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1.
Ecology of a marineRivularia population 总被引:1,自引:1,他引:0
An account is given of the environmental chemistry and physiological ecology of a population ofRivularia atra growing in the upper eulittoral of Tyne Sands, a sheltered bay in S-E. Scotland. Large masses of detached seaweed tend to
be deposited in the supralittoral of this bay and their decay leads to elevated levels of dissolved phosphate (typically 50–150
μg 1−1 P) in the water of shallow pools of the upper eulittoral. Much (usually 50%) of this phosphate is organic, as opposed to
phosphate in the open sea just outside the bay, where it is almost entirely inorganic. This organic phosphate is presumably
available to theRivularia, as colonies show marked alkaline phosphatase activity. The colonies are small (mostly <1 mm diameter), but with a high nitrogenase
activity (expressed per unit chlorophyll) in the light are high (sometimes approaching 0.2 nM C2H4 μg chl a−1 min−1 × 10−3) but there is a rapid and very marked drop on transfer to the dark. It is suggested that this latter feature may be of adaptive
significance for this population, as colonies in many pools are covered intermittently by sand. 相似文献
2.
M. Cavelier 《Journal of Phytopathology》1986,116(2):147-161
Several crosses between monokaryotic strains of Typhula incarnata Lasch ex Fr. have given rise to hypoaggressive dikaryons under laboratory conditions. Winter barley plants, preinoculated in cold chamber by these strains, were, fully protected against the harmful effects of the aggressive strains inoculated 15 days later. The experiments have stressed the role of plant cold-hardening on their susceptibility to Typhula. Under field conditions, when inoculated to winter barley seedlings, a mixture of aggressive and nonaggressive strains produced an attack which was intermediate between the severe one of the former and the almost indiscernible one of the latter strain. Moreover, in cold chamber, mixed sclerotia from two equally aggressive strains induced as much damage as each strain inoculated separately. Insofar as the extent of barley infection by T. incarnata can be measured by the dry weight of the infected plants before stem elongation and by the number of ears at harvest, our results indicate the determinant role of the first infective strain upon the ultimate degree of the attack. The eventual role of crosses between strains is discussed. 相似文献
3.
Stefano Mancuso 《Plant signaling & behavior》2010,5(9):1067-1071
In 1867, Federico Delpino, with his seminal work Pensieri sulla Biologia Vegetale (Thoughts on Plant Biology) established plant biology by defining it not in the broad general sense, namely as the science of living beings, but as a branch of natural science dedicated to the study of plant life in relation to the environment. Today, the figure and achievements of this outstanding plant scientist is almost unknown. In the following pages, I will concisely describe the main realizations of Federico Delpino and outline the significance of his work for modern plant science.Key words: Charles Darwin, evolution, history of botany, myrmecophily, plant biology, plant intelligence, plant-insect 相似文献
4.
Frédéric Gosselin 《Biodiversity and Conservation》2009,18(4):777-793
The case of the Northern spotted owl (Strix occidentalis caurina) has now become a classic case study in conservation biology, characterized by a harsh social battle but also by the quantity
and quality of the research performed. Based on this example, I study the way the research-management interface was organized.
The main lessons I have learned were: 1. laws that involve science in management are crucial but should be more precise; 2.
scientific ad-hoc groups are useful reviewers of management plans and interpreters of the best scientific data available,
even if more transparent scientific argumentation is needed on some points; 3. in such applied cases, even science that has
not been strongly integrated with management can produce results that are useful for management; 4. stronger links between
science and management appear necessary, but difficult to implement. This last point makes me wonder whether environmental
laws should not more frequently target the incorporation of science into the management process itself rather than “only”
basing management on the best scientific data available. On a more ecological level, perhaps the habitat issue has been underrated
during the last few years compared to other emerging threats such as the invasion of the spotted owl range by barred owls. 相似文献
5.
We observed a case of infant adoption in an unprovisioned group of wild black-fronted titi monkeys (Callicebus nigrifrons). During our long-term field study we noticed that an infant had moved from one of our study groups (“Desbotado”) to another
(“Rio”). Observations of the adoptive group confirm that it was being cared for by the adult male, and initially the group’s
adult female was nursing the infant alongside her biological infant. Interestingly, the native and adoptive groups have frequent
inter-group interactions, but at no point have we observed the native group trying to retrieve its infant. As of April 2007
the infant has been living in its adoptive group for 19 months. These data document the first case of adoption in this genus;
they suggest that infant recognition is poorly developed in this species and that under certain circumstances wild groups
of C.
nigrifrons can successfully rear twins. In our study population reproductive females give birth to one infant every year; the only case
when this has not happened is with the group that adopted the infant, suggesting that adoption may generate a reproductive
cost. 相似文献
6.
