Reindeer husbandry, an essential part of Sámi culture in northern Scandinavia, faces multiple challenges including climate change, competing land use, and increased predation pressure. These pressures may be creating a "perfect storm" that threatens the sustainability of reindeer populations. In this context, understanding the genetic health and adaptive potential of reindeer populations is crucial. One key indicator of genetic health is the presence and pattern of runs of homozygosity (ROH) in the genome, which can reveal information about past demographic events and inbreeding levels. ROH are continuous stretches of homozygous genotypes that are inherited from parents sharing common ancestors. The length and frequency of these segments can help track changes in effective population size over time and identify potential genetic vulnerabilities. Problem Formulation: This internship project aims to analyze whole-genome sequencing data from reindeer to investigate their demographic history and population genetic health. Specifically, it aims to identify ROH in reindeer and use this patterns to estimate historical effective population sizes to assess the potential implications for the reindeer populations’ adaptive capacity given current environmental challenges. The results will contribute to our understanding of reindeer population genetics and may inform future management strategies for maintaining genetic diversity in these important populations. This work is part of a larger project investigating the resilience of reindeer populations to multiple stressors, including climate change and increased disease pressure