| 1. |
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| 2. |
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| 3. |
- Arlt, D, et al.
(författare)
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Breeding synchrony does not affect extra-pair paternity in great reed warblers
- 2004
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Ingår i: Behaviour. - : Brill. - 1568-539X .- 0005-7959. ; 141:7, s. 863-880
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Tidskriftsartikel (refereegranskat)abstract
- Breeding synchrony is hypothesised to influence the occurrence and frequency of extra-pair fertilisations (EPFs) in birds irrespective of the social mating system. The two proposed hypotheses make opposite predictions. (1) Synchronous breeding leads to a lower frequency of EPFs because males face a trade-off between mate guarding and obtaining additional matings via extra-pair copulations (EPCs) ('guarding constraint' hypothesis). (2) Synchronous breeding promotes EPFs because females are able to compare displaying males simultaneously, which provides them with more reliable cues for extra-pair mate choice ('mate assessment' hypothesis). In a study of great reed warblers (Acrocephalus arundillaceus) from 1987-1998, annual breeding was asynchronous and the frequency of EPFs was rather low (extra-pair young occurring in 6.4% of the broods). Within this population, however, there was no relationship between the frequency of EPFs and breeding synchrony, thus not favouring any of the two hypotheses. Contrary to assumptions of the hypotheses, mate guarding did not seem to constrain males from engaging in EPCs (disfavouring the 'guarding constraint' hypothesis), and females seem to have repeated opportunities to compare males irrespective of breeding synchrony (disfavouring the 'mate assessment' hypothesis). Our results suggest that breeding synchrony is not an important factor influencing patterns of EPFs in great reed warblers. The low frequency of EPFs may instead be explained by the socially polygynous mating system, where females are less constrained in their choice of a social male.
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| 4. |
- Erlinge, Sam, et al.
(författare)
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Can vertebrate predators regulate their prey?
- 1984
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Ingår i: The American Naturalist. ; 123:1, s. 125-133
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Tidskriftsartikel (refereegranskat)abstract
- Whether vertebrate predators can regulate their prey or not has long been a controversial question. At the one extreme it has been claimed that predators have no impact on prey numbers but consume only a doomed surplus (Errington 1946), and at the other that predators strongly interact with their prey causing either stable equilibria or cycles (Tanner 1975; Keith et al. 1977). However,.there are no field studies showing a regulatory effect of predation among vertebrates. Here we report on such a study.
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| 5. |
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| 6. |
- Hansson, Bengt, et al.
(författare)
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Increase of genetic variation over time in a recently founded population of great reed warblers (Acrocephalus arundinaceus) revealed by microsatellites and DNA fingerprinting
- 2000
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 9:10, s. 1529-1538
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Tidskriftsartikel (refereegranskat)abstract
- Genetic similarity within pairs of individuals was examined using both 10 polymorphic microsatellite loci and multi-locus DNA fingerprinting profiles in a semi-isolated population of great reed warblers at Lake Kvismaren, south Central Sweden, in 1987-1993. The population was founded by a few individuals in 1978, followed by a gradual increase in numbers until 1988, since when the population has remained relatively stable with about 60 breeding birds. We have previously found that high genetic similarity between pairmates in the population during the early part of the study period reduced egg hatching success, and hence reproductive success. The measures of pairwise genetic similarity, microsatellite allele sharing and DNA fingerprinting band sharing, were highly correlated with pedigree-based relatedness. Both microsatellite and DNA fingerprinting similarities between pair-mates declined significantly over the study period, and the pattern was most pronounced in the DNA fingerprinting data. Analyses restricted to the microsatellite data showed that the average annual microsatellite similarity between pairwise combinations of individuals, as well as individual homozygosity in males, declined significantly over the study period, and that several immigrants carrying novel alleles entered the population during the study. Hence, the temporal decline in genetic similarity of mates in the population is probably a consequence of increased immigration, facilitated by the recent expansion of the species in the region. These results suggest that the population has now recovered genetically, or is in the process of recovering, from a recent founder event.
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| 7. |
- Hansson, Maria, et al.
(författare)
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Characterization of two distinct aryl hydrocarbon receptor (AhR2) genes in Atlantic salmon (Salmo salar) and evidence for multiple AhR2 gene lineages in salmonid fish
- 2003
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Ingår i: Gene. - 1879-0038. ; 303, s. 197-206
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Tidskriftsartikel (refereegranskat)abstract
- The aryl hydrocarbon receptor (AhR) mediates the toxicity of several environmental contaminants, e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin, and other halogenated hydrocarbons in vertebrates. This receptor initiates the transcription of several biotransformation enzymes, which in turn are responsible for causing severe harm to biological tissue. Here we describe the isolation and complete characterization of the first two AhR genes from the teleost fish Atlantic salmon (Salmo salar). The predicted amino acid sequences contain regions characteristic of other vertebrate AhRs including basic helix-loop-helix (bHLH) and PER-ARNT-SIM (PAS) domains but show little similarity to other vertebrate AhRs across the C-terminal half. Furthermore, they do not contain distinct Q-rich domains as found in the mammalian AhR, which is in line with previously described fish AhR genes. The salmon cDNAs encode 1106 and 1107 putative residues, respectively, approximately 50 amino acids longer than previously characterized AhR genes. Phylogenetic analyses demonstrated that the two salmon AhR sequences cluster within the AhR subfamily of the bHLH-PAS family, in a clade containing fish AhR2 genes. Although the two AbR2 forms are 92% identical at the amino acid level, the distribution of sequence differences and the presence of both forms in 30 tested individuals suggest that they are not allelic but derived from separate loci. Interestingly, they are not orthologs of the rainbow trout (Oncorhynchus mykiss) AhR2alpha and beta genes and the new salmon loci are therefore here designated AhR2gamma and AhR2delta. In line with this, PCR with DNA from rainbow trout revealed a new trout AhR locus that was more similar to the two salmon genes than to the trout AhR2alpha and beta genes, suggesting that the rainbow trout possesses at least three distinct AhR2 genes. The presence of multiple AhR genes in these species is probably a consequence of the genome duplications that occurred in the early evolution of fish and later also specifically in the salmonid lineage. Reverse transcription-PCR analyses revealed that both AhR2gamma and AhR2delta are transcribed in the liver, spleen and muscles of adult salmon.
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| 8. |
- Hansson, Maria, et al.