John M. Kirkwood 《Polar Biology》1996,16(7):527-530
Euphausia crystallorophias is the dominant zooplankton species in the neritic seas of Antarctica, where it occurs in similar abundances to those of
Euphausia superba in more offshore areas. Despite its great abundance and probable ecological significance, few details are known of this species’
development, life history and ecology. This study found that E. crystallorophias spawned in Ellis Fjord from late November to early December and completed its larval development under the sea ice during
the Antarctic winter. The mean time for E. crystallorophias eggs to develop to furcilia stage VI was 235.5 days, which is virtually identical to the developmental time already reported
in the laboratory, but almost twice that of E. superba. This slow development rate is likely to be due either to the low water temperatures (<0°C) in which E. crystallorophias lives, or to low levels of food being available over winter.
Received: 30 August 1995/Accepted: 11 December 1995 相似文献
7.
James Maclaurin 《Biology & philosophy》2011,26(1):151-158
In Molecular Models: Philosophical Papers on Molecular Biology, Sahotra Sarkar presents a historical and philosophical analysis of four important themes in philosophy of science that have
been influenced by discoveries in molecular biology. These are: reduction, function, information and directed mutation. I
argue that there is an important difference between the cases of function and information and the more complex case of scientific
reduction. In the former cases it makes sense to taxonomise important variations in scientific and philosophical usage of
the terms “function” and “information”. However, the variety of usage of “reduction” across scientific disciplines (and across
philosophy of science) makes such taxonomy inappropriate. Sarkar presents reduction as a set of facts about the world that
science has discovered, but the facts in question are remarkably disparate; variously semantic, epistemic and ontological.
I argue that the more natural conclusion of Sarkar’s analysis is eliminativism about reduction as a scientific concept. 相似文献
8.
Jafelice RM de Barros LC Bassanezi RC Gomide F 《Bulletin of mathematical biology》2004,66(6):1597-1620
This paper introduces a model for the evolution of positive HIV population and manifestation of AIDS (acquired immunideficiency
syndrome). The focus is on the nature of the transference rate of HIV to AIDS. Expert knowledge indicates that the transference
rate is uncertain and depends strongly on the viral load and the CD4+ level of the infected individuals. Here, we suggest to view the transference rate as a fuzzy set of the viral load and
CD4+ level values. In this case the dynamic model results in a fuzzy model that preserves the biological meaning and nature
of the transference rate λ. Its behavior fits the natural history of HIV infection reported in the medical science domain. The paper also includes a
comparison between the fuzzy model and a classic Anderson’s model using data reported in the literature. 相似文献
9.
Söderqvist T 《Journal of the history of biology》2011,44(4):633-650
Today, scientific biography is primarily thought of as a way of writing contextual history of science. But the genre has other
functions as well. This article discusses seven kinds of ideal–typical subgenres of scientific biography. In addition to its
mainstream function as an ancilla historiae, it is also frequently used to enrich the understanding of the individual construction of scientific knowledge, to promote
the public engagement with science, and as a substitute for belles-lettres. Currently less acknowledged kinds of scientific
biography include its use as a medium for public and private, respectively, commemoration. Finally, the use of scientific
biography as a research (virtue) ethical genre, providing examples of ‘the good life in science’, is emphasized. 相似文献
10.
Apodemus sylvaticus stankovici, described from the topographically rough landscape of the western Balkan glacial refugium, was recently proposed as being
either a junior synonym of Apodemus flavicollis or a species on its own right. To untangle this taxonomic vagueness, we sequenced complete cytochrome b gene in 28 field mice collected at 12 locations in the mountains of Bosnia and Herzegovina, Montenegro, western Macedonia
and northern Greece. Samples yielded 27 new haplotypes which clustered into two distinct groups. One of these clades also
included the reference haplotype of A. flavicollis, while another cluster emerged as being identical with the reference sample for A. sylvaticus. As is common in Apodemus, both species retrieved in our analysis were characterized by low levels of intraspecific variation (0.4–0.9%) as opposed
to a high level of differentiation between them (8.0–10.0%); therefore, the taxonomic classification of our material was without
doubt. We found no evidence regarding the presence of an additional cryptic species in the mountains of the western Balkans.
