| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 4. |
- Grüning, Björn, et al.
(författare)
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Bioconda: A sustainable and comprehensive software distribution for the life sciences
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present Bioconda (https://bioconda.github.io), a distribution of bioinformatics software for the lightweight, multi-platform and language-agnostic package manager Conda. Currently, Bioconda offers a collection of over 3000 software packages, which is continuously maintained, updated, and extended by a growing global community of more than 200 contributors. Bioconda improves analysis reproducibility by allowing users to define isolated environments with defined software versions, all of which are easily installed and managed without administrative privileges.
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| 5. |
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| 6. |
- Christmas, Matthew, et al.
(författare)
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Genetic Barriers to Historical Gene Flow between Cryptic Species of Alpine Bumblebees Revealed by Comparative Population Genomics
- 2021
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Ingår i: Molecular biology and evolution. - : Oxford University Press. - 0737-4038 .- 1537-1719. ; 38:8, s. 3126-3143
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Tidskriftsartikel (refereegranskat)abstract
- Evidence is accumulating that gene flow commonly occurs between recently diverged species, despite the existence of barriers to gene flow in their genomes. However, we still know little about what regions of the genome become barriers to gene flow and how such barriers form. Here, we compare genetic differentiation across the genomes of bumblebee species living in sympatry and allopatry to reveal the potential impact of gene flow during species divergence and uncover genetic barrier loci. We first compared the genomes of the alpine bumblebee Bombus sylvicola and a previously unidentified sister species living in sympatry in the Rocky Mountains, revealing prominent islands of elevated genetic divergence in the genome that colocalize with centromeres and regions of low recombination. This same pattern is observed between the genomes of another pair of closely related species living in allopatry (B. bifarius and B. vancouverensis). Strikingly however, the genomic islands exhibit significantly elevated absolute divergence (d(XY)) in the sympatric, but not the allopatric, comparison indicating that they contain loci that have acted as barriers to historical gene flow in sympatry. Our results suggest that intrinsic barriers to gene flow between species may often accumulate in regions of low recombination and near centromeres through processes such as genetic hitchhiking, and that divergence in these regions is accentuated in the presence of gene flow.
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| 7. |
- Christmas, Matthew, et al.
(författare)
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Social Parasitism in the Honeybee (Apis mellifera) Is Not Controlled by a Single SNP
- 2019
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 36:8, s. 1764-1767
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Tidskriftsartikel (refereegranskat)abstract
- The Cape bee (Apis mellifera capensis) is a subspecies of the honeybee, in which workers commonly lay diploid unfertilized eggs via a process known as thelytoky. A recent study aimed to map the genetic basis of this trait in the progeny of a single capensis queen where workers laid either diploid (thelytokous) or haploid (arrhenotokous) eggs. A nonsynonymous single nucleotide polymorphism (SNP) in a gene of unknown function was reported to be strongly associated with thelytoky in this colony. Here, we analyze genome sequences from a global sample of A. mellifera and identify populations where the proposed thelytoky allele at this SNP is common but thelytoky is absent. We also analyze genome sequences of three capensis queens produced by thelytoky and find that, contrary to predictions, they do not carry the proposed thelytoky allele. The proposed SNP is therefore neither sufficient nor required to produce thelytoky in A. mellifera.
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| 8. |
- Everitt, Turid, et al.
(författare)
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The Genomic Basis of Adaptation to High Elevations in Africanized Honey Bees
- 2023
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Ingår i: Genome Biology and Evolution. - : Oxford University Press. - 1759-6653. ; 15:9
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Tidskriftsartikel (refereegranskat)abstract
- A range of different genetic architectures underpin local adaptation in nature. Honey bees (Apis mellifera) in the Eastern African Mountains harbor high frequencies of two chromosomal inversions that likely govern adaptation to this high-elevation habitat. In the Americas, honey bees are hybrids of European and African ancestries and adaptation to latitudinal variation in climate correlates with the proportion of these ancestries across the genome. It is unknown which, if either, of these forms of genetic variation governs adaptation in honey bees living at high elevations in the Americas. Here, we performed whole-genome sequencing of 29 honey bees from both high- and low-elevation populations in Colombia. Analysis of genetic ancestry indicated that both populations were predominantly of African ancestry, but the East African inversions were not detected. However, individuals in the higher elevation population had significantly higher proportions of European ancestry, likely reflecting local adaptation. Several genomic regions exhibited particularly high differentiation between highland and lowland bees, containing candidate loci for local adaptation. Genes that were highly differentiated between highland and lowland populations were enriched for functions related to reproduction and sperm competition. Furthermore, variation in levels of European ancestry across the genome was correlated between populations of honey bees in the highland population and populations at higher latitudes in South America. The results are consistent with the hypothesis that adaptation to both latitude and elevation in these hybrid honey bees are mediated by variation in ancestry at many loci across the genome.
