虾脊兰的栽培与利用(综述)

虾脊兰具有很高的观赏价值,是一类待开发的兰花资源。我国的野生资源十分丰富,本文参考前人的研究文献,结合本身工作,着重介绍虾脊兰的分布与研究概况,对虾脊兰引种栽培和繁殖技术做简要论述,并提出我国虾脊兰属植物今后利用及研究方向的建议。     

朵椒的引种栽培试验初报

针对朵椒引种栽培中存在的关键技术难题,开展了种子处理方法、育苗密度、苗木控制措施等试验,为朵椒的规模化人工栽培奠定了技术基础。     

黄土峁状丘陵区牧草引种及立地水分动态研究

为丰富黄土高原峁状丘陵区牧草种质资源,为退耕还林还草提供科技支撑,自1998年起从国内外陆续引进牧草品种4科、14属、36种100余份,经5年的适应性驯化,鉴选出了适宜该区生态条件的优质牧草4科9属21种.鉴选出的良种牧草抗旱、耐瘠薄、优质、高产,在坡地退耕还草中有重要意义.同时对其立地条件进行了研究,结果表明不同牧草对立地土壤水分利用强度及空间分布有很大的差异,提出了不同牧草混播比例及立地范围.     

沙生灌木沙漠葳区域栽培试验

在吐鲁番、敦煌、民勤和天水4个地区进行了连续4年的沙漠葳[Chilopsis linearis（Cav．）Sweet]引种栽培试验,结果表明：沙漠葳是嗜热喜光的阳性树种,在吐鲁番生长表现良好,苗高、地茎、冠幅、主根长及侧根数等指标远高于其他试验区,苗高的年平均生长量可达2．26m,是其他3个试验区的3倍以上,2年生苗即可正常开花结实;在敦煌和民勤地区,沙漠葳能开花但种子不能成熟,植株生长量小,且受冬季低温和初春大气干旱的危害严重;在天水地区沙漠葳生长表现较好并能越冬存活,但不能正常开花结实。沙漠蒇的营养生长与年均温度和≥10℃有效积温呈显著正相关,相关系数分别达0．9868和0．9921,而与日照时数和相对湿度的相关性不显著。     

PHYLOGEOGRAPHY OF CUTLERIA CYLINDRICA (CUTLERIALES,PHAEOPHYCEAE) IN NORTHEASTERN ASIA,AND THE IDENTITY OF AN INTRODUCED POPULATION IN CALIFORNIA1

Cutleria cylindrica Okamura was described from Japan in 1902 and has been reported only from northwestern Asia until its relatively recent discovery in California, USA, and Baja California, Mexico. To clarify the genetic relationships within and among the disjunct populations, we carried out a molecular phylogenetic study, as well as the examination of sex ratio and the life‐history patterns, of populations in Japan, Korea, and California. Based on the DNA sequences of mitochondrial genes cox2, cox3, the open reading frame (ORF) region, and the spacer between cox3 and ORF, a total of 23 haplotypes were detected in the 85 individuals from 20 localities in Japan, Korea, and California. All localities in Japan and Korea included multiple haplotypes, but only a single haplotype was found in California. There was a positive relationship between distance and genetic divergence in Japan and Korea. The single haplotype found in California was the same as one occurring in Japan (Aomori Pref. and Fukuoka Pref.) and Korea (Daedaepo, Pusan). Both male and female gametophytes were distributed in most northeastern Asian populations. Only female gametophytes, developing parthenogenetically from female gametes, were found in California and Aomori Pref., Japan. On the basis of these results, we conclude that the disjunct population of C. cylindrica in California originated from a relatively recent introduction from Japan and shares its origin with the parthenogenetic population in the Tsugaru Strait.     

Restoration of genetic connectivity among Northern Rockies wolf populations

Probably no conservation genetics issue is currently more controversial than the question of whether grey wolves (Canis lupus) in the Northern Rockies have recovered to genetically effective levels. Following the dispersal‐based recolonization of Northwestern Montana from Canada, and reintroductions to Yellowstone and Central Idaho, wolves have vastly exceeded population recovery goals of 300 wolves distributed in at least 10 breeding pairs in each of Wyoming, Idaho and Montana. With >1700 wolves currently, efforts to delist wolves from endangered status have become mired in legal battles over the distinct population segment (DPS) clause of the Endangered Species Act (ESA), and whether subpopulations within the DPS were genetically isolated. An earlier study by vonHoldt et al. (2008) suggested Yellowstone National Park wolves were indeed isolated and was used against delisting in 2008. Since then, wolves were temporarily delisted, and a first controversial hunting season occurred in fall of 2009. Yet, concerns over the genetic recovery of wolves in the Northern Rockies remain, and upcoming District court rulings in the summer of 2010 will probably include consideration of gene flow between subpopulations. In this issue of Molecular Ecology, vonHoldt et al. (2010) conduct the largest analysis of gene flow and population structure of the Northern Rockies wolves to date. Using an impressive sampling design and novel analytic methods, vonHoldt et al. (2010) show substantial levels of gene flow between three identified subpopulations of wolves within the Northern Rockies, clarifying previous analyses and convincingly showing genetic recovery.     