The very similar values of genetic variability in the two species imply their common evolutionary history of a long-term coexistence
in the western Balkan refugium. 相似文献
11.
E. Trucco 《Bulletin of mathematical biology》1970,32(4):459-473
As was done by Sinclair and Ross (1969(, we consider a cellular population that consists initially (at time zero) ofN
0 newborn cells, all with the same volumev
o. It is assumed that the occurrence of cell division is determined only by a cell’s age, and not by its volume. The frequency
function of interdivision times, τ, is denoted byf(τ). If cell death is negligible, the expected number of cells,N(t), will increase according to the laws of a simple age-dependent branching process. The expression forN(t) is obtained as a sum over all generations; thevth term of this sum, in turn, is a multiple convolution integral, reflecting the life history ofvth generation cells (i.e., the lengths of thev successive interdivision periods plus the age of the cell at timet). Assuming that cell volume is a given function of cell age, e.g., linear or exponential, and that cellular volume is exactly
halved at each division, it is possible to calculate the volume of a cell with a given life history, and thus the average
cellular volume of the whole population as a function of time. If at time zero the volumes differ from cell to cell, the final
equation must be modified by averaging over initial volumes. In the case of linear volume increase with age, a very simple
asymptotic expression is found for the average cellular volume ast→∞. The case of exponential volume increase with age also leads to a simple asymptotic formula, but the resulting volume distribution
is unstable.
The mean cellular volume at birth and the second moment of the volume distribution can be calculated in a similar manner.
Work supported by the U.S. Atomic Energy Commission. 相似文献
12.
Donald Favareau 《Biosemiotics》2008,1(1):5-23
With the publication of this inaugural issue of the internationally peer-reviewed journal Biosemiotics, our still-developing young interdiscipline marks yet another milestone in its journey towards adulthood. For this occasion,
the editors of Biosemiotics have asked me to provide for those readers who may be newcomers to our field a very brief overview of the history of biosemiotics,
contextualizing it within and against the larger currents of philosophical and scientific thinking from which it has emerged.
To explain the origins of this most twenty-first century endeavour effectively, however, will require tracing—at least to
the level of a thumbnail sketch—how the ‘sign’ concept appeared, was lost, and now must be painstakingly rediscovered and
refined in science. To relate this long history, this article will appear in Biosemiotics in three instalments, examining, respectively: (1) The History of the Sign Concept in Pre-Modernist Science, (2) The History
of the Sign Concept in Modernist Science, and (3) The Biosemiotic Attempt to Develop a More Useful Sign Concept for Contemporary
Science. In this instalment, we begin our introductory ‘stroll through the woods of sciences and signs’ by following the development
of the sign concept within the context of scientific inquiry, in necessarily broad outline, from the beginnings of such inquiry
in sixth century BCE, through its long development in the Middle Ages, and up unto the onset of modernity. For only within
this larger historical context can our contemporary attempt to develop a naturalistic understanding of sign relations be understood.
相似文献
Donald FavareauEmail: |
13.
Human lipoprotein lipase last exon is not translated,in contrast to lower vertebrates 总被引:1,自引:0,他引:1
F. Arnault J. Etienne L. Noé A. Raisonnier D. Brault J. W. Harney M. J. Berry C. Tse C. Fromental-Ramain J. Hamelin F. Galibert 《Journal of molecular evolution》1996,43(2):109-115
We have sequenced the first fish (zebrafish,Brachydanio rerio) lipoprotein lipase (LPL) cDNA clone. Similarities were found in mammalian LPL cDNA, but the codon spanning the last two
exons (which is thus split by the last intron) is AGA (Arg) as opposed to TGA in mammals. Exon 10 is thus partially translated.
These results were confirmed with rainbow trout (Oncorhynchus mykiss). We also investigated whether mammal TGA coded for selenocystein (SeCys), the 21st amino acid, but found that this was not
the case: TGA does not encode SeCys but is a stop codon. It thus appears that the sense codon AGA (fish) has been transformed
into a stop codon TGA (human) during the course of evolution. It remains to be determined if the “loss” of the C-terminal
end of mammalian LPL protein has conferred an advantage in terms of LPL activity or, on the contrary, a disadvantage (e.g.,
susceptibility to diabetes or atherosclerosis).
Correspondence to: J. Etienne 相似文献
14.
