Primula sieboldii E. Morren is a perennial clonal herb that is widely distributed in Japan, but in danger of extinction in the wild. In a previous study, we revealed the genetic diversity of the species using chloroplast and nuclear DNA and used this information to define conservation units. However, we lacked information on adaptive genetic diversity, which is important for long-term survival and, thus, for the definition of conservation units. In order to identify adaptive traits that showed adaptive differentiation among populations, we studied the genetic variation in six quantitative traits within and among populations for 3 years in a common garden using 110 genets from five natural populations from three regions of Japan. The number of days to bud initiation was adaptive quantitative trait for which the degree of genetic differentiation among populations (QST) was considerably larger than that in eight microsatellite markers (FST). The relationship between this trait and environmental factors revealed that the number of days to bud initiation was negatively correlated, with the mean temperature during the growing period at each habitat. This suggests that adaptive differentiation in the delay before bud initiation was caused by selective pressure resulting from temperature differences among habitats. Our results suggest that based on adaptive diversity and neutral genetic diversity, the Saitama population represents a new conservation unit.

A number of farmed species are characterized by breeding populations of large full-sib families, including aquaculture species and outcrossing plant species. Whole genome association studies in such species must account for stratification arising from the full-sib family structure to avoid high rates of false discovery. Here, we demonstrate the value of selective genotyping strategies which balance the contribution of families across high and low phenotypes to greatly reduce rates of false discovery with a minimal effect on power.

A triosephosphate isomerase (TPI) mutant, Tpi1a-m6Neu, with approximately 57% residual enzyme activity in blood compared with wild-type was detected among offspring of triethylenemelamine-treated male mice. Homozygous mutants with about 13% residual enzyme activity were recovered in progeny of inter se matings of heterozygotes. The loss of TPI activity was evident both in blood and in other tissue extracts. Values for haematocrit, haemoglobin, number of red blood cells (RBC), mean corpuscular volume of RBC, mean corpuscular haemoglobin concentration and spleen weight show significant differences between wild-type animals and homozygous mutants. Sequence analysis revealed a substitution (c.A149G) in the Tpi1 gene. This mutation results in an Asp to Gly substitution at codon 49 in exon 2 at a highly conserved position located in the functional domain of the TPI protein which is responsible for the correct dimerization of the subunits. As a potential animal model, Tpi1a-m6Neu represents the only available TPI-deficient homozygous viable mouse mutation.

In mapping of quantitative trait loci (QTLs), performing hypothesis tests of linkage to a phenotype of interest across an entire genome involves multiple comparisons. Furthermore, linkage among loci induces correlation among tests. Under many multiple comparison frameworks, these problems are exacerbated when mapping multiple QTLs. Traditionally, significance thresholds have been subjectively set to control the probability of detecting at least one false positive outcome, although such thresholds are known to result in excessively low power to detect true positive outcomes. Recently, false discovery rate (FDR)-controlling procedures have been developed that yield more power both by relaxing the stringency of the significance threshold and by retaining more power for a given significance threshold. However, these procedures have been shown to perform poorly for mapping QTLs, principally because they ignore recombination fractions between markers. Here, I describe a procedure that accounts for recombination fractions and extends FDR control to include simultaneous control of the false non-discovery rate, i.e. the overall error rate is controlled. This procedure is developed in the Bayesian framework using a direct posterior probability approach. Data-driven significance thresholds are determined by minimizing the expected loss. The procedure is equivalent to jointly maximizing positive and negative predictive values. In the context of mapping QTLs for experimental crosses, the procedure is applicable to mapping main effects, gene–gene interactions and gene–environment interactions.

Genomic selection describes a selection strategy based on genomic breeding values predicted from dense single nucleotide polymorphism (SNP) data. Multiple methods have been proposed but the critical issue is how to decide whether an SNP should be included in the predictive set to estimate breeding values. One major disadvantage of the traditional Bayes B approach is its high computational demands caused by the changing dimensionality of the models. The use of stochastic search variable selection (SSVS) retains the same assumptions about the distribution of SNP effects as Bayes B, while maintaining constant dimensionality. When Bayesian SSVS was used to predict genomic breeding values for real dairy data over a range of traits it produced accuracies higher or equivalent to other genomic selection methods with significantly decreased computational and time demands than Bayes B.