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| 9. |
- Montero-Mendieta, Santiago, et al.
(författare)
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The genomic basis of adaptation to high-altitude habitats in the eastern honey bee (Apis cerana)
- 2019
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Ingår i: Molecular Ecology. - : WILEY. - 0962-1083 .- 1365-294X. ; 28:4, s. 746-760
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Tidskriftsartikel (refereegranskat)abstract
- The eastern honey bee (Apis cerana) is of central importance for agriculture in Asia. It has adapted to a wide variety of environmental conditions across its native range in southern and eastern Asia, which includes high-altitude regions. eastern honey bees inhabiting mountains differ morphologically from neighbouring lowland populations and may also exhibit differences in physiology and behaviour. We compared the genomes of 60 eastern honey bees collected from high and low altitudes in Yunnan and Gansu provinces, China, to infer their evolutionary history and to identify candidate genes that may underlie adaptation to high altitude. Using a combination of F-ST-based statistics, long-range haplotype tests and population branch statistics, we identified several regions of the genome that appear to have been under positive selection. These candidate regions were strongly enriched for coding sequences and had high haplotype homozygosity and increased divergence specifically in highland bee populations, suggesting they have been subjected to recent selection in high-altitude habitats. Candidate loci in these genomic regions included genes related to reproduction and feeding behaviour in honey bees. Functional investigation of these candidate loci is necessary to fully understand the mechanisms of adaptation to high-altitude habitats in the eastern honey bee.
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| 10. |
- Sanchez-Donoso, Ines, et al.
(författare)
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Massive genome inversion drives coexistence of divergent morphs in common quails
- 2022
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Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 32:2, s. 462-
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Tidskriftsartikel (refereegranskat)abstract
- The presence of population-specific phenotypes often reflects local adaptation or barriers to gene flow. The co-occurrence of phenotypic polymorphisms that are restricted within the range of a highly mobile species is more difficult to explain. An example of such polymorphisms is in the common quail Coturnix coturnix, a small migratory bird that moves widely during the breeding season in search of new mating opportunities, following ephemeral habitats,(1,2) and whose females may lay successive clutches at different locations while migrating.(3) In spite of this vagility, previous studies reported a higher frequency of heavier males with darker throat coloration in the southwest of the distribution (I. Jimenez-Blasco et al., 2015, Int. Union Game Biol., conference). We used population genomics and cytogenetics to explore the basis of this polymorphism and discovered a large inversion in the genome of the common quail. This inversion extends 115 Mbp in length and encompasses more than 7,000 genes (about 12% of the genome), producing two very different forms. Birds with the inversion are larger, have darker throat coloration and rounder wings, are inferred to have poorer flight efficiency, and are geographically restricted despite the high mobility of the species. Stable isotope analyses confirmed that birds carrying the inversion have shorter migratory distances or do not migrate. However, we found no evidence of pre- or post-zygotic isolation, indicating the two forms commonly interbreed and that the polymorphism remains locally restricted because of the effect on behavior. This illustrates a genomic mechanism underlying maintenance of geographically structured polymorphisms despite interbreeding with a lineage with high mobility.
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| 11. |
- Smith, Madison M., et al.
(författare)
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Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features
- 2023
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Ingår i: Elementa: Science of the Anthropocene. - 2325-1026. ; 11:1
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Forskningsöversikt (refereegranskat)abstract
- The rapid melt of snow and sea ice during the Arctic summer provides a significant source of low-salinity meltwater to the surface ocean on the local scale. The accumulation of this meltwater on, under, and around sea ice floes can result in relatively thin meltwater layers in the upper ocean. Due to the small-scale nature of these upper-ocean features, typically on the order of 1 m thick or less, they are rarely detected by standard methods, but are nevertheless pervasive and critically important in Arctic summer. Observations during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in summer 2020 focused on the evolution of such layers and made significant advancements in understanding their role in the coupled Arctic system. Here we provide a review of thin meltwater layers in the Arctic, with emphasis on the new findings from MOSAiC. Both prior and recent observational datasets indicate an intermittent yet longlasting (weeks to months) meltwater layer in the upper ocean on the order of 0.1 m to 1.0 m in thickness, with a large spatial range. The presence of meltwater layers impacts the physical system by reducing bottom ice melt and allowing new ice formation via false bottom growth. Collectively, the meltwater layer and false bottoms reduce atmosphere-ocean exchanges of momentum, energy, and material.The impacts on the coupled Arctic system are far-reaching, including acting as a barrier for nutrient and gas exchange and impacting ecosystem diversity and productivity.
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| 12. |
- Vaysse, Amaury, et al.