Host-plant specialization by a non-herbivorous amphipod: advantages for the amphipod and costs for the seaweed 总被引:5,自引:0,他引:5
Studies of factors affecting host plant specialization by herbivores commonly highlight the value of the plant as both food
and habitat, but often cannot distinguish the relative importance of these plant traits. A different approach is to study
non-herbivorous animals that specialize on particular plants but do not feed on tissue from these plants. Such animals will
not be affected directly by the nutritional, chemical, or morphological traits that determine the value of the plant as a
food. This study reports on a filter-feeding amphipod, Ericthoniusbrasiliensis, that lives in domiciles it constructs by curling terminal segments of the green, calcified, and chemically defended seaweed
Halimedatuna. We examined the temporal (1850s–1990s) and spatial (Caribbean, Mediterranean, and Pacific regions) scale of the association,
the factors that may select for specialization on H. tuna, and the effect of the amphipod on growth of its host. Sampling along 125 km of coral reefs in the Florida Keys (USA) indicated
that almost all populations of H. tuna had been colonized by this amphipod. Infested plants occurred on nine of ten reefs that supported H. tuna populations, with between 8 and 75% of the plants on those reefs colonized by the amphipod. For infested plants, 2–23% of
all segments on each plant had been curled by the amphipod. Common co-occurring congeners of H. tuna (H. opuntia and H. goreaui) were never used for domicile construction. A survey of 1498 Halimeda specimens collected during the last 140 years and archived in the U.S. National Museum of Natural History (Smithsonian Institution,
Washington, D.C.) indicated that the association has existed for >100 years and occurs throughout the Caribbean region, never
in the Indo-Pacific or Mediterranean, and only on H. tuna. Predation by fishes could select for amphipod specialization on H. tuna. Laboratory experiments demonstrated that amphipods inhabiting curled segments of H. tuna were relatively immune from fish predation while those on the exterior surface of the plant or in open water were rapidly
eaten. Segments of H. tuna are large enough to provide full protection from predators, while those of the co-occurring congeners H. goreaui and H. opuntia are of a size that may provide only partial protection. Experimental addition of E. brasiliensis to H. tuna plants in the field significantly decreased segment accumulation on infested relative to uninfested control plants. Whether
this negative effect was a direct or indirect consequence of amphipod occupancy is unclear. Rolling plant portions into domiciles
could directly decrease host growth by increasing shading and decreasing exposure of plant surface area to water column nutrient
flux. Amphipod occupancy could indirectly slow net host growth if fishes selectively feed on plant sections occupied by amphipods.
Underwater video showed that herbivorous fishes did not graze infested plants more than uninfested plants, but small predatory
fishes did prefer feeding from infested plants. These non-herbivorous fishes may slow host growth by damaging the terminal
meristematic tissues of plants during attacks on amphipods. This study demonstrates that habitat specialists can negatively
impact hosts without consuming them and that specialization on a plant can occur due to its habitat value alone (as opposed
to its value as a food).
Received: 24 March 1998 / Accepted: 1 November 1998 相似文献
15.
Evidence for a substantial host‐use bottleneck following the invasion of an exotic,polyphagous weevil
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ERIC R. D. MOISE GLEN B. H. FORBES ANDREW MORRISON JON D. SWEENEY NEIL K. HILLIER ROB C. JOHNS 《Ecological Entomology》2015,40(6):796-804
1. The successful establishment of novel plant–insect interactions may depend on the availability of suitable hosts, which itself is influenced by the inherent flexibility of the herbivore for the native plants in its new range. The polyphagous beech leaf mining weevil, Orchestes fagi L., is a recent invader to eastern Canada, and while beech is a primary host, it remains unclear the extent to which it might also utilise co‐occurring secondary hosts, as has been observed in its native European range. 2. A combination of field and laboratory feeding trials were used to quantify weevil secondary host use. Based on its expansive native host range in Europe, it was predicted that American beech (Fagus grandifolia Ehrh.), as well as several additional plant species, would be susceptible to weevil damage. 3. Contrary to this prediction, weevil feeding was almost entirely exclusive to beech in both the field and laboratory feeding trials. This result is further supported by field observations that revealed an absence of weevils and eggs on species other than beech. In general, the lack of pre‐diapause feeding on any alternate host species represented an extreme departure from feeding habits observed within the native range. 4. Overall, this host‐use bottleneck suggests that the adoption of a novel primary host by O. fagi, in this case American beech, may remove the normal requirement for secondary hosts and suggests a significant departure from native feeding habits with possible consequences for related life‐history parameters such as overwintering survival and fecundity. 相似文献
16.