(författare)
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Polychlorinated biphenyl load, aryl hydrocarbon receptor, and cytochrome P4501A1 induction in a wild population of Atlantic salmon (Salmo salar) from the Baltic Sea
- 2006
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Ingår i: Environmental Toxicology and Chemistry. - 0730-7268. ; 25:8, s. 2197-2207
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Tidskriftsartikel (refereegranskat)abstract
- The toxicity induced by several environmental pollutants is mediated by the aryl hydrocarbon receptor (AHR), which controls the expression of many biotransformation genes, such as cytochrome P4501A1 (CYP1A1). Previous studies have indicated that fish populations can evolve tolerance to persistent chlorinated pollutants by down-regulating the AHR pathway. Here, we measure to what extent tissue loads of polychlorinated biphenyl (PCB) congeners and AHR genotypes contribute to biotransformation capacity in wild, foraging Atlantic salmon (Salmo salar L.) from the Baltic Sea. In muscle, the sum of the 21 most common PCB congeners (ΣPCB) was correlated with three extracted AHR agonists (PCBs 77/110, 118/123/149, and 105/132/153). Both the AHR agonists as well as ΣPCB were correlated with lipid content. The ΣPCB, controlled for the effects of sex and lipid content in muscle tissue, did not predict mRNA transcript levels of the measured AHRs (AHR2α, AHR2γ, and AHR2δ) or CYP1A1 in liver. However, all AHR2 mRNA transcript levels were positively correlated with CYP1A1 level. In turn, the CYP1A1 level was negatively correlated with concentration of the muscle-tissue antioxidant astaxanthin, suggesting that astaxanthin is depleted when biotransformation processes (CYP1A1) are activated. No correlation was found between ethoxyresorufin-O-deethylase activity and ΣPCB, CYP1A1, or antioxidant levels. In 5′-flanking regions of the AHR2 genes, we identified multiple allelic variants that were used for genotyping. The mRNA transcript level of AHR2α was significantly associated with the AHR2α 5′-flanking region genotype and with the interaction of the genotype and individual PCB level. These results suggest that in wild Atlantic salmon from the Baltic Sea, active production of AHR2 mRNA by means of PCB exposure may be affected by genetic polymorphisms at the AHR2 loci.
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| 9. |
- Hansson, Maria, et al.
(författare)
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Polychlorinated biphenyl (PCB) load, lipid reserves and biotransformation activity in migrating Atlantic salmon from River Mörrum, Sweden.
- 2009
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 157:12, s. 3396-3403
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Tidskriftsartikel (refereegranskat)abstract
- Atlantic salmon accumulate high levels of contaminants such as polychlorinated biphenyls (PCBs) in their lipids during the adult growth phase spent at sea. The lipids are later utilized during migration for swimming and biological adaptations. We hypothesize that migrating salmons' biotransformation processes are affected by the high levels of built-up PCBs compared to salmon that in a pre-migrational stage. For these analyses we sampled adult Atlantic salmon during migration in the Swedish River Mörrum and measured the 21 most common PCB congeners ( summation operatorPCB) and lipid levels in muscle tissue, aryl hydrocarbon receptor (AHR2) and cytochrome P4501A1 (CYP1A1) transcript levels as well as ethoxyresorufin-O-deethylase activity (EROD) in liver. We also determined which AHR2 genotypes the salmon carried. We show that EROD activity is correlated to CYP1A1 level but not to summation operatorPCB concentration. summation operatorPCB concentration does not predict levels of neither the AHR2 nor CYP1A1 genes. We find no associations between specific AHR2 transcription levels and AHR2 genotypes or a correlation between AHR2 and CYP1A1 transcription levels, which is in direct contrast to pre-migrational adult salmon from the Baltic Sea. When we compare River Mörrum to salmon we have previously sampled in the Baltic Sea we show that migrating salmon have significantly lower lipid levels in their muscles; higher muscle concentrations of summation operatorPCB on a lipid basis; and significantly lower CYP1A1 and EROD levels compared to salmon from the Baltic Sea. Also, transcript levels of three out of four AHR2 genes are significantly different. In conclusion, migrating Swedish Atlantic salmon carry higher concentrations of PCBs in their lipids compared to salmon in the Baltic Sea, but have lower activation of biotransformation genes and enzymes. Our results indicate that accumulated pollutants from the Baltic Sea are deactivated inside the migrating salmon's lipid tissues and increase in concentration when migration is initiated thereby limiting their impact on biotransformation processes.
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| 10. |
- Hansson, Maria, et al.
(författare)
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Unprecedented genomic diversity of AhR1 and AhR2 genes in Atlantic salmon (Salmo salar L.)
- 2004
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Ingår i: Aquatic Toxicology. - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 68:3, s. 219-232
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Tidskriftsartikel (refereegranskat)abstract
- Aryl hydrocarbon receptor (AhR) genes encode proteins involved in mediating the toxic responses induced by several environmental pollutants. Here, we describe the identification of the first two AhR1 (alpha and beta) genes and two additional AhR2 (alpha and beta) genes in the tetraploid species Atlantic salmon (Salmo salar L.) from a cosmid library screening. Cosmid clones containing genomic salmon AhR sequences were isolated using a cDNA clone containing the coding region of the Atlantic salmon AhR2gamma as a probe. Screening revealed 14 positive clones, from which four were chosen for further analyses. One of the cosmids contained genomic AhR sequences that were highly similar to the rainbow trout (Oncorhynchus mykiss) AhR2alpha and beta genes. SMART RACE amplified two complete, highly similar but not identical AhR type 2 sequences from salmon cDNA, which from phylogenetic analyses were determined as the rainbow trout AhR2alpha and beta orthologs. The salmon AhR2alpha and beta encode proteins of 1071 and 1058 residues, respectively, and encompass characteristic AhR sequence elements like a basic-helix-loop-helix (bHLH) and two PER-ARNT-SIM (PAS) domains. Both genes are transcribed in liver, spleen and muscle tissues of adult salmon. A second cosmid contained partial sequences, which were identical to the previously characterized AhR2gamma gene. The last two cosmids contained partial genomic AhR sequences, which were more similar to other AhR type 1 fish genes than the four characterized salmon AhR2 genes. However, attempts to amplify the corresponding complete cDNA sequences of the inserts proved very difficult, suggesting that these genes are non-functional or very weakly transcribed in the examined tissues. Phylogenetic analyses of the conserved regions did, however, clearly indicate that these two AhRs belong to the AhR type 1 clade and have been assigned as the Atlantic salmon AhR1alpha and AhR1beta genes. Taken together, these findings demonstrate that multiple AhR genes are present in Atlantic salmon genome, which likely is a consequence of previous genome duplications in the evolutionary past of salmonids. Plausible explanations for the high incidence of AhR genes in fish and more specifically in salmortids, like rapid divergences in specialized functions, are discussed.
