Resource partitioning and interspecific competition in two two-species insular anolis lizard communities

Population experiments with Anolis lizard species demonstrate a relation between the amount of between-species competition and the degree of interspecific resource partitioning (the more the partitioning the less the competition). Specifically, the amount of resource partitioning between the two species (Anolis gingivinus and Anolis wattsi pogus) on the island of St. Maarten is less than that between the two species (Anolis bimaculatus and Anolis wattsi schwartzi) on the island of St. Eustatius. The presence of Anolis wattsi both lowers the growth rates and raises the perch heights of Anolis gingivinus individuals. In contrast, Anolis wattsi has no effect on Anolis bimaculatus. Thus, when there is less resource partitioning, Anolis wattsi has a greater competitive effect. This verifies, for these species, a central assumption of competition theory: the strength of between-species competition is inversely related to the amount of interspecific resource partitioning.     

The Ecological Significance of Sexual Dimorphism in Size in the Lizard Anolis conspersus

Adult males of Anolis conspersus capture prey of significantly larger size and occupy perches of significantly greater diameter and height than do adult females; similarly, these three dimensions of the niche are significantly larger for adult females than for juveniles. Adult males on the average eat a smaller number of prey, and the range in size of prey is larger. The relationship between the average length of the prey and that of the predator is linear when the predator size is above 36 millimeters, but becomes asymptotic when it is below that value. Subadult males as long as adult females eat significantly larger food than do the latter, but only in the larger lizards is this correlated with a relatively larger head. Anolis conspersus selects prey from a wide range of taxa and shows no obvious intraspecific specialization not connected to differences in microhabitat and prey size. The efficiency of this system for solitary species is pointed out.     

Presence of lateral eye lens crystallins in the median eye of the american chameleon

With the use of immunofluorescence techniques, gamma globulin antibody specific for the crystallins of Anolis carolinensis lateral eye lens was applied to sections through the median (parapineal) eye of Anolis carolinensis. Only the median eye lens exhibited fluorescence specific for the crystallins; other structures were negative. These results indicate that the lens of the reptilean median eye shares tissue-specific antigenic determinants with the lens of the lateral eye. This suggests a possible evolutionary relation between the two structures, based on biochemical, as well as previously reported anatomical, criteria.     

拟水狼蛛染色体的初步观察

以附肢形成之前的蜘蛛胚胎细胞为材料,经秋水仙素处理、纸渗、固定、制片及染色,对拟水狼蛛的体细胞染色体进行了初步观察．结果表明：拟水狼蛛的染色体数为：雄性２ｎ＝２６,雌性２ｎ＝２８,性别决定机制为Ｘ１Ｘ２Ｏ．Ｃ－带分析表明,所有染色体都为端着丝粒染色体,端部有特异性染色质存在．     

Behavioral thermoregulation in lizards: importance of associated costs

The Puerto Rican lizard Anolis cristatellus behaviorally regulates body temperature in an open habitat but passively tolerates lower and more variable temperatures in an adjacent forest where basking sites are few and distant. Thermoregulation may be adaptive only when costs resulting from associated losses of time and energy are low.     

Calcium requirement for melanophore-stimulating hormone action on melanophores

The calcium ion is specifically required for the action of melanophorestimulating hormone on melanosome dispersion within lizard (Anolis carolinensis) melanophores in vitro. The response to this hormone is directly related to the concentration of the Ca(2+) ion. Lithium, choline, rubidium, and cesium will replace the sodium and potassium of Ringer solution if Ca(2+) is present. Calcium ions are not required for melanosome dispersion itself, since theophylline or dibutyryl cyclic adenosine monophosphate reversibly darkens lizard skins in the absence of calcium.     

甘蔗染色体的研究

所观察的4个甘蔗栽培种染色体数目分别为 F 134 2n=114、闽选703 2n=113、C0419 2n=112和闽糖70/611 2n=106。闽选703(X=57)的组型分析结果,甘蔗中期染色体的绝对长度为1.5～5.5μ。有47对染色体具中部着丝点,5对具亚中部着丝点,两对染色体具随体,3对染色体没有染色单体结构的分化。经低温预处理,以 Giemsa 染色的 Co419染色体能显示差异染色,其染色区域所占的比例较大,示明 Co419(杂交种)含量高的异染色质可能与杂种优势性状有关。进一步的探讨可为甘蔗杂交育种选择亲本提供细胞学指标。     