In genetic and biological studies, the F2 population is one of the most popular and commonly used experimental populations mainly because it can be readily produced and its genome structure possesses several niceties that allow for productive investigation. These niceties include the equivalence between the proportion of recombinants and recombination rates, the capability of providing a complete set of three genotypes for every locus and an analytically attractive first-order Markovian property. Recently, there has been growing interest in using the progeny populations from F2 (advanced populations) because their genomes can be managed to meet specific purposes or can be used to enhance investigative studies. These advanced populations include recombinant inbred populations, advanced intercrossed populations, intermated recombinant inbred populations and immortalized F2 populations. Due to an increased number of meiosis cycles, the genomes of these advanced populations no longer possess the Markovian property and are relatively more complicated and different from the F2 genomes. Although issues related to quantitative trait locus (QTL) mapping using advanced populations have been well documented, still these advanced populations are often investigated in a manner similar to the way F2 populations are studied using a first-order Markovian assumption. Therefore, more efforts are needed to address the complexities of these advanced populations in more details. In this article, we attempt to tackle these issues by first modifying current methods developed under this Markovian assumption to propose an ad hoc method (the Markovian method) and explore its possible problems. We then consider the specific genome structures present in the advanced populations without invoking this assumption to propose a more adequate method (the non-Markovian method) for QTL mapping. Further, some QTL mapping properties related to the confounding problems that result from ignoring epistasis and to mapping closely linked QTL are derived and investigated across the different populations. Simulations show that the non-Markovian method outperforms the Markovian method, especially in the advanced populations subject to selfing. The results presented here may give some clues to the use of advanced populations for more powerful and precise QTL mapping.

Increasing resistance to acute salmonellosis (defined as bacteraemia in animals showing symptoms) is not sufficient for food safety, because of the risk of carrier state (when animals excrete bacteria without showing any symptoms). Increased resistance to Salmonella carrier state is therefore needed. Two experiments of divergent selection on resistance at a younger and a later age lead to significant differences between lines and allowed estimating genetic parameters on 4262 animals. Heritability of resistance was estimated at 0·16 in chicks, while it varied from 0·14 to 0·23 with analysed organ in adult hens. Genetic correlations between contamination of the different organs ranged from 0·46 to 0·67, while correlations between resistance at both ages were estimated at −0·50, showing that increasing genetic resistance of hens will reduce resistance in chicks. Highest estimated absolute values of genetic correlations between resistance and production traits were, for chicken contamination level, with number of eggs laid between 41 and 60 (0·37) and, for adult contamination, with number of eggs laid between 18 and 24 (0·37) or 25 and 40 (−0·33) weeks of age.

The prevalence of female multiple mating in natural populations is important for many questions in mating system evolution. Several statistical techniques use genetic data to estimate the number of fathers that contribute gametes to broods, but they have not been widely compared to assess the magnitude of differences in their performance. With a combination of new data and reanalysis of previously published data, we compared five analytical approaches: (1) allele-counting, (2) parental reconstruction in GERUD, (3) a Bayesian probability model to estimate the frequency of multiple mating (FMM), (4) computer simulations based on population allele frequencies in HAPLOTYPES and (5) Bayesian parental reconstruction in PARENTAGE. The results show that choice of analysis technique can significantly affect estimates of sire number. Estimates from GERUD conformed exactly to results obtained from strict exclusion of potential sires in an experimental context. However, estimates yielded by HAPLOTYPES and PARENTAGE sometimes exceeded the numbers from GERUD by as much as 120 and 55%, respectively. We recommend GERUD over these other approaches for most purposes because of its accuracy and consistency in this analysis. Our novel genetic data set allowed us to investigate the extent and frequency of multiple paternity in a marbled salamander (Ambystoma opacum) population in South Carolina, USA. A. opacum contrasted with other salamander species by having relatively low levels of multiple paternity (only 31–54% compared with 71–96%). Although A. opacum had the lowest level of multiple paternity under all analytical approaches used here, the magnitude of differences among species varied.

