Eleven polymorphic microsatellites isolated from red swamp crayfish, Procambarus clarkii

Eleven microsatellites were isolated from a genomic DNA library enriched for CA- and GA-repeats, and were characterized in 48 individuals of red swamp crayfish Procambarus clarkii. All 11 microsatellites were polymorphic with an average of allele number of 6.6 per locus. Genotypic distributions of these 11 markers were found to be in conformance with the expectations of Hardy-Weinberg equilibrium. All 11 markers were unlinked. These markers are being used to study the invasion routine, genetic diversity and population structure of the species P. clarkii.     

Assessing mate size in the red swamp crayfish Procambarus clarkii: effects of visual versus chemical stimuli

1. Mate assessment requires an efficient system of information exchange between the sexes and often relies on several forms of communication. Both sexes of the crayfish, Procambarus clarkii , select a mate on the basis of its body size, independently of chelar size/symmetry and dominance status, large size being a proxy for a high quality partner. Here, we explored the effects that visual and chemical stimuli, emitted alone or in combination, exert on the assessment of size of a potential mate.
2. We followed a binary choice test paradigm, in which two male or female 'targets', of either large or small size, were simultaneously presented to a female or a male 'chooser'. We recorded the first target visited, the total duration of the visits per target, and the behaviour of the chooser when approaching the target area.
3. Our results show that females require a combination of visual and chemical stimuli to select the larger male. A more complex pattern was found when males were the choosers. While visual and chemical cues together rendered them willing to mate with the larger female, their initial choice and the total time spent near her depended only on smell. In mate assessment by P. clarkii , visual and chemical information seem to act as 'non-redundant signals'.     

Managing invasive crayfish: use of X-ray sterilisation of males

1. In the last decade, many attempts have been made to contain the spread of the North American crayfish Procambarus clarkii , an invader of many European water bodies, but none has been successful.
2. This study investigates the effects that ionising irradiation has on the reproduction of P. clarkii males by analysing the behaviour of the treated individuals, their reproductive output, the vitality and survival of their offspring and the damages induced to their gonads.
3. We found that a dose of 20 Gy X-rays did not compromise either the survival or the mating ability of males, but reduced the size of their testes and significantly altered spermatogenesis. The number of aborted eggs was larger in clutches sired by treated males, with a consequent reduction (by 43%) in the number of offspring.
4. These results foster hopes in our efforts to control invasive crayfish, showing the potential effectiveness of ionising irradiation to reduce male fertility in the perspective of adopting the Sterile Male Release Technique to control P. clarkii populations.     

外来种入侵的生物学与生态学基础的若干问题

外来物种的入侵及其所造成的危害已越来越为人们所认识。一个外来物种入侵一个新的生境无疑要具备一定的条件 ,尽管目前对这种条件的研究还只是初步的。首先从其自身来说 ,需要有足够的入侵性 ,这可以认为是入侵种的生物学基础 ,可能表现为具有多倍性、一定的遗传变异、杂合性或表型可塑性 ,以及不同的交配系统等 ;其次一个物种的入侵成功还取决于入侵生境的可入侵性 ,这可以认为是入侵种的生态学基础 ,而新的种间关系的形成 ,尤其是入侵种与其他种类的互惠共生关系的建成是关键。本文主要介绍了有关入侵种的生物学和生态学基础中的一些最新进展 ,希望有助于我国学者对相关研究内容的开展以及对有害外来种入侵的防治     

Zambian Invertebrate Scoring System (ZISS): A macroinvertebrate-based biotic index for rapid bioassessment of southern tropical African river systems

