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Bart Kempenaers - One of the best experts on this subject based on the ideXlab platform.
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female mating preferences and offspring survival testing hypotheses on the genetic basis of mate choice in a wild lekking bird
Molecular Ecology, 2014Co-Authors: Rebecca J. Sardell, Bart Kempenaers, Emily H DuvalAbstract:: Indirect benefits of mate choice result from increased offspring genetic quality and may be important drivers of female behaviour. 'Good-genes-for-viability' models predict that females prefer mates of high additive genetic value, such that offspring survival should correlate with male attractiveness. Mate choice may also vary with genetic diversity (e.g. Heterozygosity) or compatibility (e.g. relatedness), where the female's genotype influences choice. The relative importance of these nonexclusive hypotheses remains unclear. Leks offer an excellent opportunity to test their predictions, because lekking males provide no material benefits and choice is relatively unconstrained by social limitations. Using 12 years of data on lekking lance-tailed manakins, Chiroxiphia lanceolata, we tested whether offspring survival correlated with patterns of mate choice. Offspring recruitment weakly increased with father attractiveness (measured as reproductive success, RS), suggesting attractive males provide, if anything, only minor benefits via offspring viability. Both male RS and offspring survival until fledging increased with male Heterozygosity. However, despite parent-offspring correlation in Heterozygosity, offspring survival was unrelated to its own or maternal Heterozygosity or to parental relatedness, suggesting survival was not enhanced by Heterozygosity per se. Instead, offspring survival benefits may reflect inheritance of specific alleles or nongenetic effects. Although inbreeding depression in male RS should select for inbreeding avoidance, mates were not less related than expected under random mating. Although mate Heterozygosity and relatedness were correlated, selection on mate choice for Heterozygosity appeared stronger than that for relatedness and may be the primary mechanism maintaining genetic variation in this system despite directional sexual selection.
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Heterozygosity fitness correlations in zebra finches microsatellite markers can be better than their reputation
Molecular Ecology, 2012Co-Authors: Wolfgang Forstmeier, Holger Schielzeth, Jakob C Mueller, Hans Ellegren, Bart KempenaersAbstract:Numerous studies have reported associations between Heterozygosity in microsatellite markers and fitness-related traits (Heterozygosity–fitness correlations, HFCs). However,it has often been questioned whether HFCs reflect general inbreeding depression, because a small panel of microsatellite markers does not reflect very well an individual’s inbreeding coefficient (F) as calculated from a pedigree. Here, we challenge this prevailing view. Because of chance events during Mendelian segregation, an individual’s realized proportion of the genome that is identical by descent (IBD) may substantially deviate from the pedigree-based expectation (i.e. F). This Mendelian noise may result in a weak correlation between F and multi-locus Heterozygosity, but this does not imply that multi-locus Heterozygosity is a bad estimator of realized IBD. We examined correlations between 11 fitness-related traits measured in up to 1192 captive zebra finches and three measures of inbreeding: (i) Heterozygosity across 11 microsatellite markers, (ii) Heterozygosity across 1359 single-nucleotide polymorphism (SNP) markers and (iii) F, based on a 5th-generation pedigree. All 11 phenotypic traits showed positive relationships with measures of Heterozygosity, especially traits that are most closely related to fitness. Remarkably, the small panel of microsatellite markers produced equally strong HFCs as the large panel of SNP markers. Both marker-based approaches produced stronger correlations with phenotypes than the pedigree-based F, and this did not seem to result from the shortness of our pedigree. We argue that a small panel of microsatellites with high allelic richness may better reflect an individual’s realized IBD than previously appreciated, especially in species like the zebra finch, where much of the genome is inherited in large blocks that rarely experience cross-over during meiosis.
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mate choice and genetic quality a review of the Heterozygosity theory
Advances in The Study of Behavior, 2007Co-Authors: Bart KempenaersAbstract:Publisher Summary This chapter presents a review of mate choice and genetic quality, defines mate choice, and discusses some of the key issues about how individuals can benefit from being choosy, including the distinction between two main types of genetic benefits. It also focuses on Heterozygosity and fitness and presents an overview of the methods that have been used to estimate individual Heterozygosity or relatedness among individuals. It also presents a review of the studies that have found correlations between individual Heterozygosity and a variety of fitness‐related traits. The chapter consists of two parts—mate choice based on relatedness with the partner, which is choice to optimize offspring Heterozygosity and the link between the evolution of promiscuity and inbreeding avoidance.
