Risk of ectoparasitism and genetic diversity in a wild lesser kestrel population

Abstract

Parasites and infectious diseases are major determinants of population dynamics and adaptive processes, imposing fitness costs to their hosts and promoting genetic variation in natural populations. In the present study, we evaluate the role of individual genetic diversity on risk of parasitism by feather lice Degeeriella rufa in a wild lesser kestrel population (Falco naumanni). Genetic diversity at 11 microsatellite loci was associated with risk of parasitism by feather lice, with more heterozygous individuals being less likely to be parasitized, and this effect was statistically independent of other nongenetic parameters (colony size, sex, location, and year) which were also associated with lice prevalence. This relationship was nonlinear, with low and consistent prevalences among individuals showing high levels of genetic diversity that increased markedly at low levels of individual heterozygosity. This result appeared to reflect a genome-wide effect, with no single locus contributing disproportionably to the observed effect. Thus, overall genetic variation, rather than linkage of markers to genes experiencing single-locus heterosis, seems to be the underlying mechanism determining the association between risk of parasitism and individual genetic diversity in the study host-parasite system. However, feather lice burden was not affected by individual heterozygosity; what suggest that differences in susceptibility, rather than variation in defences once the parasite has been established, may shape the observed pattern. Overall, our results highlight the role of individual genetic diversity on risk of parasitism in wild populations, what has both important evolutionary implications and major consequences for conservation research on the light of emerging infectious diseases that may endanger genetically depauperated populations.

Individual genetic diversity correlates with the size and spatial isolation of natal colonies in a bird metapopulation

“…We used two metrics to estimate individual genetic diversity: (i) uncorrected heterozygosity (H O ), calculated as the proportion of loci at which an individual is heterozygous and (ii) homozygosity by locus (HL), a microsatellite derived measure that improves heterozygosity estimates in open populations by weighting the contribution of each locus to the homozygosity value depending on its allelic variability (Aparicio et al 2006;Ortego et al 2007b). Particularly, HL improves heterozygosity estimates when markers are highly different in variability, as is the case in this study (Ortego et al 2007a;e.g. Ortego et al 2007c).…”

“…During the years 2000-2006, we have studied a total of 37 breeding colonies clustered in two subpopulations separated by 30 km: 'Villacañ as' (39830 0 N, 3820 0 W; 17 colonies) and 'Consuegra' (39835 0 N, 3840 0 W; 6 colonies) subpopulations (figure 1). However, in spite of the low exchange of individuals between both subpopulations, Bayesian modelbased clustering analyses (STRUCTURE v. 2.1, Pritchard et al 2000) indicated that they are not genetically differentiated (maximum number of clusters modelledZ10; Ortego et al 2007aOrtego et al , 2008.…”

“…In natural populations, many empirical studies have also provided supporting evidence for a positive relationship between individual genetic diversity measured at neutral markers and different components of fitness, including disease resistance (Acevedo-Whitehouse et al 2003Ortego et al 2007a), fecundity (Ortego et al 2007b) and survival probability (Hoffman et al 2004;Markert et al 2004), although the possible role of inbreeding in such correlations has been recently put into question (Balloux et al 2004;Pemberton 2004). At the population level, low genetic diversity is suspected to reduce the ability of populations to respond to novel and changing environmental conditions ( Willi et al 2006) and compromise their long-term viability (Saccheri et al 1998;Westemeier et al 1998;Nieminen et al 2001;Spielman et al 2004;Frankham 2005).…”

Biogeographical patterns and co-occurrence of pathogenic infection across island populations of Berthelot’s pipit (Anthus berthelotii)

“…2010), driving genetic variation (Acevedo-Whitehouse et al 2003;Ortego et al 2007;Spurgin and Richardson 2010) and sexual selection (Hamilton and Zuk 1982). Understanding how patterns of pathogen-mediated selection vary across populations may therefore provide new insights into the mechanistic processes behind adaptation and natural selection.…”

Heterozygosity-based assortative mating in blue tits (Cyanistes caeruleus): implications for the evolution of mate choice

“…Foerster et al 2003;Ortego et al 2007a), immunocompetence (e.g. Hawley et al 2005), parasite resistance (Acevedo-Whitehouse et al 2003;Ortego et al 2007b) and survival probability (e.g. Kruuk et al 2002;Van de Casteele et al 2003).…”