中国雉鸡(Phasianus colchicus)染色体组型、G-带和高分辨G-带研究

 本文报道了分布于我国云南中部的中国雉鸡(Phasianus colchicus)的染色体组型、G-带及高分辨G-带带型。染色体数目2n=82。性染色体雄性为ZZ、雌性为ZW。40对常染色体中,1号为近中着丝粒染色体,5号为近端着丝粒染色体,其余皆为端部着丝粒染色体;性染色体Z为中着丝粒染色体,W为近端着丝粒染色体。全部染色体进行测量分析,计算相对长度和双臂染色体着丝粒指数。根据相对长度和着丝粒指数,绘制了染色体组模式图。制作了1—20号常染色体和性染色体Z的中期G-带以及全部染色体的高分辨G-带,并进行了两种G-带带型特征的描述和比较,绘制了两种G-带比较模式图。     

Permanent translocation heterozygosity and sex determination in East african mistletoes

Viscum fischeri has 2n = 23 chromosomes in male plants. These fornm 7 bivalents and a translocation chain of 9 chromosomes during meiosis. Pollen with 11-and 12-chromosome genomes is thus produced. Female plants have 2n = 22 chromosomes and produce 11 bivalents during meiosis. Sex determination is technically a rare multiple X-multiple Y type, but more importantly it provides the mechanism whereby permanent translocation heterozygosity is maintained in the system. In a second species, Viscum engleri, male plants have 2n=28 chromosomes associating as 11 bivalents and a ring of 6 chomosomes at meiosis.     

3个黄牛品种染色体的G带模式图研究

对秦川牛、岭南牛、西镇牛的染色体进行了 G带研究 ,结果表明 ,这 3个黄牛品种除 Y染色体以外的所有染色体对 ,其 G带带型基本一致。每对染色体都有其独有的带纹特征 ,可用于识别牛的每条染色体。Y染色体有中部 (或亚中部 )和近端着丝粒染色体。根据 3个黄牛品种 G带带型的共同特点 ,对其染色体带型进行了描述、分区和命名 ,并绘制了牛 86个区 354条带的 G带模式图     

Island biogeography of populations: an introduced species transforms survival patterns

Population phenomena, which provide much of the underlying basis for the theoretical structure of island biogeography, have received little direct study. We determined a key population trait-survival-in the Bahamian lizard Anolis sagrei on islands with an experimentally introduced predatory lizard and on neighboring unmanipulated islands. On unmanipulated islands, survival declined with several variables, most notably vegetation height: The island with the shortest vegetation had nearly the highest survival recorded for any lizard. On islands with the introduced predator, which forages mostly on the ground, A. sagrei shifted to taller vegetation; unlike on unmanipulated islands, its survival was very low on islands with the shortest vegetation but was higher on the others. Thus, species introduction radically changed a resident species' relation of survival to a key island-biogeographical variable.     

簇毛麦染色体的形态学及Gie msa-C带的多态性研究Ⅱ.簇毛麦染色体在人工双二倍体中的C-带变化

对硬粒小麦 -簇毛麦双二倍体纯系的簇毛麦染色体C -显带研究表明 ,纯系中每一条簇毛麦染色体的带型及分布具有相当的稳定性 ,为簇毛麦染色体导入小麦后进行鉴定提供了可靠的保证。双二倍体纯系中的簇毛麦与自然群体中簇毛麦染色体的带型比较发现 ,尽管带型有一定的可比性 ,但仍然存在一定的差异。自然群体的簇毛麦染色体带型多态性远大于纯系 ,特别是 3V和 7V染色体 ,发生了较大变化。因此该结果表明 ,把簇毛麦种质导入小麦后 ,为了对导入的簇毛麦染色体或片段进行准确的鉴定 ,最好采用双二倍体纯系作为供体亲本     

An alternative pathway for meiotic chromosome segregation in yeast

In meiosis I of most organisms, homologous chromosomes pair, recombine, and then segregate to opposite poles of the cell. Crossing-over is normally necessary to ensure the proper segregation of the homologs. Recently developed techniques have made it possible to study meiosis with highly defined artificial chromosomes. These techniques were used to demonstrate the existence of a system capable of segregating pairs of nonrecombined artificial chromosomes, regardless of the extent of their sequence homology. This system may contribute to the high fidelity of meiosis by mediating the segregation of pairs of natural chromosomes that have failed to recombine.     