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| 11. |
- Kjellman, Christian, et al.
(författare)
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Expression of TGF-beta isoforms, TGF-beta receptors, and SMAD molecules at different stages of human glioma
- 2000
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Ingår i: International Journal of Cancer. - 0020-7136. ; 89:3, s. 251-258
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Tidskriftsartikel (refereegranskat)abstract
- Human gliomas express TGF-beta but, so far the expression of downstream mediators has been investigated in only a few cell lines. We have examined tissue specimens of 23 gliomas: 3 astrocytomas grade II (AST), 8 anaplastic astrocytomas grade III (AAST), and 12 glioblastoma multiforme grade IV (GBM). We analyzed the mRNA expression of TGF-beta1, TGF-beta2, TGF-beta3, the TGF-beta receptors type I (TbetaR-I) and type II (TbetaR-II), Smad2, Smad3, and Smad4. mRNA expression of IL-10 and CD95 (FAS/APO-1) were also studied. We detected increased mRNA levels of the 3 TGF-beta isoforms, correlating with the degree of malignancy. TGF-beta3 mRNA was increased, particularly in AST and AAST, while TGF-beta1 and TGF-beta2 mRNAs were strongly expressed in GBM. TGF-beta normally up-regulates the TGF-beta receptors, and TbetaR-I and TbetaR-II showed stronger expression in all gliomas when compared to normal tissues. However, the mRNA expression of Smad2, Smad3, and Smad4 was decreased in GBM. IL-10 mRNA expression was detected in glioma tissues but not in glioma cell lines. No marked increase in the expression of soluble CD95 splicing variants was found in the gliomas compared with normal tissue. However, total CD95 mRNA was elevated among GBM tissues.
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| 12. |
- Langefors, Åsa, et al.
(författare)
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Allelic polymorphism in MHC class IIB in four populations of Atlantic salmon (Salmo salar)
- 2001
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Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 53:4, s. 329-336
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Tidskriftsartikel (refereegranskat)abstract
- We sequenced exon 2 of the MHC class II B gene in Atlantic salmon from the Baltic Sea and identified 17 different exon 2 alleles among 22 different restriction fragment length polymorphism haplotypes. The sequences differed at between I and 34 bases. Two different tests were used to estimate the importance of recombination in the generation of new alleles. Recombination events appear to have occurred between three and nine times. Only two pairs of sequences differed by less than five nucleotides', minimizing the importance of point mutations for generating new alleles. Phylogenetic analysis showed that sequences did not cluster according to populations, and genetic distances between populations were small compared to those obtained by allele frequency data. These results, together with the similarity found between exon 2 sequences from Baltic salmon and Norwegian salmon, indicate that all of the identified alleles were present in the ancient salmon population colonizing the Baltic rivers after the last glaciation.
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| 13. |
- Langefors, Åsa, et al.
(författare)
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Allelic variation of Mhc class II in Atlantic salmon; a population genetic analysis
- 1998
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 1365-2540 .- 0018-067X. ; 80:5, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the degree of genetic variation at a variable Mhc class II beta gene in four populations of Atlantic salmon Salmo salar by using RFLPs. The class II beta gene encodes the part of the Mhc class II molecule that contains the antigen binding region and is therefore essential for disease resistance. There was extensive genetic variation in all four populations; the expected heterozygosity (H-si) varied between 0.50 and 0.81. Heterozygosity tended to be higher in broods surviving a syndrome causing high mortalities (60-95%) in Swedish salmon hatcheries. Populations that had experienced more incidences of genetic bottlenecks (years when fewer than 60 adults had been used for breeding) and had a lower average effective population size (N-e), had a lower degree of heterozygosity. The four populations differed significantly in allele frequencies as measured by F-ST = 0.13 and Nei's genetic distance (D = 0.09 - infinity). Pairwise F-ST values varied between 0.01 and 0.23, all but one being highly significant, indicating a differentiation between the populations in Mhc class II beta. This study shows that the four populations of Atlantic salmon have a high degree of polymorphism in the Mhc class II beta gene. However, there was great variation between different hatcheries, both in heterozygosity levels and allele frequencies.
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| 14. |
- Langefors, Åsa, et al.
(författare)
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Association between major histocompatibility complex class IIB alleles and resistance to Aeromonas salmonicida in Atlantic salmon
- 2001
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 268:1466, s. 479-485
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Tidskriftsartikel (refereegranskat)abstract
- We have tested the importance of genetic variation in the major histocompatibility complex (MHC) class IIB in Atlantic salmon (Salmo salar) for survival after challenge with a highly virulent bacterial pathogen. Forty juvenile full siblings from each of 120 families were infected with the bacterium Aeromonas salmonicida, which causes high mortality in salmon due to furunculosis. Fishes from high-resistance (HR, < 35% mortality) and low-resistance (LR, > 80% mortality) families were screened for their MHC class IIB genotypes using the denaturing gradient gel electrophoresis (DGGE) technique. The exon 2 sequences, encoding the major part of the peptide-binding region, were established far each DGGE fragment. One allele, e, containing a missense single base substitution was significantly more prevalent in HR families than in LR families. An odds-ratio test showed that broods carrying this allele had a 12-fold higher chance of being HR than broods without the e allele. A second allele, i, showed significantly higher frequencies in uninfected and surviving individuals than in infected dead individuals. A third allele, j, tended to be more prevalent both in LR families and in individuals that had died of the infection. There was no correlation between MHC heterozygosity and resistance to A. salmonicida. Our results support the hypothesis that MHC polymorphism is maintained through pathogen-driven selection acting by means of frequency-dependent selection rather than heterozygous advantage.
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| 15. |
- Langefors, Åsa, et al.