Male Drosophila melanogaster transfers many accessory-gland proteins to females during copulation. Sex peptide (SP) is one of these and one of its main effects is to decrease female remating propensity. To date, there has been no investigation of genetic variation in SP-gene expression levels, or if such potential variation directly influences female remating behaviour. We assessed both these possibilities and found significant variation in expression levels of the SP gene across D. melanogaster isolines. A non-linear association between SP expression levels and female remating delay suggestive of disruptive selection on expression levels was also documented. Finally, while some isolines were infected with the endosymbiont Wolbachia, no association between Wolbachia and SP expression level was found.

This paper calls attention to an overlooked logical difficulty that has impeded the directed mutation debate for over half a century. It further suggests that the random mutation hypothesis be regarded at present as a null hypothesis in evolutionary biology.

Gap junction protein connexin43 (Cx43), encoded by the GJA1 gene, is the most abundant connexin in the cardiovascular system and was reported as a crucial factor maintaining cardiac electrical conduction, as well as having a very important function in facilitating the recycling of potassium ions from hair cells in the cochlea back into the cochlear endolymph during auditory transduction processes. In mammals, bats are the only taxon possessing powered flight, placing exceptional demand on many organismal processes. To meet the demands of flying, the hearts of bats show many specialties. Moreover, ultrasonic echolocation allows bat species to orientate and often detect and locate food in darkness. In this study, we cloned the full-length coding region of GJA1 gene from 12 different species of bats and obtained orthologous sequences from other mammals. We used the maximum likelihood method to analyse the evolution of GJA1 gene in mammals and the lineage of bats. Our results showed this gene is much conserved in mammals, as well as in bats' lineage. Compared with other mammals, we found one private amino acid substitution shared by bats, which is located on the inner loop domain, as well as some species-specific amino acid substitutions. The evolution rate analyses showed the signature of purifying selection on not only different classification level lineages but also the different domains and amino acid residue sites of this gene. Also, we suggested that GJA1 gene could be used as a good molecular marker to do the phylogenetic reconstruction.

Epistasis is an important feature of the genetic architecture of quantitative traits. Previously, we showed that startle-induced locomotor behaviour of Drosophila melanogaster, a critical survival trait, is highly polygenic and exhibits epistasis. Here, we characterize epistatic interactions among homozygous P-element mutations affecting startle-induced locomotion in the Canton-S isogenic background and in 21 wild-derived inbred genetic backgrounds. We find pervasive epistasis for pairwise combinations of homozygous P-element insertional mutations as well as for mutations in wild-derived backgrounds. In all cases, the direction of the epistatic effects is to suppress the mutant phenotypes. The magnitude of the epistatic interactions in wild-derived backgrounds is highly correlated with the magnitude of the main effects of mutations, leading to phenotypic robustness of the startle response in the face of deleterious mutations. There is variation in the magnitude of epistasis among the wild-derived genetic backgrounds, indicating evolutionary potential for enhancing or suppressing effects of single mutations. These results provide a partial glimpse of the complex genetic network underlying the genetic architecture of startle behaviour and provide empirical support for the hypothesis that suppressing epistasis is the mechanism underlying genetic canalization of traits under strong stabilizing selection. Widespread suppressing epistasis will lead to underestimates of the main effects of quantitative trait loci (QTLs) in mapping experiments when not explicitly accounted for. In addition, suppressing epistasis could lead to underestimates of mutational variation for quantitative traits and overestimates of the strength of stabilizing selection, which has implications for maintenance of variation of complex traits by mutation–selection balance.

Alterations in the activity level or temporal expression of key signalling genes elicit profound patterning effects during development. Consequently, gain-of-function genetic schemes that overexpress or misexpress such loci can identify novel candidates for functions essential for a developmental process. GAL4-Upstream Activating Sequence (UAS)-targeted regulation of gene expression in Drosophila has allowed rapid analyses of coding sequences for potential roles in specific tissues at particular developmental stages. GAL4 has also been combined with randomly mobilized transposons capable of UAS-directed misexpression or overexpression of flanking sequences. This combination has produced a genetic screening system that can uncover novel loci refractory to standard loss of function genetic approaches, such as redundant genes. Available libraries of strains with sequenced insertion sites can allow direct correlation of phenotypes to genetic function. These techniques have also been applied to genetic interaction screening, where a GAL4 driver and UAS-regulated insertion collection are combined with an extant mutant genotype. In this article, we summarize studies that have utilized GAL4-UAS overexpression or misexpression of random loci to screen for candidates involved in specific developmental processes.

