基于AFLP方法对不同地理种群棉褐带卷蛾遗传分化的研究

利用3对AFLP引物对我国棉褐带卷蛾Adoxophyes orana(Fischer von Rosslerstamm)4个地理种群进行了遗传分化研究。共扩增得到224个DNA条带,其中多态条带195个;遗传多样性分析表明各群体均具有较高的遗传多样性水平,Nei遗传多样性指数为0.1425⁰.1578,Shannon多样性指数为0.21370.1578,Shannon多样性指数为0.2137⁰.2383。群体间的遗传分化系数(Gst)和基因流(Nm)分析结果表明,北方的苹小卷叶蛾与南方茶小卷叶蛾之间产生了明显的遗传分化,而北方的苹小卷叶蛾不同种群间则存在着大量的基因交流,遗传分化程度很弱。AMOVA分析结果显示66.81%的变异来源于种群内。UMAGA聚类分析表明,北京种群、陕西种群和山东种群间遗传距离较小,聚在一起为一分支,福建的茶小卷蛾单独为一分支。推测棉褐带卷蛾种群间的遗传分化与寄主有关联,与地理距离不相关。     

水稻品种抗性对褐飞虱和白背飞虱种群动态的影响

用ＴＮ１、Ｎ２２、ＡｓＤ７和Ｐｔｂ３３等４个抗虫性差异明显的水稻品种测定了褐飞虱和白背飞虱在它们上面的栖息率、落卵量、卵存活率、若虫存活和发育状况,以及后代种群数量表现。结果表明,Ｐｔｂ３３通过减少２种飞虱的栖息率、落卵量,降低卵和若虫存活率,延长若虫的发育时间,抑制后代的种群数量增长,表现出明显的抗性。Ｎ２２对白背飞虱、ＡｓＤ７对褐飞虱的后代种群建立与发展均表现明显的抑制作用。２种飞虱在ＴＮ１上     

黄腹角雉生态群养技术研究

模拟黄腹角雉野外生存环境和自然种群结构,采用较大空间散放与多个体群养相结合的方法进行饲养试验,其笼养繁殖性能比对照组传统对养方式显著提高．通过两年来的试验研究,结果表明：试验组平均产卵量为8．5枚,卵受精率为82．6％,受精卵孵化率为88．7％;对照组平均产卵量5．7枚,卵受精率50．3％,受精卵孵化率72．4％,试验组明显高于对照组．同时对两组间的卵重、卵形、产卵期进行了测定,无显著差异。     

三种稻飞虱在高温变温下的生态表现

在大型人工气候箱内模拟自然高温变温(27℃-38℃)下研究褐飞虱、白背飞虱、灰飞虱等3种稻飞虱种群的表现,并以恒温28．3℃为对照。发现3种稻飞虱的卵孵化率在变温下暴露5天,10天后,除白背飞虱卵孵化率在10天处理下比对照下降30％外,其他几种处理均和对照无显著差异;从发育历期来看,各虫种卵的发育速率随变温处理时间的延长而加快;3种稻飞虱若虫在变温处理5天后,褐飞虱,白背飞虱和灰飞虱的生存率依次为20％,30％和55%,明显低于对照;变温处理10天后,白背飞虱无一个体生存;褐飞虱比对照低75％．灰飞虱低50％;褐飞虱和白背飞虱雌成虫寿命明显比对照短;灰飞虱雌成虫的产卵量各处理间无显著差异,但白背飞虱和褐飞虱的产卵量在变温处理8天后,仅为对照的40％和80％,变温处理15天后,分别为对照的15％和54％。     

广聚萤叶甲地理种群间交配选择及子代的发育表现

为探究分布于我国不同地域的广聚萤叶甲(Ophraella communa)种群之间的分化现状,本文对来自南京、长沙和福州等3个地理种群的交配选择行为及杂交后代发育表现进行了研究.结果表明,在试验观察的6 h内南京种群与福州种群间个体发生交配的概率显著低于对照(种群内雌雄个体间的交配),但南京种群与长沙种群个体间发生交配的概率与对照无显著差异;南京和福州种群的雄性与同种群雌性交配选择次数显著多于与异种群雌性交配的次数,但南京与长沙种群间个体交配的次数与对照无显著差异.3个地理种群间个体杂交后代在卵孵化率、幼虫化蛹率和成虫羽化率等发育特性上与对照(种群内个体自交)无显著差异.根据研究结果推测,广聚萤叶甲南京种群与福州种群间在个体交配行为上存在着一定程度的交配前隔离.     

