Microsatellite Loci Reveal Sex-Dependent Responses to Inbreeding and Outbreeding in Red Deer Calves

Abstract

Mean d is a recently devised microsatellite-based measure that is hypothesised to allow the detection of inbreeding depression and heterosis in free-living populations. Two studies that have investigated the measure have both demonstrated an association between mean d and traits related to fitness. Here we present an association between mean d and an important component of fitness, first-year overwinter survival, in a population of red deer on the Isle of Rum, Scotland. The association between survival and mean d differed between males and females. As predicted, outbred female calves (high mean d ) survived better than those that were inbred (low mean d ). However, the association was in the opposite direction in male calves. We suggest that this difference is due to different early growth strategies between the sexes. The association between mean d and survival was not significantly influenced by any single locus. Decomposition of mean d into a recent inbreeding component and an outbreeding component showed that it was the degree of outbreeding that influenced survival in males and both the degree of outbreeding and recent inbreeding that influenced survival in females. Our analyses suggest that mean d is an easy-to-calculate measure of inbreeding and degree of outbreeding that can reveal interesting interactions between genetics and ecology.

Three genetically divergent lineages of the Oryx in eastern Africa: Evidence for an ancient introgressive hybridization

“…In contrast to this, our data (this study) and that of Pitra et al (2002) suggest that intraspecific outbreeding actually happens in nature when individuals from distinct populations/lineages meet. Our data further indicates that crossing geographically distinct populations of a wild species seems to have beneficial effects by increasing genetic variability, although we do not know about possible detrimental effects on the reproductive fitness of the progeny caused by outbreeding depression when the two taxa originally met (but see Greig 1979;Coulson et al 1999;Marshall and Spalton 2000;Pitra et al 2002). There is no suggestion that this ancient introgressive hybridization has left any signs of outbreeding depression in O. beisa of today.…”

Genetic diversity-fitness correlation revealed by microsatellite analyses in European alpine marmots (Marmota marmota)

“…Assuming that microsatellites evolve under the stepwise mutation model (SMM) (Valdes et al 1993), mean d 2 and mean d 2 outbreeding provide a measure of the genetic distance between parental gamete genomes and appear particularly sensitive to outbreeding (Coulson et al 1998(Coulson et al , 1999. The fit of each locus distribution to expected distribution under three different mutation models, the SMM, the IAM (infinite allele model) and an intermediate two-phase model (TPM) was tested using the program BOTTLENECK (Cornuet and Luikart 1996).…”

“…LDO=log 10 (mean d 2 outbreeding +1) where mean d 2 outbreeding is the mean d 2 score excluding homozygous loci (Coulson et al 1999).…”

“…Studies reporting negative results exist (Rowe and Beebee 2001;Duarte et al 2003) and may be underrepresented because of publication bias in favour of positive results. On the other hand, many recent studies report a correlation between heterozygosity at neutral microsatellite markers and individual fitness-related traits such as survival (Coltman et al 1998;Coulson et al 1998Coulson et al , 1999Rossiter et al 2001;Markert et al 2004), reproductive success and recruitment (Slate et al 2000;Ho¨gl-und et al 2002;Foerster et al 2003;Hansson et al 2001Hansson et al , 2004Hoffman et al 2004;Markert et al 2004;Seddon et al 2004), and disease resistance (Coltman et al 1999). In a meta-analysis, Coltman and Slate (2003) found that positive associations between neutral marker heterozygosity and traits or components of individual fitness were common but weak.…”

“…First, we investigate GDFC in the alpine marmot, Marmota marmota, using the classical measure of heterozygosity (H), and measures introduced by Coulson et al (1998Coulson et al ( , 1999 (d 2 and d 2 outbreeding ). GDFC remains difficult to investigate in the wild, and few studies have considered ecological variables in their analysis.…”