Joaquin Ortego - One of the best experts on this subject based on the ideXlab platform.
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the strength of the association between Heterozygosity and probability of interannual local recruitment increases with environmental harshness in blue tits
Ecology and Evolution, 2016Co-Authors: Vicente Garcianavas, Esperanza S Ferrer, Juan Jose Sanz, Joaquin OrtegoAbstract:The extent of inbreeding depression and the magnitude of Heterozygosity–fitness correlations (HFC) have been suggested to depend on the environmental context in which they are assayed, but little evidence is available for wild populations. We combine extensive molecular and capture–mark–recapture data from a blue tit (Cyanistes caeruleus) population to (1) analyze the relationship between Heterozygosity and probability of interannual adult local recruitment and (2) test whether environmental stress imposed by physiologically suboptimal temperatures and rainfall influence the magnitude of HFC. To address these questions, we used two different arrays of microsatellite markers: 14 loci classified as neutral and 12 loci classified as putatively functional. We found significant relationships between Heterozygosity and probability of interannual local recruitment that were most likely explained by variation in genomewide Heterozygosity. The strength of the association between Heterozygosity and probability of interannual local recruitment was positively associated with annual accumulated precipitation. Annual mean Heterozygosity increased over time, which may have resulted from an overall positive selection on Heterozygosity over the course of the study period. Finally, neutral and putatively functional loci showed similar trends, but the former had stronger effect sizes and seemed to better reflect genomewide Heterozygosity. Overall, our results show that HFC can be context dependent, emphasizing the need to consider the role of environmental heterogeneity as a key factor when exploring the consequences of individual genetic diversity on fitness in natural populations.
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temporal variation of Heterozygosity based assortative mating and related benefits in a lesser kestrel population
Journal of Evolutionary Biology, 2009Co-Authors: Joaquin Ortego, Gustau Calabuig, Raul Bonal, Alberto Munoz, Jose Miguel Aparicio, Pedro J CorderoAbstract:Heterozygosity as a target of mate choice has received much attention in recent years and there is growing evidence supporting its role in the evolution of mate preferences. In this study we analyse mating patterns in relation to Heterozygosity in a lesser kestrel (Falco naumanni) population intensively monitored over six study years (2002–2007). The magnitude of Heterozygosity-based assortative mating varied over time, being particularly patent in the last study years (2006, 2007). We have found evidence that this mating pattern entails both direct and indirect-genetic benefits. Clutch size increased with female Heterozygosity and more heterozygous males raised a higher number of fledglings particularly in those years when the strength of the Heterozygosity-based assortative mating was markedly higher. In the last study year, parent–offspring correlation of Heterozygosity was stronger and higher than the expected if individuals would have randomly mated with respect to Heterozygosity. Overall, our results offer empirical support to the heterozygous mate hypothesis of sexual selection but suggest that genetic diversity may act as a temporally variable target for mate choice.
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Heterozygosity based assortative mating in blue tits cyanistes caeruleus implications for the evolution of mate choice
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Vicente Garcianavas, Juan J. Sanz, Joaquin OrtegoAbstract:The general hypothesis of mate choice based on non-additive genetic traits suggests that individuals would gain important benefits by choosing genetically dissimilar mates (compatible mate hypothesis) and/or more heterozygous mates (heterozygous mate hypothesis). In this study, we test these hypotheses in a socially monogamous bird, the blue tit (Cyanistes caeruleus). We found no evidence for a relatedness-based mating pattern, but Heterozygosity was positively correlated between social mates, suggesting that blue tits may base their mating preferences on partner's Heterozygosity. We found evidence that the observed Heterozygosity-based assortative mating could be maintained by both direct and indirect benefits. Heterozygosity reflected individual quality in both sexes: egg production and quality increased with female Heterozygosity while more heterozygous males showed higher feeding rates during the brood-rearing period. Further, estimated offspring Heterozygosity correlated with both paternal and maternal Heterozygosity, suggesting that mating with heterozygous individuals can increase offspring genetic quality. Finally, plumage crown coloration was associated with male Heterozygosity, and this could explain unanimous mate preferences for highly heterozygous and more ornamented individuals. Overall, this study suggests that non-additive genetic traits may play an important role in the evolution of mating preferences and offers empirical support to the resolution of the lek paradox from the perspective of the heterozygous mate hypothesis.