不同水稻生育期对稻粉虱种群动态的影响

本主要研究了不同水稻生育期对稻粉虱Aleurocybotus indicus种群动态的影响。研究结果表明,水稻分蘖期至拔节期最容易受稻粉虱为害,卵孵化率为88．1％,拟蛹的羽化率为82．9％,孵化率和羽化率均高于水稻其它生育期。     

相对湿度对苹小卷叶蛾实验种群的影响

为明确相对湿度对苹小卷叶蛾生长发育及繁殖的影响,在室内(25±1) ℃和12L∶12D条件下,分别设置40%、50%、60%、70%、80%、90% 6个相对湿度(RH),研究其对苹小卷叶蛾生长、发育、存活及繁殖的影响.结果表明: 在40%～90%RH范围内,随湿度升高苹小卷叶蛾未成熟期逐渐缩短,由40%RH时30.31 d缩短至90%RH的25.87 d,未成熟期存活率逐渐升高.湿度对卵的孵化具有显著影响,40%RH下卵的孵化率最低,为39.3%.在80% RH条件下,成虫寿命最长,单雌产卵量最多(110.8粒),卵和幼虫的存活率最高,净生殖率(R₀)和内禀增长率(r_m)最高,分别为26.46和0.1018．说明较高湿度能促进苹小卷叶蛾生长发育,提高其繁殖力.
     

萼花臂尾轮虫休眠卵大小变异在其生活史对策中的作用

以周期性孤雌繁殖的淡水浮游生物——萼花臂尾轮虫（Brachionus calyciflorus）为研究对象．对其安徽品系的休眠卵进行了大、中、小分组,在2个不同食物浓度条件下培养并观察其种群增长、有性生殖方面的特点,以及后代形态大小和新产休眠卵大小。实验发现休眠卵大小对轮虫种群瞬时增长率、混交雌体百分率和后代形态均没有显著影响;而食物浓度则对轮虫种群的瞬时增长率有显著影响;休眠卵大小和食物浓度均显著影响后代休眠卵的大小。     

三种稻飞虱在恒定高温胁迫下的生态表现

对揭飞虱、白背飞虱、灰飞虱等3种稻飞虱的不同虫态在38℃恒温下,暴露不同时间后的生存率进行了研究。结果表明,随高温处理时间的延长．卵孵化率明显下降,卵历期延长。褐飞虱、白背飞虱卵在38℃恒温下暴露12h后．卵孵化率比对照分别低34%和45%;暴露24h后,两种稻飞虱的卵孵化率均比对照低25％;致死中时值LT50分别为11h和10h。3种稻飞虱8日龄若虫及羽化后3天的雌雄成虫的生存率,随处理时间的延长而呈显著下降趋势,褐飞虱、自背飞虱和灰飞虱若虫的致死中时值LT50依次为15．6h、17．8h和25．9h,长翅型雌成虫依次为34．7h、17．1h和43．2h．长翅型雄成虫依次为28．9h、23．2h和54．5h。另外,高温处理过的若虫,其羽化出成虫的体重明显下降,在高温下暴露30h后,白背飞虱长趣型雌成虫的体重比对照低32％,褐飞虱短翅型雌成虫低50％;高温处理后存活的白背飞虱雌成虫产出的卵块较小,总产卵量也明显下降。     

