黑腹果蝇种组的核型与进化研究

观察了国内黑腹果蝇种组34种果蝇的有丝分裂中期核型,其中首次描述了一些新核型。系统地分析了黑腹果蝇种组8个种亚组之间的核型进化关系及种间亲缘关系。结果是:elegans种亚组的核型为A型;eugracilis、melanogaster和ficusphila种亚组的核型为C型;takahashii和suzukii种亚组的核型为C型和D型;montium种亚组的核型为B、C、C’、D、D’、和E型;ananassae种亚组的核型为F、G和H型。从核型分化的角度可以将黑腹果蝇种组分为5个谱系:elegans,eugracilis-melanogaster-ficusphila,takkahashii-suzukii,montium,ananassae。这与2004年Yang等的观点基本一致,正好从核型进化的角度验证了Yang通过DNA序列分析所得到的结果。差别只在于elegans种亚组,作者把它单独列为一支,认为是祖先种亚组。通过选取同一种果蝇的几个不同地域单雌系的核型分析,结果表明:同一种果蝇的核型存在地域差异。这种差异可能是由于不同生境造成,也可能是本身进化程度的差异,或是两种因素相互作用的结果。     

中国云南果蝇属暗果蝇种组的核型分化

观察了新近发现于我国云南的果蝇属暗果蝇种组(Drosophila obscura species group)种类D．luguensis、D．dianensis和D．limingi的有丝分裂中期核型,并将3个种的核型与各自的近缘种类进行了比较。D．luguensis具2n=12条染色体,包括3对中央着丝粒(V形)染色体、2对近端着丝粒(棒状)染色体以及1对微小(点状)染色体。其中X和Y染色体均为中央着丝粒染色体。D．dianensis和D．limingi具2n=10条染色体,包括1对大的V形常染色体,1对小的V形常染色体,2对J形(亚中着丝粒型)常染色体和1对点状染色体。其中X染色体为J形,Y染色体为短棒状。基于核型比较的结果以及D．sinobscura亚组地理分布的资料,结合种间系统发育关系研究结果,认为D．luguensis可能保留了该亚组祖先种类的核型。D．sinobscum的核型(2n=12：2V,1J,2R,1D)可能由一个pre-“sinobscura-hubeiensis”谱系的一个分支通过臂间倒位演化而来,而D．hubeiensis的核型(2n=10：4V,1D)可能由该谱系的另一分支通过着丝粒融合(2对近端着丝粒常染色体的融合)而形成。推测在D．dianensis和近缘欧洲种D．subsilvestris(2n=12：3V,2R,1D)间、D．limingi和东亚近缘种D．tsukubaensis(2n=12：3V,2R,1D)间的物种分化过程中,可能有相似的染色体变异类型发生。     

三黄果蝇(Drosophila trilutea)近黄果蝇(D.paralutea)的有丝分裂中期染色体

这两种果蝇隶属果蝇科 Drosophilidae 果蝇属 Drosophila (Sophophora) 黑腹果蝇 D.melanogaster 种组(species group)中的D.takahashii 亚组(subgroup)。Bock和Wheeler(1972)在报道新种的文献中,曾记述其有丝分裂中期染色体的形态结构为2对中着丝粒(V形),1对棒状(R)。其中X染色体为棒状,Y染色体稍短。据此,其二倍体染色体数目推测为2n=6。我们观察的结果则与之显然不同。     

果蝇属拱背果蝇亚属七新种：（双翅目：果蝇科）

本文记述果蝇属Drosophila拱背果蝇亚属Lordiphosa在中国的分布,包括七新种:等枝拱背果蝇Drosophila (Lordiphosa) ramipata sp.nov.,不对称拱背果蝇Drosophila (Lordiphosa) acongruens sp.nov.,突弓拱背果蝇Drosophila (Lordiphosa) protrusa sp.nov.,多枝拱背果蝇Drosopkila (Lordiphota) ramosisslma sp.nov.,双突拱背果蝇Drosophila (Lordiphosa) biconvexa sp.nov.,黑拱背果蝇Drosophila (Lordiphosa) picea sp.nov.,和黄拱背果蝇Drosophila (Lordiphosa) flava sp.nov.     

中国特有的弯头果蝇种亚组及二新种记述(双翅目，果蝇科)

本文记述弯头果蝇种亚组的二新种,施氏果蝇 Drosophila (Drosophila) shi sp. nov.,短乳突果蝇Drosophila (Drosophila) brevipapilla sp.nov.,并对中国特有的弯头果蝇种亚组中11 个种的分布进行了分析。     

黑腹果蝇种组五种核型的报道

通过传统的敲片、Giemsa染色的方法, 本文首次对果蝇属黑腹果蝇种组的5种果蝇 （D. constricta、D. ohnishii、D. ogumai、D. pseudobaimaii、D. tani）染色体的数目和形态进行了分析报道。分析发现：这5个种具有相同的染色体数目（2n=8）和不同的形态。D. pseudobaimaii和D. tani 为2V,1R,1D型;D. constricta染色为2V,1R,1D型且其点状染色体难以辨认;D. ohnishii和D. ogumai 具有相同形态为2V,2R。另外,还发现核型与亲缘关系之间有一定的对应性。     

