Calibration of the great american interchange

From radioisotopic (potassium-argon) age determinations of tuffs and magnetostratigraphy of Late Tertiary mammal-bearing beds in Catamarca Province, northwest Argentina, refined estimates have been obtained for the durations and boundaries of beds of Chasicoan (Middle Miocene) through Chapadmalalan (Pliocene) age. An age of 9.0 million years is tentatively accepted for the Chasicoan-Huayquerian boundary, 5.0 million years for the Huayquerian-Montehermosan boundary, and 3.0 million years for the Montehermosan-Chapadmalalan boundary. Procyonids (raccoons and their allies), a group of North American origin, are first recorded in South America in a level immediately below a unit dated at 6.0 million years. Cricetine rodents of the tribe Sigmodontini are first recorded in South America in beds of Montehermosan age in Argentina. Ground sloths, a group of South American origin, first appear in North America in Early Hemphillian time in beds dated between 9.5 and 9.0 million years. The Panamanian land bridge was established by 3.0 million years ago, and an interchange of the terrestrial faunas was well under way by Late Blancan time (around 2.5 million years before present) in North America and by Chapadmalalan time in South America.     

First record of giant anteater (xenarthra, myrmecophagidae) in north america

A right metacarpal III represents the first North American record of the giant anteater (Myrmecophaga tridactyla). Recovered in northwestern Sonora, Mexico, with a rich vertebrate fauna of early Pleistocene (Irvingtonian) age, it belongs to a cohort of large mammals that dispersed from South America to North America along a savanna corridor. Presumably habitat and climatic changes have subsequently driven this mammalian family more than 3000 kilometers back into Central America from its former expansion into temperate North America.     

宜黄华南虎自然保护区大型真菌区系分析

在野外调查及查阅资料的基础上,对宜黄华南虎自然保护区的大型真菌区系进行了分析,结果表明:该自然保护区内共有大型真菌175种,隶属于35科87属。区系分析结果表明:从科的地理分布型上看,该保护区热带亚热带分布科有2科,占总科数的5.71%,东亚—北美分布科有1科,占总科数的2.86%,北温带分布科有3科,占总科数的8.57%,其余均为世界分布,不存在特有科的分布。从属的分布型来看,属的分布区主要是以世界广布成分(70.01%)为主,其次是泛热带成分(13.79%)和北温带成分(9.20%)。该地区的大型真菌种类不仅具备热带—亚热带区系特征,还具有一定比例的北温带成分。     

秦岭火地塘伞菌区系组成特征

对秦岭火地塘伞菌进行了调查,鉴定出192种,隶属于55属、17科。并对其区系进行了初步分析表明,含10种以上的科为口蘑科、丝膜菌科、鬼伞科、红菇科、蘑菇科、球盖菇科;含10种以上的属为杯伞属、小皮伞属、丝膜菌属。从种的区系地理成分上可分为8个分布型:世界广布成分(17.4%)、北温带成分(64.8%)、东亚—北美成分(3.5%)、旧世界温带成分(3.1%)、中国—喜马拉雅成分(3.6%)、中国—日本成分(2.6%)、泛热带成分(3.1%)、热带亚洲—热带非洲成分(1.6%),表现出典型的温带区系特征,与内蒙古大青山比较相似。同时表明该地区与北美、日本、非洲在伞菌区系上有着一定的联系。     

Calibration of the beginning of the age of mammals in patagonia

Beds of the Rio Chico Formation containing the earliest known land mammals in Patagonia, southern Argentina, were calibrated by potassium-argon age determinations and paleomagnetic polarity data. The Riochican land mammal age encompasses the middle and late Paleocene and corresponds in time with Torrejonian and Tiffanian land mammal faunas in North America.     

THE RELATIONS OF THE NORTH AMERICAN FLORA TO THAT OF SOUTH AMERICA

Reviewing the floral relations of North and South America as illustrated in the foregoing instances, we may say that the phenomena of distribution agree fairly with the record of physical conditions which have succeeded each other and those which still exist, and upon which we might almost a priori have predicted an analogous set of distribution phenomena. In this relationship we may distinguish three categories of distribution: (1) Those due to the conditions of human civilization, commerce, etc. This has resulted in placing the same species in similar regions of both continents, as, for example, Fagonia cretica in Lower California and Chile; Munroa squarrosa, western plains of North America, plains of Argentine and high plateaus of Chile and Bolivia; Frankenia grandiflora, Southern California and Arizona, coast lands of Chile; Oxytheca dendroidea, Lastarricea chilensis, and Chorizanthe comrnmissuralis, all in Southern California and Western Chile. (2) Those due to the operation of natural causes acting unde present conditions of climate, geology, etc. Under this head may be cited such species as sida leprosa, hastata, anomala, Cienfugosia sulphurea, Spergulariaplattensis and, in general, elements of Gulf zone distribution; also certain elements which still find a pathway along the continental axis, including some alpine and mountain xerophilous genera. (3) The third category of distribution would include those phenomena due to geological and climatic changes acting through long periods. Under this head are included the elements of greatest significance in the relationsip of the North and South America floras. The endemic boreal flora of the Andes, the equally endemic boreal flora of the Mexican Cordilleras, and genera with sharply distinct species or sub-genera in the arid extra-tropical regions of both continents, which may be called remnant elements.     

