The Effect of Fish Introductions on the Diatom and Cladoceran Communities of Lake Opeongo,Ontario, Canada

Fish introductions are one of the most widespread anthropogenic perturbations to aquatic ecosystems. Paradoxically, the effects of these introductions on aquatic ecosystems are typically poorly documented. This project studied the effect of fish introductions on Lake Opeongo, an oligotrophic lake in Algonquin Provincial Park, Ontario, Canada (45° 42′ N, 78° 22′ W), using the remains of algae (diatoms) and zooplankton (cladocerans) preserved in the sediments. It was hypothesized that the introduction of cisco or lake herring (Coregonus artedii Lesueur) in 1948, which filled the underutilized pelagic forage fish niche, should have altered nutrient availability for phytoplankton. Prior to cisco introduction, the diatom community of Lake Opeongo reflected a relatively stable oligotrophic state established before European settlement, and consisted of the Cyclotella stelligera complex with subdominants Tabellaria flocculosa IIIp and the Aulacoseira distans complex. No marked changes occurred until ca. 1962 when the diatom community shifted to an assemblage with increased total phosphorus preferences, consisting of Asterionella formosa and lesser amounts of Cyclotella bodanica var lemanica, the C. stelligera complex, Fragilaria crotonensis and T. flocculosa IIIp. The dominant cladoceran Bosmina longirostris increased significantly in relative abundance since the introduction of cisco. The most likely cause of this shift was increased nutrient recycling and/or trophic level changes caused by human manipulation of the fish community of the lake.     

Single-family versus multi-family introductions

The early success of plant introduction as a function of source material and habitat quality was tested in Arnica montana to determine whether different introduction strategies could affect plant viability of the introduced population. Plants originating from related (single-family introductions) and unrelated (multi-family introductions) individuals were introduced into undisturbed sites and into sites which were limed, turf cut, or both turf cut and limed. For four consecutive years, we analysed plant performance by measuring survival time, growth, and reproductive capacity. Introduction success was found to be strongly affected by habitat quality. Turf cutting in combination with additional liming significantly increased reproductive capacity and stimulated early flowering. To restore eutrophic and acidified soil conditions, turf cutting with additional liming prior to introduction is recommended. Furthermore, a significant effect of multi-family introductions was observed. Multi-family introductions showed higher introduction success compared to single-family introductions. Although the long-term effects of multi-family introductions will emerge after several generations, the preliminary results suggest multi-family introductions as the most successful introduction strategy.     

Biological Control of <Emphasis Type="Italic">Melanaspis Obscura</Emphasis> on Oaks in Northern California

In 1988, Encarsia aurantii (Howard) (Hymenoptera: Aphelinidae) was introduced into northern California to control an isolated infestation of obscure scale, Melanaspis obscura (Comstock) (Coccoidea: Diaspididae), on native and exotic oaks (Quercus spp.) in Sacramento’s Capitol Park. By 2002, there was no longer any need for chemical control of the scale (i.e., complete biological control). Both parasite and host are univoltine; peak emergence of adult parasites coincides with the peak of newly settled, first-instar scales. Increase of the parasite and concomitant decline of the scale from 1992 to 2004 are documented for one native and one exotic oak tree. During spring of 2004, mean density of female scales (based on 100 twigs per tree) on 12 previously infested oak trees was generally low, ranging from <1 (eight trees) to ∼15 (single tree) scales/twig. Mean percentage parasitization (per twig) ranged from ∼30 to ∼85%, and was density independent (spatial context) for each of five trees. Two refuges for the scale population were noted: some scale crawlers settled and developed under the parental scale cover (spatial refuge) and some female scales continued to produce crawlers into late summer and early fall, when adult parasites were no longer available (temporal refuge). This case illustrates how an introduction strategy (i.e., single-species release of E. aurantii), which was derived from an analysis of the parasite guild of the pest, was executed in the field and ultimately led to successful biological control.     

Mitochondrial DNA Diversity in two populations of Taiwanese macaque (Macaca cyclopis)

Current genetic composition of a population is influenced by site-specific demographic history. We compared genetic diversity in two populations of Taiwanese macaques (Macaca cyclopis) with different site characteristics. Mitochondrial DNA variation in 145 individuals from one central, continuous population (Yushan) and one peripheral, isolated population (Shoushan) was ascertained by sequencing and PCR–SSCP of the 5 end hypervariable segment of the control region amplified from hair and fecal samples. All the samples from Yushan were of the same haplotype whereas those from Shoushan fell into 13 haplotypes. The mtDNA homogeneity in Yushan may indicate a local concentration of troops status of the population or the result of population bottleneck in the recent past by severe hunting. The relatively higher genetic diversity in the Shoushan population was contributed by released or escaped captive macaques. In addition, a simple method for preserving fecal sample as a DNA source is also recommended in the study.     

珙桐的引种繁殖研究

珙桐是我国特有的珍稀植物,为保护、发展这一树种,对珙桐进行了引种实验和一系列的繁殖研究。     

Reconstructing routes of invasion using genetic data: why,how and so what?

