Genetic linkage maps are valuable tools in evolutionary biology;however, their availability for wild populations is extremely limited. Fundulus heteroclitus (Atlantic killifish) is a non-migratory estuarine fish that ...Genetic linkage maps are valuable tools in evolutionary biology;however, their availability for wild populations is extremely limited. Fundulus heteroclitus (Atlantic killifish) is a non-migratory estuarine fish that exhibits high allelic and phenotypic diversity partitioned among subpopulations that reside in disparate environmental conditions. An ideal candidate model organism for studying gene-environment interactions, the molecular toolbox for F. heteroclitus is limited. We identified hundreds of novel microsatellites which, when combined with existing microsatellites and single nucleotide polymorphisms (SNPs), were used to construct the first genetic linkage map for this species. By integrating independent linkage maps from three genetic crosses, we developed a consensus map containing 24 linkage groups, consistent with the number of chromosomes reported for this species. These linkage groups span 2300 centimorgans (cM) of recombinant genomic space, intermediate in size relative to the current linkage maps for the teleosts, medaka and zebrafish. Comparisons between fish genomes support a high degree of synteny between the consensus F. heteroclitus linkage map and the medaka and (to a lesser extent) zebrafish physical genome assemblies.展开更多
Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar appl...Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar application is a promising approach to lower soil greenhouse gas emissions,particularly under high soil moisture conditions where denitrification is the primary N-transformation pathway.In a replicated field trial,we evaluated the effects of two contrasting biochars derived from poul-try litter and from hardwood on soil N_(2)O emissions,soil ammonium(NH4^(+))and nitrate(NO3^(−))status,pasture productivity and herbage nutrient content.A liming treatment to mimic the liming equivalence of the poultry litter biochar was used to separate any effects observed from changes in soil pH.To further separate the effects of biochars on soil N status,N_(2)O emissions and pasture N uptake,high and low N fertiliser doses(annual application of 672 kg N ha^(−1),336 kg N ha^(−1))were superimposed across all of the treatments.The N fertiliser dose had no significant impact on pasture yield.Application of poultry litter biochar resulted in significant increases in pasture productivity under both high and low N inputs.This was achieved by alleviating soil P,and possibly K nutritional constraints that are typical in Australian Ferralsols.Under the high N fertiliser dose,emissions of N_(2)O from the treatments and control were not significantly different(p>0.05)and ranged between 1.14 and 1.78 kg N_(2)O-N ha^(−1)across the 11-month study.The low N dose resulted in significantly lower emissions of N_(2)O of between 0.80 and 0.84 kg N_(2)O-N ha^(−1),but biochar had no significant effect on net emissions across the season.The lack of impact of biochar on N_(2)O emissions was attributed to the relatively dry conditions over the trial period resulting in nitrification being the most likely N-transformation pathway.During brief episodes of high soil moisture,peak emissions from the biochar plots were lower than from the control or lime treatment,but these differences did not impact on the emis-sion budget over the 11-month sampling campaign.展开更多
文摘Genetic linkage maps are valuable tools in evolutionary biology;however, their availability for wild populations is extremely limited. Fundulus heteroclitus (Atlantic killifish) is a non-migratory estuarine fish that exhibits high allelic and phenotypic diversity partitioned among subpopulations that reside in disparate environmental conditions. An ideal candidate model organism for studying gene-environment interactions, the molecular toolbox for F. heteroclitus is limited. We identified hundreds of novel microsatellites which, when combined with existing microsatellites and single nucleotide polymorphisms (SNPs), were used to construct the first genetic linkage map for this species. By integrating independent linkage maps from three genetic crosses, we developed a consensus map containing 24 linkage groups, consistent with the number of chromosomes reported for this species. These linkage groups span 2300 centimorgans (cM) of recombinant genomic space, intermediate in size relative to the current linkage maps for the teleosts, medaka and zebrafish. Comparisons between fish genomes support a high degree of synteny between the consensus F. heteroclitus linkage map and the medaka and (to a lesser extent) zebrafish physical genome assemblies.
文摘Dairy pastures can be a major source of soil nitrous oxide(N_(2)O)emissions due to the combination of intensive nitrogen(N)fertiliser use and high soil water content,from either rainfall and/or irrigation.Biochar application is a promising approach to lower soil greenhouse gas emissions,particularly under high soil moisture conditions where denitrification is the primary N-transformation pathway.In a replicated field trial,we evaluated the effects of two contrasting biochars derived from poul-try litter and from hardwood on soil N_(2)O emissions,soil ammonium(NH4^(+))and nitrate(NO3^(−))status,pasture productivity and herbage nutrient content.A liming treatment to mimic the liming equivalence of the poultry litter biochar was used to separate any effects observed from changes in soil pH.To further separate the effects of biochars on soil N status,N_(2)O emissions and pasture N uptake,high and low N fertiliser doses(annual application of 672 kg N ha^(−1),336 kg N ha^(−1))were superimposed across all of the treatments.The N fertiliser dose had no significant impact on pasture yield.Application of poultry litter biochar resulted in significant increases in pasture productivity under both high and low N inputs.This was achieved by alleviating soil P,and possibly K nutritional constraints that are typical in Australian Ferralsols.Under the high N fertiliser dose,emissions of N_(2)O from the treatments and control were not significantly different(p>0.05)and ranged between 1.14 and 1.78 kg N_(2)O-N ha^(−1)across the 11-month study.The low N dose resulted in significantly lower emissions of N_(2)O of between 0.80 and 0.84 kg N_(2)O-N ha^(−1),but biochar had no significant effect on net emissions across the season.The lack of impact of biochar on N_(2)O emissions was attributed to the relatively dry conditions over the trial period resulting in nitrification being the most likely N-transformation pathway.During brief episodes of high soil moisture,peak emissions from the biochar plots were lower than from the control or lime treatment,but these differences did not impact on the emis-sion budget over the 11-month sampling campaign.
