversity and therefore the adaptive potential of a population, which is crucial knowledge especially for captive breeding groups and small reintroduced populations. Pedigree analyses therefore play an important role in uncovering the species' reproductive behavior. Traditional genetic tools such as microsatellites have provided valuable insights but often lack the resolution needed for confidently assigning parentage in populations. Moreover, this data is not well comparable between laboratories. Therefore, we aim to establish a SNP-based pedigree reconstruction as a more accurate and scalable method for reliable mating system analyses in E. orbicularis. Combined with the behavioral and social data, a better understanding of the drivers of genetic diversity will enable stake holders to better assess the sustainability of conservation initiatives.
