Ecological and phylogenetic determinants of life-history patterns among ten loricariid species

We analysed the influence of ecological factors, phylogenetic history and trade-offs between traits on the life-history variation among 10 loricariid species of the middle Paraná River. We measured eight life-history variables and classified the life-history strategies following the equilibrium–periodic–opportunistic (EPO) model. Principal-component analysis of life-history traits segregated species along a gradient from small opportunistic (low fecundity, low parental investment) to large equilibrium (low-medium fecundity, high parental investment) species. A clear periodic strategist was absent in the analysed assemblage. Variation partitioning by canonical phylogenetic ordination analysis showed both a component of variation uniquely explained by phylogenetic history (PH; 32.2%) and a component shared between PH and ecological factors (EF; 37%). The EPO model is a useful tool for predicting correlations among life-history traits and understanding potential demographic responses of species to environmental variation. Life-history patterns observed throughout Loricariidae suggests that this family has diversified across all three endpoint strategies of the EPO model. Our study indicates that evolutionary lineage affiliation at the level of subfamily can be a strong predictor of the life-history strategy used by each species.     

Cross‐taxon congruence of multiple diversity facets of freshwater assemblages is determined by large‐scale processes across China

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Cheilolejeunea morganii Bever. & Glenny (Lejeuneaceae,Marchantiopsida), a newly described species from lowland indigenous forest sites in New Zealand

Introduction. Cheilolejeunea morganii Bever. & Glenny, a new species of Cheilolejeunea from a lowland forest habitat in eastern Taranaki in the North Island of New Zealand, is described and illustrated.

Methods. DNA sequences were extracted from recently collected material at two locations and compared with those for species in a published phylogeny of the genus to establish the position of C. morganii. Photographic images were obtained of key features of the species for the preparation of illustrations for publication.

Key results. Cheilolejeunea morganii does not match any species described for New Zealand or Australia. The sequencing results indicate its position in the phylogeny is close to Section Paroicae. A key to the New Zealand species of Cheilolejeunea is provided.

Conclusions. In the Australasian flora, C. morganii is distinguished from other species by its combination of monoicy, pycnolejeuneoid gynoecial innovations, lobule length less than 50% lobe length and a multicellular second lobule tooth with 3–4 cells uniseriate. A case is presented for the recognition of the species as a New Zealand endemic.     

Gene mapping in fishes: a means to an end

Genetic research in fishes is poised to contribute a vast amount of information on the structural organization and function of vertebrate genomes. Recent advances in molecular biology have made possible the widescale characterization of genomes in all living organisms. This includes defining chromosomes at the cytological level down to their linear composition at individual nucleotide base pairs. Pioneering gene mapping studies into the genomes of fishes will only serve as the starting point for more detailed studies into the function of these genomes. Future research directed at understanding the mechanisms of gene actions and interactions will benefit all areas of biology, including ecology, ethology, evolution, and physiology. Gene mapping data from brown trout and rainbow trout are used to exemplify how basic information on gene transmission in a species may help to localize centromeres onto a genetic map and identify chromosomal regions possessing a high degree of segregation distortion. Genetic maps may also be used to identify differences in recombination levels among individuals and between the sexes when multiple mapping families are utilized in studies. Observations of this type are the antecedents to more complex biological investigations on the genetic architecture underlying these phenomena.     

Development and Validation of Dose-Response Relationship for Listeria monocytogenes

Listeria monocytogenes is a foodborne pathogen internationally and in the U.S. The objective of this work was to develop and validate a dose-response model for infection by this organism. Only animal data was available in the literature. The beta-Poisson dose response model provided good fit to the data, and one of the two data sets was found to be concordant with attack rates noted in human outbreaks. There are differences, however, between the dose-response relationship and endemic illness rates computed from market basket surveys of the prevalence of L. monocytogenes. Further work to elucidate the bases for this difference is necessary.     

海南岛海水鱼类单殖吸虫研究Ⅴ——鲻鱼虫属一新种记述

在大鳞Ｌｉｚａｍａｃｒｏｌｅｐｉｓ鳃上检获到鲻鱼虫属１新种,小钩鲻鱼虫,新种ＬｉｇｏｐｈｏｒｕｓｈａｍｕｌｏｓｕｓＰａｎ＆Ｚｈａｎｇ,ｓｐ．ｎｏｖ．。以其后吸器两对中央大钩的形态结构以及背、腹中央大钩量度上的差异,背联结片的结构和交接器形态结构不同而区别于ＬｉｇｏｐｈｏｒｕｓｉｍｉｔａｎｓＥｕｚｅｔ＆Ｓｕｒｉａｎｏ,１９７７。     