(författare)
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Identification of genomic regions associated with phenotypic variation between dog breeds using selection mapping
- 2011
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 7:10, s. e1002316-
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Tidskriftsartikel (refereegranskat)abstract
- The extraordinary phenotypic diversity of dog breeds has been sculpted by a unique population history accompanied by selection for novel and desirable traits. Here we perform a comprehensive analysis using multiple test statistics to identify regions under selection in 509 dogs from 46 diverse breeds using a newly developed high-density genotyping array consisting of >170,000 evenly spaced SNPs. We first identify 44 genomic regions exhibiting extreme differentiation across multiple breeds. Genetic variation in these regions correlates with variation in several phenotypic traits that vary between breeds, and we identify novel associations with both morphological and behavioral traits. We next scan the genome for signatures of selective sweeps in single breeds, characterized by long regions of reduced heterozygosity and fixation of extended haplotypes. These scans identify hundreds of regions, including 22 blocks of homozygosity longer than one megabase in certain breeds. Candidate selection loci are strongly enriched for developmental genes. We chose one highly differentiated region, associated with body size and ear morphology, and characterized it using high-throughput sequencing to provide a list of variants that may directly affect these traits. This study provides a catalogue of genomic regions showing extreme reduction in genetic variation or population differentiation in dogs, including many linked to phenotypic variation. The many blocks of reduced haplotype diversity observed across the genome in dog breeds are the result of both selection and genetic drift, but extended blocks of homozygosity on a megabase scale appear to be best explained by selection. Further elucidation of the variants under selection will help to uncover the genetic basis of complex traits and disease.
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| 13. |
- Borge, Kaja Sverdrup, et al.
(författare)
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The ESR1 gene is associated with risk for canine mammary tumours
- 2013
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Ingår i: BMC Veterinary Research. - : Springer Science and Business Media LLC. - 1746-6148. ; 9, s. 69-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The limited within-breed genetic heterogeneity and an enrichment of disease-predisposing alleles have made the dog a very suitable model for the identification of genes associated with risk for specific diseases. Canine mammary cancer is an example of such a disease. However, the underlying inherited risk factors for canine mammary tumours (CMTs) are still largely unknown. In this study, 52 single nucleotide polymorphisms (SNPs) in ten human cancer-associated genes were genotyped in two different datasets in order to identify genes/alleles associated with the development of CMTs. The first dataset consisted of English Springer Spaniel (ESS) CMT cases and controls. ESS is a dog breed known to be at increased risk of developing CMTs. In the second dataset, dogs from breeds known to have a high frequency of CMTs were compared to dogs from breeds with a lower occurrence of these tumours. Results: We found significant associations to CMT for SNPs and haplotypes in the estrogen receptor 1 (ESR1) gene in the ESS material (best P-Bonf = 0.021). A large number of SNPs, among them several SNPs in ESR1, showed significantly different allele frequencies between the high and low risk breed groups (best P-Bonf = 8.8E-32, best P-BPerm = 0.076). Conclusions: The identification of CMT-associated SNPs in ESR1 in two independent datasets suggests that this gene might be involved in CMT development. These findings also support that CMT may serve as a good model for human breast cancer research.
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| 14. |
- Borge, Thomas, et al.
(författare)
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Contrasting patterns of polymorphism and divergence on the Z chromosome and autosomes in two Ficedula flycatcher species
- 2005
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Ingår i: Genetics. - : Oxford University Press (OUP). - 0016-6731 .- 1943-2631. ; 171:4, s. 1861-1873
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Tidskriftsartikel (refereegranskat)abstract
- In geographic areas where pied and collared flycatchers (Ficedula hypoleuca and F. albicollis) breed in sympatry, hybridization occurs, leading to gene flow (introgression) between the two recently diverged species. Notably, while such introgression is observable at autosomal loci it is apparently absent at the Z chromosome, suggesting an important role for genes on the Z chromosome in creating reproductive isolation during speciation. To further understand the role of Z-linked loci in the formation of new species, we studied genetic variation of the two species from regions where they live in allopatry. We analyzed patterns of polymorphism and divergence in introns from 9 Z-linked and 23 autosomal genes in pied and collared flycatcher males. Average variation on the Z chromosome is greatly reduced compared to neutral expectations based on autosomal diversity in both species. We also observe significant heterogeneity between patterns of polymorphism and divergence at Z-linked loci and a relative absence of polymorphisms that are shared by the two species on the Z chromosome compared to the autosomes. We suggest that these observations may indicate the action of recurrent selective sweeps on the Z chromosome during the evolution of the two species, which may be caused by sexual selection acting on Z-linked genes. Alternatively, reduced variation on the Z chromosome could result from substantially higher levels of introgression at autosomal than at Z-linked loci or from a complex demographic history, such as a population bottleneck.
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| 15. |
- Dyrhage, Karl, et al.