(författare)
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Extra-pair fertilizations in the Sedge Warbler
- 1998
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 29:2, s. 134-144
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Tidskriftsartikel (refereegranskat)abstract
- Parentage of 201 young (from 44 broods) in a population of Sedge Warblers Acrocephalus schoenobaenus in South Central Sweden, 1990-1992, was determined by using multilocus DNA fingerprinting. The frequency of extra-pair young (EPY) was 7.5% and they occurred in 23% of the broods. For 11 out of 15 extra-pair young we could identify the true father; in all of the cases he was a close neighbour. Among ten broods with extra-pair young, nine contained only one extra-pair sire and the remaining brood two extra-pair sires. The frequency of EPF varied among years (1.8-11.8%). The seasonal timing of broods with and without extra-pair young did not differ, and the occurrence of extra-pair fertilizations (EPF) was not related to the length of the pair male's mate-guarding period. EPF were not related to breeding synchrony (estimated as the mean number of fertile females per day during a female's fertile period). Pairs whose nests contained extra-pair young had more territories within 100 m of their nest than pairs without extra-pair young. Females that engaged in EPF had fewer attractive (i.e. singing) males to choose among the day before and at the day they formed their pair bend. Moreover, in all but one case the extra-pair male was not singing (i.e. not available as pair mate) the day the EPF-female settled. Males that fertilized extra-pair young tended to arrive earlier and to have higher pairing success than both males that were cuckolded and other males. Hence, female Sedge Warblers engaged in extra-pair fertilizations with attractive male neighbours. These results are consistent with the hypotheses that females participating in EPF are seeking genetic benefits to their offspring, but we cannot exclude the alternative explanation that attractive males are more efficient in forcing females to accept EPF.
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| 16. |
- Langefors, Åsa, et al.
(författare)
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Screening of Mhc variation in Atlantic salmon (Salmo salar) : a comparison of restriction fragment length polymorphism (RFLP), denaturing gradient gel electrophoresis (DGGE) and sequencing
- 2000
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 9:2, s. 215-219
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Tidskriftsartikel (refereegranskat)abstract
- We compared three different molecular methods currently used for screening of Mhc variation in population studies of Atlantic salmon. Restriction fragment length polymorphism (RFLP) of the entire class II gene detected 22 haplotypes. Seventeen exon 2 sequences were obtained from individuals carrying the 22 haplotypes, two of which had not been detected by RFLP. The six alleles (27%) detected by RFLP and not by exon 2 sequencing probably resulted from sequence variation outside exon 2. Within exon 2, RFLP differentiated 88% of the sequences. Alternatively, denaturing gradient gel electrophoresis (DGGE) performed under two run conditions detected 94% of the sequence variation. Both RFLP using different probes, and the two PCR-based methods using three different primer pairs, suggest that there is only a single Mhc class II B gene in the Baltic populations of Atlantic salmon.
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| 17. |
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| 18. |
- Lillandt, B G, et al.
(författare)
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Family structure in the Siberian Jay as revealed by microsatellite analyses
- 2003
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Ingår i: The Condor: ornithological applications. - 0010-5422. ; 105:3, s. 505-514
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Tidskriftsartikel (refereegranskat)abstract
- The Siberian Jay (Perisoreus infaustus) lives in resident, territorial family groups outside the breeding season, but does not breed cooperatively. Thereby it offers an opportunity to study the evolution of territorial group living, without confounding effects of reproductive cooperation. During a long-term study in Finland 1974-2000, we observed Siberian Jay group composition in autumn. Using microsatellite analysis based on feather or blood samples we clarified kin relations within the groups. We found that out of 311 groups that included at least one more individual than the territory holders, 74% were nuclear families, including breeding birds and 1-3 retained offspring. However, 26% of the groups were not families, but consisted of pairs accompanied only by individuals that were not their offspring. According to extensive pedigrees we found that 70% of the 82 immatures associated with a nonparent pair were not related to either territory holder. Of these 82 immatures, 91% were associated with pairs that had no offspring on their own, suggesting that they were failed breeders or newly established pairs. The composition of groups was mostly unchanged during the observation period within each season, regardless of kinship. Previous studies have reported apparent nepotism between parents and retained offspring in the Siberian Jay, and a high degree of aggression toward nonoffspring, so we did not expect to find such high frequency and remarkable within-season stability of nonfamily groups. These observations suggest that there are important fitness benefits to gain from territoriality and group living, regardless of kinship.
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| 19. |
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| 20. |
- Lohm, Jakob, et al.
(författare)
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Experimental evidence for major histocompatibility complex-allele-specific resistance to a bacterial infection
- 2002
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 269:1504, s. 2029-2033
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Tidskriftsartikel (refereegranskat)abstract
- The extreme polymorphism found at some major histocompatibility complex (MHC) loci is believed to be maintained by balancing selection caused by infectious pathogens. Experimental support for this is inconclusive. We have studied the interaction between certain MHC alleles and the bacterium Aeromonas salmonicida, which causes the severe disease furunculosis, in Atlantic salmon (Salmo salar L.). We designed full-sibling broods consisting of combinations of homozygote and heterozygote genotypes with respect to resistance or susceptibility alleles. The juveniles were experimentally infected with A. salmonicida and their individual survival was monitored. By comparing full siblings carrying different MHC genotypes the effects on survival due to other segregating genes were minimized. We show that a pathogen has the potential to cause very intense selection pressure on particular MHC alleles; the relative fitness difference between individuals carrying different MHC alleles was as high as 0.5. A co-dominant pattern of disease resistance/susceptibility was found, indicative of qualitative difference in the immune response between individuals carrying the high- and low-resistance alleles. Rather unexpectedly, survival was not higher among heterozygous individuals as compared with homozygous ones.
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| 21. |
- Naurin, Sara, et al.
(författare)
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A microarray for large-scale genomic and transcriptional analyses of the zebra finch (Taeniopygia guttata) and other passerines
- 2008
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Ingår i: Molecular Ecology Notes. - : Wiley. - 1471-8278 .- 1755-098X. ; 8:2, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- The microarray technology has revolutionized biological research in the last decade. By monitoring the expression of many genes simultaneously, microarrays can elucidate gene function, as well as scan entire genomes for candidate genes encoding complex traits. However, because of high costs of sequencing and design, microarrays have largely been restricted to a few model species. Cross-species microarray (CSM) analyses, where microarrays are used for other species than the one they were designed for, have had varied success. We have conducted a CSM analysis by hybridizing genomic DNA from the common whitethroat (Sylvia communis) on a newly developed Affymetrix array designed for the zebra finch (Taeniopygia guttata), the Lund-zf array. The results indicate a very high potential for the zebra finch array to act as a CSM utility in other passerine birds. When hybridizing zebra finch genomic DNA, 98% of the gene representatives had higher signal intensities than the background cut-off, and for the common whitethroat, we found the equivalent proportion to be as high as 96%. This was surprising given the fact that finches and warblers diverged 25-50 million years ago, but may be explained by a relatively low sequence divergence between passerines (89-93%). Passerine birds are widely used in studies of ecology and evolution, and a zebra finch array that can be used for many species may have a large impact on future research directions.
