| 1. |
- Anderson, Jennifer L, et al.
(författare)
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Outcrossing and the maintenance of males within C. elegans populations.
- 2010
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 101 Suppl 1
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Tidskriftsartikel (refereegranskat)abstract
- Caenorhabditis elegans is an androdioecious nematode with both hermaphrodites and males. Although males can potentially play an important role in avoiding inbreeding and facilitating adaptation, their existence is evolutionarily problematic because they do not directly generate offspring in the way that hermaphrodites do. This review explores how genetic, population genomic, and experimental evolution approaches are being used to address the role of males and outcrossing within C. elegans. Although theory suggests that inbreeding depression and male mating ability should be the primary determinants of male frequency, this has yet to be convincingly confirmed experimentally. Genomic analysis of natural populations finds that outcrossing occurs at low, but not negligible levels, and that observed patterns of linkage disequilibrium consistent with strong selfing may instead be generated by natural selection against outcrossed progeny. Recent experimental evolution studies suggest that males can be maintained at fairly high levels if populations are initiated with sufficient genetic variation and/or subjected to strong natural selection via a change in the environment. For example, as reported here, populations adapting to novel laboratory rearing and temperature regimes maintain males at frequencies from 5% to 40%. Laboratory and field results still await full reconciliation, which may be facilitated by identifying the loci underlying among-strain differences in mating system dynamics.
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| 2. |
- Andersson, Stefan, et al.
(författare)
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Quantitative genetic effects of bottlenecks : experimental evidence from a wild plant species, Nigella degenii
- 2010
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 101:3, s. 298-307
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the genetic consequences of changes in population size is fundamental in a variety of contexts, such as adaptation and conservation biology. In the study presented here, we have performed a replicated experiment with the plant Nigella degenii to explore the quantitative genetic effects of a single-founder bottleneck. In agreement with adetive theory, the bottleneck reduced the mean (co)variance within lines and caused stochastic, line-specific changes in the genetic (co)variance structure. However, a significant portion of the (co)variance structure was conserved, and 2 characters—leaf and flower (sepal) size—turned out to be positively correlated in all data sets, indicating a potential for correlated evolution in these characters, even after a severe bottleneck. The hierarchical partitioning of genetic variance for flower size was in good agreement with predictions from additive theory, whereas the remaining characters showed an excess of within-line variance and a deficiency of among-line variance. The latter discrepancies were most likely a result of selection, given the small proportion of lines (23%) that remained viable until the end of the experiment. Our results suggest that bottlenecked populations of N. degenii generally have a lower adaptive potential than the ancentral population but also highlight the idiosyncratic nature of bottleneck effects.
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| 3. |
- Andersson, Stefan, et al.
(författare)
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The genetic basis of naturally occurring pollen color dimorphisms in Nigella degenii (Ranunculaceae)
- 2005
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 96:5, s. 550-556
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Tidskriftsartikel (refereegranskat)abstract
- Nigella degenii ssp. barbro and ssp. jenny differ from related taxa in being dimorphic for pollen color, with some plants having dark pollen and others light pollen. In this study we performed experimental crosses to determine whether the difference in pollen color is governed by few or many loci and whether the two subspecies utilize the same gene to control pollen color. Patterns of segregation in crosses between morphs show that dark pollen is dominant over light pollen and that a single major gene is responsible for most of the variation in pollen color. Consequently it should be relatively easy for pollen color dimorphisms to establish and spread in these subspecies. Aberrant segregation ratios were attributed to genetic factors that reduced the expression of the allele conferring dark pollen or processes that sorted between color morphs during seed development. Crosses between dark pollen plants from different subspecies showed signs of complementation in the F-2 generation, but the frequency of the light morph was too low to support a model involving complementary action of recessive alleles at two separate loci. Based on this and other observations, we hypothesize that the pollen color difference is controlled by the same major locus in the two subspecies.