An extensive survey of tropical rivers, conducted during 2009–2012 throughout Zambia, collected 151 samples of benthic macroinvertebrates, located on 95 rivers in six of the nine freshwater ecoregions. Associated data for physico-chemistry, human activities and ecosystem stressors were collected. Data were used to develop and test a new Rapid Bioassessment Protocol (the Zambian Invertebrate Scoring System: ZISS) for assessment of water quality and river condition in both wadeable and non-wadeable rivers. ZISS, which is based on the South African Scoring System (SASS), includes a total of 85 taxa, of which 79 are shared with SASS. Assignment of sensitivity weightings to new ZISS taxa was based on sensitivity weightings of closely related SASS families; known life-history modes and anatomical adaptations; and correlation of occurrence to impact ratings. The ability of the ZISS to measure impacts was assessed by determining the relationships between ZISS metrics and impacts. ZISS data for the Kafue River demonstrated the efficacy of the ZISS for detecting moderate to high impacts on water quality and river condition. ZISS represents a major step in developing a user-friendly, widely applicable, macroinvertebrate-based biotic index, which can provide easily interpretable assessments of river condition for southern tropical African rivers.     

Morphological and genetic differentiation between populations of river crabs (Decapoda: Potamonautidae) from the Western Gape, South Africa, with a taxonomic re-examination of Gecarcinautes brincki

As part of a larger study on the systematics of river crabs of the family Potamonautidae in southern Africa, several populations of potamonautid crabs were collected from the Cape Peninsula and surrounds, Western Cape. Two species were represented: Gecarcinautes brincki and Potamonautes perlatus. The structure of the mandibular palp in the eight populations of G. brincki examined was variable, and in four populations, the structure of this palp was the same as that which can be found in species of Potamonautes. This paper re-examines the taxonomic status of G. brincki , quantifies the morphological and genetic differentiation between populations of G. brincki and P. perlatus from the Cape Peninsula, and determines the extent of morphological and genetic differentiation among geographically separated populations of G. brincki. Examination of type and other material confirmed that Gecarcinautes brincki conforms to the current diagnosis of the genus Potamonautes (family Potamonautidae) to which it is therefore transferred. Discriminant functions analysis and protein gel electrophoresis showed that P. perlatus and P. brincki are morphometrically and genetically distinct, with the three P. perlatus populations separating from the six P. brincki populations at a genetic identity value of I = 0.66 (D = 0.419). The results also showed that P. brincki is a highly structured entity, with die populations collected from the Cape Peninsula clearly separating both genetically (I = 0.75, corresponding to D = 0.296), and morphologically (presence or absence of a flange on the terminal segment of the mandibular palp) from those collected further east. The lack of gene flow between populations of this species is discussed in the light of current species concepts.     

Extensive contiguous north–south range expansion of the original population of an invasive lizard in Florida

Florida has one of the two worst non-indigenous invasive species problems in the United States, and all such species are considered by statute to be a potential ecological problem. Unfortunately, little information is available about most of Florida's invasive species. Here, we provide information on range expansion of a population of one of the lesser-known species. The Palm Beach County, Florida, population of the northern curly-tailed lizard, Leiocephalus carinatus armouri, was examined for north–south expansion of its previously documented range. Observations were conducted as contiguous expansion outward from the previously known range. We found a substantial contiguous range expansion by a minimum of 46.3 km to the south and 34.1 km to the north. This species appears to be closely associated with coastal habitat degradation in the form of human infrastructure, especially ageing pavement, sea walls, buildings, and bridge bases.     

不受欢迎的生物多样性：香港的外来植物物种

香港早在19世纪中叶开始就有外来植物入侵的记录,迄今为止,已发现多达238种已归化的外来或怀疑为外来的植物,其中又以薇甘菊（Mikania micrantha)、五爪金龙（Ipomoea cairica)、假臭草（Eupatorium catarium)、大黍（Panicum maximum)等最常见,外来植物最常见于受人为干扰的生境,例如荒废农田及路旁等,而较少在天然林地生境及贫瘠的灌草丛中发现,外来植物的对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少了生境及贫瘠的灌草丛中发现,外来植物对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少少了生境及动植物的多样性,外来动物对香港原生植物影响最大的是于20世纪70年代入侵的松树线虫（Bur-saphelenchus xylophilus)。外来的脊椎动物也有可能对香港的植物被演替产生影响,目前香港的外来植物当中,有些在大陆较少分布或没有记录,作为华南最大的港口,香港对外来物种的引入扮演着重要的角色,因此制定控制外来种在香港及华南地区的引入及传播的政策及措施非常重要。