The consequences of historical overhunting
Our team, led by Fabian Kellner and Dr. Mathilde Le Moullec, has completed a study of the implications of the historical period of mass hunting of the Svalbard reindeer. In this scientific publication, we use whole-genome sequence information derived from the remains of reindeer that lived during a span of the past 4000 years. Our analysis shows that historical overharvesting caused major changes in the genetic structure of Svalbard reindeer and decreased genetic diversity by 23%. The biggest temporal changes occurred in diverse genetic pathways that play roles in the animals’ neurological, cardiovascular, metabolic, and sexual functioning. Genetic diversity is the raw material with which biological species can adapt to future environmental changes and maintain healthy populations. Svalbard is the fastest warming place on Earth, so environmental change will play a major role in the future success of this remote population.
Link to the paper in the journal Molecular Ecology: A palaeogenomic investigation of overharvest implications in an endemic wild reindeer subspecies. https://doi.org/10.1016/j.isci.2023.107811
Overharvest can severely reduce the abundance and distribution of a species and thereby impact its genetic diversity and threaten its future viability. Overharvest remains an ongoing issue for Arctic mammals, which due to climate change now also confront one of the fastest changing environments on Earth. The high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus), endemic to Svalbard, experienced a harvest-induced demographic bottleneck that occurred during the 17–20th centuries. Here, we investigate changes in genetic diversity, population structure, and gene-specific differentiation during and after this overharvesting event. Using whole-genome shotgun sequencing, we generated the first ancient and historical nuclear (n = 11) and mitochondrial (n = 18) genomes from Svalbard reindeer (up to 4000 BP) and integrated these data with a large collection of modern genome sequences (n = 90) to infer temporal changes. We show that hunting resulted in major genetic changes and restructuring in reindeer populations. Near-extirpation followed by pronounced genetic drift has altered the allele frequencies of important genes contributing to diverse biological functions. Median heterozygosity was reduced by 26%, while the mitochondrial genetic diversity was reduced only to a limited extent, likely due to already low pre-harvest diversity and a complex post-harvest recolonization process. Such genomic erosion and genetic isolation of populations due to past anthropogenic disturbance will likely play a major role in metapopulation dynamics (i.e., extirpation, recolonization) under further climate change. Our results from a high-arctic case study therefore emphasize the need to understand the long-term interplay of past, current, and future stressors in wildlife conservation.
