Waterdraken en -salamanders op het droge: Ontrafelen van de invloed van het landschap op genetische diversiteit en connectiviteit

While we have some understanding of what makes a good breeding pond for newts, our knowledge is less comprehensive when it comes to the terrestrial habitat. Quality and composition of the landscape play a pivotal role in determining a species' potential to thrive. To gain a better understanding of how the landscape influences the genetic diversity and connectivity for newts, we conducted two studies. In both studies we considered the scale at which to assess the landscape, acknowledging that choosing only a single scale might miss certain landscape effects. The first study examined the influence of landscape features around breeding ponds on genetic diversity and effective population size of the Vulnerable (Flemish Red List) Great Crested Newt Triturus
cristatus. We investigated twelve spatially structured populations of Great Crested Newt across Flanders and one in Wallonia. We collected genetic information from these populations as well as data on the landscapes they inhabit. The land cover types studied here appeared to be mostly relevant on smaller spatial scales. Short distances between breeding ponds had a positive effect on genetic diversity, whereas the influence of other land cover types, such as woodland, arable land,
pastures and roads varied depending on scale and measure of genetic
diversity considered. In the second study, conducted in an area characterized
by agriculture and urban development, we explored the connectivity between subpopulations of the Great Crested Newt and the more abundant and widespread Smooth Newt Lissotriton vulgaris. Genetic differences and similarities between these two species became evident, with Great Crested Newt subpopulations appearing more isolated than those of Smooth Newt. However both species faced similar challenges, with landscape features like managed grasslands, posing barriers to gene flow. The intensively managed grassland lacked the structural heterogeneity necessary for newts. In conclusion, our studies elucidated the intricate relationship between newts and their habitat, emphasizing the importance of landscape features like closely spaced ponds
and spatial patchiness. These findings contribute to the development of effective conservation strategies for these species, ensuring their continued survival in the face of environmental challenges.