PSVIII-22 Microsatellite-based heterozygosity fitness correlations in reindeer

Inbred individuals often show reduced fitness due to increased number of loci identical by descent as the loss of heterozygosity may lead to the unmasking of deleterious recessive alleles. Inbreeding level can be measured either based on pedigree or genetic markers. The latter can be used for heterozygosity fitness correlation (HFC) studies in populations which pedigrees are unknown. Here, we estimated individual heterozygosity level in reindeer based on ten STR and investigated heterozygosity fitness correlations. A total of 64 individuals were divided into two groups: males (M, n = 16) and females (F, n = 48). The influence of inbreeding on height at withers (HaW), chest depth (CD), chest width (CW), chest girth (CG), wrist girth (WG), body length(BL), head length (HL), body weight (BW), hip width (HW) and loin width (LW) was examined. R package “inbreedR” was used for statistical analysis. Identity disequilibrium point estimate - g2 was calculated to estimate the correlations between inbreeding, multilocus heterozygosity (MLH) and fitness. For M group the measure of g2 was 0.03390±0.02564, p (g2 >0) = 0.017, and for F group - 0.03973±0.02377, p (g2 > 0) = 0.006. Expected r2 between inbreeding level and heterozygosity was 0.49795 and 0.40812 for M and F, respectively. The highest HFCs in M group were detected for CG - 0.35, WG – 0.26, BW – 0.18 and HW – 0.14 i.e. traits that are characteristics for body composition. The highest HFCs in F group were for LW – 0.22, CW – 0.16 and HaW – 0.15 i.e. traits related to reproductivity. For all the other traits HFCs were close to zero. Our study demonstrated that STR can be used for calculations of MLH and inbreeding correlations as well as for detecting traits that are influenced by inbreeding in reindeer. The study was supported by Russian Science Foundation (Pr. no.16-16-10068).