Epigenetic aspects of X-chromosome dosage compensation

The X chromosomes of mammals and fruit flies exhibit unusual properties that have evolved to deal with the different dosages of X-linked genes in males (XY) and females (XX). The X chromosome dosage-compensation mechanisms discovered in these species are evolutionarily unrelated, but exhibit surprising parallels in their regulatory strategies. These features include the importance of noncoding RNAs, and epigenetic spreading of chromatin-modifying activities. Sex chromosomes have posed a fascinating puzzle for biologists. The dissimilar organization, gene content, and regulation of the X and Y chromosomes are thought to reflect selective forces acting on original pairs of identical chromosomes (1-3). The result in many organisms is a male-specific Y chromosome that has lost most of its original genetic content, and a difference in dosage of the X chromosome in males (XY) and females (XX).     

黄麻染色体组型研究

本文比较研究了圆果黄麻“粤圆5号”和长果黄麻“翠绿”的染色体组型。结果是:圆果黄麻和长果黄麻的染色体组型均为 K(2n)=14=12M+2M~(sat),即其染色体均属于中部着丝粒染色体。前者的第5对染色体为随体染色体,后者的第6对染色体为随体染色体。     

豆类植物三种类型染色体(大、中、小)核型分析方法的研究

本文选用三种豆类植物———蚕豆、豌豆、大豆、分别代表大、中、小三种不同类型的染色体 ,研究了其核型 ,并对研究方法进行了讨论。结果表明 ,蚕豆属于大型染色体 ,6对染色体平均长度为 11 33μm ,核型分类为2A ,核型公式为 2n =2x =12 =4m + 4Sm (2SAT) + 2ST + 2T ,豌豆属于中等大小染色体 ,7对染色体平均长度为 5 5 0μm ,核型分类为 2A ,核型公式 2n =2x =14=2M + 4m + 8sm ;大豆属于小染色体 ,2 0对染色体的平均长度为 1 93μm ,核型属于 2B类型 ,核型公式为 2n =2x =40 =2M + 30m + 8sm (2SAT)     

Genetic transfer in plants through interspecific protoplast fusion

Protoplasts of sexually incompatible species have been fused and in some combinations have given rise to somatic hybrid plants. Partial elimination of parental chromosomes from either species is common in such hybrids, but total chromosome loss has generally occurred only with phylogenetically unrelated pairings. Genetic function of one parent may be retained despite a complete loss of its chromosomes, suggesting that genetic introgression is possible in the absence of complete donor chromosomes. A model interspecific combination for such studies is the potato-tomato somatic hybrid for which numerous phenotypes and karyotypes are encountered at the outset, with a broader range observed in the second somatic generation.     

Anolis carolinensis: Effects of Feeding on Reaction to Aposematic Prey

During a 15-day experiment, green anoles, Anolis carolinensis, were: (i) presented with one of two aposematic insects, Oncopeltus fasciatus or Photinus pyralis, during days 4, 6, and 8; (ii) maintained on one of four different food levels during days 9-14; and (iii) presented with the original model on day 15. Lizards on low rations tended to capture more Photinus on day 15 than did anoles on higher rations. No such correlation was observed with Oncopeltus.     

Mapped SSR markers unevenly distributed on the cotton chromosomes

In the past 15 years, more than 9000 SSR markers have been developed, which are a valuable resource for cotton genetics and breeding. Many of them have been mapped in cotton, and several high-density genetic maps have been constructed. In this paper, we jointly analyzed the mapped SSRs to characterize their motifs on cotton chromosomes. The results showed that SSR loci were distributed unevenly on cotton chromosomes with more on C11 and C19 and less on C02 and C04. Different sources of SSRs contributed different predominant SSR types, which were also distributed unequally on cotton chromosomes. Compared to SSRs derived from enriched libraries and BAC end sequences, EST-SSRs could generate novel SSR motifs especially for AT/TA of di-, tetra-, penta- and hexanucleotide. SSR motifs showed a biased distribution on cotton chromosomes with more on C05, C11, and C19, and less on C02 and C04. The uneven distribution of SSRs on cotton chromosomes would help us to enrich the cotton genetic map by motif-specific SSRs. This analysis gave us new knowledge on the architecture of the cotton genome.