鸟类核型研究XIV.heng形目14种

本文报道了heng形目14种鸟的核型，并发现该目种类间染色体数目变异很大，由石heng的2n=40至沙锥的2n=98不等。这种变异是由原始的2n=80核型通过两种方式形成的：在heng小目中，小染色体相互融合而造成染色体数目的减少；在鹬小目中，大染色体的着丝点分离而造成染色体数目的增加。     

鸟类核型研究XⅥ，Hang形目14种

本文报道了Hang形目14种鸟的核型,并发现该中类间染色体数目变异很大,由石Hang的2n=40至沙锥的2nm=98不等,这种变异是由原始的2n=80核型通过两种方式形成的,在Hang小目中,小染色体相互融合而造成染色体数目的减少,在鹬小目中,大染色体的着丝点分离 而 造成染色体数目的增加。     

八种国产葱属植物染色体研究

本文对国产葱属Allium 8个种的14个居群的染色体进行了研究。其染色体基数均为x=8,其中7个居群为二倍体(2n=2x=16),6个居群为四倍体(2n=4x=32),1个居群为多倍体复合体(2n=4x=32,2n=6x=48,2n=8x=64和2n=9x=72)。并发现随体染色体十分活跃,在多倍体中其数目并不都与其倍性相对应,并有“串状随体”现象出现;在有些类群中其形态变异较大,而随体染色体杂合形式的多态现象也较普遍。本文重点讨论了随体染色体的数目、形态变异及杂合现象在葱属进化中的作用,认为随体染色体形态变异及杂合现象的出现是葱属中遗传变异的重要源泉之一。并对葱属中的染色体基数及种内多倍性问题进行了初步讨论。     

小麦族几种近缘植物细胞在长期离体培养中的染色体变异

对小麦及其4种近缘属间禾草进行了长时间 (0.5～5.7年, 个别8.6年) 的愈伤组织培养,在继代过程中染色体数目的变异在染色体倍性低的簇毛麦(Haynaldia villosa, 2n=2x=14)及新麦草(Psathyrostachys juncea, 2n=2x=14) 倾向于数目的增大;染色体倍性高的小麦 (Triticum aestivum, 2n=6x=42) 趋向于数目的减少;而倍性居中的羊草 (Leymus chinensis, 2n=4x=28) 既有增大也有减小;染色体倍性最高的高冰草 (Agropyron elongatum, 2n=6x=70) 最为稳定,但也有减少的趋向。愈伤组织的胚性主要与二倍体及亚二倍体的总水平相关。     

藏狐、虎鼬、艾鼬的核型分析

本文报道了产于新疆的3种食肉目动物的染色体组型。藏狐2n=36,全部为双臂染色体。虎鼬2n=38,由33条双臂染色体,5条单臂染色体组成;在第1—3对染色体的长臂上恒定地出现次缢痕。艾鼬2n=38,由32条双臂染色体,6条单臂染色体组成。其染色体组型与等(1976)报道的艾鼬(新西伯利亚,诺俄尔比斯克)2n=38较为接近,而与王宗仁等(1984)报道的艾鼬(河北,怀来)2n=36,差异较大。     

黄精属的细胞分类学研究——Ⅱ.8个种的核型和进化

作者研究了中国产黄精属8个种的核型,结果如下:热河黄精,2n=22=14m(4SAT)+2sm(SAT)+6st;多花黄精,2n=22=8m+8sm(2sc)+6st(2sc);玉竹,2n=20=12m+8sm;小玉竹,2n=20=8m(2sc)+8sm+4st;长梗黄精,2n=16(18)=10m+4sm+2st;二苞黄精,2n=18=8m+10sm;黄精,2n=24=4m+8sm(2sc)+12st(2sc);卷叶黄精,2n=20=12m(2sc)+8sm。作者推测该属的染色体基数x=10。染色体数目进化的趋势是:非整倍性变异为主,整倍性变异为次;上升性变异为主,下降性变异为次。按照核型不对称程度,8个种的核型可分为三个等级。核型由对称向不对称进化是与染色体数目的进化趋势大体上相关的。     