幼虫密度对马铃薯块茎蛾生殖的影响

[目的]为了研究马铃薯块茎蛾Phthorimaea operculella(Zeller)幼虫的饲养密度对生殖的影响。[方法]本实验研究并比较了两种幼虫密度(15头/130 g块茎、45头/130 g块茎)的马铃薯块茎蛾成虫按照1:5和1:1比例交配后代的产卵量、畸形卵率、孵化率、化蛹率、羽化率、性比等生物学参数。[结果]高幼虫密度饲养的马铃薯块茎蛾化蛹率、羽化率、存活率、性比均显著较低,而幼虫~蛹的历期显著短于正常幼虫密度的。两种密度成虫按1:5头配对产卵,若雄性亲本为高幼虫密度饲养则卵的孵化率显著较低,若雌性亲本为高幼虫密度饲养则产卵量较低,畸形卵率显著较高。两种密度雌雄虫均为5头进行配对时,正常幼虫密度雌虫其所产卵的畸形率显著较低,产卵量、卵孵化率均显著较高,后代幼虫历期、化蛹率显著较高。而高幼虫密度雌虫其所产卵则受雄虫影响,亲代为高密度雄虫则畸形率较低,孵化率较高。[结论]高幼虫密度饲养的雄、雌虫生殖活力均降低。高幼虫密度雌虫可受高幼虫密度雄虫的诱导提高生殖能力,并影响其后代性比从而调节其种群动态。     

Patterns of Inheritance of Mating Signals in Sailfin and Shortfin Mollies (Poeciliidae: Poecilia: Mollienesia)

Divergence in mating signals is a primary factor leading to reproductive isolation, and thus, speciation. However, the genetic changes underlying such divergence are poorly understood, especially in vertebrates. We used two species of poeciliid fishes, Poecilia velifera and P. mexicana , to explore the link between genes and mating behaviors that has resulted in pre-mating reproductive isolation between these species. Using backcross hybrids created from the F1 male offspring of reciprocal interspecific crosses between a sailfin molly ( P. velifera ) and a shortfin molly ( P. mexicana ), we examined the effects of Y-linkage and autosomal contributions on the expression of two male mating behaviors: courtship displays and gonopodial thrusts. The F1 hybrid males displayed a strong influence of sire on courtship display rates, with F1 males sired by the sailfin species showing courtship display rates that were up to three times higher than the rates of displays performed by F1 males sired by the shortfin species. These results suggest a Y-linked genetic effect on the expression of courtship display behavior. Comparisons between backcross hybrid males with sailfin Y-chromosomes or shortfin Y-chromosomes suggested that the interaction of autosomal genes also influences the inheritance of courtship display rates. Sailfin autosomal genes significantly increased the probability of performing courtship displays for hybrid males, and increased display rate for males from the sailfin Y-chromosome line. Autosomal genes had less of an impact on gonopodial thrusting behavior, however, thrust rates did significantly decrease with an increasing proportion of sailfin autosomes in males from the shortfin Y-chromosome line. These results suggest that the inheritance of species differences in mating signals between shortfin and sailfin mollies involves both genes found on the Y-chromosome and autosomal gene influences on their expression.     

Genetic studies of two sister species in the Drosophila melanogaster subgroup, D. yakuba and D. santomea

We performed genetic analysis of hybrid sterility and of one morphological difference (sex-comb tooth number) on D. yakuba and D. santomea, the former species widespread in Africa and the latter endemic to the oceanic island of S?o Tomé, on which there is a hybrid zone. The sterility of hybrid males is due to at least three genes on the X chromosome and at least one on the Y, with the cytoplasm and large sections of the autosomes having no effect. F1 hybrid females carrying two X chromosomes from either species are perfectly fertile despite their genetic similarity to completely sterile F1 hybrid males. This implies that the appearance of Haldane's rule in this cross is at least partially due to the faster accumulation of genes causing male than female sterility. The larger effects of the X and Y chromosomes than of the autosomes, however, also suggest that the genes causing male sterility are recessive in hybrids. Some female sterility is also seen in interspecific crosses, but this does not occur between all strains. This is seen in pure-species females inseminated by heterospecific males (probably reflecting incompatibility between the sperm of one species and the female reproductive tract of the other) as well as in inseminated F1 and backcross females, probably reflecting genetically based incompatibilities in hybrids that affect the reproductive system. The latter 'innate' sterility appears to involve deleterious interactions between D. santomea chromosomes and D. yakuba cytoplasm. The difference in male sex-comb tooth number appears to involve fairly large effects of the X chromosome. We discuss the striking evolutionary parallels in the genetic basis of sterility, in the nature of sexual isolation, and in morphological differences between the D. santomea/D. yakuba divergence and two other speciation events in the D. melanogaster subgroup involving island colonization.     

