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Genetic assessment of translocations: a case study of two endangered amphibian species

Müller, R.
54 Seiten

Müller, R., 2016: Genetic assessment of translocations: a case study of two endangered amphibian species. Master thesis. 54 p.


Mueller, R. P. 2016. Genetic assessment of translocations: a case study of two endangered amphibians. Master Thesis, University of Zurich and WSL. Supervisors: Dr. B. Schmidt, PD Dr. J. Bolliger, Prof. Dr. A. Ozgul.


Conservation managers face complex decisions in the attempt to halt further population decline and biodiversity loss. Instead of basing decisions on personal belief, scientifically validated conservation is needed. Such an evidence-based approach has been applied to various conservation strategies, including translocations. They have been proven to be an effective tool for restoring endangered populations to portions of their former range. Especially when natural recolonisation is absent and/or too patchy. Unfortunately, the assessment of the genetic consequences of translocations are still lacking for various projects.

In this Master Thesis, I examined the genetic consequences of translocations for two endangered amphibians occurring in Switzerland; midwife toad (Alytes obstetricans) and natterjack toad (Epidalea calamita). Each species was genotyped with 13 microsatellite markers in order to deduce the genetic consequences of the translocations. For both species translocated populations were not genetically impoverished in comparison to the natural populations for either species. The populations that were created with several hundred individuals from mixed donor sites were more genetically diverse and admixed than other translocated populations, which were established with a limited founder group size from a single donor population.
Natterjack toads were only released where recolonisation through natural migration was not expected. I tested whether there were signs of natural migration with gene flow, network and landscape analysis in the region. Results from gene flow indicated strong evidence that the investigated E. calamita populations are even more connected than previously assumed and that the species can cover up to 25.4 km between potential habitats in the study region. Landscape and network investigations suggest that there are no substantial barriers to gene flow in the area and further support the gene flow calculations.

These findings indicate that future translocations can create genetically diverse and structurally admixed populations given that they are conducted with several hundred individuals from multiple populations. The results also suggest that gene flow between seemingly isolated natterjack toad populations is higher than previously thought. However, future conservation to enhance natural gene flow would be beneficial for all populations.