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1.
2.
Genotyping strategy matters when analyzing hypervariable major histocompatibility complex‐Experience from a passerine bird
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Silje L. Rekdal Jarl Andreas Anmarkrud Arild Johnsen Jan T. Lifjeld 《Ecology and evolution》2018,8(3):1680-1692
Genotyping of classical major histocompatibility complex (MHC) genes is challenging when they are hypervariable and occur in multiple copies. In this study, we used several different approaches to genotype the moderately variable MHC class I exon 3 (MHCIe3) and the highly polymorphic MHC class II exon 2 (MHCIIβe2) in the bluethroat (Luscinia svecica). Two family groups (eight individuals) were sequenced in replicates at both markers using Ion Torrent technology with both a single‐ and a dual‐indexed primer structure. Additionally, MHCIIβe2 was sequenced on Illumina MiSeq. Allele calling was conducted by modifications of the pipeline developed by Sommer et al. (BMC Genomics, 14, 2013, 542) and the software AmpliSAS. While the different genotyping strategies gave largely consistent results for MHCIe3, with a maximum of eight alleles per individual, MHCIIβe2 was remarkably complex with a maximum of 56 MHCIIβe2 alleles called for one individual. Each genotyping strategy detected on average 50%–82% of all MHCIIβe2 alleles per individual, but dropouts were largely allele‐specific and consistent within families for each strategy. The discrepancies among approaches indicate PCR biases caused by the platform‐specific primer tails. Further, AmpliSAS called fewer alleles than the modified Sommer pipeline. Our results demonstrate that allelic dropout is a significant problem when genotyping the hypervariable MHCIIβe2. As these genotyping errors are largely nonrandom and method‐specific, we caution against comparing genotypes across different genotyping strategies. Nevertheless, we conclude that high‐throughput approaches provide a major advance in the challenging task of genotyping hypervariable MHC loci, even though they may not reveal the complete allelic repertoire. 相似文献
3.
Xueling Yi Deahn M. Donner Paula E. Marquardt Jonathan M. Palmer Michelle A. Jusino Jacqueline Frair Daniel L. Lindner Emily K. Latch 《Ecology and evolution》2020,10(18):10031-10043
White‐nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans (Pd), has driven alarming declines in North American hibernating bats, such as little brown bat (Myotis lucifugus). During hibernation, infected little brown bats are able to initiate anti‐Pd immune responses, indicating pathogen‐mediated selection on the major histocompatibility complex (MHC) genes. However, such immune responses may not be protective as they interrupt torpor, elevate energy costs, and potentially lead to higher mortality rates. To assess whether WNS drives selection on MHC genes, we compared the MHC DRB gene in little brown bats pre‐ (Wisconsin) and post‐ (Michigan, New York, Vermont, and Pennsylvania) WNS (detection spanning 2014–2015). We genotyped 131 individuals and found 45 nucleotide alleles (27 amino acid alleles) indicating a maximum of 3 loci (1–5 alleles per individual). We observed high allelic admixture and a lack of genetic differentiation both among sampling sites and between pre‐ and post‐WNS populations, indicating no signal of selection on MHC genes. However, post‐WNS populations exhibited decreased allelic richness, reflecting effects from bottleneck and drift following rapid population declines. We propose that mechanisms other than adaptive immunity are more likely driving current persistence of little brown bats in affected regions. 相似文献
4.