Molecular phylogeographic analyses of the loach Oxynoemacheilus bureschi reveal post‐glacial range extensions across the Balkans

Rivers on the Balkan Peninsula can be separated into ichthyofaunistic areas with different endemic fish species. The Vardar River contains a particularly large number of endemics, indicating its complete and long‐term isolation from neighbouring river systems. One of the few species shared with other rivers is the loach species Oxynoemacheilus bureschi. In this study, the genetic analyses of 175 individuals of O. bureschi from 17 sites, covering the entire distribution of the species, including the Rivers Vardar (= Axios), Struma (= Strymon), Mesta (= Nestos) and Danube, were performed using one mitochondrial and one nuclear marker. Genetic differentiation among populations was in general low. Shared haplotypes were common and occurred even between distant localities and different river systems. This points to a high degree of gene flow among populations and rejects the hypothesis that the population in the Vardar River represents a relict from an early colonization of the Balkan Peninsula. In contrast, the results suggest that populations in the Vardar River, as well as those in the Danube River, are of recent origin, and a human‐mediated introduction cannot be excluded. On the other hand, the populations in the Aggitis River, a left tributary of the lower Struma River, were clearly separated from the rest of the species and represent a long‐term isolated lineage. Demographic analyses suggest a recent population expansion for O. bureschi, in which the population in the Aggitis River was not involved.     

Can We Infer Island Introduction and Naturalization Rates from Inventory Data? Evidence from Introduced Plants in Galapagos

Studies of human-mediated rates of introduction of organisms to islands are few, results fall into two models (linear and exponential), and relationships with human population and activities are obscure. Owing to their late settlement and good scientific record, data from Galapagos may be exceptionally informative. The rate of introduction of vascular plant species to Galapagos has been suggested to be exponential, paralleling the rise in human population. However, detailed reconstruction of growth in numbers of introduced plant species, based on historical and recent records, reveals changes in study criteria over the last two centuries, which obscure the true introduction rate. At first, cultivated species were deliberately excluded from most studies. From the 1960s, naturalized cultivated species were included more consistently, but non-naturalized species were still excluded. From the mid-1980s, the latter were deliberately included. Accidental introductions increased linearly from 1807 (the first records) to the present. Escapes from cultivation show increases in rate around 1906 and in the period 1970–1990, the latter coinciding with the first studies directed at areas affected by human activities. Non-naturalized cultivated species rose abruptly from the late 1980s, as they became deliberately studied. There seems to be no direct link with human population size. Data represent rate of discovery rather than true introduction rate, and the changing overall rate reflects changing botanical interests and research effort. Data from other islands also suggest that linear increases in naturalized plants are the norm. Galapagos data do not permit confident statements about the introduction rate of cultivated species, but suggest that this may depend more on human activities than human population size.     

Molecular Evidence for an Extreme Genetic Bottleneck During Introduction of an Invading Grass to California

Although exotic species cause tremendous economic and ecological loss, we know relatively little about the post-introduction evolutionary dynamics of the invasive species themselves. Barbed goatgrass, Aegilops triuncialis L., is a cleistogamous annual grass with a native range throughout the Mediterranean Basin and Asia and introduced to California during the last century. It is considered a serious noxious range weed and is one of the few exotic plant species that is invading serpentine soil habitats. We examined whether patterns of molecular variation are consistent with a single or multiple introduction events into California and further, if individual populations show evidence for a genetic bottleneck during introduction. Fingerprinting patterns, using microsatellite loci derived from Triticum aestivum, were investigated for 57 Eurasian accessions, broadly spanning the native range and for 108 individuals from 11 localities in California. There is strong evidence for an extreme bottleneck in this species as it colonizes its new range because we detected only three multilocus genotypes occurring in California and 36 genotypes in Eurasia. In California one of the genotypes differs from one other by only one fragment and only occurs in one individual. This suggests two separate introductions. Each population is composed of highly uniform individuals and the two main genotypes are geographically separated. A. triuncialis is still expanding its range in California despite genomic uniformity after a strong bottleneck and its recently increased rate of spread is not correlated to a high within-population variability created by multiple introductions.     

A null model of temporal trends in biological invasion records

Biological invasions are a growing aspect of global biodiversity change. In many regions, introduced species richness increases supralinearly over time. This does not, however, necessarily indicate increasing introduction rates or invasion success. We develop a simple null model to identify the expected trend in invasion records over time. For constant introduction rates and success, the expected trend is exponentially increasing. Model extensions with varying introduction rate and success can also generate exponential distributions. We then analyse temporal trends in aquatic, marine and terrestrial invasion records. Most data sets support an exponential distribution (15/16) and the null invasion model (12/16). Thus, our model shows that no change in introduction rate or success need be invoked to explain the majority of observed trends. Further, an exponential trend does not necessarily indicate increasing invasion success or 'invasional meltdown', and a saturating trend does not necessarily indicate decreasing success or biotic resistance.