Genetic structure analysis of a highly inbred captive population of the African antelope Addax nasomaculatus. Conservation and management implications

The African antelope Addax nasomaculatus is a rare mammal at high risk of extinction, with no more than 300 individuals in the wild and 1,700 captive animals distributed in zoos around the world. In this work, we combine genetic data and genealogical information to assess the structure and genetic diversity of a captive population located at Parque Lecocq Zoo (N=27), originated from only two founders. We amplified 39 microsatellites previously described in other Artiodactyls but new to this species. Seventeen markers were polymorphic, with 2–4 alleles per locus (mean=2.71). Mean expected heterozygosity (He) per locus was between 0.050 (marker ETH3) and 0.650 (marker D5S2), with a global He of 0.43. The mean inbreeding coefficient of the population computed from pedigree records of all registered individuals (N=53) was 0.222. The mean coancestry of the population was 0.298 and F_IS index was ?0.108. These results reflect the importance of an adequate breeding management on a severely bottlenecked captive population, which would benefit by the incorporation of unrelated individuals. Thanks to the successful amplification of a large number of microsatellites commonly used in domestic bovids, this study will provide useful information for the management of this population and serve as future reference for similar studies in other captive populations of this species. Zoo Biol 30:399–411, 2011. © 2010 Wiley‐Liss, Inc.     

Evolutionary origins of taro (Colocasia esculenta) in Southeast Asia

As an ancient clonal root and leaf crop, taro (Colocasia esculenta, Araceae) is highly polymorphic with uncertain genetic and geographic origins. We explored chloroplast DNA diversity in cultivated and wild taros, and closely related wild taxa, and found cultivated taro to be polyphyletic, with tropical and temperate clades that appear to originate in Southeast Asia sensu lato. A third clade was found exclusively in wild populations from Southeast Asia to Australia and Papua New Guinea. Our findings do not support the hypothesis of taro domestication in Papua New Guinea, despite archaeological evidence for early use or cultivation there, and the presence of apparently natural wild populations in the region (Australia and Papua New Guinea).     

Effects of captivity,diet, and relocation on the gut bacterial communities of white‐footed mice

Microbes can have important impacts on their host's survival. Captive breeding programs for endangered species include periods of captivity that can ultimately have an impact on reintroduction success. No study to date has investigated the impacts of captive diet on the gut microbiota during the relocation process of generalist species. This study simulated a captive breeding program with white‐footed mice (Peromyscus leucopus) to describe the variability in gut microbial community structure and composition during captivity and relocation in their natural habitat, and compared it to wild individuals. Mice born in captivity were fed two different diets, a control with dry standardized pellets and a treatment with nonprocessed components that reflect a version of their wild diet that could be provided in captivity. The mice from the two groups were then relocated to their natural habitat. Relocated mice that had the treatment diet had more phylotypes in common with the wild‐host microbiota than mice under the control diet or mice kept in captivity. These results have broad implications for our understanding of microbial community dynamics and the effects of captivity on reintroduced animals, including the potential impact on the survival of endangered species. This study demonstrates that ex situ conservation actions should consider a more holistic perspective of an animal's biology including its microbes.     

基于染色体置换系的普通野生稻耐盐性QTL定位

本研究分别利用SSR标记、InDel标记以及简化基因组测序技术对一套以普通野生稻为供体亲本,9311为受体亲本的染色体置换系进行基因型鉴定,并通过对其不同生育期的耐盐性鉴定,共发掘2个与发芽期耐盐相关的QTL,13个与苗期耐盐性相关的QTL。其中与苗期存活率相关的QTL qSSR5.1、苗期耐盐等级相关的QTL qSSG5.1均被定位于同一位点,该位点对苗期存活率、苗期耐盐等级均具有增效作用,贡献率分别为6.36%、8.13%。在此QTL内包含与非生物胁迫相关基因OsDi19-1。经序列比对发现,OsDi19-1启动子区域在两亲本间存在较大差异,且受到盐胁迫时该基因表达量上升。同时,鉴定出水稻芽期耐盐的优异种质资源CSSL72、苗期耐盐的优异种质资源CSSL23、CSSL153,为水稻育种中耐盐性的改良提供了新的种质资源。     