A linkage–linkage disequilibrium map that describes the pattern and extent of linkage dis-equilibrium (LD) decay with genomic distance has now emerged as a viable tool to unravel the genetic structure of population differentiation and fine-map genes for complex traits. The prerequisite for constructing such a map is the simultaneous estimation of the linkage and LD between different loci. Here, we develop a computational algorithm for simultaneously estimating the recombination fraction and LD in a natural outcrossing population with multilocus marker data, which are often estimated separately in most molecular genetic studies. The algorithm is founded on a commonly used progeny test with open-pollinated offspring sampled from a natural population. The information about LD is reflected in the co-segregation of alleles at different loci among parents in the population. Open mating of parents will reveal the genetic linkage of alleles during meiosis. The algorithm was constructed within the polynomial-based mixture framework and implemented with the Expectation–Maximization (EM) algorithm. The by-product of the derivation of this algorithm is the estimation of outcrossing rate, a parameter useful to explore the genetic diversity of the population. We performed computer simulation to investigate the influences of different sampling strategies and different values of parameters on parameter estimation. By providing a number of testable hypotheses about population genetic parameters, this algorithmic model will open a broad gateway to understand the genetic structure and dynamics of an outcrossing population under natural selection.

The X-linked telomeric P elements TP5 and TP6 interact synergistically with non-telomeric P elements to repress hybrid dysgenesis. In this repression, the telomeric P elements exert maternal effects, which, however, are not sufficient to establish synergism with the non-telomeric P elements. Once synergism is established, the capacity to repress dysgenesis in the offspring of a cross persists for at least two generations after removing the telomeric P element from the genotype. At the molecular level, synergism between telomeric and non-telomeric P elements is correlated with effective elimination of P-element mRNA in the germ line. Maternally transmitted mutations in the genes aubergine, piwi and Suppressor of variegation 205 [Su(var)205] block the establishment of synergism between telomeric and non-telomeric P elements, and paternally transmitted mutations in piwi and Su(var)205 disrupt synergism that has already been established. These findings are discussed in terms of a model of cytotype regulation of P elements based on Piwi-interacting RNAs (piRNAs) that are amplified by cycling between sense and antisense species.

Fine scale analyses of signatures of selection allow assessing quantitative aspects of a species' evolutionary genetic history, such as the strength of selection on genes. When several selected loci lie in the same genomic region, their epistatic interactions may also be investigated. Here, we study how the neutral polymorphism pattern was shaped by two close recombining loci that cause ‘sex-ratio’ meiotic drive in Drosophila simulans, as an example of strong selection with potentially strong epistasis. We compare the polymorphism data observed in a natural population with the results of forward stochastic simulations under several contexts of epistasis between the candidate loci for the drive. We compute the likelihood of different possible scenarios, in order to determine which configuration is most consistent with the data. Our results highlight that fine scale analyses of well-chosen candidate genomic regions provide information-rich data that can be used to investigate the genotype–phenotype–fitness map, which can hardly be studied in genome-wide analyses. We also emphasize that initial conditions and time of observation (here, time after the interruption of a partial selective sweep) are crucial parameters in the interpretation of real data, while these are often overlooked in theoretical studies.

Strains carrying the X-linked telomeric P elements TP5 or TP6 varied in their ability to repress hybrid dysgenesis. The rank ordering of these strains was consistent across different genetic assays and was not related to the type of telomeric P element (TP5 or TP6) present. Strong repression of dysgenesis was associated with weak expression of mRNA from the telomeric P element and also with a reduced amount of mRNA from a transposase-producing P element contained within a transgene inserted on an autosome. A strictly maternal component of repression, transmitted independently of the telomeric P element, was detected in the daughters but not the sons of females from the strongest repressing strains. However, this effect was seen only when dysgenesis was induced by crossing these females to males from a P strain, not when it was induced by crossing them to males homozygous for a single transposase-producing P element contained within a transgene. These findings are consistent with the hypothesis that the P cytotype, the condition that regulates P elements, involves an RNA interference mechanism mediated by piRNAs produced by telomeric P elements such as TP5 and TP6 and amplified by RNAs produced by other P elements.