(författare)
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Genome Evolution of a Symbiont Population for Pathogen Defence in Honeybees
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Ingår i: Genome Biology and Evolution. - 1759-6653.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The honeybee gut microbiome is thought to be important for bee health, but the role of the individual members is poorly understood. Here, we present closed genomes and associated mobilomes of 102 Apilactobacillus kunkeei isolates obtained from the honey crop (foregut) of honeybees sampled from beehives in Helsingborg in the south of Sweden and from the islands Gotland and Åland in the Baltic Sea. Each beehive contained a unique composition of isolates and repeated sampling of similar isolates from two beehives in Helsingborg suggests that the bacterial community is stably maintained across bee generations during the summer months. The sampled bacterial population contained an open pan- genome structure with a high genomic density of transposons. A subset of strains affiliated with phylogroup A inhibited growth of the bee pathogen Melisococcus plutonius, all of which contained a 19.5 kb plasmid for the synthesis of the antimicrobial compound kunkecin A, while a subset of phylogroups B and C strains contained a 32.9 kb plasmid for the synthesis of a putative polyketide antibiotic. This study suggests that the mobile gene pool of A. kunkeei plays a key role in pathogen defence in honeybees, providing new insights into the evolutionary dynamics of defensive symbiont populations.
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| 16. |
- Dyrhage, Karl, et al.
(författare)
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Genome Evolution of a Symbiont Population for Pathogen Defense in Honeybees
- 2022
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653. ; 14:11
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Tidskriftsartikel (refereegranskat)abstract
- The honeybee gut microbiome is thought to be important for bee health, but the role of the individual members is poorly understood. Here, we present closed genomes and associated mobilomes of 102 Apilactobacillus kunkeei isolates obtained from the honey crop (foregut) of honeybees sampled from beehives in Helsingborg in the south of Sweden and from the islands Gotland and angstrom land in the Baltic Sea. Each beehive contained a unique composition of isolates and repeated sampling of similar isolates from two beehives in Helsingborg suggests that the bacterial community is stably maintained across bee generations during the summer months. The sampled bacterial population contained an open pan-genome structure with a high genomic density of transposons. A subset of strains affiliated with phylogroup A inhibited growth of the bee pathogen Melissococcus plutonius, all of which contained a 19.5 kb plasmid for the synthesis of the antimicrobial compound kunkecin A, while a subset of phylogroups B and C strains contained a 32.9 kb plasmid for the synthesis of a putative polyketide antibiotic. This study suggests that the mobile gene pool of A. kunkeei plays a key role in pathogen defense in honeybees, providing new insights into the evolutionary dynamics of defensive symbiont populations.
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| 17. |
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| 18. |
- Han, Fan, et al.
(författare)
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Gene flow, ancient polymorphism, and ecological adaptation shape the genomic landscape of divergence among Darwin's finches
- 2017
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 27:6, s. 1004-1015
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Tidskriftsartikel (refereegranskat)abstract
- Genomic comparisons of closely related species have identified "islands" of locally elevated sequence divergence. Genomic islands may contain functional variants involved in local adaptation or reproductive isolation and may therefore play an important role in the speciation process. However, genomic islands can also arise through evolutionary processes unrelated to speciation, and examination of their properties can illuminate how new species evolve. Here, we performed scans for regions of high relative divergence (FST) in 12 species pairs of Darwin's finches at different genetic distances. In each pair, we identify genomic islands that are, on average, elevated in both relative divergence (FST) and absolute divergence (dXY). This signal indicates that haplotypes within these genomic regions became isolated from each other earlier than the rest of the genome. Interestingly, similar numbers of genomic islands of elevated dXY are observed in sympatric and allopatric species pairs, suggesting that recent gene flow is not a major factor in their formation. We find that two of the most pronounced genomic islands contain the ALX1 and HMGA2 loci, which are associated with variation in beak shape and size, respectively, suggesting that they are involved in ecological adaptation. A subset of genomic island regions, including these loci, appears to represent anciently diverged haplotypes that evolved early during the radiation of Darwin's finches. Comparative genomics data indicate that these loci, and genomic islands in general, have exceptionally low recombination rates, which may play a role in their establishment.
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| 19. |
- Henriques, Dora, et al.
