Do pollinators determine hybridization patterns in sympatricSatyrium (Orchidaceae) species?

The breakdown of species integrity was studied in three sympatricSatyrium (Orchidaceae) species at a site in the Western Cape province of South Africa. Hybrids with intermediate morphology were identified using multivariate analysis.Satyrium erectum ×S. bicorne andS. erectum ×S. coriifolium hybrids were common, while only oneS. bicorne ×S. coriifolium hybrid was found (a new record). Reciprocal artificial crossing experiments confirmed that genetic compatibility exists between all three species. However, the species have different pollinators: moths inS. bicorne, bees inS. erectum and sunbirds inS. coriifolium. Pollinators, rather than genetic factors, therefore, appear to be responsible for reproductive isolation between these species. Breakdown in pollinator specificity results in interspecific pollen transfer and the formation of hybrids. Overlap in floral signals, including nocturnal scent in bothS. erectum andS. bicorne, and bright coloration in bothS. erectum andS. coriifolium, facilitates the formation of hybrids between these species pairs. The brown, scented flowers ofS. bicorne, on the other hand, share no obvious floral signals with the bright orange, unscented flowers ofS. coriifolium, accounting for the rarity of hybrids between this species pair. Differences in floral morphology also result in mechanical isolation between these two species. Since the three species are sympatric in a very small part of their geographic ranges, it is unlikely that avoidance of hybridization has been an important selective factor in the evolution of specialized pollination systems.     

DEMOGRAPHY AND BREEDING BIOLOGY OF A SMALL,LOCALIZED POPULATION OF SOUTHERN ELEPHANT SEALS (MIROUNGA LEONINA)

Southern elephant seals have been studied in depth in most of their breeding range. One notable exception is the Falkland Islands population. We present data on demography and breeding biology of elephant seals of Sea Lion Island, the main breeding site of this species in the Falklands. Sea Lion Island shelters a small, localized population of southern elephant seals (516 breeding females in 1995 and 518 in 1996). Comparison with the few available census data collected prior to our study suggests that the population has been stable in the short term (1989-1996). Females produced pups at maximum rate and pup mortality was low (2.13%). Breeding sex ratio was strongly unbalanced, with about 14 females per breeding male and 47 females per harem-holding male at peak haul-out. Survival rate between breeding seasons was 67.4% for females and 50% for males. Timing of the breeding season was very similar to that recorded in other populations and was in accordance with clinal variation with latitude. Sex ratio at birth was balanced, and no significant weight dimorphism at weaning between sexes was detected (males: 135.4 kg; females: 132.0 kg). Weaning weight was correlated with size class of the mother.     

Identification of Sources of Resistance to Four Species of Root-knot Nematodes in Tobacco

Resistance to the southern root-knot nematode, Meloidogyne incognita races 1 and 3, has been identified, incorporated, and deployed into commercial cultivars of tobacco, Nicotiana tabacum. Cultivars with resistance to other economically important root-knot nematode species attacking tobacco, M. arenaria, M. hapla, M. javanica, and other host-specific races of M. incognita, are not available in the United States. Twenty-eight tobacco genotypes of diverse origin and two standard cultivars, NC 2326 (susceptible) and Speight G 28 (resistant to M. incognita races 1 and 3), were screened for resistance to eight root-knot nematode populations of North Carolina origin. Based on root gall indices at 8 to 12 weeks after inoculation, all genotypes except NC 2326 and Okinawa were resistant to M. arenaria race 1, and races 1 and 3 of M. incognita. Except for slight root galling, genotypes resistant to M. arenaria race 1 responded similarly to races 1 and 3 of M. incognita. All genotypes except NC 2326, Okinawa, and Speight G 28 showed resistance to M. javanica. Okinawa, while supporting lower reproduction of M. javanica than NC 2326, was rated as moderately susceptible. Tobacco breeding lines 81-R-617A, 81-RL- 2K, SA 1213, SA 1214, SA 1223, and SA 1224 were resistant to M. arenaria race 2, and thus may be used as sources of resistance to this pathogen. No resistance to M. hapla and only moderate resistance to races 2 and 4 of M. incognita were found in any of the tobacco genotypes. Under natural field infestations of M. arenaria race 2, nematode development on resistant tobacco breeding lines 81-RL-2K, SA 1214, and SA 1215 was similar to a susceptible cultivar with some nematicide treatments; however, quantity and quality of yield were inferior compared to K 326 plus nematicides.     