The class I genes of the major histocompatibility complex (Mhc) are here investigated for the first time in a passerine bird. The great reed warbler is a rare species in Sweden with a
few semi-isolated populations. Yet, we found extensive Mhc class I variation in the study population. The variable exon 3, corresponding to the α2 domain, was amplified from genomic DNA with degenerated primers. Seven different genomic class I sequences were detected
in a single individual. One of the sequences had a deletion leading to a shift in the reading frame, indicating that it was
not a functional gene. A randomly selected clone was used as a probe for restriction fragment length polymorphism (RFLP) studies
in combination with the restriction enzyme Pvu II. The RFLP pattern was complex with 21–25 RFLP fragments per individual and extensive variation. Forty-nine RFLP genotypes
were detected in 55 tested individuals. To study the number of transcribed genes, we isolated 14 Mhc class I clones from a cDNA library from a single individual. We found eight different sequences of four different lengths
(1.3–2.2 kilobases), suggesting there are at least four transcribed loci. The number of nonsynonymous substitutions (d
N
) in the peptide binding region of exon 3 were higher than the number of synonymous substitutions (d
S
), indicating balancing selection in this region. The number of transcribed genes and the numerous RFLP fragments found so
far suggest that the great reed warbler does not have a "minimal essential Mhc" as has been suggested for the chicken.
Received: 13 May 1998 / Revised: 18 August 1998 相似文献
5.
Donald C. Dearborn Andrea B. Gager Andrew G. McArthur Morgan E. Gilmour Elena Mandzhukova Robert A. Mauck 《Molecular ecology》2016,25(17):4355-4367
Genes of the major histocompatibility complex (MHC) exhibit heterozygote advantage in immune defence, which in turn can select for MHC‐disassortative mate choice. However, many species lack this expected pattern of MHC‐disassortative mating. A possible explanation lies in evolutionary processes following gene duplication: if two duplicated MHC genes become functionally diverged from each other, offspring will inherit diverse multilocus genotypes even under random mating. We used locus‐specific primers for high‐throughput sequencing of two expressed MHC Class II B genes in Leach's storm‐petrels, Oceanodroma leucorhoa, and found that exon 2 alleles fall into two gene‐specific monophyletic clades. We tested for disassortative vs. random mating at these two functionally diverged Class II B genes, using multiple metrics and different subsets of exon 2 sequence data. With good statistical power, we consistently found random assortment of mates at MHC. Despite random mating, birds had MHC genotypes with functionally diverged alleles, averaging 13 amino acid differences in pairwise comparisons of exon 2 alleles within individuals. To test whether this high MHC diversity in individuals is driven by evolutionary divergence of the two duplicated genes, we built a phylogenetic permutation model. The model showed that genotypic diversity was strongly impacted by sequence divergence between the most common allele of each gene, with a smaller additional impact of monophyly of the two genes. Divergence of allele sequences between genes may have reduced the benefits of actively seeking MHC‐dissimilar mates, in which case the evolutionary history of duplicated genes is shaping the adaptive landscape of sexual selection. 相似文献
6.
Baojun Zhao Xue Zhang Bo Li Pengfei Du Lupeng Shi Yuehuan Dong Xiaodong Gao Weilai Sha Honghai Zhang 《Ecology and evolution》2020,10(7):3439-3449
The molecules encoded by major histocompatibility complex (MHC) genes play an essential role in the adaptive immune response among vertebrates. We investigated the molecular evolution of MHC class I genes in the sable Martes zibellina. We isolated 26 MHC class I sequences, including 12 putatively functional sequences and 14 pseudogene sequences, from 24 individuals from two geographic areas of northeast China. The number of putatively functional sequences found in a single individual ranged from one to five, which might be at least 1–3 loci. We found that both balancing selection and recombination contribute to evolution of MHC class I genes in M. zibellina. In addition, we identified a candidate nonclassical MHC class I lineage in Carnivora, which may have preceded the divergence (about 52–57 Mya) of Caniformia and Feliformia. This may contribute to further understanding of the origin and evolution of nonclassical MHC class I genes. Our study provides important immune information of MHC for M. zibellina, as well as other carnivores. 相似文献
7.