(författare)
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Developing reduced SNP assays from whole-genome sequence data to estimate introgression in an organism with complex genetic patterns, the Iberian honeybee (Apis mellifera iberiensis)
- 2018
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Ingår i: Evolutionary Applications. - : WILEY. - 1752-4571. ; 11:8, s. 1270-1282
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Tidskriftsartikel (refereegranskat)abstract
- The most important managed pollinator, the honeybee (Apis mellifera L.), has been subject to a growing number of threats. In western Europe, one such threat is large-scale introductions of commercial strains (C-lineage ancestry), which is leading to introgressive hybridization and even the local extinction of native honeybee populations (M-lineage ancestry). Here, we developed reduced assays of highly informative SNPs from 176 whole genomes to estimate C-lineage introgression in the most diverse and evolutionarily complex subspecies in Europe, the Iberian honeybee (Apis mellifera iberiensis). We started by evaluating the effects of sample size and sampling a geographically restricted area on the number of highly informative SNPs. We demonstrated that a bias in the number of fixed SNPs (F-ST=1) is introduced when the sample size is small (N10) and when sampling only captures a small fraction of a population's genetic diversity. These results underscore the importance of having a representative sample when developing reliable reduced SNP assays for organisms with complex genetic patterns. We used a training data set to design four independent SNP assays selected from pairwise F-ST between the Iberian and C-lineage honeybees. The designed assays, which were validated in holdout and simulated hybrid data sets, proved to be highly accurate and can be readily used for monitoring populations not only in the native range of A.m.iberiensis in Iberia but also in the introduced range in the Balearic islands, Macaronesia and South America, in a time- and cost-effective manner. While our approach used the Iberian honeybee as model system, it has a high value in a wide range of scenarios for the monitoring and conservation of potentially hybridized domestic and wildlife populations.
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| 20. |
- Henriques, Dora, et al.
(författare)
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Whole genome SNP-associated signatures of local adaptation in honeybees of the Iberian Peninsula
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The availability of powerful high-throughput genomic tools, combined with genome scans, has helped identifying genes and genetic changes responsible for environmental adaptation in many organisms, including the honeybee. Here, we resequenced 87 whole genomes of the honeybee native to Iberia and used conceptually different selection methods (Sam beta ada, LFMM, PCAdapt, iHs) together with in sillico protein modelling to search for selection footprints along environmental gradients. We found 670 outlier SNPs, most of which associated with precipitation, longitude and latitude. Over 88.7% SNPs laid outside exons and there was a significant enrichment in regions adjacent to exons and UTRs. Enrichment was also detected in exonic regions. Furthermore, in silico protein modelling suggests that several non-synonymous SNPs are likely direct targets of selection, as they lead to amino acid replacements in functionally important sites of proteins. We identified genomic signatures of local adaptation in 140 genes, many of which are putatively implicated in fitness-related functions such as reproduction, immunity, olfaction, lipid biosynthesis and circadian clock. Our genome scan suggests that local adaptation in the Iberian honeybee involves variations in regions that might alter patterns of gene expression and in protein-coding genes, which are promising candidates to underpin adaptive change in the honeybee.
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| 21. |
- Kawakami, Takeshi, et al.
(författare)
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Substantial Heritable Variation in Recombination Rate on Multiple Scales in Honeybees and Bumblebees
- 2019
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Ingår i: Genetics. - : GENETICS SOCIETY AMERICA. - 0016-6731 .- 1943-2631. ; 212:4, s. 1101-1119
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Tidskriftsartikel (refereegranskat)abstract
- Meiotic recombination shuffles genetic variation and promotes correct segregation of chromosomes. Rates of recombination vary on several scales, both within genomes and between individuals, and this variation is affected by both genetic and environmental factors. Social insects have extremely high rates of recombination, although the evolutionary causes of this are not known. Here, we estimate rates of crossovers and gene conversions in 22 colonies of the honeybee, Apis mellifera, and 9 colonies of the bumblebee, Bombus terrestris, using direct sequencing of 299 haploid drone offspring. We confirm that both species have extremely elevated crossover rates, with higher rates measured in the highly eusocial honeybee than the primitively social bumblebee. There are also significant differences in recombination rate between subspecies of honeybee. There is substantial variation in genome-wide recombination rate between individuals of both A. mellifera and B. terrestris and the distribution of these rates overlap between species. A large proportion of interindividual variation in recombination rate is heritable, which indicates the presence of variation in trans-acting factors that influence recombination genome-wide. We infer that levels of crossover interference are significantly lower in honeybees compared to bumblebees, which may be one mechanism that contributes to higher recombination rates in honeybees. We also find a significant increase in recombination rate with distance from the centromere, mirrored by methylation differences. We detect a strong transmission bias due to GC-biased gene conversion associated with noncrossover gene conversions. Our results shed light on the mechanistic causes of extreme rates of recombination in social insects and the genetic architecture of recombination rate variation.
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| 22. |
- Lamichhaney, Sangeet, 1984-, et al.