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| 4. |
- Banabazi, Mohammad Hossein
(författare)
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Weighted Single-Step GWAS for Body Mass Index and Scans for Recent Signatures of Selection in Yorkshire Pigs
- 2022
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 113, s. 325-335
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Tidskriftsartikel (refereegranskat)abstract
- Controlling extra fat deposition is economically favorable in modern swine industry. Understanding the genetic architecture of fat deposition traits such as body mass index (BMI) can help in improving genomic selection for such traits. We utilized a weighted single-step genome-wide association study (WssGWAS) to detect genetic regions and candidate genes associated with BMI in a Yorkshire pig population. Three extended haplotype homozygosity (EHH)-related statistics were also incorporated within a de-correlated composite of multiple signals (DCMS) framework to detect recent selection signatures signals. Overall, the full pedigree consisted of 7016 pigs, of which 5561 had BMI records and 598 pigs were genotyped with an 80 K single nucleotide polymorphism (SNP) array. Results showed that the most significant windows (top 15) explained 9.35% of BMI genetic variance. Several genes were detected in regions previously associated with pig fat deposition traits and treated as potential candidate genes for BMI in Yorkshire pigs: FTMT, SRFBP1, KHDRBS3, FOXG1, SOD3, LRRC32, TSKU, ACER3, B3GNT6, CCDC201, ADCY1, RAMP3, TBRG4, CCM2. Signature of selection analysis revealed multiple candidate genes previously associated with various economic traits. However, BMI genetic variance explained by regions under selection pressure was minimal (1.31%). In conclusion, candidate genes associated with Yorkshire pigs' BMI trait were identified using WssGWAS. Gene enrichment analysis indicated that the identified candidate genes were enriched in the insulin secretion pathway. We anticipate that these results further advance our understanding of the genetic architecture of BMI in Yorkshire pigs and provide information for genomic selection for fat deposition in this breed.
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| 5. |
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| 6. |
- Bererhi, Badreddine, et al.
(författare)
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Limited effects of inbreeding on breeding coloration
- 2023
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 114:2, s. 143-151
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Tidskriftsartikel (refereegranskat)abstract
- Animal color signals may function as indicators of fighting ability when males compete for access to females. This allows opponents to settle aggressive interactions before they escalate into physical combat and injury. Thus, there may be strong directional selection on these traits, toward enhanced signal quality. This renders sexually selected traits particularly susceptible to inbreeding depression, due to relatively low ratios of additive genetic variance to dominance variance. We measured the effects of inbreeding on an intrasexually selected color signal (the badge) in a population of Swedish sand lizards (Lacerta agilis) using the Rhh software based on 17 to 21 microsatellites. Males of this sexually dichromatic species use the badge during aggressive interactions to display, and assess, fighting ability. We found negative effects of homozygosity on badge size, saturation, and brightness. However, no such effects were observed on color hue. Pairwise correlations between badge size, hue, and saturation were all statistically significant. Thus, the sand lizard "badge" is a multicomponent signal with variation explained by covariation in badge size, saturation, and color hue. Body mass corrected for skeletal size (body condition) positively predicted badge size and saturation, encouraging future research on the extent that sexual signals may convey information on multigene targets (i.e. "genic capture").
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| 7. |
- Carlborg, Örjan, et al.
(författare)
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Parallel computing in interval mapping of quantitative trait loci.
- 2002
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Ingår i: Journal of Heredity. - 0022-1503 .- 1465-7333. ; 92:5
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Tidskriftsartikel (refereegranskat)abstract
- Linear regression analysis is considered the least computationally demanding method for mapping quantitative trait loci (QTL). However, simultaneous search for multiple QTL, the use of permutations to obtain empirical significance thresholds, and larger experimental studies significantly increase the computational demand. This report describes an easily implemented parallel algorithm, which significantly reduces the computing time in both QTL mapping and permutation testing. In the example provided, the analysis time was decreased to less than 15% of a single processor system by the use of 18 processors. We indicate how the efficiency of the analysis could be improved by distributing the computations more evenly to the processors and how other ways of distributing the data facilitate the use of more processors. The use of parallel computing in QTL mapping makes it possible to routinely use permutations to obtain empirical significance thresholds for multiple traits and multiple QTL models. It could also be of use to improve the computational efficiency of the more computationally demanding QTL analysis methods.
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| 8. |
- Catania, Francesco, et al.