An innovative approach to tree breeding called ‘breeding without breeding’ (BWB) is presented. The method, as applied on the material in hand, allows the capture of 75–85% of the genetic response to selection attained through conventional programmes without the need to do any controlled pollination and simplified or possibly no experimental field testing: both considered to be the most resource-demanding activities in breeding programmes. BWB combines the use of genotypic or phenotypic pre-selection of superior individuals, informative DNA markers for fingerprinting and pedigree reconstruction of offspring to assemble naturally created full- and half-sib families resulting from mating among selected parents, and quantitative genetics analyses to identify elite genotypes for further genetic improvement or the establishment of production populations. BWB utility is demonstrated using a retrospective study of Douglas-fir (Pseudotsuga menziesii) progeny tests consisting of offspring produced from 150 controlled crosses among 60 parents and established over three sites. The empirical results are supported by theoretical expectations demonstrating anticipated minimum genetic response compared with conventional approaches. The method's simplicity offers an exceptional opportunity for the development of comparable breeding efforts in developing countries, advanced and new breeding programmes, and economically important and ‘minor’ species.

Effective population size (Ne) is an important parameter in the conservation of genetic diversity. Comparative studies of empirical data that gauge the relative accuracy of Ne methods are limited, and a better understanding of the limitations and potential of Ne estimators is needed. This paper investigates genetic diversity and Ne in four populations of wild anadromous Atlantic salmon (Salmo salar L.) in Europe, from the Rivers Oir and Scorff (France) and Spey and Shin (Scotland). We aimed to understand present diversity and historical processes influencing current population structure. Our results showed high genetic diversity for all populations studied, despite their wide range of current effective sizes. To improve understanding of high genetic diversity observed in the populations with low effective size, we developed a model predicting present diversity as a function of past demographic history. This suggested that high genetic diversity could be explained by a bottleneck occurring within recent centuries rather than by gene flow. Previous studies have demonstrated the efficiency of coalescence models to estimate Ne. Using nine subsets from 37 microsatellite DNA markers from the four salmon populations, we compared three coalescence estimators based on single and dual samples. Comparing Ne estimates confirmed the efficiency of increasing the number and variability of microsatellite markers. This efficiency was more accentuated for the smaller populations. Analysis with low numbers of neutral markers revealed uneven distributions of allelic frequencies and overestimated short-term Ne. In addition, we found evidence of artificial stock enhancement using native and non-native origin. We propose estimates of Ne for the four populations, and their applications for salmon conservation and management are discussed.

By analysing N2 mice from a cross between the inbred C57BL strain B10.Q and the NMRI-related NFR/N strain, we recently identified a quantitative trait locus (QTL) influencing litter size. This locus is now denoted Fecq4, and it is present on the murine chromosome 9. In the present paper, we describe how the Fecq4 fragment originating form the NFR/N mouse strain will affect B10.Q mice by means of breeding capacity, super-ovulation rate and embryonic development in vitro. Our results show that both the breeding capacity (number of pups produced/breeding cage during a 5 months period) and the mean litter size are significantly increased in B10.Q.NFR/N-Fecq4 congenic mice. Furthermore. B10.Q.NFR/N-Fecq4 congenic mice (both homozygous and heterozygous) did respond much better to super-ovulation than wild-type mice, resulting in a dramatically increased yield of fertilized 1-cell embryos. In addition, embryos containing the Fecq4 fragment were easy to cultivate in vitro, resulting in a higher yield of embryos reaching the blastocyst stage. We propose that B10.Q.NFR/N-Fecq4 congenic mice may be used to improve breeding or super-ovulation rate in different types of genetically modified mice (on C57BL background) that exhibit severe breeding problems. The Fecq4 fragment has been described in detail, and the possible role of polymorphic candidate genes near the linkage peak (58 Mb) has been discussed. Genes of the cytochrome P450 family (1, 11 and 19), such as Cyp19a1, are assumed to be particularly interesting, since they are known to exhibit female-associated reproductive phenotypes, affecting the ovulation rate, if mutated.