黄精属细胞分类学研究Ⅱ.四川金佛山地区黄精属植物核型

本文对四川金佛山地区4种黄精属植物的核型进行了研究,其结果为:滇黄精:2n=26=6m+12sm(2SAT)+8st(2SAT);距药黄精:2n=26=10m+4sm+12st;垂叶黄精:2n=30=14m(2SAT)+4sm+10st+2t、2n=28=14m+6sm+6st+2t;湖北黄精:2n=30=12m+8sm+10st、2n=28=6m+10sm+10st+2t、2n=22=2m+12sm 8st。通过与其它地区黄精属植物染色体数目与形态的比较,发现本地区所有种类的染色体数目普遍偏高,无论在染色体基数或染色体形态上都比较接近喜马拉雅山地区分布的种类。从实验结果进一步看出了黄精属的染色体变异是相当明显的,并主要表现为非整倍性变异;在有些情况下,染色体数目与结构的变异能与某些形态学特征相联系。     

黄精属细胞分类学研究——Ⅱ.四川金佛山地区黄精属植物核型

本文对四川金佛山地区4种黄精属植物的核型进行了研究,其结果为:滇黄精:2n=26=6m+12sm(2SAT)+8st(2SAT);距药黄精:2n=26=10m+4sm+12st;垂叶黄精:2n=30=14m(2SAT)+4sm+10st+2t、2n=28=14m+6sm+6st+2t;湖北黄精:2n=30=12m+8sm+10st、2n=28=6m+10sm+10st+2t、2n=22=2m+12sm 8st。通过与其它地区黄精属植物染色体数目与形态的比较,发现本地区所有种类的染色体数目普遍偏高,无论在染色体基数或染色体形态上都比较接近喜马拉雅山地区分布的种类。从实验结果进一步看出了黄精属的染色体变异是相当明显的,并主要表现为非整倍性变异;在有些情况下,染色体数目与结构的变异能与某些形态学特征相联系。     

黄精属的细胞分类学研究Ⅰ.8个种的核型和进化

作者研究了中国产黄精属8个种的核型,结果如下:热河黄精,2n=22=14m(4SAT)+2sm(SAT)+6st;多花黄精,2n=22=8m+8sm(2sc)+6st(2sc);玉竹,2n=20=12m+8sm;小玉竹,2n=20=8m(2sc)+8sm+4st;长梗黄精,2n=16(18)=10m+4sm+2st;二苞黄精,2n=18=8m+10sm;黄精,2n=24=4m+8sm(2sc)+12st(2sc);卷叶黄精,2n=20=12m(2sc)+8sm。作者推测该属的染色体基数x=10。染色体数目进化的趋势是:非整倍性变异为主,整倍性变异为次;上升性变异为主,下降性变异为次。按照核型不对称程度,8个种的核型可分为三个等级。核型由对称向不对称进化是与染色体数目的进化趋势大体上相关的。     

番木瓜核型和减数分裂研究

对番木瓜核型和花粉母细胞减数分裂行为的研究表明,番木瓜染色体数目为 2n = 18,由 9 对中部着丝粒染色体组成。核型公式为 2n = 2x = 18m。花粉母细胞减数分裂正常,在终变期和中期Ⅰ观察到 9 个二价体,未观察到染色体结构变异和行为异常。     

鸟类核型研究——Ⅻ.非雀形目10科5种鸟类

本文报道了非雀形目鸟类10科15种的核型,并对鸟类中某些核型分类与传统形态学分类不一致之处作了初步的分析。     

鸟类核型研究Ⅳ.鸻形目(CHARADRIIFORMES,AVES)10种

本文报道了鸻形目鸟类2科10种的核型。并和已报道过的鸻形目6种21种的核型进行了比较研究。我们发现鸻形目鸟类中存在两种截然不同的核型,推断它们可能有不同的进化起源。这与Sibley等人(1987)通过对DNA—DNA杂交数据的分析得出的结果相似。     