(författare)
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Endogenous Mechanisms for the Origins of Spliceosomal Introns
- 2009
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 100:5, s. 591-596
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Tidskriftsartikel (refereegranskat)abstract
- Over 30 years since their discovery, the origin of spliceosomal introns remains uncertain. One nearly universally accepted hypothesis maintains that spliceosomal introns originated from self-splicing group-II introns that invaded the uninterrupted genes of the last eukaryotic common ancestor (LECA) and proliferated by “insertion” events. Although this is a possible explanation for the original presence of introns and splicing machinery, the emphasis on a high number of insertion events in the genome of the LECA neglects a considerable body of empirical evidence showing that spliceosomal introns can simply arise from coding or, more generally, nonintronic sequences within genes. After presenting a concise overview of some of the most common hypotheses and mechanisms for intron origin, we propose two further hypotheses that are broadly based on central cellular processes: 1) internal gene duplication and 2) the response to aberrant and fortuitously spliced transcripts. These two nonmutually exclusive hypotheses provide a powerful way to explain the establishment of spliceosomal introns in eukaryotes without invoking an exogenous source.
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| 9. |
- Chen, Zhiqiang, et al.
(författare)
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Increased Prediction Ability in Norway Spruce Trials Using a Marker X Environment Interaction and Non-Additive Genomic Selection Model
- 2019
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 110, s. 830-843
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Tidskriftsartikel (refereegranskat)abstract
- A genomic selection study of growth and wood quality traits is reported based on control-pollinated Norway spruce families established in 2 Northern Swedish trials at 2 locations using exome capture as a genotyping platform. Nonadditive effects including dominance and first-order epistatic interactions (including additive-by-additive, dominance-by-dominance, and additive-by-dominance) and marker-by-environment interaction (MxE) effects were dissected in genomic and phenotypic selection models. Genomic selection models partitioned additive and nonadditive genetic variances more precisely than pedigree-based models. In addition, predictive ability in GS was substantially increased by including dominance and slightly increased by including MxE effects when these effects are significant. For velocity, response to genomic selection per year increased up to 78.9/80.8%, 86.9/82.9%, and 91.3/88.2% compared with response to phenotypic selection per year when genomic selection was based on 1) main marker effects (M), 2) M + MxE effects (A), and 3) A + dominance effects (AD) for sites 1 and 2, respectively. This indicates that including MxE and dominance effects not only improves genetic parameter estimates but also when they are significant may improve the genetic gain. For tree height, Pilodyn, and modulus of elasticity (MOE), response to genomic selection per year improved up to 68.9%, 91.3%, and 92.6% compared with response to phenotypic selection per year, respectively.
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| 10. |
- Collins, Lesley J., et al.
(författare)
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The Modern RNP World of Eukaryotes
- 2009
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 100:5, s. 597-604
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Forskningsöversikt (refereegranskat)abstract
- Eukaryote gene expression is mediated by a cascade of RNA functions that regulate, process, store, transport, and translate RNA transcripts. The RNA network that promotes this cascade depends on a large cohort of proteins that partner RNAs; thus, the modern RNA world of eukaryotes is really a ribonucleoprotein (RNP) world. Features of this "RNP infrastructure" can be related to the high cytosolic density of macromolecules and the large size of eukaryote cells. Because of the densely packed cytosol or nucleoplasm (with its severe restriction on diffusion of macromolecules), partitioning of the eukaryote cell into functionally specialized compartments is essential for efficiency. This necessitates the association of RNA and protein into large RNP complexes including ribosomes and spliceosomes. This is well illustrated by the ubiquitous spliceosome for which most components are conserved throughout eukaryotes and which interacts with other RNP-based machineries. The complexes involved in gene processing in modern eukaryotes have broad phylogenetic distributions suggesting that the common ancestor of extant eukaryotes had a fully evolved RNP network. Thus, the eukaryote genome may be uniquely informative about the transition from an earlier RNA genome world to the modern DNA genome world.
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| 11. |
- Fegraeus, K. Jaderkvist, et al.