Implications of fish home range size and relocation for marine reserve function

Reserves are being used increasingly to conserve fish communities and populations under threat from overfishing, but little consideration has been given to how fish behavior might affect reserve function. This review examines the implications of how fish use space, in particular the occurrence and size of home ranges and the frequency and direction of home range relocations. Examples are drawn primarily from the literature on coral reef fishes, but the principles apply to other habitats. Reserves can protect fish species only if individuals restrict their movements to a localized home range during at least part of the life cycle. Home range sizes increase with body size. In small reserves, a significant proportion of fish whose home ranges are centered within the reserve can be exposed to fishing mortality because their home ranges include non-reserve areas. Relocation of home ranges following initial settlement increases exposure to the fishery, especially if habitat selection is frequency-dependent. Distance, barriers, and costs of movement counter such redistribution. These considerations lead to predictions that population density and mean fish size (1) will form gradients across reserve boundaries with maxima in the center of the reserve and minima outside the reserve away from the boundary; (2) will increase rapidly in newly established reserves, only later providing spillover to adjacent fisheries as density-dependent emigration begins to take effect; and (3) will be higher in reserves that are larger and have higher area:edge ratios, more habitat types, natural barriers between reserve and non-reserve areas, and higher habitat quality inside than outside the reserve. (4) Species with low mobility and weak density-dependence of space use will show the greatest increase in reserves and the strongest benefit for population reproductive capacity, but those with intermediate levels of these traits will provide the greatest spillover benefit to nearby fisheries.     

Genetic diversity and multilocus genetic structure in the relictual endemic herb<Emphasis Type="Italic"> Japonolirion osense</Emphasis> (Petrosaviaceae)

Plant clonality may greatly reduce effective population size and influence management strategies of rare and endangered species. We examined genetic diversity and the extent of clonality in four populations of the monotypic herbaceous perennial Japonolirion osense, which is one of the most rare flowering plants in Japan. Allozyme analysis revealed moderate levels of genetic variation, and the proportion of polymorphic loci (P=66.7%) was higher than the value for species with similar life-history traits. With four polymorphic loci, 19 multilocus genotypes were observed among 433 aerial shoot samples and 10 (52%) were found only in single populations. The proportion of distinguishable genotypes (PD=0.10) and Simpson's index of diversity (D=0.52) also exhibited moderate levels of genotypic diversity compared to other clonal plants, with genotype frequencies at Hardy-Weinberg equilibrium. The distributions of genotypes were often localized and they were mostly found within a radius of 5 m. Spatial autocorrelation analysis showed that shoot samples located 4 m apart were expected to be genetically independent. The results suggest that the spatial extent of genets was relatively narrow and thus the clonality was not extensive.     

Identification of P18, a surface protein produced by the fish pathogen Flavobacterium psychrophilum

AIMS: This study was focused on the identification of associated outer membrane proteins which may play a role in the specific interactions between Flavobacterium psychrophilum (the aetiological agent of cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide) and the fish tissues. METHODS AND RESULTS: The surface protein interactions with the outer membrane being mainly ionic, different methods were used for the detachment of proteins from the cell surface of Fl. psychrophilum involving detergent-free buffers or solutions known to perturb the ionic interactions. Such treatments led to the isolation of a surface protein, named P18 in accordance with its relative molecular mass. The expression of P18 was not related to the growth conditions (liquid or solid medium, temperature and aeration) or the strains of Fl. psychrophilum tested here. CONCLUSIONS: Preliminary characterization indicated that P18 is a surface antigen which is not sugar-modified and might be a subunit of a surface layer (i.e. S-layer), one of the most common surface structures on bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Data reported here should be used as the basis for further works involving the purification and characterization of P18 to identify the specific roles of such a surface protein, especially the interaction between this protein and the host surface.     

Molecular phylogeny of two lineages of Leuciscinae cyprinids (Telestes and Scardinius) from the peri-Mediterranean area based on cytochrome b data

We examined phylogenetic relationships in two lineages of Leuciscinae cyprinid fishes based on the sequence data of the complete mitochondrial DNA region coding for the cytochrome b gene (1140 bp). Telestes includes obligate riverine, moderately cold water-adapted species whereas Scardinius comprises warm-adapted species living in lowland lakes and still waters of rivers and streams. We also analysed selected representatives of Leuciscus and Phoxinellus because the taxonomic status of some species belonging to these genera is dubious and they could be placed in the genus Telestes. The study includes 18 species, 43 populations, and 111 individuals from 9 of the 14 peri-Mediterranean ichthyogeographic districts. Clades recovered from the phylogenetic analyses do not support previous taxonomic assumptions based on morphology. Telestes, Leuciscus, and Phoxinellus do not form monophyletic assemblages; phylogenetic analyses suggest that L. polylepis, L. turskyi, P. croaticus, and P. metohiensis should be included in Telestes. Similarly, populations of Scardinius erythrophthalmus do not cluster together and the endangered S. scardafa, endemic to central Italy and surviving in a single locality, is nested within them. The radiations of Telestes and Scardinius occurred in different time periods. A major diversification of Telestes is consistent with a sea dispersal during the freshwater Messinian "Lago Mare" phase of the Mediterranean Sea. Cladogenetic events within Scardinius are likely related to the extension and confluence of river drainages in lowlands following multiple lowering of the sea level during the Quaternary glaciations.