Juan J. Sanz - One of the best experts on this subject based on the ideXlab platform.
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Heterozygosity based assortative mating in blue tits cyanistes caeruleus implications for the evolution of mate choice
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Vicente Garcianavas, Juan J. Sanz, Joaquin OrtegoAbstract:The general hypothesis of mate choice based on non-additive genetic traits suggests that individuals would gain important benefits by choosing genetically dissimilar mates (compatible mate hypothesis) and/or more heterozygous mates (heterozygous mate hypothesis). In this study, we test these hypotheses in a socially monogamous bird, the blue tit (Cyanistes caeruleus). We found no evidence for a relatedness-based mating pattern, but Heterozygosity was positively correlated between social mates, suggesting that blue tits may base their mating preferences on partner's Heterozygosity. We found evidence that the observed Heterozygosity-based assortative mating could be maintained by both direct and indirect benefits. Heterozygosity reflected individual quality in both sexes: egg production and quality increased with female Heterozygosity while more heterozygous males showed higher feeding rates during the brood-rearing period. Further, estimated offspring Heterozygosity correlated with both paternal and maternal Heterozygosity, suggesting that mating with heterozygous individuals can increase offspring genetic quality. Finally, plumage crown coloration was associated with male Heterozygosity, and this could explain unanimous mate preferences for highly heterozygous and more ornamented individuals. Overall, this study suggests that non-additive genetic traits may play an important role in the evolution of mating preferences and offers empirical support to the resolution of the lek paradox from the perspective of the heterozygous mate hypothesis.
William Amos - One of the best experts on this subject based on the ideXlab platform.
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no correlation between multi locus Heterozygosity and fitness in the common buzzard despite heterozygote advantage for plumage colour
Journal of Evolutionary Biology, 2013Co-Authors: Martina Boerner, William Amos, Joseph I Hoffman, Nayden Chakarov, Oliver KrugerAbstract:Correlations between Heterozygosity and fitness are frequently found but rarely well understood. Fitness can be affected by single loci of large effect which correlate with neutral markers via linkage disequilibrium, or as a result of variation in genome-wide Heterozygosity following inbreeding. We explored these alternatives in the common buzzard, a raptor species in which three colour morphs differ in their lifetime reproductive success. Using 18 polymorphic microsatellite loci, we evaluated potential genetic differences among the morphs which may lead to subpopulation structuring and tested for correlations between three fitness-related traits and Heterozygosity, both genome wide and at each locus separately. Despite their assortative mating pattern, the buzzard morphs were found to be genetically undifferentiated. Multilocus Heterozygosity was only found to be correlated with a single fitness-related trait, infection with the blood parasite, Leucocytozoon buteonis, and this was via interactions with vole abundance and age. One locus also showed a significant relationship with blood parasite infection and ectoparasite infestation. The vicinity of this locus contains two genes, one of which is potentially implicated in the immune system of birds. We conclude that genome-wide Heterozygosity is unlikely to be a major determinant of parasite burden and body condition in the polymorphic common buzzard.