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| 22. |
- Richardson, David, et al.
(författare)
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MHC-based patterns of social and extra-pair mate choice in the Seychelles warbler
- 2005
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 272:1564, s. 759-767
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Tidskriftsartikel (refereegranskat)abstract
- The existence and nature of indirect genetic benefits to mate choice remain contentious. Major histocompatibility complex (MHC) genes, which play a vital role in determining pathogen resistance in vertebrates, may be the link between mate choice and the genetic inheritance of vigour in offspring. Studies have shown that MHC-dependent mate choice can occur in mammal and fish species, but little work has focused on the role of the MHC in birds. We tested for MHC-dependent mating patterns in the Seychelles warbler (Acrocephalus sechellensis). There was no influence of MHC class I exon 3 variation on the choice of social mate. However, females were more likely to obtain extra-pair paternity (EPP) when their social mate had low MHC diversity, and the MHC diversity of the extra-pair male was significantly higher than that of the cuckolded male. There was no evidence that females were mating disassortatively, or that they preferred males with an intermediate number of MHC bands. Overall, the results are consistent with the I good genes' rather than the 'genetic compatibility' hypothesis. As female choice will result in offspring of higher MHC diversity, MHC-dependent EPP may provide indirect benefits in the Seychelles warbler if survival is positively linked to MHC diversity.
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| 23. |
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| 24. |
- Smith, Henrik, et al.
(författare)
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Adoption or infanticide: Options of replacement males in the European starling
- 1996
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 38:3, s. 191-197
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Tidskriftsartikel (refereegranskat)abstract
- The behaviour of a male bird towards a potential mate and her clutch may depend both on his expected paternity and on the likelihood that she will produce a replacement clutch if he commits infanticide. In this study we evaluate the choices made by replacement male European starlings Sturnus vulgaris. By removing males before and during laying, we induced other males, mainly neighbours, to mate with the reproductively active females. When the original male was removed before laying, a new male adopted the subsequent clutch in 14 out of 15 cases. When ten females were widowed during their laying period, replacement males never adopted their clutches. The paternity of replacement males was a function of when they replaced the former male. When replacement occurred more than 3 days before egglaying, the new male fathered nearly all offspring; when it occurred the day before laying, the new male still fathered more than every second young. When the original male was removed during his mate's laying period, in five out of ten cases a replacement male committed infanticide by throwing out the eggs, but this only occurred in one out of 15 cases when removal took place before laying. The evidence for infanticide actually being committed by the replacement male was circumstantial. Four out of six of the females affected by apparent infanticide produced replacement clutches in which the male presumably had higher paternity than in the original clutch. In all cases, the male adopted the replacement clutch. In five cases when the original male was removed during laying, the neighbours neither adopted the brood nor committed infanticide, although they sometimes were seen courting the widowed female and copulating with her. These cases occurred later during laying than those were males comitted infanticide. The time from infanticide to the laying of the replacement clutch tended to increase as infanticide was committed later in the laying sequence. We conclude that strategies of potential replacement males are influenced by their expected paternity in the current brood and the probability that the female will produce an early replacement clutch.
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| 25. |
- Smith, Henrik, et al.
(författare)
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Extra-Pair Paternity in the European Starling: The Effect of Polygyny
- 1993
-
Ingår i: The Condor: ornithological applications. - 0010-5422. ; 95:4, s. 1006-1015
-
Tidskriftsartikel (refereegranskat)abstract
- We determined the frequency of extra-pair paternity and intraspecific brood parasitism in European Starlings (Sturnus vulgaris) by performing multilocus DNA fingerprinting on 22 complete families from a population in southern Sweden. Among 92 nestlings, we did not detect any successful intraspecific brood parasitism. This confirms observational data that successful intraspecific brood parasitism is rare in this population. We detected eight extra-pair young. Except for one case, where all (two) nestlings were fathered by another male than the one attending the nest, no more than one nestling in each nest was fathered by an extra-pair male. Although the degree of extra-pair paternity was higher in nests of secondary females than in those of primary and monogamous females, this difference was not significant. There was no relationship between a male's paternity with his primary and secondary female during the same reason. There was a tendency for males to loose paternity in the broods of secondary females when the fertile periods of his females overlapped considerably. We suggest that the relative ease by which female Starlings can be mate-guarded, the fact that mate-attraction and mate-guarding do not have to be exclusive activities and the high within pair copulation frequency in Starlings may keep the degree of extra-pair paternity low.
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| 26. |
- Smith, Henrik, et al.
(författare)
-
Sperm competition in the European starling (Sturnus vulgaris): An experimental study of mate switching
- 1996
-
Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 263:1371, s. 797-801
-
Tidskriftsartikel (refereegranskat)abstract
- In apparently monogamous or polygynous birds, sperm from several males may compete to fertilize the eggs laid by one female. In this study we evaluate sperm competition in the European starling (Sturnus vulgaris) by means of a mate-switching experiment. Already-mated males were removed between 1-7 d before their mates started egg-laying, resulting in the female remating with a new male. The original males' parentage in the subsequent clutches was evaluated using DNA-fingerprinting. The original males fathered only two out of 46 eggs of those which were not likely to have been fertilized already when the males were removed. The low success of the original males can be attributed to a high within-pair copulation frequency during the assumed fertile period before laying and throughout the laying period, resulting in replacement males fathering most offspring. Thus the success of extra-pair copulations more than 2 d before egg-laying is probably very low. The results are discussed in relation to contrasting results from other mate-switching studies.
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| 27. |
- Tufvesson, M., et al.