鸟类核型研究：Ⅴ.攀禽类20种（Climbers,Aves）

本文报道了攀禽类8科20种的核型,并对已报道过的16科96种攀禽类鸟类的核型进行了比较研究。攀禽类通常依据表型差异被划分为对趾型,并趾型和异趾型三个类群。Sibley(1988)等则依据DNA差异(通过DNA-DNA分子杂交测定)分为三个小纲:啄木鸟小纲,佛法僧小纲和雀小纲。这两种划分是截然不同的。核型比较的结果支持了Sibley对攀禽类的划分。     

四种风毛菊属植物的核型研究

本文首次报道产于我国华北地区风毛菊属（ＳａｕｓｓｕｒｅａＤＣ．）４种植物的染色体数目和核型。四个种的染色体数目均是２ｎ＝２６,都是２倍体。它们的核型是：糠风毛菊（Ｓ．Ｐａｌｅａｔａ）Ｚｎ＝２ｘ＝２６＝１８ｍ＋６ｓｍ＋２ｓｔ,属２Ｂ型,华北风毛菊（Ｓ．ｍｏｎｇｏｌｉｃａ）Ｚｎ＝２ｘ＝２６＝１４ｍ＋４ｓｍ＋８ｓｔ,属２Ｂ型;狭苞凤毛菊（Ｓ．ｄｉｅｌｓｉａｎａ）Ｚｎ＝２ｘ＝２６＝８ｍ＋１２ｓｍ＋６ｓｔ,属２Ｃ型;银背凤毛菊（Ｓ．ｎｉｖｅａ）２ｎ＝２ｘ＝２６＝１８ｍ＋６ｓｍ＋２ｓｔ,属２Ａ型。染色体中均未发现随体。     

Study on the inheritance of the centric fusion in the blue fox,Alopex lagopus

The inheritance of a centric fusion in the blue fox,Alopex lagopus was investigated in 38 litters (258 animals) originated from matings of parents (64 animals) with all possible diploid numbers of chromosomes (2n=50, 49 and 48). In general, the Robertsonian translocation was inherited in accordance with the Mendelian principle. However, in the matings of females with 2n=49 and males with 2n=50 a significantly higher number of animals with 2n=50 was observed in the progeny. Moreover, observations on two litters indicated thede novo occurrence of the centric fusion and fission.     

Karyology and phylogeny of some Mesoamerican species of Zamia (Zamiaceae)

Chromosome numbers and karyotypes of four species of Zamia L. (Zamiaceae) are described. Plants of Z. manicata from Colombia are 2n = 18 with eight metacentric (M), four submetacentric (S), two acrocentric (A), and four telocentric (T) chromosomes. Plants of Z. ipetiensis from Panama are 2n = 23 with 3M + 4S + 2A + 14T. Plants of Z. cunaria from Panama have two different chromosome numbers, 2n = 23 with 3M + 4S + 2A + 14T and 2n = 24 with 2M + 4S + 2A + 16T. Plants of Z. acuminata from Costa Rica and Panama are 2n = 24 with 2M + 4S + 2A + 16T. On the basis of the occurrence of a one-to-two-ratio in the variation of M- and T-chromosome numbers in the karyotypes, centric fission or fusion are considered for their potential involvement in the chromosome variation of these plants. Data deriving from morphology and karyology, interpreted in a cladistic framework, suggest that centric fission rather than centric fusion is involved in the karyotype diversification of the four species and their closest Mesoamerican allies.     

X chromosomes of American marsupials contain minimal amounts of euchromatin

The karyotypes of four South American didelphid marsupials, representing diploid numbers of 2n = 14 and 18, have been analyzed by a variety of banding techniques. The 2n = 14 karyotypes display a high degree of homoeology, but there also exist distinct similarities between the 2n = 14 and 2n = 18 karyotypes. The interspecific differences found are due to centric fissions, pericentric inversions, and variations in the amount and composition of the constitutive heterochromatin. Contrary to the evolutionary conservation of the banding patterns in all autosomal arms, there are multiple differences in the number and chromosomal location of the nucleolus organizer regions. In species with X-linked nucleolus organizers, the 18S + 28S ribosomal RNA genes escape inactivation in female cells. Measurements on the X chromosomes of Marmosa fuscata and Micoureus demerarae unexpectedly reveal the lowest quantities of euchromatin so far determined in the X chromosomes of mammals: 1.5% and 1.8%, respectively, of their haploid female genomes. This is significantly less than the amount of euchromatin in the basic X chromosomes of other marsupials (3%) or eutherians (5%).     

