Plant dispersal by teal (Anas crecca) in the Camargue: duck guts are more important than their feet

1. Migratory waterbirds are major vectors for the dispersal of aquatic plants. However, quantitative field studies of the frequency of transport are scarce, and the relative importance of internal and external transport remains unclear. 2. We quantified and compared the rates of internal and external transport of aquatic plant propagules by teal (Anas crecca) in the Camargue (southern France), inspecting the lower gut contents of birds that had been shot (n = 366) and washing birds that had been live‐trapped (n = 68) during the winters of 2006–2007 and 2007–2008. 3. Intact propagules (n = 902) of 21 plant taxa were recorded in the rectum of teal, of which 16 germinated or were shown to be viable. Intact propagules were recorded in the rectum of 20% of teal, with up to 171 propagules per individual bird. Chara oogonia were most abundant (60% of intact propagules), suggesting that small size favours internal transport. Eleocharis palustris, Juncus spp. and Potamogeton pusillus (17, 7 and 6% of intact propagules, respectively) were also very abundant. 4. Intact propagules (n = 12) of 10 plant taxa were found on the outside of live teal, and four of these taxa later germinated. Intact propagules were found on 18% of teal. No teal was found to carry more than one propagule externally. There was no difference in size between propagules transported internally and externally. 5. Teal are major dispersers of plants within the Camargue, despite being highly granivorous. Contrary to widespread assumptions in the literature, endozoochory by ducks appears to be a much more important mode of dispersal for aquatic plants than exozoochory. We found no evidence of changes in the probability of plant propagule dispersal at a landscape scale over the course of the winter, so propagule production and zoochory appear to be decoupled over time in aquatic systems.     

The fossil record and biogeography of the Ciehlidae (Actinopterygii: Labroidei)

The family Ciehlidae is a large group of tropical fishes in the order Perciformes, with an estimated number of living species exceeding 1400. The modern distribution of the family Ciehlidae is predominantly in fresh waters of Central and South America, Africa, Madagascar, India and the Middle East, with fossil members known from Africa, Saudi Arabia, the Levant, Europe, South America and Haiti. Many authors have referred to the distribution as being Gondwanan and have postulated that cichlids originated over 130 million years ago, in the Early Cretaceous. However, the suggested evidence for an Early Cretaceous origin of cichlids is equally or more compatible with a much younger age of origin. Based on the biology and distribution of modern and fossil cichlids, it is more probable that they arose less than 65 million years ago, in the Early Tertiary, and crossed marine waters to attain their current distribution.     

Post-glacial range formation of temperate forest understorey herbs – Insights from a spatio-temporally explicit modelling approach

Aim

Our knowledge of Pleistocene refugia and post-glacial recolonization routes of forest understorey plants is still very limited. The geographical ranges of these species are often rather narrow and show highly idiosyncratic, often fragmented patterns indicating either narrow and species-specific ecological tolerances or strong dispersal limitations. However, the relative roles of these factors are inherently difficult to disentangle.

Location

Central and south-eastern Europe.

Time period

17,100 BP – present.

Major taxa studied

Five understorey herbs of European beech forests: Aposeris foetida, Cardamine trifolia, Euphorbia carniolica, Hacquetia epipactis and Helleborus niger.

Methods

We used spatio-temporally explicit modelling to reconstruct the post-glacial range dynamics of the five forest understorey herbs. We varied niche requirements, demographic rates and dispersal abilities across plausible ranges and simulated the spread of species from potential Pleistocene refugia identified by phylogeographical analyses. Then we identified the parameter settings allowing for the most accurate reconstruction of their current geographical ranges.

Results

We found a largely homogenous pattern of optimal parameter settings among species. Broad ecological niches had to be combined with very low but non-zero rates of long-distance dispersal via chance events and low rates of seed dispersal over moderate distances by standard dispersal vectors. However, long-distance dispersal events, although rare, led to high variation among replicated simulation runs.

Main conclusions

Small and fragmented ranges of many forest understorey species are best explained by a combination of broad ecological niches and rare medium- and long-distance dispersal events. Stochasticity is thus an important determinant of current species ranges, explaining the idiosyncratic distribution patterns of the study species despite strong similarities in refugia, ecological tolerances and dispersal abilities.     

