Linking size‐based trophodynamics and morphological traits in marine fishes

The rule of thumb in marine trophodynamics indicates that the bigger an organism, the higher its trophic level (TROPH). This generalization leads to the assumption that fishes increase their TROPH with growth. However, a recent review showed that for many species, TROPH does not increase with body size, suggesting that size‐independent feeding is not rare in marine fishes. Here, we assessed some morphological traits of marine fishes that could potentially be used as indicators for the ability to vary TROPH with body size. Stable isotope values of nitrogen were used as a proxy TROPH. The specific objectives were as follows: (a) to evaluate the relationship between the oral gape and the trophodynamic trend and (b) to quantify the relevance of 11 external morphological traits in determining the size‐based trophodynamics. We used random forest models to identify the morphological traits that would help predict which species would have the potential to increase TROPH with growth and which would have not. The selected traits included the pelvic fin relative position, the dorsal fin shape, total length, and relative mouth size. Our results also showed a marked relationship between the rate of increase in the oral gape and TROPH. The analyses presented here provide the first comprehensive and quantitative review aiming at linking the trophodynamics of marine fishes with external morphological traits.     

三江源区不同建植年限人工草地根系动态特征

根系动态特征能够反映人工草地植物利用土壤资源的效率和群落恢复演替的程度。本研究以三江源区不同建植年限（5、6、9和13年）人工草地植物根系为研究对象，利用“微根管”技术，连续两个生长季（2015年5-9月和2016年5-9月）探究了4个建植年限人工草地根系动态特征。结果表明：地上生物量和丰富度在建植5~9年呈下降趋势，建植9~13年显著上升；土壤理化性质呈“N”字型变化，不同建植年限间差异显著；随建植年限增加，根系寿命、累积生产量和累积死亡量均波动上升，根系的生长和死亡主要发生在0~10 cm土层；根系平均现存量随建植年限增加持续增加，建植6~9年趋于深层化；根系生产量、死亡量和现存量具有明显季节变化，6月为生长高峰期，7月为现存量高峰期，8月为死亡高峰期，建植9年人工草地根系正生长高峰期迟于其他建植年限；建植年限和土层深度直接影响根系寿命，其余环境因子通过影响土壤速效养分或地上生物量间接影响根系现存量。综上所述，建植人工草地能够增加地上生物量和丰富度，改善土壤质量，促进根系现存量的增加，建植6~9年人工草地的二次退化现象只是暂时性过渡阶段，可在此阶段制定合理的人工管理措施来保证土壤养分的稳定输入，加快群落正向演替的进程，从而提高人工草地的群落稳定性和恢复力。     

Genetic parameters for growth‐related traits and survival with age in the Kuruma shrimp Marsupenaeus japonicus

Genetic parameters were estimated for growth‐related traits and survival of the Kuruma shrimp Marsupenaeus japonicus based on 66 families, including 30 paternal half‐sib families, which were obtained using artificial insemination of two females by each male. The variance components for growth‐related trait and survival were estimated using a single‐trait animal model and a sir‐dam model, respectively, and genetic parameters were estimated using the restricted maximum likelihood method. The coefficients of variation for growth‐related traits such as body length (BL), abdominal length (AL), and body weight (BW) were 9.36%–22.44%, 10.61%–21.92%, and 26.47%–58.33%, respectively, at different ages (45, 75, 105, 135, and 165 days). The corresponding heritability estimates for each growth trait were 0.1545–0.1951, 0.1672–0.1905, and 0.1596–0.1934, respectively, all of which were found to be at moderate levels and increased with age. The heritability of survival on day 165 was low (0.003). The genetic correlations among growth traits were positive and high (0.7316–0.9896) at the different ages, suggesting that selection to improve any single growth trait will cause positive responses in other growth traits examined in M. japonicus. The genetic correlations between growth traits and survival were also positive but low (0.005–0.087), which indicated that only selecting for growth traits may not cause a positive correlated response in the survival of the core population. According to the above results, we suggested that growth and survival traits should be taken as improving targets of breeding in M. japonicus. These results provided reference data for selective breeding and multitrait selection of M. japonicus.     

家兔HSL基因多态性及其与生产性状关联性分析

本实验采用PCR-SSCP方法对齐卡巨型白兔和齐兴肉兔HSL基因外显子1的遗传多态性进行研究,并进一步分析HSL基因对生产性状的遗传效应。结果表明:HSL基因外显子1第784位处发生了碱基突变(A→C),共出现AA、AB和BB 3种基因型,在2个品种兔群体中AA型均为优势基因型,A均为优势等位基因;卡方适合性检验表明,2个品种兔群体均显著偏离哈代-温伯格平衡(P0.05);在齐卡巨型白兔中,HSL基因AA型和AB型个体的宰前活体重均显著高于BB型个体(P0.05),AA、BB型个体的全净膛屠宰率和半净膛屠宰率均显著低于AB型个体(P0.05);在齐兴肉兔中,HSL基因AA型个体的宰前活体重显著高于AB、BB型个体(P0.05),BB型个体的全净膛屠宰率和半净膛屠宰率均显著低于AA、AB型个体(P0.05);在2个品种兔群体中,不同基因型个体的滴水损失和剪切力差异均不显著(P0.05)。     