Medium‐term changes in coastal bird communities in the Western Cape,South Africa

There are few studies of medium‐term, quantitative changes in faunal communities in the southern hemisphere. The linear nature of coastlines makes populations of coastal birds easy to count. Repeat surveys of 278 km of coastline in three regions of the Western Cape, South Africa show marked differences in coastal bird community structure over the last 30 years, despite limited human impacts on coastal habitats (mainly increased human disturbance). The total number of birds has not changed, but species richness increased following colonization of the coast by Egyptian geese (Alopochen aegyptiaca, Anatidae) and three species of ibises (Threskiornithidae). Biomass also increased due to greater numbers of large‐bodied birds. Contrary to the prediction that large birds are more susceptible to human disturbance, most small birds decreased in abundance. Among waders that breed along the coastline, numbers of African oystercatchers (Haematopus moquini, Haematopodidae) doubled, linked to increased food availability following invasions by alien mussels (Mytilidae). By comparison, numbers of white‐fronted plovers (Charadrius marginatus, Charadriidae) decreased by 37% (59% close to Cape Town), at least in part as a result of increasing human disturbance. The greatest decreases occurred among migrant waders (Scolopacidae and Charadriidae), with numbers of the four most abundant species falling by >50%, and both common Calidris species by >90%. Migrant wader populations decreased in all three regions, irrespective of whether surveys were in protected areas or not, suggesting that factors outside the region are driving these trends. Some species may have decreased due to changes in their preferred wintering areas, but others probably reflect population decreases, confirming the generally poor conservation status of migrant waterbirds worldwide.     

Cytogenetics, cytotaxonomy and chromosomal evolution of Chrysomelinae revisited (Coleoptera, Chrysomelidae)

Nearly 260 taxa and chromosomal races of subfamily Chrysomelinae have been chromosomally analyzed showing a wide range of diploid numbers from 2n = 12 to 2n = 50, and four types of male sex-chromosome systems. with the parachute-like ones Xy(p) and XY(p) clearly prevailing (79.0%), but with the XO well represented too (19.75%). The modal haploid number for chrysomelines is n = 12 (34.2%) although it is not probably the presumed most plesiomorph for the whole subfamily, because in tribe Timarchini the modal number is n = 10 (53.6%) and in subtribe Chrysomelina n = 17 (65.7%). Some well sampled genera, such as Timarcha, Chrysolina and Cyrtonus, are variable in diploid numbers, whereas others, like Chrysomela, Paropsisterna, Oreina and Leptinotarsa, are conservative and these differences are discussed. The main shifts in the chromosomal evolution of Chrysomelinae seems to be centric fissions and pericentric inversions but other changes as centric fusions are also clearly demonstrated. The biarmed chromosome shape is the prevalent condition, as found in most Coleoptera, although a fair number of species hold a few uniarmed chromosomes at least. A significant negative correlation between the haploid numbers and the asymmetry in size of karyotypes (r = -0.74) has been found from a large sample of 63 checked species of ten different genera. Therefore, the increases in haploid number are generally associated with a higher karyotype symmetry.     

盾叶薯蓣自然变异类型间的比较研究

对取自云南期纳的二倍体和三倍体盾叶薯蓣植株以及重庆城口的四倍体植株进行了形态学、染色体数目及同工酶的比较研究。结果表明,这3种类型植株在叶片形态上有明显的差异。二倍体的染色体数目是2n=2x=20,三倍体为2n=3x=30,四倍体为2n=4x=40;酯酶(EST)和超氧化物歧化酶(SOD)酶谱显示,3种类型植株之间具有明显的相关性,但多倍体较二倍体的酶带条数少且着色浅。这些差异除了有地理分布不同的因素外,倍性的不同也是很重要的因素。