The major histocompatibility complex (MHC) is central to the vertebrate immune system and its highly polymorphic genes are considered to influence several life-history traits of individuals. To characterize the MHC in a natural population of blue tits (Cyanistes caeruleus) we investigated the class I exon 3 diversity of more than 900 individuals. We designed two pairs of motif-specific primers that reliably amplify independent subsets of MHC alleles. Applying denaturing gradient gel electrophoresis (DGGE) we obtained 48 independently inherited units of unique band patterns (DGGE-haplogroups), which were validated in a segregation analysis within 105 families. In a second approach, we extensively sequenced 6 unrelated individuals to confirm that DGGE-haplogroup composition reflects individual allelic variation. The highest number of different DGGE-haplogroups in a single individual corresponded in 19 MHC exon 3 sequences, suggesting a minimum of 10 amplified MHC class I loci in the blue tit. In total, we identified 50 unique functional and 3 non-functional sequences. Functional sequences showed high levels of recombination and strong positive selection in the antigen binding region, whereas nucleotide diversity was comparatively low in the range of all passerine species. Finally, in a phylogenetic comparison of passerine MHC class I exon 3 sequences we discuss conflicting evolutionary signals possibly due to recent gene duplication, recombination events and concerted evolution. Our results indicate that the described method is suitable to effectively explore the MHC diversity and its ecological impacts in blue tits in future studies. 相似文献
8.
The strength of the association between heterozygosity and probability of interannual local recruitment increases with environmental harshness in blue tits
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Esperanza S. Ferrer Vicente García‐Navas Juan José Sanz Joaquín Ortego 《Ecology and evolution》2016,6(24):8857-8869
The extent of inbreeding depression and the magnitude of heterozygosity–fitness correlations (HFC) have been suggested to depend on the environmental context in which they are assayed, but little evidence is available for wild populations. We combine extensive molecular and capture–mark–recapture data from a blue tit (Cyanistes caeruleus) population to (1) analyze the relationship between heterozygosity and probability of interannual adult local recruitment and (2) test whether environmental stress imposed by physiologically suboptimal temperatures and rainfall influence the magnitude of HFC. To address these questions, we used two different arrays of microsatellite markers: 14 loci classified as neutral and 12 loci classified as putatively functional. We found significant relationships between heterozygosity and probability of interannual local recruitment that were most likely explained by variation in genomewide heterozygosity. The strength of the association between heterozygosity and probability of interannual local recruitment was positively associated with annual accumulated precipitation. Annual mean heterozygosity increased over time, which may have resulted from an overall positive selection on heterozygosity over the course of the study period. Finally, neutral and putatively functional loci showed similar trends, but the former had stronger effect sizes and seemed to better reflect genomewide heterozygosity. Overall, our results show that HFC can be context dependent, emphasizing the need to consider the role of environmental heterogeneity as a key factor when exploring the consequences of individual genetic diversity on fitness in natural populations. 相似文献
9.
Jostein Gohli Erica H. Leder Eduardo Garcia‐del‐Rey Lars Erik Johannessen Arild Johnsen Terje Laskemoen Magnus Popp Jan T. Lifjeld 《Molecular ecology》2015,24(1):180-191
A common challenge in phylogenetic reconstruction is to find enough suitable genomic markers to reliably trace splitting events with short internodes. Here, we present phylogenetic analyses based on genomewide single‐nucleotide polymorphisms (SNPs) of an enigmatic avian radiation, the subspecies complex of Afrocanarian blue tits (Cyanistes teneriffae). The two sister species, the Eurasian blue tit (Cyanistes caeruleus) and the azure tit (Cyanistes cyanus), constituted the out‐group. We generated a large data set of SNPs for analysis of population structure and phylogeny. We also adapted our protocol to utilize degraded DNA from old museum skins from Libya. We found strong population structuring that largely confirmed subspecies monophyly and constructed a coalescent‐based phylogeny with full support at all major nodes. The results are consistent with a recent hypothesis that La Palma and Libya are relic populations of an ancient Afrocanarian blue tit, although a small data set for Libya could not resolve its position relative to La Palma. The birds on the eastern islands of Fuerteventura and Lanzarote are similar to those in Morocco. Together they constitute the sister group to the clade containing the other Canary Islands (except La Palma), in which El Hierro is sister to the three central islands. Hence, extant Canary Islands populations seem to originate from multiple independent colonization events. We also found population divergences in a key reproductive trait, viz. sperm length, which may constitute reproductive barriers between certain populations. We recommend a taxonomic revision of this polytypic species, where several subspecies should qualify for species rank. 相似文献
10.