(författare)
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Different DMRT3 Genotypes Are Best Adapted for Harness Racing and Riding in Finnhorses
- 2015
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 106:6, s. 734-740
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies showed a positive effect of the DMRT3 "gait keeper" mutation on harness racing performance in Standardbreds, French-, and Nordic trotters. The mutation has also been shown to influence riding traits in multiple breeds. This study investigated the effect of the DMRT3 mutation on harness racing performance and riding traits in Finnhorses. Finnhorses used for harness racing (n = 180) and for riding (n = 59) were genotyped for the DMRT3 mutation. For the trotters the genotypes were evaluated for association with racing performance (number of starts, victories, placings, earnings, and race times). At 3-6 years of age the AA genotype was superior compared with the CA and CC genotypes. The AA horses had a significantly higher proportion of victories (P = 1.4 x 10(-6)) and placings (P = 4.1 x 10(-7)), better race times (P = 0.01), and earned more money (P = 0.009) compared with C-horses. For the Finnhorses used for riding the owners answered a questionnaire to score how well the horse performed the gaits walk, trot, and canter on a scale from 1 to 6. These scores were tested for association with the DMRT3 genotypes. Although AA horses were more successful as racehorses, the CC and CA horses appear more adapted for classical riding disciplines. The AA horses received significantly lower gait scores compared with C-horses for the majority of gaits. Except for rhythm in extended canter (P = 0.05), there were no significant differences between CA and CC horses. This study shows that there are different optimal genotypes for different disciplines and the DMRT3 mutation clearly influences gaits and performance in Finnhorses.
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| 12. |
- Francois, Liesbeth, et al.
(författare)
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Conformation Traits and Gaits in the Icelandic Horse are Associated with Genetic Variants in Myostatin (MSTN)
- 2016
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 107:5, s. 431-437
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Tidskriftsartikel (refereegranskat)abstract
- Many genes are known to have an influence on conformation and performance traits; however, the role of one gene, Myostatin (MSTN), has been highlighted in recent studies on horses. Myostatin acts as a repressor in the development and regulation of differentiation and proliferative growth of skeletal muscle. Several studies have examined the link between MSTN, conformation, and performance in racing breeds, but no studies have investigated the relationship in Icelandic horses. Icelandic horses, a highly unique breed, are known both for their robust and compact conformation as well as their additional gaits tolt and pace. Three SNPs (g.65868604G>T [PR8604], g.66493737C>T [PR3737], and g.66495826A>G [PR5826]) flanking or within equine MSTN were genotyped in 195 Icelandic horses. The SNPs and haplotypes were analyzed for association with official estimated breeding values (EBV) for conformation traits (n = 11) and gaits (n = 5). The EBV for neck, withers, and shoulders was significantly associated with both PR8604 and PR3737 (P < 0.05). PR8604 was also associated with EBV for total conformation (P = 0.05). These associations were all supported by the haplotype analysis. However, while SNP PR5826 showed a significant association with EBVs for leg stance and hooves (P < 0.05), haplotype analyses for these traits failed to fully support these associations. This study demonstrates the possible role of MSTN on both the form and function of horses from non-racing breeds. Further analysis of Icelandic horses as well as other non-racing breeds would be beneficial and likely help to completely understand the influence of MSTN on conformation and performance in horses.
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| 13. |
- Gonzalez, Elena G., et al.
(författare)
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Phylogeography and Population Genetic Analyses in the Iberian Toothcarp (Aphanius iberus Valenciennes, 1846) at Different Time Scales
- 2018
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 109:3, s. 253-263
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Tidskriftsartikel (refereegranskat)abstract
- Secondary freshwater fish species inhabiting fluctuating and extreme environments are susceptible to changes in dispersion, effective population size, and genetic structure. The Iberian toothcarp Aphanius iberus is an endemic cyprinodontid of the Iberian Peninsula restricted to brackish water of salt marshes and coastal lagoons on the eastern Spanish Mediterranean coast. In this study, we analyzed mitochondrial cytochrome b (cyt b) DNA and microsatellite variation to evaluate ways in which the processes of extinction, dispersal, and colonization of A. iberus across its geographic distribution have affected its population genetic structure over time and space. The A. iberus network reconstruction indicated subtle levels of phylogeographic structuring.This, combined with substantial mitochondrial DNA (mtDNA) genetic diversity, suggests that Pleistocene glaciations had a lesser effect on the demographic structure of its populations than was the case for Iberian freshwater species with a similar distribution. Haplotype network, hierarchical analysis of molecular variance, and pairwise ΦST comparisons involving some Levantine samples showed a relatively high degree of mtDNA differentiation, which could be explained by historical isolation of the Villena Lagoon population. Conversely, significant genetic differentiation that follows an isolation-by-distance pattern, and a reduction in Ne though time was detected with microsatellites, suggesting extensive habitat fragmentation on the Mediterranean coast of the Iberian Peninsula over the past hundreds of years. At a smaller geographical scale (Mar Menor Lagoon), habitat fragmentation, probably due to human activity, appears to have resulted in substantially reduced migration and increased genetic drift, as shown by expanded genetic differentiation of populations.Subject areas: Population structure and phylogeography, Conservation
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| 14. |
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| 15. |
- Hedrick, Philip W., et al.