(författare)
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Female-biased gene flow between two species of Darwin’s finches
- 2020
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Ingår i: Nature Ecology & Evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 4:7, s. 979-986
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Tidskriftsartikel (refereegranskat)abstract
- The mosaic nature of hybrid genomes is well recognized, but little is known of how they are shaped initially by patterns of breeding, selection, recombination and differential incompatibilities. On the small Galápagos island of Daphne Major two species of Darwin’s finches, Geospiza fortis and G. scandens, hybridize rarely and backcross bidirectionally with little or no loss of fitness under conditions of plentiful food. We used whole genome sequences to compare genomes from periods before and after successful interbreeding followed by backcrossing. We inferred extensive introgression from G. fortis to G. scandens on autosomes and mitochondria but not on the Z chromosome. The unique combination of long-term field observations and genomic data shows that the reduction of gene flow for Z-linked loci reflects female-biased gene flow, arising from hybrid male disadvantage in competition for territories and mates, rather than from genetic incompatibilities at Z-linked loci.
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| 23. |
- Lamichhaney, Sangeet, 1984-, et al.
(författare)
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Rapid hybrid speciation in Darwin's finches
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 359:6372, s. 224-228
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Tidskriftsartikel (refereegranskat)abstract
- Homoploid hybrid speciation in animals has been inferred frequently from patterns of variation, but few examples have withstood critical scrutiny. Here we report a directly documented example, from its origin to reproductive isolation. An immigrant Darwin's finch to Daphne Major in the Galápagos archipelago initiated a new genetic lineage by breeding with a resident finch (Geospiza fortis). Genome sequencing of the immigrant identified it as a G. conirostris male that originated on Española >100 kilometers from Daphne Major. From the second generation onward, the lineage bred endogamously and, despite intense inbreeding, was ecologically successful and showed transgressive segregation of bill morphology. This example shows that reproductive isolation, which typically develops over hundreds of generations, can be established in only three.
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| 24. |
- Makino, Takashi, et al.
(författare)
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Elevated proportions of deleterious genetic variation in domestic animals and plants
- 2018
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Ingår i: Genome Biology and Evolution. - : Oxford University Press. - 1759-6653. ; 10:1, s. 276-290
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Tidskriftsartikel (refereegranskat)abstract
- A fraction of genetic variants segregating in any population are deleterious, which negatively impacts individual fitness. The domestication of animals and plants is associated with population bottlenecks and artificial selection, which are predicted to increase the proportion of deleterious variants. However, the extent to which this is a general feature of domestic species is unclear. Here we examine the effects of domestication on the prevalence of deleterious variation using pooled whole-genome resequencing data from five domestic animal species (dog, pig, rabbit, chicken and silkworm) and two domestic plant species (rice and soybean) compared to their wild ancestors. We find significantly reduced genetic variation and increased proportion of nonsynonymous amino acid changes in all but one of the domestic species. These differences are observable across a range of allele frequencies, both common and rare. We find proportionally more SNPs in highly conserved elements in domestic species and a tendency for domestic species to harbour a higher proportion of changes classified as damaging. Our findings most likely reflect an increased incidence of deleterious variants in domestic species, which is most likely attributable to population bottlenecks that lead to a reduction in the efficacy of selection. An exception to this pattern is displayed by European domestic pigs, which do not show traces of a strong population bottleneck and probably continued to exchange genes with wild boar populations after domestication. The results presented here indicate that an elevated proportion of deleterious variants is a common, but not ubiquitous, feature of domestic species.
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| 25. |
- Montero-Mendieta, Santiago, et al.
(författare)
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A practical guide to build de-novo assemblies for single tissues of non-model organisms : the example of a Neotropical frog
- 2017
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Ingår i: PeerJ. - : PEERJ INC. - 2167-8359. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Whole genome sequencing (WGS) is a very valuable resource to understand the evolutionary history of poorly known species. However, in organisms with large genomes, as most amphibians, WGS is still excessively challenging and transcriptome sequencing (RNA-seq) represents a cost-effective tool to explore genome-wide variability. Non-model organisms do not usually have a reference genome and the transcriptome must be assembled de-novo. Weused RNA-seq to obtain the transcriptomic profile for Oreobates cruralis, a poorly known South American direct-developing frog. In total, 550,871 transcripts were assembled, corresponding to 422,999 putative genes. Of those, we identified 23,500, 37,349, 38,120 and 45,885 genes present in the Pfam, EggNOG, KEGG and GO databases, respectively. Interestingly, our results suggested that genes related to immune system and defense mechanisms are abundant in the transcriptome of O. cruralis. We also present a pipeline to assist with pre-processing, assembling, evaluating and functionally annotating a de-novo transcriptome from RNA-seq data of non-model organisms. Our pipeline guides the inexperienced user in an intuitive way through all the necessary steps to build de-novo transcriptome assemblies using readily available software and is freely available at: https://github. com/biomendi/TRANSCRIPTOMEASSEMBLY- PIPELINE/wiki.
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| 26. |
- Nelson, Ronald M., et al.
