Sonesinh Keobouasone

Highlights • Caribou are genetically diverse and form nine lineages across North America • Levels of inbreeding vary, with some highly inbred caribou in some locations • Regardless of inbreeding level, high genetic load is observed across all lineages • Genetically diverse species may be especially vulnerable to inbreeding depression Summary High intra-specific genetic diversity is associated with adaptive potential, which is key for resilience to global change.

1 INTRODUCTION Microsatellites are short motif (1 to 6) nucleotide arrays (Ellegren, 2004; Jarne & Lagoda, 1996; Verbiest et al., 2023; Vieira et al., 2016). They are highly polymorphic and abundant within eukaryotic genomes due to a combination of processes during DNA replication, such as replication errors, DNA polymerase slippage and limited selection pressures (Ellegren, 2004; Jarne & Lagoda, 1996; Verbiest et al., 2023; Vieira et al., 2016).

Abstract High intra-specific genetic diversity is associated with adaptive potential which is key for resilience to global change. However, high variation may also support deleterious alleles through genetic load, unless purged, thereby increasing the risk of inbreeding depression if population sizes decrease rapidly. Purging of deleterious variation has now been demonstrated in some threatened species.