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31.
The relationships among multiple-locus heterozygosity, age, reproduction and growth were examined over the ca. 2-yr lifespan of a cohort of northern bay scallops, Argopecten irradians irradians (Lamarck), from the Niantic River estuary, Connecticut, USA. Electrophoretic analyses revealed a relatively low proportion of polymorphic loci (=0.35) and low level of heterozygote deficiency ( D. across 6 loci=-0.05) in this population. Allele frequency distributions showed a high degree of temporal stability within and among cohorts. No significant correlation was found between multiple-locus heterozygosity and either somatic or reproductive growth. Our results lend support to the postulated linkage between low heterozygote deficit and lack of a heterozygosity/growth association in marine bivalves, and in the pectinid group in particular. Partial reproductive senility occurs in these scallops in their second year of life. Somatic tissue weight increased exponentially with increasing shell height, whereas pre-spawning gonad mass attained asymptotic values in 2-yr-old scallops. Thus, weight-specific reproductive effort was significantly lower in second- than first-year scallops (24 and 33% respectively). This pattern could be generated if high individual reproductive effort in the first year were correlated with accelerated (early) post-reproductive senescence. This kind of resource allocation, in which somatic growth is given precedence over reproductive growth in older individuals, has been previously reported in only one other bivalve, a pectinid (Chlamys islandica), in which the decline in reproductive effort occurs only after the scallops reach an age of ca. 20 yr. 相似文献
32.
Of the recent sauropsid skin appendage types, only feathers develop from a cylindrical epidermal invagination, the follicle, and show hierarchical branching. Fossilized integuments of Mesozoic diapsids have been interpreted as follicular and potential feather homologues, an idea particularly controversially discussed for the elongate dorsal skin projections of the small diapsid Longisquama insignis from the Triassic of Kyrgyzstan. Based on new finds and their comparison with the type material, we show that Longisquama's appendages consist of a single-branched internal frame enclosed by a flexible outer membrane. Not supporting a categorization either as feathers or as scales, our analysis demonstrates that the Longisquama appendages formed in a two-stage, feather-like developmental process, representing an unusual early example for the evolutionary plasticity of sauropsid integument. 相似文献
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34.
Muleja Anga Adolph Yangkou Mbianda Xavier Pillay Kriveshini Krause Rui 《环境科学学报(英文版)》2012,24(6):1133-1141
Synthesised triphenylphosphine-linked multiwalled carbon nanotubes (Tpp-MWCNTs) were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs. The adsorption capacity increased with an increase in pH for all adsorbents. The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs, respectively. Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R2 close to 1 for all adsorbents. On the other hand, the experimental data fitted well with a pseudo second-order model. The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs. The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature. 相似文献
35.
Feathers from carcasses of the Lesser Flamingo (Phoeniconaias minor), which had died after ingesting cyanobacterial toxins (cyanotoxins) contained between 0.02 and 30.0?µg microcystin-LR equivalents per gram of feather according to HPLC and ELISA analysis of feather extracts. Anatoxin-a was detected less frequently in the Lesser Flamingo feathers, up to 0.8?µg anatoxin-a per gram of feather being recorded. When feathers from different body regions were analysed and compared for microcystins and anatoxin-a, wing feathers were found to contain the highest concentrations of these cyanotoxins, the order of concentration and frequency of analytical detection being wing?>?breast?>?head. Consistent with the presence of the microcystins and anatoxin-a in gut contents and the livers of the dead birds and negligible in vitro adsorption to feathers, the cyanotoxins associated with the feathers of the dead wild flamingos are inferred to be primarily of dietary origin. 相似文献
36.
Thomas?KlefothEmail author Christian?Skov Jens?Krause Robert?Arlinghaus 《Behavioral ecology and sociobiology》2012,66(4):547-559
To showcase the importance of genotype × environment interactions and the presence of predation risk in the experimental assessment
of boldness in fish, we investigated boldness in terms of feeding behavior and refuge use in two genetically different populations
of juvenile carp (Cyprinus carpio) in two replicated experimental conditions in ponds and laboratory tanks. The populations were expected to exhibit genetic
differences in boldness due to differential evolutionary adaptation to low-predation-risk pond aquaculture conditions. Boldness
was measured in variants of open-field trials with and without implementation of additional predation risk-stimuli by angling
on feeding spots. Without explicit implementation of risk, genotypes adapted to low-risk environments, i.e., domesticated
mirror carp behaved consistently bolder than their less domesticated scaled conspecifics in the pond environment, but not
in the laboratory environment. When we implemented artificial risk-stimuli by angling on previously safe feeding spots, boldness
differences among genotypes also emerged in the laboratory environment, indicating strong genotype × environment effects on
boldness behavior of carp. The expected genetic basis of boldness differences among genotypes was clearly supported in the
pond environment, while the laboratory study revealed these patterns only under inclusion of explicit risk-stimuli. Our study
thus underscores that boldness may involve both a basal component that is expressed independently of obvious predation risk
(e.g., in open fields) and a component revealed in relation to explicit predation risk, and both dimensions may respond differently
in behavioral tests. 相似文献
37.
Stefan Krause Lutz Mattner Richard James Tristan Guttridge Mark J. Corcoran Samuel H. Gruber Jens Krause 《Behavioral ecology and sociobiology》2009,63(7):1089-1096
Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in
ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder
et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in
the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary
analysis of a network of associations among eagle rays.
相似文献
Stefan KrauseEmail: |
38.
Animal social networks: an introduction 总被引:1,自引:1,他引:0
Network analysis has a long history in the mathematical and social sciences and the aim of this introduction is to provide
a brief overview of the potential that it holds for the study of animal behaviour. One of the most attractive features of
the network paradigm is that it provides a single conceptual framework with which we can study the social organisation of
animals at all levels (individual, dyad, group, population) and for all types of interaction (aggressive, cooperative, sexual
etc.). Graphical tools allow a visual inspection of networks which often helps inspire ideas for testable hypotheses. Network
analysis itself provides a multitude of novel statistical tools that can be used to characterise social patterns in animal
populations. Among the important insights that networks have facilitated is that indirect social connections matter. Interactions
between individuals generate a social environment at the population level which in turn selects for behavioural strategies
at the individual level. A social network is often a perfect means by which to represent heterogeneous relationships in a
population. Probing the biological drivers for these heterogeneities, often as a function of time, forms the basis of many
of the current uses of network analysis in the behavioural sciences. This special issue on social networks brings together
a diverse group of practitioners whose study systems range from social insects over reptiles to birds, cetaceans, ungulates
and primates in order to illustrate the wide-ranging applications of network analysis.
This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and
R. James). 相似文献
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