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preliminary association of microsatellite Heterozygosity with footrot in domestic sheep
Livestock Science, 2012Co-Authors: Edward M Smith, Joseph I Hoffman, Laura E Green, William AmosAbstract:Abstract Genetic Heterozygosity in wild, unmanaged animal populations is often associated with protection against infectious disease. However, little is known about the relationship between Heterozygosity and disease susceptibility in domesticated livestock, where disease resistance has the potential to improve animal welfare and productivity. We have investigated whether susceptibility to footrot, an important cause of poor welfare and reduced productivity in sheep, is associated with Heterozygosity at 14 candidate microsatellite loci. Heterozygosity at locus BMC5221 was associated with resistance to footrot ( P = 0.0034). This locus was selected based on a gene ontology classification of ‘response to Gram-negative bacteria’. Sheep homozygous at BMC5221 were at increased risk of virulent footrot (OR = 4.8, 95% CI = 1.5–15.3), with a dose response relationship between homozygosity and disease severity. A highly significant homozygote deficit was observed in sheep without virulent footrot (observed = 4, expected = 21, χ 2 = 13.76, P = 0.0002) but not in sheep that had clinical disease, suggesting homozygotes were disproportionately likely to contract virulent footrot. Our results indicate that genetic Heterozygosity might be important for healthy immune function in domesticated livestock. The use of gene ontology codes might prove a useful strategy to target selection of candidate markers in future studies.
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exploring the mechanisms underlying a Heterozygosity fitness correlation for canine size in the antarctic fur seal arctocephalus gazella
Journal of Heredity, 2010Co-Authors: Joseph I Hoffman, Jaume Forcada, William AmosAbstract:Although Heterozygosity-fitness correlations (HFCs) are widely reported in the literature, most studies use too few markers to allow the proximate mechanisms to be convincingly resolved. Two competing hypotheses have been proposed: the general effect hypothesis, in which marker Heterozygosity correlates with genome-wide Heterozygosity and hence the inbreeding coefficient f, and the local effect hypothesis, in which one or more of the markers by chance exhibit associative overdominance. To explore the relative contributions of general and local effects in a free-ranging marine mammal population, we revisited a strong HFC found using 9 microsatellite loci for canine tooth size in 84 male Antarctic fur seals Arctocephalus gazella (Hoffman JI, Hanson N, Forcada J, Trathan PN, Amos W. 2010. Getting long in the tooth: a strong positive correlation between canine size and Heterozygosity in the Antarctic fur seal Arctocephalus gazella. J Hered.). Increasing the number of markers to 76, we find that Heterozygosity is uncorrelated across loci, indicating that inbred individuals are rare or absent. Similarly, while the HFC based on overall Heterozygosity is lost, stochastic simulations indicate that when an HFC is due to inbreeding depression, increasing marker number invariably strengthens the HFC. Together these observations argue strongly that the original HFC was not due to inbreeding depression. In contrast, a subset of markers show individually significant effects, and these are nonrandomly distributed across the marker panel, being preferentially associated with markers cloned from other species. Using basic alignment search tool searches, we were able to locate 94% of loci to unique locations in the dog genome, but the local genes are functionally diverse, and the majority cannot be linked directly to growth. Our results suggest that inbreeding depression contributes little if at all to the relationship between Heterozygosity and tooth size but that instead the primary mechanism involves associative overdominance. These findings contribute to a growing body of evidence suggesting that general effects are likely to be uncommon in natural populations.
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does Heterozygosity estimate inbreeding in real populations
Molecular Ecology, 2004Co-Authors: Francois Balloux, William Amos, Tim CoulsonAbstract:Many recent studies report that individual Heterozygosity at a handful of apparently neutral microsatellite markers is correlated with key components of fitness, with most studies invoking inbreeding depression as the likely underlying mechanism. The implicit assumption is that an individual's inbreeding coefficient can be estimated reliably using only 10 or so markers, but the validity of this assumption is unclear. Consequently, we have used individual-based simulations to examine the conditions under which Heterozygosity and inbreeding are likely to be correlated. Our results indicate that the parameter space in which this occurs is surprisingly narrow, requiring that inbreeding events are both frequent and severe, for example, through selfing, strong population structure and/or high levels of polygyny. Even then, the correlations are strong only when large numbers of loci (~200) can be deployed to estimate Heterozygosity. With the handful of markers used in most studies, correlations only become likely under the most extreme scenario we looked at, namely 20 demes of 20 individuals coupled with strong polygyny. This finding is supported by the observation that Heterozygosity is only weakly correlated among markers within an individual, even in a dataset comprising 400 markers typed in diverse human populations, some of which favour consanguineous marriages. If Heterozygosity and inbreeding coefficient are generally uncorrelated, then Heterozygosity-fitness correlations probably have little to do with inbreeding depression. Instead, one would need to invoke chance linkage between the markers used and one or more gene(s) experiencing balancing selection. Unfortunately, both explanations sit somewhat uncomfortably with current understanding. If inbreeding is the dominant mechanism, then our simulations indicate that consanguineous mating would have to be vastly more common than is predicted for most realistic populations. Conversely, if heterosis provides the answer, there need to be many more polymorphisms with major fitness effects and higher levels of linkage disequilibrium than are generally assumed.