V. García‐Navas E. S. Ferrer J. J. Sanz J. Ortego 《Journal of evolutionary biology》2014,27(8):1590-1603
Dispersal and local patterns of adaptation play a major role on the ecological and evolutionary trajectory of natural populations. In this study, we employ a combination of genetic (25 microsatellite markers) and field‐based information (seven study years) to analyse the impact of immigration and local patterns of adaptation in two nearby (< 7 km) blue tit (Cyanistes caeruleus) populations. We used genetic assignment analyses to identify immigrant individuals and found that dispersal rate is female‐biased (72%). Data on lifetime reproductive success indicated that immigrant females produced fewer local recruits than their philopatric counterparts whereas immigrant males recruited more offspring than those that remained in their natal location. In spite of the considerably higher immigration rates of females, our results indicate that, in absolute terms, their demographic and genetic impact in the receiving populations is lower than that in immigrant males. Immigrants often brought novel alleles into the studied populations and a high proportion of them were transmitted to their recruits, indicating that the genetic impact of immigrants is not ephemeral. Although only a few kilometres apart, the two study populations were genetically differentiated and showed strong divergence in different phenotypic and life‐history traits. An almost absent inter‐population dispersal, together with the fact that both populations receive immigrants from different source populations, is probably the main cause of the observed pattern of genetic differentiation. However, phenotypic differentiation (PST) for all the studied traits greatly exceeded neutral genetic differentiation (FST), indicating that divergent natural selection is the prevailing factor determining the evolutionary trajectory of these populations. Our study highlights the importance of integrating individual‐ and population‐based approaches to obtain a comprehensive view about the role of dispersal and natural selection on structuring the genotypic and phenotypic characteristics of natural populations. 相似文献
11.
Rebekah A. Oomen Roxanne M. Gillett Christopher J. Kyle 《Molecular ecology resources》2013,13(1):103-116
Characterization and population genetic analysis of multilocus genes, such as those found in the major histocompatibility complex (MHC) is challenging in nonmodel vertebrates. The traditional method of extensive cloning and Sanger sequencing is costly and time‐intensive and indirect methods of assessment often underestimate total variation. Here, we explored the suitability of 454 pyrosequencing for characterizing multilocus genes for use in population genetic studies. We compared two sample tagging protocols and two bioinformatic procedures for 454 sequencing through characterization of a 185‐bp fragment of MHC DRB exon 2 in wolverines (Gulo gulo) and further compared the results with those from cloning and Sanger sequencing. We found 10 putative DRB alleles in the 88 individuals screened with between two and four alleles per individual, suggesting amplification of a duplicated DRB gene. In addition to the putative alleles, all individuals possessed an easily identifiable pseudogene. In our system, sequence variants with a frequency below 6% in an individual sample were usually artefacts. However, we found that sample preparation and data processing procedures can greatly affect variant frequencies in addition to the complexity of the multilocus system. Therefore, we recommend determining a per‐amplicon‐variant frequency threshold for each unique system. The extremely deep coverage obtained in our study (approximately 5000×) coupled with the semi‐quantitative nature of pyrosequencing enabled us to assign all putative alleles to the two DRB loci, which is generally not possible using traditional methods. Our method of obtaining locus‐specific MHC genotypes will enhance population genetic analyses and studies on disease susceptibility in nonmodel wildlife species. 相似文献
12.
