Different newt species, similar obstacles
To avoid loss or weakening of local populations of a given species, individuals must be able to occasionally migrate from one population to another. Thus, genes are exchanged and inbreeding is avoided. This also applies to newts living in different ponds. But how does the landscape affect gene flow between ponds? We investigated this in an area characterized by agriculture and urban development in Temse and Kruibeke, where several species live: the greatcrested newt, which is relatively rare, and thesmooth newt, which is quite common.
The subpopulations of great crested newts appear to be mostly isolated. The groups of smooth newts are more interconnected. Smooth newts are considered to be less sensitive to human influences. Nevertheless, we did observe some inbreeding among the smooth newts in our study area and a genetic substructure with clusters of subpopulations. This may indicate a recent decline in connectivity between subpopulations.
At the same time, both species show a similar pattern of genetic diversity in pools where they co-occur. For example, we find that genetic variation in the two species is lower in artificial pools and garden ponds than in the remaining (more) natural pools and watering ponds for cattle. For each species, we made a map of the area showing the barriers to gene exchange. Both maps are surprisingly similar.
For the great crested newt, areas with few trees or lots of arable fields are not ideal. Intensively managed grasslands lack structure. Spatial variation in vegetation is a must for both species. Adding pons of different sizes near existing ones and switching to landscape management that includes more hedgerows and hedges would benefit both species.
This study was performed in collaboration with Regionaal Landschap Schelde-Durme vzw.
Read more: Cox K., Schepers R., Van Breusegem A., & Speybroeck J. (2023). The common ground in landscape effects on gene flow in two newt species in an agroecosystem. Conservation Genetics. https://doi.org/10.1007/s10592-023-01539-w or in PDF formaat.
Image above: smooth newt (photo Rollin Verlinde - Vildaphoto)
Staalname in poel in Temse (foto INBO)