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male Heterozygosity predicts territory size song structure and reproductive success in a cooperatively breeding bird
Proceedings of The Royal Society B: Biological Sciences, 2004Co-Authors: Nathalie Seddon, William Amos, Raoul A Mulder, Joseph A TobiasAbstract:Recent studies of non-social animals have shown that sexually selected traits signal at least one measure of genetic quality: Heterozygosity. To determine whether similar cues reveal group quality in more complex social systems, we examined the relationship between territory size, song structure and Heterozygosity in the subdesert mesite (Monias benschi), a group-living bird endemic to Madagascar. Using nine polymorphic microsatellite loci, we found that Heterozygosity predicted both the size of territories and the structure of songs used to defend them: more heterozygous groups had larger territories, and more heterozygous males used longer, lower-pitched trills in their songs. Heterozygosity was linked to territory size and song structure in males, but not in females, implying that these traits are sexually selected by female choice and/or male-male competition. To our knowledge, this study provides the first direct evidence in any animal that territory size is related to genetic diversity. We also found a positive association between seasonal reproductive success and Heterozygosity, suggesting that this heritable characteristic is a reliable indicator of group quality and fitness. Given that Heterozygosity predicts song structure in males, and can therefore be determined by listening to acoustic cues, we identify a mechanism by which social animals may assess rival groups, prospective partners and group mates, information of potential importance in guiding decisions related to conflict, breeding and dispersal.
Joseph I Hoffman - One of the best experts on this subject based on the ideXlab platform.
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high throughput sequencing reveals inbreeding depression in a natural population
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Joseph I Hoffman, Fraser Simpson, Patrice David, Jolianne M Rijks, Thijs Kuiken, Michael A S Thorne, Robert C Lacy, Kanchon K DasmahapatraAbstract:Proxy measures of genome-wide Heterozygosity based on approximately 10 microsatellites have been used to uncover Heterozygosity fitness correlations (HFCs) for a wealth of important fitness traits in natural populations. However, effect sizes are typically very small and the underlying mechanisms remain contentious, as a handful of markers usually provides little power to detect inbreeding. We therefore used restriction site associated DNA (RAD) sequencing to accurately estimate genome-wide Heterozygosity, an approach transferrable to any organism. As a proof of concept, we first RAD sequenced oldfield mice (Peromyscus polionotus) from a known pedigree, finding strong concordance between the inbreeding coefficient and Heterozygosity measured at 13,198 single-nucleotide polymorphisms (SNPs). When applied to a natural population of harbor seals (Phoca vitulina), a weak HFC for parasite infection based on 27 microsatellites strengthened considerably with 14,585 SNPs, the deviance explained by Heterozygosity increasing almost fivefold to a remarkable 49%. These findings arguably provide the strongest evidence to date of an HFC being due to inbreeding depression in a natural population lacking a pedigree. They also suggest that under some circumstances Heterozygosity may explain far more variation in fitness than previously envisaged.
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no correlation between multi locus Heterozygosity and fitness in the common buzzard despite heterozygote advantage for plumage colour
Journal of Evolutionary Biology, 2013Co-Authors: Martina Boerner, William Amos, Joseph I Hoffman, Nayden Chakarov, Oliver KrugerAbstract:Correlations between Heterozygosity and fitness are frequently found but rarely well understood. Fitness can be affected by single loci of large effect which correlate with neutral markers via linkage disequilibrium, or as a result of variation in genome-wide Heterozygosity following inbreeding. We explored these alternatives in the common buzzard, a raptor species in which three colour morphs differ in their lifetime reproductive success. Using 18 polymorphic microsatellite loci, we evaluated potential genetic differences among the morphs which may lead to subpopulation structuring and tested for correlations between three fitness-related traits and Heterozygosity, both genome wide and at each locus separately. Despite their assortative mating pattern, the buzzard morphs were found to be genetically undifferentiated. Multilocus Heterozygosity was only found to be correlated with a single fitness-related trait, infection with the blood parasite, Leucocytozoon buteonis, and this was via interactions with vole abundance and age. One locus also showed a significant relationship with blood parasite infection and ectoparasite infestation. The vicinity of this locus contains two genes, one of which is potentially implicated in the immune system of birds. We conclude that genome-wide Heterozygosity is unlikely to be a major determinant of parasite burden and body condition in the polymorphic common buzzard.