(författare)
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Genomewide analysis of admixture and adaptation in the Africanized honeybee
- 2017
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 26:14, s. 3603-3617
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Tidskriftsartikel (refereegranskat)abstract
- Genetic exchange by hybridization or admixture can make an important contribution to evolution, and introgression of favourable alleles can facilitate adaptation to new environments. A small number of honeybees (Apis mellifera) with African ancestry were introduced to Brazil similar to 60 years ago, which dispersed and hybridized with existing managed populations of European origin, quickly spreading across much of the Americas in an example of a massive biological invasion. Here, we analyse whole-genome sequences of 32 Africanized honeybees sampled from throughout Brazil to study the effect of this process on genome diversity. By comparison with ancestral populations from Europe and Africa, we infer that these samples have 84% African ancestry, with the remainder from western European populations. However, this proportion varies across the genome and we identify signals of positive selection in regions with high European ancestry proportions. These observations are largely driven by one large gene-rich 1.4-Mbp segment on chromosome 11 where European haplotypes are present at a significantly elevated frequency and likely confer an adaptive advantage in the Africanized honeybee population. This region has previously been implicated in reproductive traits and foraging behaviour in worker bees. Finally, by analysing the distribution of ancestry tract lengths in the context of the known time of the admixture event, we are able to infer an average generation time of 2.0 years. Our analysis highlights the processes by which populations of mixed genetic ancestry form and adapt to new environments.
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| 27. |
- Olsson, Mia, et al.
(författare)
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A Novel Unstable Duplication Upstream of HAS2 Predisposes to a Breed-Defining Skin Phenotype and a Periodic Fever Syndrome in Chinese Shar-Pei Dogs
- 2011
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 7:3, s. e1001332-
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Tidskriftsartikel (refereegranskat)abstract
- Hereditary periodic fever syndromes are characterized by recurrent episodes of fever and inflammation with no known pathogenic or autoimmune cause. In humans, several genes have been implicated in this group of diseases, but the majority of cases remain unexplained. A similar periodic fever syndrome is relatively frequent in the Chinese Shar-Pei breed of dogs. In the western world, Shar-Pei have been strongly selected for a distinctive thick and heavily folded skin. In this study, a mutation affecting both these traits was identified. Using genome-wide SNP analysis of Shar-Pei and other breeds, the strongest signal of a breed-specific selective sweep was located on chromosome 13. The same region also harbored the strongest genome-wide association (GWA) signal for susceptibility to the periodic fever syndrome (p(raw) = 2.3 x 10(-6), p(genome) = 0.01). Dense targeted resequencing revealed two partially overlapping duplications, 14.3 Kb and 16.1 Kb in size, unique to Shar-Pei and upstream of the Hyaluronic Acid Synthase 2 (HAS2) gene. HAS2 encodes the rate-limiting enzyme synthesizing hyaluronan (HA), a major component of the skin. HA is up-regulated and accumulates in the thickened skin of Shar-Pei. A high copy number of the 16.1 Kb duplication was associated with an increased expression of HAS2 as well as the periodic fever syndrome (p, < 0.0001). When fragmented, HA can act as a trigger of the innate immune system and stimulate sterile fever and inflammation. The strong selection for the skin phenotype therefore appears to enrich for a pleiotropic mutation predisposing these dogs to a periodic fever syndrome. The identification of HA as a major risk factor for this canine disease raises the potential of this glycosaminoglycan as a risk factor for human periodic fevers and as an important driver of chronic inflammation.
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| 28. |
- Wallberg, Andreas, et al.
(författare)
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A hybrid de novo genome assembly of the honeybee, Apis mellifera, with chromosome-length scaffolds
- 2019
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Ingår i: BMC Genomics. - : BMC. - 1471-2164. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe ability to generate long sequencing reads and access long-range linkage information is revolutionizing the quality and completeness of genome assemblies. Here we use a hybrid approach that combines data from four genome sequencing and mapping technologies to generate a new genome assembly of the honeybee Apis mellifera. We first generated contigs based on PacBio sequencing libraries, which were then merged with linked-read 10x Chromium data followed by scaffolding using a BioNano optical genome map and a Hi-C chromatin interaction map, complemented by a genetic linkage map.ResultsEach of the assembly steps reduced the number of gaps and incorporated a substantial amount of additional sequence into scaffolds. The new assembly (Amel_HAv3) is significantly more contiguous and complete than the previous one (Amel_4.5), based mainly on Sanger sequencing reads. N50 of contigs is 120-fold higher (5.381 Mbp compared to 0.053 Mbp) and we anchor >98% of the sequence to chromosomes. All of the 16 chromosomes are represented as single scaffolds with an average of three sequence gaps per chromosome. The improvements are largely due to the inclusion of repetitive sequence that was unplaced in previous assemblies. In particular, our assembly is highly contiguous across centromeres and telomeres and includes hundreds of AvaI and AluI repeats associated with these features.ConclusionsThe improved assembly will be of utility for refining gene models, studying genome function, mapping functional genetic variation, identification of structural variants, and comparative genomics.
