Umbilical cords, hatchlings, and nesting females of Caretta caretta from western Mediterranean nests
High-throughput sequencing has revolutionised conservation genomics by enabling genome-wide information even in non-model species. However, obtaining non-invasive samples for genomics remains challenging in species like sea turtles, which spend most of their lives in the open ocean. In addition, traditional sampling methods are often impractical or unsafe for hatchlings, highlighting the need for alternative approaches. We investigated the potential of umbilical cords (UCs), both proximal and distal region, as a non-invasive sampling method. We assessed their suitability, genetic origin (mother or offspring), and prevalence under different incubation conditions. We analysed 76 samples with 2bRAD from five Spanish emerging nests, including UCs from 13 hatchlings (both proximal and distal region), 48 hatchling blood samples (four with genotyped UCs) and blood from two breeding females. Using the Percentage of Shared Genotype (PSG) analysis, we determined that the UC genotype from both sides matched the hatchling blood genotype (97.7%), while PSG were lower between related individuals (73.5%) and even lower between unrelated individuals (56.5%). UC prevalence varied by incubation type, appearing in 100% of artificially incubated nests in Spain, in 25% of Spain's naturally incubated nests, an emergent nesting population, and in only 4.5% of nests naturally incubated in Cape Verde, an established nesting population. Our findings establish UCs as a reliable non-invasive DNA source for hatchlings, particularly in incubator-hatched eggs. This study highlights UCs as a promising non-invasive method for sea turtle research, advancing genomic analysis while minimising disturbance and offering insights into population genetics and conservation strategies.
High-throughput sequencing has revolutionised conservation genomics by enabling genome-wide information even in non-model species. However, obtaining non-invasive samples for genomics remains challenging in species like sea turtles, which spend most of their lives in the open ocean. In addition, traditional sampling methods are often impractical or unsafe for hatchlings, highlighting the need for alternative approaches. We investigated the potential of umbilical cords (UCs), both proximal and distal region, as a non-invasive sampling method. We assessed their suitability, genetic origin (mother or offspring), and prevalence under different incubation conditions. We analysed 76 samples with 2bRAD from five Spanish emerging nests, including UCs from 13 hatchlings (both proximal and distal region), 48 hatchling blood samples (four with genotyped UCs) and blood from two breeding females. Using the Percentage of Shared Genotype (PSG) analysis, we determined that the UC genotype from both sides matched the hatchling blood genotype (97.7%), while PSG were lower between related individuals (73.5%) and even lower between unrelated individuals (56.5%). UC prevalence varied by incubation type, appearing in 100% of artificially incubated nests in Spain, in 25% of Spain's naturally incubated nests, an emergent nesting population, and in only 4.5% of nests naturally incubated in Cape Verde, an established nesting population. Our findings establish UCs as a reliable non-invasive DNA source for hatchlings, particularly in incubator-hatched eggs. This study highlights UCs as a promising non-invasive method for sea turtle research, advancing genomic analysis while minimising disturbance and offering insights into population genetics and conservation strategies.
universitat de barcelona