越冬栽培稻产量性状相关QTL定位

越冬栽培稻是一类能越过自然冷冬季节并在第2年春季萌芽、正常开花结实、收获稻谷的水稻品种。本文通过对越冬栽培稻产量性状QTL分析,明确产量相关性状的遗传规律,旨在进一步解析越冬栽培稻产量性状的遗传机制,为育种创新利用提供理论依据。以3份越冬栽培稻构建的3个半同胞F2群体为材料。各考察15个产量相关性状,利用Excel 2003、GraphPad Prism 5.0和QTL IciMapping 4.10软件分析数据、绘制遗传图谱、定位QTL和联合分析。结果表明,产量性状表型值在3群体中呈连续正态分布,表现为数量性状遗传。共检测到37个QTL和26对上位性QTL,贡献率分别介于2.32%～36.31%和1.04%～2.05%;检测到9个同时影响2个及以上产量性状(一因多效)QTL标记区间;以联合分析检测到13个产量性状相关QTL,其中4个QTL区间与单群体检测QTL区间重叠;越冬栽培稻产量相关性状QTL以加–显性效应遗传为主、上位性遗传效应为辅。本研究将为越冬栽培稻产量相关基因挖掘及育种创新利用奠定基础。     

蓖麻株高性状主基因+多基因遗传分析

本研究选用蓖麻YC2×YF1高、矮秆组合的2组6世代群体(P1、P2、F1、B1、B2和F2),对株高性状进行了主基因+多基因混合遗传模型分析。结果表明,蓖麻株高受1对主基因和多基因共同控制。2组群体在B1、B2和F2三个分离世代中主基因遗传率分别为37.05%/49.57%、30.51%/34.48%和43.98%/43.64%;主穗位高和主茎节数均受2对主基因和多基因共同控制,且主基因的互作效应显性效应加性效应。3个分离世代中,2组群体主穗位高主基因遗传率分别为67.91%/92.72%、86.89%/92.13%和60.18%/66.87%,主茎节数主基因遗传率分别为91.83%/91.50%、35.22%/63.37%和85.76%/94.58%。主茎节长由多基因控制,遗传率分别为47.64%/47.64%、38.87%/38.87%和25.25%/52.71%。以上遗传模式决定了蓖麻杂种后代株高、主穗位高和主茎节长的正向超亲遗传,而主茎节数则倾向于低值亲本。因此,主穗位高和主茎节数可以作为株高的早期间接选择指标。     

干尖线虫病对不同水稻品种（系）产量相关性状的影响

[目的]该研究旨在了解干尖线虫病对不同水稻品种的影响。[方法]通过田间表型观察与室内考种试验，对自然发病状态下的4个常规粳稻品种（系）和粳稻恢复系 R161进行了观察和分析。[结果]不同水稻品种（系）被侵染后的症状存在差异，常规粳稻宁1707、宁1818、镇稻88和南粳9108被侵染后表现"干尖"和"小穗头"症状，粳稻恢复系R161只表现"干尖"，不表现"小穗头"症状，且"干尖"的位置不同，分别位于剑叶叶尖，整片剑叶及倒二叶。供试材料被水稻干尖线虫侵染后均能抽穗，但是株高、穗长、结实率和千粒重均受到不同程度的影响。此外，R161被干尖线虫侵染后，不同发病部位对水稻产量的影响不同，整片剑叶干枯扭曲的稻穗受影响最大。[结论]该研究为进一步阐明我国水稻干尖线虫病的危害规律和制定相应的防治措施提供依据。     

刺参生殖腺发育的生物学零度和有效积温研究

[目的]为刺参的繁殖以及工厂化人工育苗提供理论基础。[方法]以渤海湾地区刺参为试验材料,研究渤海湾地区刺参生殖腺发育生物学零度及其性成熟的有效积温。[结果]渤海湾地区刺参生殖腺发育的生物学零度为6.14℃,而有效积温为800.19℃·d。[结论]该研究在渤海湾地区刺参育苗生产中具有重要的参考价值。     

Legume–barley intercropping stimulates soil N supply and crop yield in the succeeding durum wheat in a rotation under rainfed conditions

Legume–cereal intercropping is increasingly being appreciated in dryland areas, where severe climatic conditions and intensive agricultural practices, generally dominated by continuous cereal cultivation, determine depletion of soil nutrient resources and decline of soil fertility. This research aimed to assess whether and to what extent a newly introduced legume-based intercropping system is able to ameliorate the biological fertility status of an arable soil in a way that is still noticeable during the succeeding durum wheat cropping season in terms of changes in bacterial community structure, soil C and N pools, and crop yield. A field experiment was carried out under rainfed conditions in Southern Italy on a sandy clay loam soil cultivated with durum wheat following in the rotation a recently established grain legume (pea, faba bean)–barley intercropping. Soil chemical, biochemical and eco-physiological variables together with compositional shifts in the bacterial community structure by LH-PCR fingerprinting were determined at four sampling times during the durum wheat cropping season. Soil fertility was estimated by using a revised version of the biological fertility index. Results showed that even though the microbial biomass was significantly altered, the preceding legume intercrops stimulated C-related functional variables thus leading to an increased release of mineral N, which was larger in crop treatments succeeding pea-based than faba bean-based intercropping. The increased N made available in soil enabled the succeeding durum wheat to achieve an adequate grain yield with a reduced N-fertilizer use. Soil type and environmental conditions rather than crop treatments were major determinants of bacterial community structure. The biological fertility status was not varied, suggesting that in intensively managed rainfed areas long-term crop rotations with intercropped legumes are needed to consistently ameliorate it.