利用地域野生资源创制地方适栽的优质香菇新品种

香菇是我国深受欢迎的食药用菌,产量居食用菌产业之首。为拓宽栽培香菇菌株的遗传背景,解决现有主栽香菇菌株种性退化的问题,本研究以香菇‘808’菌株与3个香菇野生资源、3个栽培菌株（辽抚4号、BY1和荷香）开展单-双杂交育种,开发适合当地栽培环境的主栽品种。研究结果显示：在270对单-双杂交组合中,通过锁状联合观察和与亲本的拮抗试验,鉴定出89个杂交子,进一步通过栽培试验筛选出10个性状相对优良的候选菌株;最终通过农艺性状对比试验,筛选出ZJXG 5和ZJXG 8两个优良杂交菌株,这两个菌株均以当地长白山野生资源S1和本地主栽菌株BY1为双核杂交亲本选育而来,表现出超亲显著、菇形圆整、颜色呈浅褐色的特性,前4潮生物学效率在86%-88%之间。本研究结果揭示,在香菇杂交育种中,当亲本菌株来源地域与杂交后代菌株筛选地域相近时,单双杂交亲和率、杂交菌株的出菇率和丰产性指标较高,这提示我们,利用当地野生香菇资源更有利于创制适合当地自然环境的地方品种。     

Environmental DNA analysis shows high potential as a tool for estimating intraspecific genetic diversity in a wild fish population

Environmental DNA (eDNA) analysis has recently been used as a new tool for estimating intraspecific diversity. However, whether known haplotypes contained in a sample can be detected correctly using eDNA‐based methods has been examined only by an aquarium experiment. Here, we tested whether the haplotypes of Ayu fish (Plecoglossus altivelis altivelis) detected in a capture survey could also be detected from an eDNA sample derived from the field that contained various haplotypes with low concentrations and foreign substances. A water sample and Ayu specimens collected from a river on the same day were analysed by eDNA analysis and Sanger sequencing, respectively. The 10 L water sample was divided into 20 filters for each of which 15 PCR replications were performed. After high‐throughput sequencing, denoising was performed using two of the most widely used denoising packages, unoise3 and dada2 . Of the 42 haplotypes obtained from the Sanger sequencing of 96 specimens, 38 (unoise3 ) and 41 (dada2 ) haplotypes were detected by eDNA analysis. When dada2 was used, except for one haplotype, haplotypes owned by at least two specimens were detected from all the filter replications. Accordingly, although it is important to note that eDNA‐based method has some limitations and some risk of false positive and false negative, this study showed that the eDNA analysis for evaluating intraspecific genetic diversity provides comparable results for large‐scale capture‐based conventional methods. Our results suggest that eDNA‐based methods could become a more efficient survey method for investigating intraspecific genetic diversity in the field.     

西南特有濒危植物大王杜鹃种群结构及动态特征

为了揭示高山杜鹃种群生存潜力和濒危原因,以西南特有濒危植物大王杜鹃(Rhododendron rex subsp. rex)为研究对象,通过对云南省轿子雪山和小百草岭2个大王杜鹃自然种群的野外植株胸径及数量的调查,采用空间代替时间的方法建立大王杜鹃种群的径级结构、静态生命表并绘制种群存活曲线,阐明其种群的结构特征,利用种群数量动态预测和时间序列预测来分析种群未来的发展趋势。结果表明：(1)云南轿子雪山和小百草岭两个样地大王杜鹃均表现出第Ⅰ~Ⅱ龄级个体不足的现象,尽管两个样地内大王杜鹃种群仍表现为稳定型种群,但其均对外界干扰具有很高的敏感性。(2)大王杜鹃存活曲线在云南轿子雪山和小百草岭2个样地都趋于Deevey Ⅱ型,个体平均生存能力的期望值均在幼年(Ⅰ和Ⅱ龄级)个体中最大,死亡率和消失率曲线的变化趋势基本一致。(3)时间序列预测分析表明,云南轿子雪山大王杜鹃种群在未来2、4、6年龄级后总体均呈下降趋势,种群面临衰退危险;小百草岭样地内,大王杜鹃种群总体上呈增长趋势,种群具有一定的恢复潜力。建议加强大王杜鹃自然种群生境的保护与管理从而维持其种群自然更新与发展的能力。     