Detailed knowledge about the geographical pathways followed by propagules from their source to the invading populations—referred to here as routes of invasion—provides information about the history of the invasion process and the origin and genetic composition of the invading populations. The reconstruction of invasion routes is required for defining and testing different hypotheses concerning the environmental and evolutionary factors responsible for biological invasions. In practical terms, it facilitates the design of strategies for controlling or preventing invasions. Most of our knowledge about the introduction routes of invasive species is derived from historical and observational data, which are often sparse, incomplete and, sometimes, misleading. In this context, population genetics has proved a useful approach for reconstructing routes of introduction, highlighting the complexity and the often counterintuitive nature of the true story. This approach has proved particularly useful since the recent development of new model‐based methods, such as approximate Bayesian computation, making it possible to make quantitative inferences in the complex evolutionary scenarios typically encountered in invasive species. In this review, we summarize some of the fundamental aspects of routes of invasion, explain why the reconstruction of these routes is useful for addressing both practical and theoretical questions, and comment on the various reconstruction methods available. Finally, we consider the main insights obtained to date from studies of invasion routes.     

GENETIC DATA HINT AT A COMMON DONOR REGION FOR INVASIVE ATLANTIC AND PACIFIC POPULATIONS OF GRACILARIA VERMICULOPHYLLA (GRACILARIALES,RHODOPHYTA)1

Gracilaria vermiculophylla (Ohmi) Papenf., an agar‐producing red alga introduced from northeast Asia to Europe and North America, is often highly abundant in invaded areas. To assay its genetic diversity and identify the putative source of invasive populations, we analyzed the mitochondrial cytochrome c oxidase subunit I (cox1) gene from 312 individuals of G. vermiculophylla collected in 37 native and 32 introduced locations. A total of 19 haplotypes were detected: 17 in northeast Asia and three in Europe and eastern and western North America, with only one shared among all regions. The shared haplotype was present in all introduced populations and in ～99% of individuals in the introduced areas. This haplotype was also found at three native locations in east Korea, west Japan, and eastern Russia. Both haplotype and nucleotide diversities were extremely low in Europe and North America compared to northeast Asia. Our study indicates that the East Sea/Sea of Japan is a likely donor region of the invasive populations of G. vermiculophylla in the east and west Atlantic and the east Pacific.     

Multi-centre testing and validation of current protocols for the identification of Gyrodactylus salaris (Monogenea)

Despite routine screening requirements for the notifiable fish pathogen Gyrodactylus salaris, no standard operating procedure exists for its rapid identification and discrimination from other species of Gyrodactylus. This study assessed screening and identification efficiencies under real-world conditions for the most commonly employed identification methodologies: visual, morphometric and molecular analyses. Obtained data were used to design a best-practice processing and decision-making protocol allowing rapid specimen throughput and maximal classification accuracy. True specimen identities were established using a consensus from all three identification methods, coupled with the use of host and location information. The most experienced salmonid gyrodactylid expert correctly identified 95.1% of G. salaris specimens. Statistical methods of classification identified 66.7% of the G. salaris, demonstrating the need for much wider training. Molecular techniques (internal transcribed spacer region-restriction fragment length polymorphism (ITS-RFLP)/cytochrome c oxidase I (COI) sequencing) conducted in the diagnostic laboratory most experienced in the analysis of gyrodactylid material, identified 100% of the true G. salaris specimens. Taking into account causes of potential specimen loss, the probabilities of a specimen being accurately identified were 95%, 87% and 92% for visual, morphometric and molecular techniques, respectively, and the probabilities of correctly identifying a specimen of G. salaris by each method were 81%, 58% and 92%. Inter-analyst agreement for 189 gyrodactylids assessed by all three methods using Fleiss’ Kappa suggested substantial agreement in identification between the methods. During routine surveillance periods when low numbers of specimens are analysed, we recommend that specimens be analysed using the ITS-RFLP approach followed by sequencing of specimens with a “G. salaris-like” (i.e. G. salaris, Gyrodactylus thymalli) banding pattern. During periods of suspected outbreaks, where a high volume of specimens is expected, we recommended that specimens be identified using visual identification, as the fastest processing method, to select “G. salaris-like” specimens, which are subsequently identified by molecular-based techniques.     

The genetic rescue of the Florida panther

We examine the consequences of panthers introduced from Texas into south Florida, an area housing a small, isolated, inbred and distinct subspecies ( Puma concolor coryi ). Once part of a continuous, widespread population, panthers became isolated in south Florida more than a century ago. Numbers declined and the occurrence of genetic defects increased. Hoping to reverse the genetic damage, managers introduced eight female panthers from Texas into south Florida in the mid-1990s. This action was highly controversial and we explain the arguments for and against the intervention. We synthesized data systematically collected on the Florida panthers from before, during and after this management intervention. These data include information on movements, breeding, mortality, survivorship and range. There is no evidence that purebred Florida females produce fewer kittens at a later age or less often than do hybrid cats (i.e. those with a Texas ancestor). Hybrid kittens have about a three times higher chance of becoming adults as do purebred ones. Hybrid adult females survive better than purebred females; there is no obvious difference between the males. Males die younger than females, are more often killed by other males and are more likely to disperse longer distances into habitats that are dangerous to them. Hybrids are expanding the known range of habitats panthers occupy and use.     

我国草坪科学的现状与发展

本文对草坪科学的主要研究方向的进展进行了综述,指出了我国草坪研究的优势、劣势及存在的主要问题,如种质资源丰富但迫切需要保护;育种工作刚刚起步;草坪管理技术落后。还阐述了今后促进草坪科学发展的工作重点。