(författare)
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Genomic Variation of Inbreeding and Ancestry in the Remaining Two Isle Royale Wolves
- 2017
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Ingår i: Journal of Heredity. - : OXFORD UNIV PRESS INC. - 0022-1503 .- 1465-7333. ; 108:2, s. 120-126
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Tidskriftsartikel (refereegranskat)abstract
- Inbreeding, relatedness, and ancestry have traditionally been estimated with pedigree information, however, molecular genomic data can provide more detailed examination of these properties. For example, pedigree information provides estimation of the expected value of these measures but molecular genomic data can estimate the realized values of these measures in individuals. Here, we generate the theoretical distribution of inbreeding, relatedness, and ancestry for the individuals in the pedigree of the Isle Royale wolves, the first examination of such variation in a wild population with a known pedigree. We use the 38 autosomes of the dog genome and their estimated map lengths in our genomic analysis. Although it is known that the remaining wolves are highly inbred, closely related, and descend from only 3 ancestors, our analyses suggest that there is significant variation in the realized inbreeding and relatedness around pedigree expectations. For example, the expected inbreeding in a hypothetical offspring from the 2 remaining wolves is 0.438 but the realized 95% genomic confidence interval is from 0.311 to 0.565. For individual chromosomes, a substantial proportion of the whole chromosomes are completely identical by descent. This examination provides a background to use when analyzing molecular genomic data for individual levels of inbreeding, relatedness, and ancestry. The level of variation in these measures is a function of the time to the common ancestor(s), the number of chromosomes, and the rate of recombination. In the Isle Royale wolf population, the few generations to a common ancestor results in the high variance in genomic inbreeding.
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| 16. |
- Häggström, Jens, et al.
(författare)
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Identification of 2 Loci Associated with Development of Myxomatous Mitral Valve Disease in Cavalier King Charles Spaniels
- 2011
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 102, s. S62-S67
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Tidskriftsartikel (refereegranskat)abstract
- Myxomatous mitral valve disease (MMVD) is the most common heart disease in dogs. It is characterized by chronic progressive degenerative lesions of the mitral valve. The valve leaflets become thickened and prolapse into the left atrium resulting in mitral regurgitation (MR). MMVD is most prevalent in small to medium sized dog breeds, Cavalier King Charles Spaniels (CKCS) in particular. The onset of MMVD is highly age dependent, and at the age of 10 years, nearly all CKCS are affected. The incidence of a similar disease in humans-mitral valve prolapse-is 1-5%. By defining CKCSs with an early onset of MMVD as cases and old dogs with no or mild signs of MMVD as controls, we conducted a genome-wide association study (GWAS) to identify loci associated with development of MMVD. We have identified a 1.58 Mb region on CFA13 (P(genome) = 4.0x 10(-5)) and a 1.68 Mb region on CFA14 (P(genome) = 7.9x 10(-4)) associated with development of MMVD. This confirms the power of using the dog as a model to uncover potential candidate regions involved in the molecular mechanisms behind complex traits.
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| 17. |
- Ingman, Max, et al.
(författare)
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Analysis of the complete human mtDNA genome : methodology and inferences for human evolution
- 2001
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Ingår i: Journal of Heredity. - 0022-1503 .- 1465-7333. ; 92:6, s. 454-61
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of mitochondrial DNA (mtDNA) sequences has been a potent tool in our understanding of human evolution. However, almost all studies of human evolution based on mtDNA sequencing have focused on the control region, which constitutes less than 7% of the mitochondrial genome. The rapid development of technology for automated DNA sequencing has made it possible to study the complete mtDNA genomes in large numbers of individuals, opening the field of mitochondrial population genomics. Here we describe a suitable methodology for determining the complete human mitochondrial sequence and the global mtDNA diversity in humans. Also, we discuss the implications of the results with respect to the different hypotheses for the evolution of modern humans.
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| 18. |
- Lionikas, Arimantas, et al.