三黄果蝇(Drosophila trilutea)近黄果蝇（D.paraiautea）的有丝分裂中期染色体

这两种果蝇隶属果蝇科Drosophilidae果蝇属Drosophila （Sophophora）黑腹果蝇D.melanogaster种组（species group）中的D.takahashii亚组（subgroup）。Bock和Wheeler (1972）在报道新种的文献中，曾记述其有丝分裂中期染色体的形态结构为2对中着丝粒（V形），1对棒状（R）。其中X染色体为棒状，Y染色体稍短。据此，其二倍体染色体数目推测为2n=6。我们观察的结果则与之显然不同。     

中国阿果蝇属五新种和二新记录种（双翅目：果蝇科）

记述采自中国大陆的阿果蝇属5新种和2新记录种:尖叶阿果蝇Amiota acutifoliolata sp.nov.,缺茎阿果蝇A.apenis sp.nov.,小叶阿果蝇A.minufoliolata sp.nov.,曲叶阿果蝇A.undulata sp.nov.,爪叶阿果蝇A.ungulfoliolata sp.nov.,须刺阿果蝇A.balaenodentata Takada,Beppu&Toda,1979和钩茎阿果蝇A.orchidea Okada,1968;这7种阿果蝇不能指派于本属已建立的7个种团中的任何一个。     

昆明果蝇属一新种：双翅目：果蝇科

长鬃果蝇Drosophila(Drosophila)Iongisetae sp.nov.新种(图A—F) 体长:4.5mm,翅长4.0mm. 头部:复眼红色,具稀疏的微毛。触角第2节黄色,具2小刚毛,第3节棕黄色,触角芒上侧具3个分枝毛,下侧具1个分枝毛,末端分叉大、下颚须黄色,具2根鬃。额黄     

云南拱背果蝇属双齿拱背果蝇种组--四新种记述及地理替代现象(双翅目:果蝇科)

概述了拱背果蝇属(Lordiphosa)中双齿拱背果蝇种组(denticeps species—group)的分类状况,并记述了分布在云南省的4个新种,即鹤颈拱背果蝇(Lordiphosa gruicollara sp.nov.),突拱背果蝇(Lordiphosa eminens sp.nov．),凹缘拱背果蝇(Lordiphosa incidens sp.nov．)和具毛拱背果蝇(Lordiphosa piliferous sp．nov．)。对目前在云南发现的该种组10个物种的地理分布做了初步分析,结果显示其分布呈明显的地理替代。模式标本均藏于北京大学生命科学学院。     

Different mechanisms underlie phenotypic plasticity and interspecific variation for a reproductive character in drosophilids (Insecta: Diptera)

The insect ovary is a modular structure, the functional unit of which is the ovariole. Ovariole number is positively correlated with potential reproductive output. Among drosophilids (Insecta: Diptera), ovariole number shows both phenotypic plasticity and substantial interspecific and interpopulational variation. Here we examine the mechanistic connection between phenotypic plasticity and genetically fixed variation in ovariole number within the melanogaster species group. When a laboratory population of Drosophila melanogaster was reared under reduced food conditions, differences in ovariole number were entirely due to alterations in cell differentiation during the wandering stage at the very end of larval development. Cell growth and cell death were not affected. When these same flies were reared under a variety of temperatures, ovariole number differences arose during the latter half of the third (final) larval instar. Cell differentiation was affected, although cell number was not, and ovariole number differences were established before metamorphosis. In contrast, genetically fixed, interspecific and interpopulational variability in ovariole number was caused by alterations in the dynamics of cell differentiation and by cell number differences. Furthermore, the stages affected were different in different species and populations in the melanogaster species group, ranging from the first (D. sechellia) through the middle of the third (D. simulans and D. mauritiana) larval stage. Therefore, the mechanistic bases for plasticity-based variability are largely distinct from the mechanistic bases for interspecific and interpopulational variability. Our results suggest that phenotypic plasticity indicates evolutionary flexibility in underlying ontogenetic processes.     

THE GENETICS OF AN ISOLATING MECHANISM BETWEEN TWO SIBLING SPECIES OF DROSOPHILA

Matings between Drosophila simulans females and males of the sibling species D. mauritiana are of abnormally short duration. These rapid matings interrupt the transfer of sperm, leading to substantial reproductive isolation in interspecific as compared to intraspecific copulations. Genetic analysis of this behavior shows that it is influenced much more by the male than the female genotype, with genes from D. simulans being dominant. In males, shortened copulation is caused by interspecific divergence at a minimum of three loci, with one gene on each of the major chromosomes. This is an underestimate of the true number of loci affecting the trait, which could be much larger. The two autosomes have the largest effect, whereas that of the X chromosome is much smaller. The genetic architecture of copulation duration and the larger effect of male than female genotype suggest that females can detect and discriminate against differences in male genitalia.     