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preliminary association of microsatellite Heterozygosity with footrot in domestic sheep
Livestock Science, 2012Co-Authors: Edward M Smith, Joseph I Hoffman, Laura E Green, William AmosAbstract:Abstract Genetic Heterozygosity in wild, unmanaged animal populations is often associated with protection against infectious disease. However, little is known about the relationship between Heterozygosity and disease susceptibility in domesticated livestock, where disease resistance has the potential to improve animal welfare and productivity. We have investigated whether susceptibility to footrot, an important cause of poor welfare and reduced productivity in sheep, is associated with Heterozygosity at 14 candidate microsatellite loci. Heterozygosity at locus BMC5221 was associated with resistance to footrot ( P = 0.0034). This locus was selected based on a gene ontology classification of ‘response to Gram-negative bacteria’. Sheep homozygous at BMC5221 were at increased risk of virulent footrot (OR = 4.8, 95% CI = 1.5–15.3), with a dose response relationship between homozygosity and disease severity. A highly significant homozygote deficit was observed in sheep without virulent footrot (observed = 4, expected = 21, χ 2 = 13.76, P = 0.0002) but not in sheep that had clinical disease, suggesting homozygotes were disproportionately likely to contract virulent footrot. Our results indicate that genetic Heterozygosity might be important for healthy immune function in domesticated livestock. The use of gene ontology codes might prove a useful strategy to target selection of candidate markers in future studies.
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exploring the mechanisms underlying a Heterozygosity fitness correlation for canine size in the antarctic fur seal arctocephalus gazella
Journal of Heredity, 2010Co-Authors: Joseph I Hoffman, Jaume Forcada, William AmosAbstract:Although Heterozygosity-fitness correlations (HFCs) are widely reported in the literature, most studies use too few markers to allow the proximate mechanisms to be convincingly resolved. Two competing hypotheses have been proposed: the general effect hypothesis, in which marker Heterozygosity correlates with genome-wide Heterozygosity and hence the inbreeding coefficient f, and the local effect hypothesis, in which one or more of the markers by chance exhibit associative overdominance. To explore the relative contributions of general and local effects in a free-ranging marine mammal population, we revisited a strong HFC found using 9 microsatellite loci for canine tooth size in 84 male Antarctic fur seals Arctocephalus gazella (Hoffman JI, Hanson N, Forcada J, Trathan PN, Amos W. 2010. Getting long in the tooth: a strong positive correlation between canine size and Heterozygosity in the Antarctic fur seal Arctocephalus gazella. J Hered.). Increasing the number of markers to 76, we find that Heterozygosity is uncorrelated across loci, indicating that inbred individuals are rare or absent. Similarly, while the HFC based on overall Heterozygosity is lost, stochastic simulations indicate that when an HFC is due to inbreeding depression, increasing marker number invariably strengthens the HFC. Together these observations argue strongly that the original HFC was not due to inbreeding depression. In contrast, a subset of markers show individually significant effects, and these are nonrandomly distributed across the marker panel, being preferentially associated with markers cloned from other species. Using basic alignment search tool searches, we were able to locate 94% of loci to unique locations in the dog genome, but the local genes are functionally diverse, and the majority cannot be linked directly to growth. Our results suggest that inbreeding depression contributes little if at all to the relationship between Heterozygosity and tooth size but that instead the primary mechanism involves associative overdominance. These findings contribute to a growing body of evidence suggesting that general effects are likely to be uncommon in natural populations.