(författare)
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Genomic Analysis of Variation in Hindlimb Musculature of Mice from the C57BL/6J and DBA/2J Lineage
- 2010
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 101:3, s. 360-367
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Tidskriftsartikel (refereegranskat)abstract
- The precise locations of attachment points of muscle to bone-the origin and insertion sites-are crucial anatomical and functional characteristics that influence locomotor performance. Mechanisms that control the development of these interactions between muscle, tendon, and bone are currently not well understood. In a subset of BXD recombinant inbred (RI) strains derived from the C57BL/6J and DBA/2J strains, we observed a soleus femoral attachment anomaly (SFAA) that was rare in both parental strains (Lionikas, Glover et al. 2006). The aim of the present study was to assess suitability of SFAA as a model to study the genetic mechanisms underlying variation in musculoskeletal anatomy. We scored the incidence of SFAA in 55 BXD strains (n = 9 to 136, median = 26, phenotyped animals per strain, for a total number of 2367). Seven strains (BXD1, 12, 38, 43, 48, 54, and 56) exhibited a high incidence of unilateral SFAA (47-89%), whereas 23 strains scored 0%. Exploration of the mechanisms underlying SFAA in 2 high incidence strains, BXD1 and BXD38, indicated that SFAA-relevant genes are to be found in both C57BL/6J and DBA/2J regions of the BXD1 genome. However, not all alleles relevant for the expression of the phenotype were shared between the 2 high-incidence BXD strains. In conclusion, the anatomical origin of the soleus muscle in mouse is controlled by a polygenic system. A panel of BXD RI strains is a useful tool in exploring the genetic mechanisms underlying SFAA and improving our understanding of musculoskeletal development.
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| 19. |
- Lotsander, Anna, et al.
(författare)
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Low persistence of genetic rescue across generations in the Arctic fox (Vulpes lagopus)
- 2021
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 112:3, s. 276-285
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Tidskriftsartikel (refereegranskat)abstract
- Genetic rescue can facilitate the recovery of small and isolated populations suffering from inbreeding depression. Long-term effects are however complex and examples spanning over multiple generations under natural conditions are scarce. The aim of this study was to test for long-term effects of natural genetic rescue in a small population of Scandinavian Arctic foxes (Vulpes lagopus). By combining a genetically verified pedigree covering almost 20 years with a long-term dataset on individual fitness (n=837 individuals), we found no evidence for elevated fitness in immigrant F2 and F3 compared to native inbred foxes. Population inbreeding levels showed a fluctuating increasing trend and emergence of inbreeding within immigrant lineages shortly after immigration. Between 0-5 and 6-9 years post immigration, the average population size decreased by almost 22 % and the average proportion of immigrant ancestry rose from 14 % to 27 %. Y chromosome analysis revealed that two out of three native male lineages were lost from the gene pool, but all founders represented at the time of immigration were still contributing to the population at the end of the study period through female descendants. The results highlight the complexity of genetic rescue and suggest that beneficial effects can be brief. Continuous gene flow may be needed for small and threatened populations to recover and persist in a longer time perspective.
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| 20. |
- Matsubara, K., et al.
(författare)
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No Interstitial Telomeres on Autosomes but Remarkable Amplification of Telomeric Repeats on the W Sex Chromosome in the Sand Lizard (Lacerta agilis)
- 2015
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Ingår i: Journal of Heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 106:6, s. 753-757
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Tidskriftsartikel (refereegranskat)abstract
- Telomeres are repeat ( TTAGGG) (n) sequences that form terminal ends of chromosomes and have several functions, such as protecting the coding DNA from erosion at mitosis. Due to chromosomal rearrangements through evolutionary history ( e.g., inversions and fusions), telomeric sequences are also found between the centromere and the terminal ends ( i.e., at interstitial telomeric sites, ITSs). ITS telomere sequences have been implicated in heritable disease caused by genomic instability of ITS polymorphic variants, both with respect to copy number and sequence. In the sand lizard ( Lacerta agilis), we have shown that telomere length is predictive of lifetime fitness in females but not males. To assess whether this sex specific fitness effect could be traced to ITSs differences, we mapped ( TTAGGG) n sequences using fluorescence in situ hybridization in fibroblast cells cultured from 4 specimens of known sex. No ITSs could be found on autosomes in either sex. However, females have heterogametic sex chromosomes in sand lizards ( ZW, 2n = 38) and the female W chromosome showed degeneration and remarkable ( TTAGGG) n amplification, which was absent in the Z chromosomes. This work warrants further research on sex chromosome content, in particular of the degenerate W chromosome, and links to female fitness in sand lizards.