Population genetic study of allozyme variation in natural populations of Drosophila antonietae (Insecta, Diptera)

Drosophila antonietae is an endemic South American cactophilic species found in relictual xerophytic vegetation, mostly associated with Cereus hildmaniannus cactus. Low differentiation among populations of this species has been detected using several markers. In this work, we performed an allozyme genetic variability analysis of 11 natural populations of D. antonietae and included a discussion about the possible influences of several evolutionary processes that might be acting to maintain the pattern observed. The genetic variability of 14 isoenzyme loci was analysed and showed a high genetic diversity (average observed heterozygosity = 0.319) and a moderate genetic differentiation among populations ( F statistics = 0.0723). A correlation between genetic and geographical and ecological distances was detected among pairs of populations and the regional equilibrium analysis was thus applied. This analysis resulted in Nm (number of migrants) of approximately 3.21, indicating that moderate levels of both gene flow and genetic drift occur in this species, with gene flow overlapping genetic drift. However, considering ecological features of drosophilids, we propose a hypothesis to explain the moderate differentiation encountered as a result of three different processes, or a combination of them: (1) gene flow; (2) a short period of differentiation, i.e. maintenance of ancestral polymorphism; and (3) action of natural selection. Moreover, if gene flow is present, the high genetic diversity compared with other cactophilic and non-cactophilic species could be due to differential selection in different populations followed by gene exchange among them. These factors are discussed in the light of D. antonietae 's historical and evolutionary association with the host cactus.     

Ecology and population genetics of Sonoran Desert Drosophila

Three species of cactophilic Drosophila endemic to the Sonoran Desert of North America, D. nigrospiracula, D. pachea and D. mettleri, experience marked differences in spatial resource availability, and the first two of these display significant differences in dispersal behaviour. We employed starch gel and cellulose acetate electrophoresis for eight allozyme loci to test for a relationship between these variables and genetic differentiation among geographical populations of each species. No evidence was found for population structure in any of the three species, populations of which were separated by geographical distances of up to 475 km. Allele frequencies for two loci, Mdh-1 and Est-2, in D. nigrospiracula and D. pachea were very similar to those obtained approximately 30 years ago by other workers, indicating that the polymorphisms are remarkably stable under the stressful and variable conditions of the desert environment. High longevity, dispersal and multiple female remating are likely to contribute to the apparent high level of gene flow in all three species.     

Simple Synthesis of the Major Sex Pheromone Components of Drosophila ananassae and D. pallidosa

The major sex pheromone components of Drosophila ananassae and D. pallidosa, (Z,Z)-5,25-hentriacontadiene and (Z,Z)-5,27-tritriacontadiene, respectively, were synthesized by using the Wittig olefination and sulfone coupling reactions as the C–C bond-forming steps.     

Interspecific transfer of P elements by crosses between Drosophila simulans and Drosophila mauritiana

Interspecific crosses were carried out between P element-transformed strains of D. simulans and a strain of D. mauritiana, a species devoid of this transposable element family. Four lines were established from hybrid females backcrossed with D. mauritiana males for four generations, and then maintained by intra-line mass mating. In situ hybridization of polytene chromosomes and southern blots showed that full-length and deleted P elements were present in all of the lines after 15 generations. We conclude that at least some of the P elements observed in two lines result from their transposition into D. mauritiana genome. Gonadal sterility, induced at 29°C in D. melanogaster by P elements also occurred with these two latter lines.     

Can competition be superior to parasitism for biological control? The case of spotted wing Drosophila (Drosophila suzukii), Drosophila melanogaster and Pachycrepoideus vindemmiae

Drosophila suzukii and Drosophila melanogaster coexist with different but overlapping resource use in the field. When forced to completely or partially share resources in the laboratory, D. melanogaster outcompetes D. suzukii. Adult D. suzukii and D. melanogaster females were allowed to compete for access to a common oviposition resource in pairwise and population scale experiments. We tracked the offspring emergence to explore the factors across life stages that might affect the success of D. suzukii in the laboratory compared to a closed field simulation cage experiment with a generalist Drosophila parasitoid, Pachycrepoideous vindemmiae. When in competition as adults, D. melanogaster produced more offspring that survived to pupation than D. suzukii. In addition, D. melanogaster produced more offspring when in competition with a conspecific than when in competition with D. suzukii. Competitor identity did not affect the number of D. melanogaster offspring in pairwise and cage experiments. However, in the presence of D. melanogaster, the number of D. suzukii offspring in both pairwise and cage experiments was dramatically reduced than in cages without this competitor. In the presence of both D. melanogaster and P. vindemmiae, there were marginally more D. suzukii than when only D. melanogaster was present. These results suggest that competition was an important factor limiting D. suzukii numbers. Limiting D. suzukii numbers through interspecies competition may eventually be an exploitable method of biocontrol in the field.