滇西苍山蝗总科昆虫垂直分布的最优分割(英文)

利用对有序样本元素的最优分割方法 ,把滇西苍山蝗总科昆虫的垂直分布划分为四段 :(1) 150 0～190 0m之间的干热河谷灌丛草坡带 ;(2 ) 190 0～ 2 30 0m之间的山地亚热带常绿阔叶林带 ;(3) 2 30 0～2 50 0m之间的山地温带针叶和阔叶林混交林带 ;和 (4 ) 2 50 0～ 2 90 0m之间的中山温性针阔混交林带。按这样的分法 ,每一个带内的差异最小 ,且每个带都具有自己的植被、气候和蝗总科昆虫特点。     

云南西部中-晚泥盆世硅质岩相地层及其放射虫动物群

本文论述的中晚泥盆世放射虫产于滇西阿里、回库、南雅、里拉、太尔市、晒经坡和长育村等地的硅质岩中,包括１５属１８种１０相似种８未定种,其中有３新种。共发现３个泥盆纪放射虫动物群,它们是Ｅｏａｌｂａｉｌｌｅｌｌａ ｌｉｌａｅｎｓｉｓ动物群（Ｄ２）;Ｈｅｌｅｎｉｆｏｒｅ ｌａｔｉｃｌａｖｉｕｍ动物群（Ｄ＾１ ３）;Ｈｏｌｏｅｃｉｓｃｕｓ ｆｏｒｅｍａｎａｅ动物群（Ｄ＾２３）。文章讨论了３个问题①Ｅｏａｌ     

南亚热带酸雨地区陆地生态系统植被、土壤与地表水现状的研究

工业化程度的不断提高给环境带来的压力是全球性的普遍问题。矿物燃料的大量使用 ,使大气中ＳＯ2 、ＮＯＸ 和其它酸性颗粒物等污染物浓度增加 ,导致大气环境质量恶化 ,影响全球植被生态系统的生产力。排放到大气中的ＳＯ2 、ＮＯＸ 是形成酸雨的重要来源 ,大范围的迁移是它的一个重要特征。国内外已取得的研究结果证明 ,ＳＯ2 、ＮＯＸ等污染气体及其沉降化合物直接导致植物生长量生物量的下降、叶伤害、光合作用减弱、呼吸作用增强。另一方面 ,酸雨的形成导致土壤酸化、土壤缓冲能力下降、Ａ1离子的释放、盐基离子的淋洗、营养亏损 ,使树…     

云南墨江下密地早二叠世常么期含 地层及 化石带

简要介绍云南墨江下密地早二叠世常么期含Ｔｉｎｇ地层,对其中Ｔｉｎｇ类动物群特征作了归纳,记述７属２９种,其中包括４新种。依据Ｔｉｎｇ类化石在该剖面中的垂直分布在常么组建立Ｅｏｐａｒａｆｕｓｕｌｉｎａ ｇｒａｃｉｌｉｓ－Ｅｏ．ｍｅｊｉａｎｇｅｎｓｉｓ带和Ｃｈａｌａｒｏｓｃｈｗａｇｅｒｉｎａ ｖｕｌｇａｒｉｓ－Ｃｈａｌａｒｏｓｃｈｗａｇｅｒｉｎａ ｐｓｅｕｄｏｖｕｌｇａｒｉｓ带。并与国内外相关地层进行     

云南古蚖属六新种(原尾纲:古蚖目)

描述了采自云南的 6个古新种 :高黎贡古Eosentomongaoligongense、怒江古E nujiangense、紫溪古E zixiensis、禄劝古E luquanense、盈江古E yingjiangense和瑞丽古E ruiliense。     

云南省颚方头泥蜂属一新种记述 (膜翅目：泥蜂科)

颚方头泥蜂属（Entomognathus Dahlbom, 1844) 世界已知4 个亚属共44种,其中我国已知2亚属3种。长脉泥蜂亚属（Koxinga Pate, 1944）的种类为一类稀有的中小型独居捕猎蜂,目前世界仅知2种,其中1 种分布于印度,另一种分布于东南亚地区。本文记述了采自我国云南省的长脉泥蜂亚属1新种。     

云南竹亚科一些属种的增订

报道了云南竹亚科新名称１个,新组合１个,新异名１个,发现１个不合格名称,１个属在云南分布的新记录和１个种在我国分布的新记录。同时讨论了单枝竹属和空竹属的地理分布。