MHC‐I provides both quantitative resistance and susceptibility to blood parasites in blue tits in the wild
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J. Rivero‐de Aguilar H. Westerdahl J. Martínez‐de la Puente G. Tomás J. Martínez S. Merino 《Journal of avian biology》2016,47(5):669-677
Major histocompatibility complex (MHC) genes are central for the adaptive immune response against parasites. Here, we investigated potential associations among MHC‐I alleles and blood parasite infections in a natural breeding population of a passerine bird, the blue tit Cyanistes caeruleus, in central Spain. We screened both infection status (presence/absence of infection) and infection intensity to the pathogenic blood parasites Haemoproteus and Leucocytozoon. Three MHC‐I alleles (UA104, UA108 and UA117) were associated with higher or lower infection intensities by Leucocytozoon. Interestingly, these associations were dependent on age and were found both among young and adult birds. No MHC alleles were associated with infection intensity by Haemoproteus parasites. In addition, no significant relationships were detected between infection status by Haemoproteus and Leucocytozoon infections and MHC alleles. The very high prevalence of these two parasites in our study population (79–100%) poses challenges to identify associations with infection status and also suggests that clearance of infections may be rare. In conclusion, associations between specific MHC‐I alleles and Leucocytozoon parasites were related to either high or low infection intensities, and hence increased susceptibility or resistance to infection. 相似文献
13.
Rapid diagnosis of rice bakanae caused by Fusarium fujikuroi and F. proliferatum using loop‐mediated isothermal amplification assays
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Zhenyang Rong Yongtian Yuan Wenwu Ye Xiaoli Wang Xiaobo Zheng 《Journal of Phytopathology》2018,166(4):283-290
Rice bakanae is an important disease that causes serious rice production loss worldwide. We describe a new method for rapid diagnosis of rice bakanae caused by Fusarium fujikuroi and F. proliferatum, based on loop‐mediated isothermal amplification (LAMP) assays. After screening, primers were selected to target FusariumDNA sequences, that is, the intergenic spacer (IGS) region of the nuclear ribosomal operon and reductase‐coding region (RED1) in F. fujikuroi and F. proliferatum, respectively. Both LAMP assays efficiently amplified target genes in 70 min at 62°C. A colour change from purple to sky blue (visible to the unaided eye) was observed in the presence of the DNA of the targeted pathogens only, by adding hydroxynaphthol blue to the reaction system prior to amplification. The minimum of genomic DNA needed in the assays was 67 and 346 pg/μl for F. fujikuroi and F. proliferatum, respectively. Using the two assays described here, we successfully and rapidly diagnosed suspected diseased rice plant and seed samples collected from Jiangsu Province. 相似文献
14.
Natural selection on MHC IIβ in parapatric lake and stream stickleback: Balancing,divergent, both or neither?
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Major histocompatibility complex (MHC) genes encode proteins that play a central role in vertebrates' adaptive immunity to parasites. MHC loci are among the most polymorphic in vertebrates' genomes, inspiring many studies to identify evolutionary processes driving MHC polymorphism within populations and divergence between populations. Leading hypotheses include balancing selection favouring rare alleles within populations, and spatially divergent selection. These hypotheses do not always produce diagnosably distinct predictions, causing many studies of MHC to yield inconsistent or ambiguous results. We suggest a novel strategy to distinguish balancing vs. divergent selection on MHC, taking advantage of natural admixture between parapatric populations. With divergent selection, individuals with immigrant alleles will be more infected and less fit because they are susceptible to novel parasites in their new habitat. With balancing selection, individuals with locally rare immigrant alleles will be more fit (less infected). We tested these contrasting predictions using three‐spine stickleback from three replicate pairs of parapatric lake and stream habitats. We found numerous positive and negative associations between particular MHC IIβ alleles and particular parasite taxa. A few allele–parasite comparisons supported balancing selection, and others supported divergent selection between habitats. But, there was no overall tendency for fish with immigrant MHC alleles to be more or less heavily infected. Instead, locally rare MHC alleles (not necessarily immigrants) were associated with heavier infections. Our results illustrate the complex relationship between MHC IIβ allelic variation and spatially varying multispecies parasite communities: different hypotheses may be concurrently true for different allele–parasite combinations. 相似文献
15.