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| 29. |
- Wallberg, Andreas, et al.
(författare)
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Two extended haplotype blocks are associated with adaptation to high altitude habitats in East African honey bees
- 2017
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Ingår i: PLOS Genetics. - : PLOS. - 1553-7390 .- 1553-7404. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the genetic basis of adaption is a central task in biology. Populations of the honey bee Apis mellifera that inhabit the mountain forests of East Africa differ in behavior and morphology from those inhabiting the surrounding lowland savannahs, which likely reflects adaptation to these habitats. We performed whole genome sequencing on 39 samples of highland and lowland bees from two pairs of populations to determine their evolutionary affinities and identify the genetic basis of these putative adaptations. We find that in general, levels of genetic differentiation between highland and lowland populations are very low, consistent with them being a single panmictic population. However, we identify two loci on chromosomes 7 and 9, each several hundred kilobases in length, which exhibit near fixation for different haplotypes between highland and lowland populations. The highland haplotypes at these loci are extremely rare in samples from the rest of the world. Patterns of segregation of genetic variants suggest that recombination between haplotypes at each locus is suppressed, indicating that they comprise independent structural variants. The haplotype on chromosome 7 harbors nearly all octopamine receptor genes in the honey bee genome. These have a role in learning and foraging behavior in honey bees and are strong candidates for adaptation to highland habitats. Molecular analysis of a putative breakpoint indicates that it may disrupt the coding sequence of one of these genes. Divergence between the highland and lowland haplotypes at both loci is extremely high suggesting that they are ancient balanced polymorphisms that greatly predate divergence between the extant honey bee subspecies.
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| 30. |
- Webster, Matthew Thomas
(författare)
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Apis mellifera
- 2019
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Ingår i: Trends in Genetics. - : Elsevier. - 0168-9525 .- 1362-4555. ; 35:11, s. 880-881
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 31. |
- Webster, Matthew Thomas, et al.
(författare)
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Fixation biases affecting human SNPs?
- 2004
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Ingår i: Trends in Genetics. - : Elsevier BV. - 0168-9525 .- 1362-4555. ; 20:3, s. 122-126
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Tidskriftsartikel (refereegranskat)abstract
- Under neutrality all classes of mutation have an equal probability of becoming fixed in a population. In this article, we describe our analysis of the frequency distributions of >5000 human SNPs and provide evident of biases in the process of fixation of certain classes of point mutation that are most likely to be attributable to biased gene conversion. The results indicate an increased fixation probability of mutations that result in the incorporation of a GC base pair. Furthermore, in transcribed regions this process exhibits strand asymmetry, and is biased towards preserving a G base on the coding strand. Biased gene conversion has the potential to explain both existence of isochores and the compositional asymmetry in mammalian transcribed regions.
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| 32. |
- Webster, Matthew Thomas
(författare)
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Population Genomics : How Do Cape Honey Bees Do Without Sex?
- 2020
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 30:14, s. R820-R821
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cape honey bee, Apis mellifera capensis, is able to produce female offspring asexually. This phenomenon has now been shown to have a simple genetic basis.
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| 33. |
- Webster, Matthew Thomas, et al.
(författare)
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Population Genomics for Insect Conservation
- 2023
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Ingår i: Annual Review of Animal Biosciences. - : ANNUAL REVIEWS. - 2165-8102 .- 2165-8110. ; 11, s. 115-140
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Tidskriftsartikel (refereegranskat)abstract
- Insects constitute vital components of ecosystems. There is alarming evidence for global declines in insect species diversity, abundance, and biomass caused by anthropogenic drivers such as habitat degradation or loss, agricultural practices, climate change, and environmental pollution. This raises important concerns about human food security and ecosystem functionality and calls for more research to assess insect population trends and identify threatened species and the causes of declines to inform conservation strategies. Analysis of genetic diversity is a powerful tool to address these goals, but so far animal conservation genetics research has focused strongly on endangered vertebrates, devoting less attention to invertebrates, such as insects, that constitute most biodiversity. Insects' shorter generation times and larger population sizes likely necessitate different analytical methods and management strategies. The availability of high-quality reference genome assemblies enables population genomics to address several key issues. These include precise inference of past demographic fluctuations and recent declines, measurement of genetic load levels, delineation of evolutionarily significant units and cryptic species, and analysis of genetic adaptation to stressors. This enables identification of populations that are particularly vulnerable to future threats, considering their potential to adapt and evolve. We review the application of population genomics to insect conservation and the outlook for averting insect declines.
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