(författare)
-
Selection for sexual male characters and their effects on other fitness related traits in white leghorn chickens
- 1999
-
Ingår i: Journal of Animal Breeding and Genetics. - : Wiley. - 0931-2668. ; 116:2, s. 127-138
-
Tidskriftsartikel (refereegranskat)abstract
- The size and shape of the cockerel comb, ran be regarded as secondary sexual characters or sexual ornaments. Sexual characters are assumed to be costly to express and the expression of a secondary sexual character is suggested to be favourably correlated with the bearer's condition or fitness. The aim of this study was to clarify the effects of selection for male sexual characters, the correlated responses in other male traits and whether selection for sexual characters affects viability. Two selection lines (lines S and H) and a control line was used for 10 generations. Line S was selected for male comb size at 29 weeks of age and from generation six onwards, comb shape (the way the cockerel bear his comb) was added. Line H was selected for high concentration of hyaluronic acid (HA) in the comb at 28 weeks of age. The average number of animals of each sex and;election line was 560 and the randomly mated control line comprised an average of 150 animals of each sex per generation. Traits recorded an analysed were comb size (CS) and body weight (BW) at 29 weeks of age, comb shape (SH) at 32 weeks of age, comb weight (CW) after slaughter and mortality (M). In line S, the genetic and phenotypic trends increased for CS, CW and BW. Both CS and SH are traits involved in the impression of comb size as visualized by females during male choice and by males during male-male competition. With artificial upward selection for the male character CS (line S), CS, CW, BW and M also increased but SH was impaired. When adding SH to the selection criteria in line S, the negative generic trend for SH was changed to positive. As CS approaches its environmental limit, the heritability and genetic progress can be expected to decline. It seems that 10 generations of selection for increased CS is not enough to reach the environmental limit at which CS is expected to stabilize at an optimum size determined by natural selection.
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| 28. |
- von Schantz, Torbjörn, et al.
(författare)
-
Artificial selection for increased comb size and its effects on other sexual characters and viability in gallus-domesticus (the domestic chicken)
- 1995
-
Ingår i: Heredity. - : Springer Science and Business Media LLC. - 1365-2540 .- 0018-067X. ; 75:5, s. 518-529
-
Tidskriftsartikel (refereegranskat)abstract
- The expression of secondary ornaments is often positively correlated with the bearer's condition. So far no study has reported on consequences of directional selection on male sexual ornaments in birds, i.e. it is unknown to what extent male sexual traits are genetically correlated and whether selection for secondary ornaments affects viability. In this study we estimate phenotypic and genotypic parameters of three male sexual traits, namely comb size, spur length and testes mass, by using two different lines of domestic chickens (Gallus domesticus). One of the two lines had been artificially selected for large comb size during nine generations whereas the other line was a randomly mated control line. As a result of the selection, male comb size was almost doubled. Data from the selection line indicate that comb size was negatively genetically correlated with testes mass and spur length. The cockerels from the selection line had accordingly lighter testes and shorter spurs than cockerels from the control line. A simple mate choice experiment with females and males from both lines indicated that preferred males had a larger joint expression of comb size and spur length than nonpreferred males. Data from three different selection lines, all with enlarged comb size, clearly reveal a negative effect of comb size on male viability.
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| 29. |
- von Schantz, Torbjörn, et al.
(författare)
-
Female choice - Reply
- 1989
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 339:6224, s. 432-433
-
Tidskriftsartikel (refereegranskat)
|
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| 30. |
- von Schantz, Torbjörn, et al.
(författare)
-
Female choice selects for a viability-based male trait in pheasants
- 1989
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 337, s. 166-169
-
Tidskriftsartikel (refereegranskat)abstract
- Recent theory on sexual selection1–4 suggests that females in species without paternal care choose mates by their secondary sexual characters because these indicate genotypic quality which will be transmitted to the offspring. These ideas are not yet empiri-cally supported as data quantifying the relationship between female mate choice and female reproductive success are lacking. Only in one case, in Colias butterflies, has it been demonstrated unequivo-cally that females choose 'good genotypes' as mates5 and there is only one study, on Drosophila, demonstrating that mate choice increases one component of offspring fitness6. Spur length of male pheasants (Phasianus colchicus) correlates with various fitness-related properties7. We here present the first experimental field data showing that female pheasants select mates on the basis of male spur length and that female mate choice correlates with female reproductive success.
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| 31. |
- von Schantz, Torbjörn, et al.
(författare)
-
Genetics of long-spurred pheasants - Reply
- 1990
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 343:6259, s. 600-600
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract is not available
|
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| 32. |
- von Schantz, Torbjörn, et al.
(författare)
-
Good genes, oxidative stress and condition-dependent sexual signals
- 1999
-
Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 266:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- The immune and the detoxication systems of animals are characterized by allelic polymorphisms, which underlie individual differences in ability to combat assaults from pathogens and toxic compounds. Previous studies have shown that females may improve offspring survival by selecting mates on the basis of sexual ornaments and signals that honestly reveal health. In many cases the expression of these ornaments appears to be particularly sensitive to oxidative stress. Activated immune and detoxication systems often generate oxidative stress by an extensive production of reactive metabolites and free radicals. Given that tolerance or resistance to toxic compounds and pathogens can be inherited, female choice should promote the evolution of male ornaments that reliably reveal the status of the bearers' level of oxidative stress. Hence, oxidative stress may be one important agent linking the expression of sexual ornaments to genetic variation in fitness-related traits, thus promoting the evolution of female mate choice and male sexual ornamentation, a controversial issue in evolutionary biology ever since Darwin.
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| 33. |
- von Schantz, Torbjörn, et al.
(författare)
-
Intersexual selection and reproductive success in the pheasant Phasianus colchicus
- 1994
-
Ingår i: American Naturalist. - 0003-0147. ; 144:3, s. 510-527
-
Tidskriftsartikel (refereegranskat)abstract
- Some recent sexual selection models predict that female choice in species without paternal care may function to discriminate among males in order to pass ''good genes'' to offspring. Data quantifying the relationship between female mate choice and reproductive success are scarce. In a Swedish population of pheasants females prefer to mate with long-spurred males. Male viability also correlates with male spur length. We used DNA fingerprinting to measure individual pheasants' reproductive success in terms of both hatchlings and surviving offspring. The data show that long-spurred males sired more hatchlings and surviving offspring and also that the females' production of surviving offspring correlated with their mate's spur length. The analyses also indicate that offspring of females who mated with long-spurred males experienced an increased survival rate.
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| 34. |
- von Schantz, Torbjörn, et al.