Salma Lasram Souheib Oueslati Hatem Ben Jouira Samir Chebil Ahmed Mliki Abdelwahed Ghorbel 《Journal of Phytopathology》2013,161(4):280-283
To characterize Aspergillus section Nigri strains involved in the ochratoxin A (OTA) contamination of Tunisian wine and table grapes, a total of 33 strains were analysed. A molecular characterization of the isolates was performed by the amplification of internal transcribed spacer (ITS1‐5.8S rDNA‐ITS2) region combined with amplicon sequencing. Analysis of similarity between the obtained sequences and those deposited in the GenBank database was performed. Twelve strains were confirmed to belong to the Aspergillus carbonarius species. Strains belonging to the Aspergillus niger aggregate group were classified by in silico RFLP assay into two patterns N and T, corresponding to A. niger and Aspergillus tubingensis. Among the 21 OTA producing isolates analysed, 13 showed the T‐type pattern and 8 showed the N‐type pattern. The presented method showed to be a reliable alternative to the classic RFLP method. Our findings unambiguously revealed that multiple aspergilli species isolated from wine and table grape in Tunisia are able to produce OTA. 相似文献
16.
The major histocompatibility complex (MHC) has a central role in the specific immune defence of vertebrates. Exon 3 of MHC class I genes encodes the domain that binds and presents peptides from pathogens that trigger immune reactions. Here we develop a fast population screening method for detecting genetic variation in the MHC class I genes of birds. We found evidence of at least 15 exon 3 sequences in the investigated great reed warbler individual. The organisation of the great reed warbler MHC class I genes suggested that a locus-specific screening protocol is impractical due to the high similarity between alleles across loci, including the introns flanking exon 3. Therefore, we used motif-specific PCR to amplify two subsets of alleles (exon 3 sequences) that were separated with by DGGE. The motif-specific primers amplify a substantial proportion of the transcribed class I alleles (2-12 alleles per individual) from as many as six class I loci. Although not exhaustive, this gives a reliable estimate of the class I variation. The method is highly repeatable and more sensitive in detecting genetic variation than the RFLP method. The motif-specific primers also allow us to avoid screening pseudogenes. In our study population of great reed warblers, we found a high level of genetic variation in MHC class I, and no less than 234 DGGE genotypes were detected among 248 screened individuals. 相似文献
17.
Shadi Shokralla Joel F. Gibson Hamid Nikbakht Daniel H. Janzen Winnie Hallwachs Mehrdad Hajibabaei 《Molecular ecology resources》2014,14(5):892-901
DNA barcoding is an efficient method to identify specimens and to detect undescribed/cryptic species. Sanger sequencing of individual specimens is the standard approach in generating large‐scale DNA barcode libraries and identifying unknowns. However, the Sanger sequencing technology is, in some respects, inferior to next‐generation sequencers, which are capable of producing millions of sequence reads simultaneously. Additionally, direct Sanger sequencing of DNA barcode amplicons, as practiced in most DNA barcoding procedures, is hampered by the need for relatively high‐target amplicon yield, coamplification of nuclear mitochondrial pseudogenes, confusion with sequences from intracellular endosymbiotic bacteria (e.g. Wolbachia) and instances of intraindividual variability (i.e. heteroplasmy). Any of these situations can lead to failed Sanger sequencing attempts or ambiguity of the generated DNA barcodes. Here, we demonstrate the potential application of next‐generation sequencing platforms for parallel acquisition of DNA barcode sequences from hundreds of specimens simultaneously. To facilitate retrieval of sequences obtained from individual specimens, we tag individual specimens during PCR amplification using unique 10‐mer oligonucleotides attached to DNA barcoding PCR primers. We employ 454 pyrosequencing to recover full‐length DNA barcodes of 190 specimens using 12.5% capacity of a 454 sequencing run (i.e. two lanes of a 16 lane run). We obtained an average of 143 sequence reads for each individual specimen. The sequences produced are full‐length DNA barcodes for all but one of the included specimens. In a subset of samples, we also detected Wolbachia, nontarget species, and heteroplasmic sequences. Next‐generation sequencing is of great value because of its protocol simplicity, greatly reduced cost per barcode read, faster throughout and added information content. 相似文献
18.