A Combined Classical Genetic and High Resolution Two-Dimensional Electrophoretic Approach to the Assessment of the Number of Genes Affecting Hybrid Male Sterility in Drosophila Simulans and Drosophila Sechellia

We have attempted to estimate the number of genes involved in postzygotic reproductive isolation between two closely related species, Drosophila simulans and Drosophila sechellia, by a novel approach that involves the use of high resolution two-dimensional gel electrophoresis (2DE) to examine testis proteins in parents, hybrids and fertile and sterile backcross progenies. The important results that have emerged from this study are as follows: (1) about 8% of about 1000 proteins examined showed divergence (presence/absence) between the two species; (2) by tracing individual proteins in parental, hybrid and backcross males, we were able to associate the divergent proteins with different chromosomes and found that most divergent proteins are associated with autosomes and very few with X chromosome, Y chromosome and cytoplasm; (3) when proteins showing both quantitative and qualitative differences between the two species were examined in F(1) hybrid males, most (97.4%) proteins were expressed at levels between the two parents and no sign of large scale changes in spot density was observed. All the proteins observed in the two parental species were present in F(1) hybrid males except two species-specific proteins that may be encoded (or regulated) by sex chromosomes; (4) when different fertile and sterile backcross male testes were compared, a few D. sechellia-specific proteins were identified to be consistently associated with male sterility. These results along with the observation that a large proportion (23.6%) of first generation backcross males were fertile show that hybrid male sterility between D. simulans and D. sechellia involves a relatively small number of genes. Role of large scale genetic changes due to general genome incompatibility is not supported. The results also suggest that the large effect of X chromosome on hybrid male sterility is not due to higher divergence of X chromosome than autosomes.     

Hst-3: an X-linked hybrid sterility gene

A gene, Hst-3, responsible for sterility in F1 males from crosses between Mus spretus and laboratory strains of mice such as C57BL/6, has been localized on the distal part of the X chromosome, using both DNA probes and biochemical markers on a panel of F1(C57BL/6 x SEG) x C57BL/6 backcross males. This gene may be a model for studying mammalian hybrid sterility.     

Genetic control of blood pressure in spontaneously hypertensive rats (SHR)

Genetic control of blood pressure in the SHR strain was studied by three separate experiments which consist of cross analysis between the SHR and Donryu, two-way selecton for high and low blood pressure levels, and successive backcrosses to the parental strains. The results obtained were as follows. 1. The data from genetic crosses between the SHR and Donryu showed the phenotype segregation ratio of 1:1 at the backcross and 1:2:1 at the F2 generation. 2. Two-way selection for high and low blood pressure levels was performed from the F2 generation onward. The separation between the two lines occurred immediately after the first selection. Thereafter, the difference increased gradually with generation. The blood pressure level at the seventh generation of selection became approximately equal to those of the parental strains. 3. Two types of the successive backcross were performed from the F1 hybrids by mating the males showing the highest blood pressure level to Donryu females and the females showing the lowest blood pressure level to SHR males on the other. Bimodality was observed in the distribution of blood pressure levels at each generation. Their phenotypic segregation ratios were accordant with 1:1 on the whole. At the intercross generation during successive backcrosses, a trimodal distribution was observed. 4. These results confirmed that the hypertensive trait of the SHR is regulated by a single major gene and other several genes with minor effect. A gene symbol ht was proposed for this major gene. Concurrently, a congenic strain having the ht gene on the genetic background of the Donryu was developed by the successive backcross system.     

Relative fitness of Cry1A-resistant and -susceptible Helicoverpa armigera (Lepidoptera: Noctuidae) on conventional and transgenic cotton

Glasshouse and laboratory experiments were conducted to evaluate the relative fitness of Cry1A-susceptible and laboratory-selected resistant strains of Helicoverpa armigera (Hübner). Life history parameters of H. armigera larvae feeding on young cotton plants showed a significant developmental delay of up to 7 d for the resistant strain compared with the susceptible strain on non-Bacillus thuringiensis (Bt) cotton. This fitness cost was not evident on artificial diet. There was no developmental delay in the F1 hybrid progeny from the reciprocal backcross of the resistant and susceptible strains, indicating that the fitness cost is recessive. In two cohorts tested, survival to pupation of resistant larvae on Bt cotton expressing Cry1Ac was 54 and 51% lower than on non-Bt cotton, whereas all susceptible and F1 larvae tested on Cry1Ac cotton were killed. Mortality of susceptible larvae occurred in the first or second instar, whereas the F1 larvae were able to develop to later instars before dying, demonstrating that resistance is incompletely recessive. The intrinsic rate of increase was reduced by >50% in the resistant strain on Cry1Ac cotton compared with the susceptible strain on non-Bt cotton. There was a significant reduction in the survival of postdiapausal adults from the resistant strain and the F1 strains, indicating that there is a nonrecessive overwintering cost associated with Cry1A resistance in H. armigera.     

