Three hundred years of continuous coal mining in Northern France have left the countryside riddled with spoil heaps – artificial mounds made from industrial waste and thin layers of soil with high metal contents. Since the end of large-scale coal extraction, the soil heaps have been accepted as part of the landscape and celebrated as an habitat to the few plant and animal species that can resist their peculiar environment.
One of these species is the natterjack toad (Bufo calamita). The natterjack lives in the coastal areas of Northern France and on the coal spoil heaps, but is completely absent in the landscapes in between.
Jean-François Arnaud, from the University of Lille, and his collegues decided to examine the genetic structure of the natterjack toad and investigate how the species colonised the spoil heaps.
To do this, the team collected samples from 1209 toads, from 68 populations living in their natural coastal habitats, on the man-made spoil heaps and elsewhere in Europe for comparison.
Making sense of thousand of genetic sequences and multilocus genotypes required sophisticated software and plenty of computing power. Arnaud and his colleagues used the compute resources made available the providers of the biomed virtual organisation and submitted over 75,000 High-Throughput jobs to the EGI infrastructure through the DIRAC portal provided by France Grilles – the French national e-Infrastructure.
For the team, the advantage of using EGI High-Throughput Compute is measured in saved time – if the analysis had been conducted in normal desktops, they would have had to wait several months for all the data to be processed.
The results show significant differences in the natterjack toad populations. The toads living in the spoil heaps show no evidence of inbreeding and are more genetically diverse. The soil heaps toads also show multiple maternal mitochondrial lineages – a strong indication for multiple colonisation events.
The findings suggest that the soil heap natterjack toad populations are not threatened under the stress of a harsh environment. They seem to be precisely the opposite: a thriving melting pot of populations that immigrated to the soil heaps over the course of the centuries.
The conclusions, published in the journal Molecular Ecology, also give strength to the argument that the French soil heaps are hotspots of ecological diversity and worthy of conservation.