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| 21. |
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| 22. |
- Merilä, J, et al.
(författare)
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Temporal stability and microgeographic homogeneity of heritability estimates in a natural bird population
- 1996
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Ingår i: Journal of Heredity. - 0022-1503 .- 1465-7333. ; 87:3, s. 199-204
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Temporal and spatial variation in heritability estimates and additive genetic covariances of seven morphological traits were studied over a 9-year period in a natural population of the collared flycatcher, Ficedula albicollis. In spite of significant differences in trait means among young born in different years, we found no evidence for between-years variation in heritability estimates in any of the traits. Likewise, the elements of genetic covariance matrices were significantly correlated among the different study years, and the null hypothesis of no similarity was rejected. Furthermore, despite significant differences in mean tarsus length of birds born in different nestbox areas (habitats), we found no evidence for differences in heritability of tarsus length in different habitats. Our results indicate that the assumption on the constancy of quantitative genetic parameters over time and environments in evolutionary models may hold at least over short temporal or spatial distances.
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| 23. |
- Mäkinen, Tuuli, 1976, et al.
(författare)
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High Levels of Multiple Paternity in Littorina saxatilis: Hedging the Bets?
- 2007
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Ingår i: The Journal of heredity. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 98:7, s. 705-11
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Tidskriftsartikel (refereegranskat)abstract
- The mating system of a species can have great effects on its genetic structure and evolution. We studied the extent of multiple paternity in a gastropod with internal fertilization, the intertidal snail Littorina saxatilis. Paternal genotype reconstruction based on microsatellite markers was performed on the offspring of wild, naturally fertilized females from 2 populations. The numbers of males contributing to the offspring per female were among the highest detected in invertebrates so far, with the exception of social insects. No reproductive skew in favor of males that were genetically more distant from the females was detected, and the pattern of fertilization appeared random. The result fits a hypothesis of indiscriminate mating, with genetic bet hedging as the most likely explanation. Bet hedging may have evolved as a form of inbreeding avoidance, if the snails are not able to recognize relatives. However, nutritional benefits from sperm or sexual conflict with males are additional possibilities that remain to be assessed in this species. Whatever the causes, such high levels of multiple paternity are remarkable and are likely to have a large impact on population structure and dynamics in a species in which migration between populations is spurious.
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| 24. |
- [Nyberg] Berglund, Anna-Britt, et al.
(författare)
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Electrophoretic evidence for disomic inheritance and allopolyploid origin of the octoploid Cerastium alpinum (Caryophyllaceae).
- 2006
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Ingår i: J Hered. - : Oxford University Press (OUP). - 0022-1503 .- 1465-7333. ; 97:3, s. 296-302
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Tidskriftsartikel (refereegranskat)abstract
- The mode of inheritance of six enzyme markers in the octoploid alpine plant Cerastium alpinum was analyzed. Offspring from crosses between heterozygotes showed fixed heterozygosity at malate dehydrogenase-2, phosphoglucoisomerase-2, triosephosphate isomerase-2, and triosephosphate isomerase-3. Phosphoglucomutase-1 also showed fixed heterozygosity except in offspring from one cross. Fixed heterozygosity in five enzyme systems suggests that C. alpinum has originated through at least some allopolyploidization. Offspring from plants heterozygous for two alleles at the menadione reductase-1 (Mr-1) locus did not deviate significantly from a 1:2:1 ratio. The large proportion of homozygotes suggests disomic inheritance because any kind of polysomic inheritance would result in a substantially increased proportion of heterozygotes relative to disomic inheritance. Assuming a diploid model for Mr-1, this locus was used to analyze the population genetic structure within C. alpinum populations. Inbreeding was found in many alpine populations. This may help explain the large genetic distances found among alpine populations in a previous study. The analysis is only based on one segregating locus, and the results should therefore be treated with caution. However, by establishing the mode of inheritance through crosses, we have been able to use a codominant marker in population genetic analysis of an octoploid plant.
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