(författare)
-
Mate choice, male condition-dependent ornamentation and MHC in the pheasant
- 1997
-
Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 1601-5223 .- 0018-0661. ; 127:2, s. 133-140
-
Tidskriftsartikel (refereegranskat)abstract
- The Hamilton and Zuk model predicts that genes for resistance to various pathogens may be continuously heritable due to selection disequilibria caused by coadaptional cycles of hosts and pathogens. The model further suggests that the expression of male secondary ornaments is condition-dependent and that only individuals with superior genetic disease resistance and vigour can fully express exaggerated secondary ornaments. Female choice is therefore expected to discriminate among males on the basis of secondary sexual characters in order to pass on genes for disease resistance that improve fitness in the offspring. In wild ring-necked pheasants, Phasianus colchicus, of the Revinge area in southern Sweden, females prefer to mate with long-spurred males and data on reproductive success indicate that they may improve their chicks' survival rate by doing so. Male spur length is positively correlated with age, body size and viability. MHC genotyping for both class I and class II B of pheasant males trapped in the study area identified eight MHC haplotypes and a total of 17 different MHC genotypes. Multivariate analyses revealed that MHC genotype is significantly associated with variation in both male spur length and male viability. These data indicate that polymorphic genes with a central role in immune recognition can be associated with viability and the expression of a condition-dependent intersexually selected male trait, thus supporting essential parts of the Hamilton and Zuk model.
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| 35. |
- von Schantz, Torbjörn, et al.
(författare)
-
MHC genotype and male ornamentation: Genetic evidence for the Hamilton-Zuk model
- 1996
-
Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 263:1368, s. 265-271
-
Tidskriftsartikel (refereegranskat)abstract
- The major histocompatibility complex (MHC) is an immunologically important cluster of highly variable genes that is known to affect fitness in domesticated mammals and birds. Spur length of male pheasants in southern Sweden correlates with male viability, female mate choice, and offspring survival rate. Here we show by genetic analyses that the MHC genotype is associated with variation in both male spur length and male viability. These are the first data that directly support a 'good genes' hypothesis by Hamilton and Zuk predicting that females discriminate among males on the basis of secondary sexual characters in order to pass on genes for disease resistance that improve fitness in their offspring.
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| 36. |
- Wennerberg, Liv, et al.
(författare)
-
Genetic and morphological variation in Dunlin Calidris alpina breeding in the Palearctic tundra
- 1999
-
Ingår i: Ibis. - 0019-1019. ; 141:3, s. 391-398
-
Tidskriftsartikel (refereegranskat)abstract
- The extensive overlap in morphological characters between populations of Dunlin Calidris alpina imposes problems of determining the origin of migrating and wintering birds. The morphology of the birds also varies between the sexes, and the sex of a Dunlin may often be difficult to determine. To clarify if mitochondrial DNA can be used to identify which breeding areas migrating Dunlin come from, we investigated the occurrence of different mtDNA haplotypes in Dunlin from eight breeding areas on the Russian and Siberian tundra. Four haplotypes were found and at most sites more than one haplotype occurred. The European haplotype predominated in the area west of the Taymyr Peninsula, the Siberian haplotype in central Siberia (from the Taymyr Peninsula to the Lopatka Peninsula) and the Beringian haplotype in eastern Siberia. One individual of an Alaskan haplotype, not detected previously among breeding birds outside North America, was found on Wrangel Island. The sex of each bird was identified genetically and the morphology of males and females was analysed separately. Birds with the European haplotype were generally smaller than birds with the Beringian or Alaskan haplotypes. Birds possessing the Siberian haplotype showed intermediate values in most cases. After compensating for differences between sites, males with the Siberian haplotype had significantly longer bills than males having the European haplotype. Multiple regressions indicate that mitochondrial DNA analysis improves models estimating the breeding origin of migrating Dunlin.
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| 37. |
|
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| 38. |
- Westerdahl, Helena, et al.
(författare)
-
Associations between malaria and MHC genes in a migratory songbird
- 2005
-
Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 272:1571, s. 1511-1518
-
Tidskriftsartikel (refereegranskat)abstract
- Malaria parasites are a widespread and species-rich group infecting many wild populations of mammals, birds and reptiles. Studies on humans have demonstrated that genetic factors play a key role in the susceptibility and outcome of malaria infections. Until the present study, it has not been examined whether genetic variation in hosts is important for the outcome of malaria infections in natural avian populations. We investigated associations between major histocompatibility complex (MHC) genes and prevalence of three different avian malaria parasites (Haemoproteus payevshyi (GRW1), Plasmodium sp. (GRW2) and Plasmodium sp. (GRW4)) in a long-term study of great reed warblers Acrocephalus arundinaceus. We hypothesized that the MHC genes could either give full protection against a malaria infection, or confer protection against lethal malaria and direct the infection towards being milder. We found a positive association between numbers of MHC class I alleles (a measure of level of heterozygosity) and prevalence of the GRW2 parasite, suggesting the latter scenario. There was also a positive association between a specific MHC allele (B4b), previously shown to be under frequency-dependent selection in the study population, and prevalence of GRW2. These associations suggest that individuals carrying either a large number of MHC alleles or a specific MHC allele are protected against lethal malaria infections.
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| 39. |
- Westerdahl, Helena, et al.
(författare)
-
Brood sex ratios, female harem status and resources for nestling provisioning in the great reed warbler (Acrocephalus arundinaceus)
- 2000
-
Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 47:5, s. 312-318
-
Tidskriftsartikel (refereegranskat)abstract
- The theory of parental investment and brood sex ratio manipulation predicts that parents should invest in the more costly sex during conditions when resources are abundant. In the polygynous great reed warbler, Acrocephalus arundinaceus. females of primary harem status have more resources for nestling provisioning than secondary females, because polygynous males predominantly assist the primary female whereas the secondary female has to feed her young alone. Sons weigh significantly more than daughters, and are hence likely to be the more costly sex. In the present study, we measured the brood sex ratio when the chicks were 9 days old, i.e. the fledging sex ratio. As expected from theory, we found that female great reed warblers of primary status had a higher proportion of sons in their broods than females of lower (secondary) harem status. This pattern is in accordance with the results from two other species of marsh-nesting polygynous birds, the oriental reed warbler, Acrocephalus orientalis, and the yellow-headed blackbird Xanthocephalus xanthocephalus. As in the oriental reed warbler, we found that great reed warbler males increased their share of parental care as the proportion of sons in the brood increased. We did not find any difference in fitness of sons and daughters raised in primary and secondary nests. The occurrence of adaptive sex ratio manipulations in birds has been questioned, and it is therefore important that three studies of polygynous bird species, including our own, have demonstrated the same pattern of a male-biased offspring sex ratio in primary compared with secondary nests.