太行山猕猴自然保护区苔藓植物区系研究

根据调查和参考有关文献,对太行山猕猴自然保护区苔藓植物区系进行了初步分析,结果发现,该区共有苔藓植物34科55属107种（包括亚种、变种、变型）,其中苔类植物8科8属8种,藓类植物26科47属99种;地理成分复杂多样,种地理成分统计分析表明,温带成分占绝对优势,东亚成分次之,中国特有种第3,热带成分也占有一定比例;该区苔藓植物区系隶属于华北地区但兼有多种成分,体现该区苔藓植物区系的南北过渡特征。     

The effects of Cenozoic global change on squirrel phylogeny

By modifying habitats and creating bridges and barriers between landmasses, climate change and tectonic events are believed to have important consequences for diversification of terrestrial organisms. Such consequences should be most evident in phylogenetic histories of groups that are ancient, widespread, and diverse. The squirrel family (Sciuridae) is one of very few mammalian families endemic to Eurasia, Africa, and North and South America and is ideal for examining these issues. Through phylogenetic and molecular-clock analyses, we infer that arrival and diversification of squirrels in Africa, on Sunda Shelf islands, across Beringea, and across the Panamanian isthmus coincide in timing and location with multiple well-documented sea-level, tectonic, and paleontological events. These precise correspondences point to an important role for global change in the diversification of a major group of mammals.     

浙江衢县木本植物区系

浙江衢县共有木本植物９３科２６９属７６３种，种类丰富，地理成分复杂，含有许多古老的科属，与世界区系有广泛的联系，且具明显的亚热带性质，通过与周围山地植物区系比较，显示出该区系以华东植物区系成分为主，华中；华南，华北及西南植物区系成分兼容并存，并显示出中亚热带从南到北和从东到西的交叉过渡。     

六盘山不全变态类昆虫区系研究

本文在考证大量文献资料和定名标本基础上整理出六盘山不全变态类昆虫名录,共计12目70科236属382种。采用二元相似性系数公式SI=C/（A＋B-C）对该区昆虫的区系特征及其相互间关系进行了分析。最后以下初步结论：六盘山不全变态类昆虫在世界动物地理区系中,突出古北区成分,共计219种,占已知总数的57.33%,古北界＋东洋界混合成分次之,共计122种,占31.94%;在中国动物地理区系中,华北动物区成分113种,占29.58%,其他成分由高到低依次为：蒙新区〉东北区〉西南区〉青藏区〉华中区〉华南区,表明该区昆虫在区系组成上的特殊性。     

明清时期玉米在我国的传播

玉米起源于南美,明中期传入我国。明后期、清中叶后随着人口增加带来的粮食压力,促使山区人民开垦土地和选择玉米这一高产农作物种植。明末、清中叶开始在淮南山区大面积种植,进而在我国南北各地逐步传播。居民迁移、政府推广、区域之间的相互学习是玉米种植发展的直接原因,最终成为我国重要的粮食作物。     

退耕还林后陕北吴起县植物区系研究

陕西省吴起县1998年确立了封山退耕的战略,并成为名副其实的全国退耕还林第一县。实施退耕还林后,吴起现有种子植物56科160属235种。其中裸子植物3科3属3种,被子植53科157属232种。中国特有属2个,包含中国特有种2个。区系地理成分复杂,包括了种子植物科的8个分布类型和2个变型,以及种子植物属的14个分布类型和11个变型。温带成分构成了本区系的主体,本区系属于温带性质。同时本区系又有丰富的热带亚热带成分,具有明显的热带亚热带向温带过渡性。     

重庆巫山五里坡自然保护区种子植物科属区系分析

通过采集标本、拍照、鉴定、统计,对重庆巫山五里坡自然保护区植物物种多样性进行了研究。结果表明:五里坡自然保护区共有野生种子植物156科796属2 379种(含种下等级);该地区植物区系成分温带性质稍强,在属的水平上,温带成分占优势,占该地区非世界性属总数的60.51%;热带成分占该地区非世界性属总数的34.50%;间断分布属占该地区非世界性属总数的20.35%,其中东亚和北美洲间断分布属占首位;中国特有属37个,占该地区非世界性属总数的4.99%。与四川地区及临近的2个自然保护区相比,五里坡和后河自然保护区的相似性最大,表现出较强的温带性质。五里坡由于其特殊的地理位置及环境,在植物区系的组成上具有较强的特殊性,对研究华中地区和西南地区植物区系具有重要意义。     