Allelic diversity at major histocompatibility complex (MHC) genes is thought to be maintained by balancing selection over long periods of time, even across multiple speciation events. Trans-species sharing of MHC alleles among genera has been supported by many studies on mammals and fish, but in rodents, the results are ambiguous. We investigated natural levels of MHC-DRB variability and evolutionary processes in the wood mouse (Apodemus sylvaticus) and the yellow-necked mouse (Apodemus flavicollis), which are common, sympatric murid rodents in European forests. Using single-strand conformation polymorphism analysis and DNA sequencing, 38 DRB exon 2 alleles were detected among 162 A. sylvaticus from nine different locations in Germany and Switzerland, and 15 DRB exon 2 alleles were detected among 60 A. flavicollis from three different locations in northern Germany. There was evidence for balancing selection in both species. Phylogenetic analysis, including additional murid taxa, showed that the DRB exon 2 sequences did not separate according to species, consistent with trans-species evolution of the MHC in these taxa. 相似文献
19.
Rebecca L. Tallmadge Julie A. Campbell Donald C. Miller Douglas F. Antczak 《Immunogenetics》2010,62(3):159-172
The genomic sequences of 15 horse major histocompatibility complex (MHC) class I genes and a collection of MHC class I homozygous
horses of five different haplotypes were used to investigate the genomic structure and polymorphism of the equine MHC. A combination
of conserved and locus-specific primers was used to amplify horse MHC class I genes with classical and nonclassical characteristics.
Multiple clones from each haplotype identified three to five classical sequences per homozygous animal and two to three nonclassical
sequences. Phylogenetic analysis was applied to these sequences, and groups were identified which appear to be allelic series,
but some sequences were left ungrouped. Sequences determined from MHC class I heterozygous horses and previously described
MHC class I sequences were then added, representing a total of ten horse MHC haplotypes. These results were consistent with
those obtained from the MHC homozygous horses alone, and 30 classical sequences were assigned to four previously confirmed
loci and three new provisional loci. The nonclassical genes had few alleles and the classical genes had higher levels of allelic
polymorphism. Alleles for two classical loci with the expected pattern of polymorphism were found in the majority of haplotypes
tested, but alleles at two other commonly detected loci had more variation outside of the hypervariable region than within.
Our data indicate that the equine major histocompatibility complex is characterized by variation in the complement of class
I genes expressed in different haplotypes in addition to the expected allelic polymorphism within loci. 相似文献
20.
Gene flow does not prevent personality and morphological differentiation between two blue tit populations
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Gabrielle Dubuc‐Messier Samuel P. Caro Charles Perrier Kees van Oers Anne Charmantier 《Journal of evolutionary biology》2018,31(8):1127-1137
Understanding the causes and consequences of population phenotypic divergence is a central goal in ecology and evolution. Phenotypic divergence among populations can result from genetic divergence, phenotypic plasticity or a combination of the two. However, few studies have deciphered these mechanisms for populations geographically close and connected by gene flow, especially in the case of personality traits. In this study, we used a common garden experiment to explore the genetic basis of the phenotypic divergence observed between two blue tit (Cyanistes caeruleus) populations inhabiting contrasting habitats separated by 25 km, for two personality traits (exploration speed and handling aggression), one physiological trait (heart rate during restraint) and two morphological traits (tarsus length and body mass). Blue tit nestlings were removed from their population and raised in a common garden for up to 5 years. We then compared adult phenotypes between the two populations, as well as trait‐specific Qst and Fst. Our results revealed differences between populations similar to those found in the wild, suggesting a genetic divergence for all traits. Qst–Fst comparisons revealed that the trait divergences likely result from dissimilar selection patterns rather than from genetic drift. Our study is one of the first to report a Qst–Fst comparison for personality traits and adds to the growing body of evidence that population genetic divergence is possible at a small scale for a variety of traits including behavioural traits. 相似文献