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| 40. |
- Westerdahl, Helena, et al.
(författare)
-
MHC class I typing in a songbird with numerous loci and high polymorphism using motif-specific PCR and DGGE
- 2004
-
Ingår i: Heredity. - : Springer Science and Business Media LLC. - 1365-2540 .- 0018-067X. ; 92:6, s. 534-542
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 41. |
- Westerdahl, Helena, et al.
(författare)
-
Mhc diversity in two passerine birds: no evidence far a minimal essential Mhc
- 2000
-
Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 52:1-2, s. 92-100
-
Tidskriftsartikel (refereegranskat)abstract
- Humans express an array of Mhc genes, while the chicken has an Mhc that is relatively small and compact with fewer expressed genes. Here we ask whether the "minimal essential Mhc" of the chicken is representative for birds. We investigated the RFLP genotypes in 55 great reed warblers Acrocephalus arundinaceus and 10 willow warblers Phylloscopus trochilus to obtain an overview of the number of class II B genes. There were 13-17 bands per individual in the great reed warblers and 25-30 in the willow warblers, and every individual had a unique RFLP genotype. The high number of RFLP bands indicates that both species have a large number of class II B genes although some may be pseudogenes. Seven different class II B sequences were detected in a great reed warbler cDNA library. There was considerable sequence divergence between the cDNA sequences in exon 2 (peptide-binding region, PBR), whereas they were very similar in exon 3. The cDNA sequences were easily alignable to a classical chicken class II B sequence, and balancing selection was acting in the PBR. One of the cDNA sequences had two deletions and is likely nonfunctional. Finally, the polymorphic class I and class II B RFLP fragments seemed to be linked in the five studied great reed warbler families. These and previous results suggest that birds of the order Passeriformes in general have more Mhc class I and II B genes than birds of the order Galliformes. This difference could be caused by their phylogenetic past, and/or by variance in the selection pressure for maintaining a high number of Mhc genes.
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| 42. |
- Westerdahl, Helena, et al.
(författare)
-
Polymorphism and transcription of Mhc class I genes in a passerine bird, the great reed warbler
- 1999
-
Ingår i: Immunogenetics. - : Springer Science and Business Media LLC. - 1432-1211 .- 0093-7711. ; 49:3, s. 158-170
-
Tidskriftsartikel (refereegranskat)abstract
- 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 alpha(2) 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.
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| 43. |
- Westerdahl, Helena, et al.
(författare)
-
Sex ratio variation among broods of great reed warblers Acrocephalus arundinaceus
- 1997
-
Ingår i: Molecular Ecology. - 0962-1083. ; 6:6, s. 543-548
-
Tidskriftsartikel (refereegranskat)abstract
- The sex of 746 great reed warbler fledglings (from 175 broods) was determined by the use of single primer polymerase-chain reaction. The reliability of the technique was confirmed as 104 of the fledglings were subsequently recorded as adults of known sex. The overall sex ratio did not differ from unity. Variation in sex ratios between broods was larger than expected from a binomial distribution. Female identity explained some of the variation of brood sex ratio indicating that certain females consistently produced sex ratios that departed from the average value in the population. The theory of sex allocation predicts that parents should adjust the sex ratio of their brood to the relative value of sons and daughters and this may vary in relation to the quality of the parents or to the time of breeding. In the great reed warbler, the proportion of sons was not related to time of breeding, or to any of five female variables. Of five male variables, males with early arrival date tended to produce more daughters. The sex ratio of fledglings that were a result of extra-pair fertilizations did not differ from that of legitimate fledglings. Hence, there is currently no evidence of that female great reed warblers invest in a higher proportion of sons when mated with attractive males.
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| 44. |
- Wittzell, Håkan, et al.
(författare)
-
MHC variation in birds and reptiles
- 1998
-
Ingår i: Genetica. - 1573-6857. ; 104:3, s. 301-309
-
Tidskriftsartikel (refereegranskat)abstract
- The major histocompatibility complex (MHC) has been studied in a multitude of mammals by now, but much less is known about its organisation and variation in other vertebrate species. The mammalian MHC is organised as a single gene cluster, but recent studies on birds suggest that this paradigm of MHC organisation has to be supplemented. The domestic chicken thus possesses two separate gene clusters which both contain MHC class I and class II B genes, and we have shown that the ring-necked pheasant Phasianus colchicus also has two unlinked clusters of class II B genes. We are studying the effect of the MHC on mate choice, survival and reproductive success in natural populations of birds and reptiles. For this reason, we are developing DNA techniques to determine the animals' MHC genotype. The amplification of the hypervariable exon 3 of the class I gene from songbirds and reptiles has provided us with species specific probes that can be used in Southern blot analysis. The first results indicate very extensive variation in all studied species, that is starlings Sturnus vulgaris, great reed warblers Acrocephalus arundinaceus and water pythons Liasis fuscus. The restriction fragment length polymorphism (RFLP) analysis also suggests that the number of MHC genes is significantly larger in these species than in pheasants and domestic chickens.
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| 45. |
- Wittzell, Håkan, et al.
(författare)
-
Molecular characterization of 3 MHC class II B haplotypes in the ring-necked pheasant
- 1994
-
Ingår i: Immunogenetics. - 1432-1211. ; 39:6, s. 395-403
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the class II B genes in a free-ranging population of the ring-necked pheasant Phasianus colchicus by a combination of restriction fragment length polymorphism (RFLP), polymerase chain reaction (PCR), and DNA sequencing. Special attention was paid to the variation in the second exon, which encodes the peptide-binding beta(i)-domain. The population was introduced, but it still exhibited major histocompatibility complex polymorphism with at least three segregating class II B haplotypes and consequently six genotypes. We found two class LI B genes associated with each haplotype. The class II B genes of birds had until then only been molecularly characterized in the domestic chicken. The pheasant genes were highly variable, although one of the amplified sequences was found in two different haplotypes. Taken together, the most polymorphic positions (residues 37 and 38) were not identical in any of the predicted protein sequences, but all except one of the motifs had already been found in the domestic chicken. Structurally important features in mammalian class II B genes were generally conserved also in the pheasant sequences, but the loss of a potential salt bridge constituent (Arg(72)) in several sequences may suggest a slightly different structure of the adjacent parts of the peptide-binding groove. The pheasant genes are most closely related to the so called B-LBII family in the chicken, indicating that this represents a major line of development among avian class II B genes.
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| 46. |
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