Do not sacrifice the snail—conservative DNA extraction for terrestrial gastropods based on periostracum fraction and pedal mucus

Tissue collection methods for sampling of biological material often present various drawbacks related to ethical concerns as well as to the conservation status of many species. In this study, a conservative noninvasive sampling technique for genetic analyses was developed and optimized in three terrestrial gastropod species, namely, <i>Cornu aspersum</i>, <i>Eobania vermiculata</i>, and <i>Helix lucorum</i>. Our approach involves the sampling of a minimal amount of periosteum and pedal mucus, providing a viable alternative that does not harm the organisms, combining a few modifications in DNA isolation procedures depending on the sample. Mitochondrial CO1 and 18S rRNA genes were successfully amplified from both pedal mucus and periostracum samples, as confirmed by sequencing and BLAST comparisons in GenBank database. Interestingly, among the different sample types, shell from dead individuals demonstrated the highest DNA purity and quantity, likely due to the lack of DNA binding. This nondestructive method provides a promising advancement for conservation genetics, allowing for the study of protected species while maintaining their survival and well-being. The results demonstrate that this technique is an efficient and ethically sound tool for genetic studies, with potential applications in biodiversity monitoring and conservation research.