Sexual Selection, Epistasis and Species Boundaries in Sympatric Hawaiian Picture-winged Drosophila

The Hawaiian picture-winged flies in the genus Drosophila are a spectacular example of rapid evolutionary diversification in which sexual selection is considered an important mechanism for reproductive isolation and speciation. We investigated the behavioral reproductive isolation of two closely related and sympatric Hawaiian picture-winged Drosophila species, D. silvestris and D. heteroneura, which are known to hybridize in nature and produce viable and fertile hybrids. We compared the mating success of parental, F1 and backcross males in pairings with D. heteroneura females. The F1 males were produced by mating D. heteroneura males with D. silvestris females, and the backcross males were produced by mating F1 females with D. heteroneura males. The mating success of backcross males paired with D. heteroneura females were significantly reduced relative to that of parental and F1 males. This reduced mating success occurred primarily at a late stage of courtship where female choice of mate may be important. Two- and three-gene models demonstrate that epistasis involving a few genes could account for the observed variation in male mating success. These results are consistent with negative epistasis in the backcross generation and support the importance of sexual selection and negative epistasis in the evolution and maintenance of these species.     

Behavioral sterility of hybrid males in acoustically communicating grasshoppers (Acrididae,Gomphocerinae)

The effectiveness of hybridization barriers determines whether two species remain reproductively isolated when their populations come into contact. We investigated acoustic mating signals and associated leg movements responsible for song creation of hybrids between the grasshopper species Chorthippus biguttulus and C. brunneus to study whether and how songs of male hybrids contribute to reproductive isolation between these sympatrically occurring species. Songs of F1, F2, and backcross hybrids were intermediate between those of both parental species in terms phrase number and duration. In contrast, species-specific syllable structure within phrases was largely lost in hybrids and was produced, if at all, in an irregular and imperfect manner. These divergences in inheritance of different song parameters are likely the result of incompatibility of neuronal networks that control stridulatory leg movements in hybrids. It is highly probable that songs of hybrid males are unattractive to females of either parental species because they are intermediate in terms of phrase duration and lack a clear syllable structure. Males of various hybrid types (F1, F2, and backcrosses) are behaviorally sterile because their songs fail to attract mates.     

An attempt at reciprocal crosses between laboratory strains of large and small musk shrews (Suncus murinus)--influence of body-weight difference between sexes on mating success

We conducted mating experiments between two laboratory strains of musk shrews (Suncus murinus), the large-sized shrews (BAN strain) originating from Bangladesh and the small-sized animals (NAG strain) from Nagasaki, Japan. In the 16 mating trials between 12 BAN females (mean body weight of 87.9 g) and 11 NAG males (52.3 g), highly aggressive fighting behaviors of the BAN females toward the NAG males were observed. The BAN females stayed in nest boxes in cages, whereas the NAG males kept out during the mating trials. No pregnant females were found in the trials. Their pregnancies were diagnosed by palpation on the day about 16 days after the separation of the pairs. Contrastively, in 6 of the 11 trials between 8 NAG females (34.2 g) and 6 BAN males (145.9 g), the viable and fertile F1 hybrids of 8 females and 8 males were produced. The F1, subsequent F2 and backcross progenies appeared neither external nor behavioral abnormalities. Various types of crosses using the F1, F2, and the two parental shrews showed that mating success was in a condition that females were nearly as heavy as males, or lighter. Although body weights of musk shrews from different geographical areas were reported to vary from 43.5 to 147.3 g in males and from 26.0 to 82.0 g in females, males in respective localities were constantly about 1.7 times heavier than the corresponding females. These results therefore suggest that body-weight differences between sexes paired greatly affect mating success in the cross between the strains of induced ovulatory shrews.