Heterozygosity‐fitness correlations of conserved microsatellite markers in Kentish plovers Charadrius alexandrinus

Abstract

Heterozygosity-fitness correlations (HFCs) are frequently used to examine the relationship between genetic diversity and fitness. Most studies have reported positive HFCs, although there is a strong bias towards investigating HFCs in genetically impoverished populations. We investigated HFCs in a large genetically diverse breeding population of Kentish plovers Charadrius alexandrinus in southern Turkey. This small shorebird exhibits highly variable mating and care systems, and it is becoming an ecological model species to understand breeding system evolution. Using 11 conserved and six anonymous microsatellite markers, we tested whether and how heterozygosity was associated with chick survival, tarsus and body mass growth controlling for nongenetic effects (chick sex, hatching date, length of biparental care and site quality) that influence survival and growth. There was no genome-wide effect of heterozygosity on fitness, and we did not find any significant effects of heterozygosity on growth rates. However, two of the 11 conserved markers displayed an association with offspring survival: one marker showed a positive HFC, whereas the other marker showed a negative HFC. Heterozygosity at three further conserved loci showed significant interaction with nongenetic variables. In contrast, heterozygosity based on anonymous microsatellite loci was not associated with fitness or growth. Markers that were correlated with chick survival were not more likely to be located in exons or introns than other markers that lacked this association.

Conflict between Genetic and Phenotypic Differentiation: The Evolutionary History of a ‘Lost and Rediscovered’ Shorebird

“…In addition, our work reveals novel insights into the distribution of a cosmopolitan superspecies of shorebird that has served as a model organism in evolutionary and ecological research (e.g. [15], [16], [17]). To fully resolve the root of the conflicting morphological and genetic data, future research will benefit from the incorporation of genome-wide sequences, from a focus on candidate loci for plumage pigmentation or from gene expression scans to characterize expression divergence.…”

“…Here we investigate the evolutionary history of the White-faced Plover ( Charadrius alexandrinus dealbatus ), an enigmatic East Asian shorebird that is often thought to be a subspecies of the Kentish Plover ( C. alexandrinus ). C. alexandrinus is a widespread breeding resident of beaches and salt pans throughout northern temperate to subtropical latitudes that has served as a model organism in ecological and evolutionary research [15], [16], [17]. Recently, Küpper et al [18] restricted its range to the Old World by showing that American populations are not its sister and therefore must be considered an independent species, the Snowy Plover ( C. nivosus ).…”

Evidence of opposing fitness effects of parental heterozygosity and relatedness in a critically endangered marine turtle?

“…To test for effects of heterozygosity associated with specific loci, we used likelihood ratio tests to compare models with a multilocus metric fitted as a linear expression against respective models with all 32 single loci fitted simultaneously as covariates (Küpper et al ., ; Szulkin et al ., ). Only if this test is significant should a single‐locus model be examined for loci with partial regression slopes significantly different from zero (Szulkin et al ., ).…”

“…Many HFC studies have reported positive linear effects (Chapman et al ., ; Küpper et al ., ). Such positive effects may have been overrepresented due to publication bias (Coltman & Slate, ; bias may be diminishing – see Chapman et al ., ), biases arising from the properties of the genetic markers used (Küpper et al ., ), and because of a tendency for HFC studies to be conducted on small populations that have high inbreeding variance (see Coltman & Slate, ; Chapman et al ., ; Küpper et al ., ). The other end of the heterozygosity spectrum – negative HFCs – has received less attention (but see Szulkin & David, ).…”

Applications and Implications of Neutral versus Non-neutral Markers in Molecular Ecology

“…Similarly, there are logistical constraints to quantifying fitness based on lifetime reproductive success, and therefore one or more surrogate measures such as clutch size, sperm count, or seed production is most commonly used (e.g., [34]). Multilocus genotype data and fitness estimates can be combined to test for heterozygosity fitness correlations (HFCs), which occur when there is a correlation between overall heterozygosity and a measure of fitness; a positive HFC suggests that low heterozygosity is reducing fitness within a population.…”