一株樱桃谷鸭源鸭腺病毒B2毒株的分离与鉴定

【背景】 2014年以来,鸭腺病毒(duck adenovirus, DAdV) B2感染引起的番鸭“白肝病”在我国番鸭群广泛流行,其他品种肉鸭未见发病,本研究发现两起樱桃谷鸭疑似“白肝病”的病例。【目的】 鉴定樱桃谷鸭“白肝病”的病原。【方法】 对送检鸭的肝脏等内脏样品进行PCR或RT-PCR检测、病原分离鉴定、序列测定及动物回归试验。【结果】 内脏组织PCR检测DAdV B2阳性,并成功分离到一株DAdV B2毒株,命名为DAdV B2/BG19。该分离株BG19感染的鸡肝癌细胞(leghorn male hepatoma cell line, LMH)变大变圆、最后崩解,形成特征性细胞病变。分离株BG19有2个fiber基因,主要功能基因如hexon、fiber 1、fiber 2及DNA polymerase基因与国内DAdV B2分离株核苷酸相似性均达98.26%以上,与DAdV B1代表株GR对应基因的核苷酸相似性分别为77.12%、30.8%、34%和99.78%;所有DAdV B1和DAdV B2分离株的DNA polymerase基因处于同一个进化分支;分离株BG19的ORF67基因从起始密码子往后的第133位碱基为T,造成提早产生终止密码子,导致ORF67基因编码蛋白比国内早前流行代表株CH-GD-12-2014少了14个氨基酸。分离株BG19人工感染2日龄樱桃谷鸭和番鸭的发病率分别为50.0%和87.5%,死亡率分别为12.5%和37.5%,病死鸭可见与自然感染病例相似的临床症状和病理变化。【结论】 从樱桃谷鸭白肝病病例成功分离鉴定一株ORF67蛋白截短表达的DAdV B2强毒株,发现DAdV B2能感染樱桃谷鸭。     

Vaccination against meningococcal disease in Europe: review and recommendations for the use of conjugate vaccines

At the end of 2005, six European countries had implemented public immunization campaigns with serogroup C conjugate vaccines, and all had experienced substantial declines in the incidence of serogroup C disease. A quadrivalent ACWY meningococcal vaccine is in use in the USA, but serogroup A is extremely rare in Europe and serogroups Y and W135 are infrequent causes of disease. This paper outlines recommendations on the use of conjugate vaccines in Europe based on the experience with meningococcal C conjugate (MCC) vaccines so far.     

Effect of predation risk, body size, and habitat characteristics on emigration decisions in mallards

Understanding the processes underlying emigrating behavior isfundamental to better understand animal dispersal. Because ofthe difficulties involved in carrying out controlled manipulationof the proximate drivers of emigration over large spatial scales,results from laboratory or small field enclosures suitable forsmall-bodied species remains to be validated in natural habitats.We investigate whether emigration is driven either by intraspecificcompetition or resulted from hunting-risk avoidance and assessedthe effect of phenotypic variation on individual decisions.We made use of a quasi-experimental situation by using huntingrecoveries of mallards (Anas platyrhynchos) released as ducklingsin a fragmented landscape managed for duck hunting. Our resultssuggest an indirect effect of hunting on emigration. Body sizeplays a major role in modulating individual emigrating decisions,with small-bodied individuals emigrating more to escape fromhigh levels of predation pressure while larger bodied individualsbeing more vulnerable to predation.     

Habitat use and dispersal of the invasive crayfish Procambarus clarkii in ephemeral water bodies of Portugal

We used radio-telemetry to analyze habitat use and dispersal of the invasive crayfish Procambarus clarkii in the extreme environmental conditions of a temporary river in southern Portugal. The rationale of this study was that an understanding of the properties that make this species a successful invader can be of help for the conservation of freshwater biodiversity. The results showed that: (1) crayfish displaced at a similar rate (ranging 2.5-38 m d^-1) as other European populations; (2) movement was faster at night; (3) crayfish movement had no clear environmental correlates, except for water temperature; (4) peaks of more intense locomotion were intercalated with longer periods of slow or null speed; and (5) P. clarkii did not excavate burrows in the study habitat, but took refuge under boulders and most often occupied complex microhabitats (e.g., vegetated sections of the river). The conclusion was that, notwithstanding their extreme conditions, ephemeral water bodies in southern Europe are highly susceptible to invasion by P. clarkii.