R. H. Marrs M. G. Le Duc S. M. Smart K. J. Kirby R. G. H. Bunce P. M. Corney 《Kew Bulletin》2010,65(4):583-594
The invasion of native habitats by exotic, or alien, plant species has received considerable attention recently from policy,
research, and practical conservation management perspectives. However, a new hypothesis for species dynamics in Britain suggests
that a small number of aggressive native plant species (termed ‘thugs’) may have an equal, or greater, impact on native species
and habitats than exotic species. Here, we examine this hypothesis using multivariate techniques with field-layer cover data
collected during a country-wide survey of British woodlands. Multivariate analysis of these data identified a north-south
gradient on the first axis, and that 20 of the 25 National Vegetation Classification woodland types were sampled within the
study. The most abundant field-layer species included three of the proposed native ‘thugs’, i.e. Rubus fruticosus, Pteridium aquilinum and Hedera helix in addition to the native woodland indicator species Mercurialis perennis. Variation partitioning was used to compare the relative importance of native field-layer ‘thug’ species with invading alien
shrub and tree species relative to other environmental drivers. The variation in the field-layer data-set explained by the
three native ‘thug’ species was significant, but they explained a relatively small proportion of the variation relative to
other environmental variables (climate, soil, management factors etc.). They did, however, explain almost four times as much
variation as the three alien species that were significantly correlated with field-layer species composition (Acer pseudoplatanus, Impatiens glandulifera, Rhododendron ponticum). The results of this analysis suggest that the field-layer of British woodlands is impacted as much by native ‘thug’ species,
as it is from ‘aliens’. Concern about the impact of these native ‘thug’ species has been reported previously, but their impact
has not previously been compared to the impact of invading aliens. It is hoped that this analysis will do two things, first
to act as a sound baseline for assessing any changing balance that should occur in the future, and second, to prompt both
ecologists and conservationists to develop woodland management policies based on sound science. 相似文献
17.
Adrian Currie 《Biology & philosophy》2012,27(1):149-158
David Sepkoski and Michael Ruse’s edited collection The Peolobiological Revolution covers the changes in paleontological science in the last half-century. The collection should be of interest to philosophers
of science (particularly those interested in non-reductive unity) as well as historians. I give an overview of the content
and major themes of the volume and draw some lessons for the philosophy of science along the way. In particular, I argue that
the history of paleontology demands a new approach to philosophical delineation of sciences. 相似文献
18.
This paper distinguishes between causal isolation robustness analysis and independent determination robustness analysis and suggests that the triangulation of the results of different epistemic means or activities serves
different functions in them. Circadian clock research is presented as a case of causal isolation robustness analysis: in this
field researchers made use of the notion of robustness to isolate the assumed mechanism behind the circadian rhythm. However,
in contrast to the earlier philosophical case studies on causal isolation robustness analysis (Weisberg and Reisman in Philos
Sci 75:106–131, 2008; Kuorikoski et al. in Br J Philos Sci 61:541–567, 2010), robustness analysis in the circadian clock research did not remain in the level of mathematical modeling, but it combined
it with experimentation on model organisms and a new type of model, a synthetic model. 相似文献
19.
20.
Many species demonstrate variation in life history attributes in response to gradients in environmental conditions. For fishes,
major drivers of life history variation are changes in temperature and food availability. This study examined large-scale
variation in the demography of four species of butterflyfishes (Chaetodon
citrinellus, Chaetodon lunulatus, Chaetodon melannotus, and Chaetodon trifascialis) between two locations on Australia’s Great Barrier Reef (Lizard Island and One Tree Island, separated by approximately 1,200 km).
Variation in age-based demographic parameters was assessed using the re-parameterised von Bertalanffy growth function. All
species displayed measurable differences in body size between locations, with individuals achieving a larger adult size at
the higher latitude site (One Tree Island) for three of the four species examined. Resources and abundances of the study species
were also measured, revealing some significant differences between locations. For example, for C. trifascialis, there was no difference in its preferred resource or in abundance between locations, yet it achieved a larger body size
at the higher latitude location, suggesting a response to temperature. For some species, resources and abundances did vary
between locations, limiting the ability to distinguish between a demographic response to temperature as opposed to a response
to food or competition. Future studies of life histories and demographics at large spatial scales will need to consider the
potentially confounding roles of temperature, resource usage and availability, and abundance/competition to disentangle the
effects of these environmental variables. 相似文献