宁夏罗山国家自然保护区蝶类区系研究

2008—2009年对宁夏罗山进行了系统的蝶类标本采集,经分类鉴定出45种,隶属6科32属,其中以蛱蝶科种类最多,计8属14种,占总种数的28.13%,灰蝶科和眼蝶科次之,分别计9属10种和8属9种,各占总种数的25%.从世界动物区系的构成来看,组成以古北区和东洋区共有种及典型古北种为主体,占总种数的46.67%,中国动物地理区划中以华北+东北+蒙新+青藏+西南+华中+华南型居多,占22.22%.罗山和贺兰山的蝶类相似性系数较高,为0.46,罗山和六盘山的蝶类相似性系数较低,为0.19,3个地区蝶类组成的相似性分析,符合宁夏昆虫地理区划特点.     

Podocarpus from the eocene of north america

A few leafy gymnosperm shoots were found in Eocene deposits of southeastern North America. Similar fossil material from Tertiary deposits in North America has been identified as Taxodium, Taxites, and Sequoia. This new fossil material is not related to these genera but belongs to Podocarpus section Stachycarpus. This is the first fossil record of this section in North America.     

黑龙江友好自然保护区自然资源的调查及评价

文章对黑龙江友好自然保护区的自然资源状况等进行了彻查.保护区植被属于温带性质,植物区系属泛北极植物区、欧亚森林植物亚区、长白植物区系,同时有蒙古植物区系、华北植物区系成分.保护区内共分布有高等植物836种,其中苔藓植物56科100属183种,蕨类植物14科26属41种,种子植物89科288属612种.共有脊椎动物330...     

新乡市区园林植物区系特征分析

在野外调查及查阅资料的基础上,对新乡市主城区园林植物资源进行区系分析,结果表明,研究区共有园林植物74科161属311种(含变种),木本植物为主体。5种以上的科有17个,含81属205种; 区域少种科和区域单种科共57科,含80属106种。科、属、种的配比特征为:较多的科、属含较少的种,较少的科、属含较多的种。热带性质的科29科,温带性质的科有23 科,中国特有分布 2科,分别占本植物区系非世界分布总科数的53.70%、42.59%和3.70%,温带性质科与热带性质科在数量上无明显优势,但含物种较多的优势科大都属于温带分布和世界分布型。热带分布属42属,以泛热带分布属最多; 温带分布属100属,北温带分布属居首位; 中国特有分布7属。新乡市园林植物的规划方向应以观赏性较好的乡土树种为主,对外来树种应加强入侵生态风险评估。     

浙江衡县木本植物区系

浙江衡县共有木本植物93科269属763种,种类丰富,地理成分复杂,含有许多古老的科属,与世界区系有广泛的联系,且具明显的亚热带性质。通过与周围山地植物区系比较,显示出该区系以华东植物区系成分为主,华中、华南、华北及西南植物区系成分兼容并存,并显示出中亚热带从南到书和从东到西的交叉过渡。     

Polyploidy and the evolution of gender dimorphism in plants

Gender dimorphism and polyploidy are important evolutionary transitions that have evolved repeatedly in many plant families. We show that gender dimorphism in North American Lycium (Solanaceae) has evolved in polyploid, self-compatible taxa whose closest relatives are cosexual, self-incompatible diploids. This has occurred independently in South African Lycium. We present additional evidence for this pathway to gender dimorphism from 12 genera involving at least 20 independent evolutionary events. We propose that polyploidy is a trigger of unrecognized importance for the evolution of gender dimorphism, which operates by disrupting self-incompatibility and leading to inbreeding depression. Subsequently, male sterile mutants invade and increase because they are unable to inbreed.     

广州从化市风水林植物群落种子植物区系特征分析

通过对广州从化市的471个村庄周围的风水林进行调查和标本采集,共收集了2 530份植物标本,存于华南农业大学植物标本馆(CANT)和中国科学院华南植物园标本馆(IBSC)。整理出从化市风水林植物名录,在此基础上对从化市风水林植物群落内的科、属植物区系进行了详细分析。结果显示:从化市风水林种子植物116科2,99属531种;其中,裸子植物3科3属5种;被子植物113科2,96属526种。风水林植物区系成分较复杂,泛热带区系成分占绝对优势,温带成分比例较少,与广州市种子植物区系特征极为相似,说明从化市风水林的地带性植被代表性较强,保存较好,可作为乡村自然保护小区的重点保护对象,优先保护。