不同温度对迷人杜鹃种子萌发与幼苗生长及生理特性的影响

该研究利用实验室不同恒温和变温控制试验,考察了不同温度[恒温(15℃、25℃、35℃)和变温(25℃/15℃、30℃/20℃,高温12 h,低温12 h)]处理对迷人杜鹃种子萌发、幼苗形态指标和生理生化指标的影响,探讨温度对迷人杜鹃种子萌发和幼苗生长的影响机制。结果表明:(1)迷人杜鹃种子在25℃/15℃变温条件下萌发率(87.69%)和萌发指数(8.65)均最高。(2)25℃/15℃变温有利于迷人杜鹃幼苗的地径、苗高、平均根长和萌枝数的增加,以及根、茎、叶生物量的积累。(3)25℃/15℃变温处理下幼苗叶片的总叶绿素、可溶性糖和可溶性蛋白含量最高,而MDA含量、CAT活性和SOD活性较低。研究认为,迷人杜鹃种子萌发和幼苗生长的最适宜温度条件为25℃/15℃(昼/夜),而在高温(35℃)和低温(15℃)环境下均会受到显著抑制。     

转基因植物与近缘种之间基因流的研究进展

随着转基因植物的大面积种植,转基因植物的生态风险受到广泛关注,其中主要的风险是转基因植物与近缘物种之间的基因流及其影响。本文综述了目前商业化种植的转基因作物油菜、棉花、玉米和大豆,以及未商业化种植的水稻、小麦的基因流研究进展;分析了不同转基因作物与其近缘种之间发生基因流的频率和最远发生距离;介绍了降低基因流发生的方法。基因流频率受物种亲缘关系、花期重叠时间、风速风向等因素的影响,最远发生距离受气候条件、传粉媒介、地理条件等因素的影响。转基因作物与其近缘种之间的基因流频率与距花粉源的距离呈负相关关系(y=-0.59x-0.46,R²=0.25,P<0.01),亲缘关系近的基因流频率高。为了降低转基因植物与其近缘物种之间的基因流风险,建议采取“分区管理”的策略,并加强基因流发生之后的生态风险评价研究。     

不同郁闭度对野外回归的梓叶槭幼树形态和生理特征的影响

濒危植物野外回归是扩大极小种群野生植物种群的有效途径。适宜的回归生境是物种生长的必要条件, 研究植物的生理生态特征对不同野外回归生境的适应性, 是科学评价濒危物种种群回归生境适宜性的关键指标。本文以野外回归的极小种群野生植物梓叶槭(Acer catalpifolium)为研究对象, 探讨了无遮荫、林缘、林隙以及林下(郁闭度由小到大) 4种不同光照条件对梓叶槭幼树的形态特征、光合特征、类黄酮指数及叶绿素含量等的影响。结果表明: (1)随着郁闭度的增大, 梓叶槭幼树的基径、冠幅以及新生枝条数量产生差异, 均呈现先增大后减小的趋势; (2)在林缘生境中, 梓叶槭幼树的单叶面积及单叶质量均最大, 比叶面积随着郁闭度的增大而增大; (3)随着郁闭度的增大, 梓叶槭叶片胞间CO₂浓度、蒸腾速率及气孔导度均呈现先减小后增大的趋势, 叶绿素含量呈现上升趋势, 类黄酮指数则呈现先增大后减小的趋势。综上可知, 林缘适宜的光照条件更适合梓叶槭野外回归。这一结果可为梓叶槭以及其他极小种群野生植物的回归生境适宜性的探索研究提供借鉴。