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1.
Common shrews (Sorex araneus) maintain a foraging territory for most of their immature life. Possessing a high-quality territory is vital for overwinter
survival in the harsh boreal climate, and hence, competitive ability in territorial disputes is expected to be an important
component of individual fitness. To test possible association between individual inbreeding and fitness, we used neutral arena
trials to assess the competitive performance of young common shrews. The experiment involved pairs of individuals originating
from small island populations, where breeding must often occur between related individuals, and from large outbred mainland
populations. The percentage of neutral arena tests that an individual won was highly significantly explained by internal relatedness,
a surrogate measure of individual inbreeding, measured using ten microsatellite markers. Body size, sex, learning, and population
type (mainland vs island) made no significant contributions. Even a low level of individual inbreeding may lead to significant
adverse consequences in multiple territorial contests, which may represent a significant cause of inbreeding depression in
many wild vertebrate populations. 相似文献
2.
The experiments were undertaken to measure, for the first time, cardiac output in yellowtail (Seriola quinqueradiata) during exposure to a harmful red tide flagellate (Chattonella marina). The responses were compared with those during exposure to environmental hypoxia to evaluate the significance of the drop of arterial oxygen partial pressure (PaO2) in the fish-kill mechanisms by C. marina. PaO2 immediately decreased, whereas heart rate (HR) was maintained until shortly before death during exposure to C. marina. Suffocation developing during the exposure resulted from a decrease in blood oxygen content, but not from lowered blood flow to the tissue. Although exposure to both C. marina and hypoxia immediately decreased PaO2, arterial oxygen content (CaO2) and pH (pHa) were significantly lower, whereas HR and cardiac output (&Qdot;) remained significantly higher, for the C. marina-exposed fish than for hypoxia-exposed fish. Although the drop in PaO2 appears to play a pivotal role in the mechanisms of fish death by C. marina, other physiological response(s) should also be considered. 相似文献
3.
Short-term (3 h) changes in concentration of chlorophylls and their derivatives in stage V Pseudodiaptomus euryhalinus and their fecal material were followed by HPLC during a 24 h experiment. Copepodites were fed with the prasinophyte Tetraselmis suecica. Intact chlorophyll a and b were found in animals and fecal material and had similar dynamics of accumulation over time. The extent of transformation of chlorophyll a and b to colorless compounds was different with chlorophyll a being more extensively degraded. Additionally, several chlorophyll derivatives (pheophytin and pyropheophytin-like pigments) were found. Pyropheophytin a was the most abundant followed by pheophytin b, pheophytin a, and pheophorbide a. Relative amounts of pheopigments were different in copepodites and fecal material, and pheophytin a, pheophorbide a, and pheophytin b concentrations were low and variable. The amount of ingested chlorophyll recovered as chlorophyll a and its derivatives in fecal and copepodite pools was generally low (<5%), with one exception occurring after 9 h, when it accounted for >70%. These data suggest individual pheopigments are produced at different rates and that chemical or enzymatic mechanisms in the gut of copepodites act on the two chlorophylls in different ways. 相似文献
4.
A. Machias S. Somarakis N. Papadroulakis M.-T. Spedicato M. Suquet G. Lembo P. Divanach 《Marine Biology》2003,142(1):45-52
The wreckfish (Polyprion americanus) is a panoceanic, long-lived, deep-water demersal species, characterized by an extended pelagic juvenile phase associated with floating objects. In the present study morphometric data from 435 specimens collected from Greece (Crete), Italy (Ionian Sea) and the Atlantic coast of France from September 1999 to March 2001 were analyzed to estimate the settlement size of the species and associated changes in morphology. The fishery sample included specimens from both the pelagic and the demersal stage. Length-at-settlement (TL50) and 95% confidence intervals were estimated by fitting a logistic function. Eleven morphometric characters were analyzed, and the existing inflection points, reflecting alterations in body shape, were defined: (1) iteratively, as the transition point, splitting the data set into two groups, for which the reduced major axis functions, between a character and total length, of the successive groups best fit (minimum sum of squares of residuals) the combined data set and (2) where the second derivative of the fitted third-order polynomial functions to morphometric ratios equaled zero. The main size range within which wreckfish settled was 56-65 cm, and the means of the inflection points defined by the two methods were 61 and 64 cm. These results indicate changes in functional morphology associated with settlement. The monitoring of wreckfish juveniles caught in the wild and kept individually in captivity showed changes in growth and food intake at approximately the estimated settlement length and suggested that temperature was the most likely factor triggering settlement. 相似文献
5.
Susanna Andersson 《Chemoecology》2003,13(1):1-11
Summary. For butterflies to be efficient foragers, they need to
be able to recognize rewarding flowers. Flower signals such as colours
and scents assist this recognition process. For plant species to attract
and keep butterflies as pollinators, species-specific floral signals are
crucial. The aim of this study is to investigate foraging responses to
floral scents in three temperate butterfly species, Inachis io L.
(Nymphalidae), Aglais urticae L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae), in behavioural choice
bioassays. The butterflies were allowed to choose bet-ween flower models
varying in scent and colour (mauve or green). Flowers or vegetative
parts from the plants Centaurea scabiosa L. (Asteraceae),
Cirsium arvense (L.) (Asteraceae), Knautia arvensis (L.)
(Dipsacaceae), Buddleja davidii Franchet (Loganicaeae), Origanum vulgareL. (Lamiaceae), Achillea millefolium L. (Asteraceae), and
Philadelphus coronarius L. (Hydrangiaceae) were used as scent
sources. All visits to the models — those that included probing and
those that did not — were counted, as was the duration of these
behaviours. Both flower-naive and flower-experienced (conditioned to
sugar-water rewards, the colour mauve, and specific floral scents)
butterflies were tested for their preference for floral versus
vegetative scents, and to floral scent versus colour. The butterflies
were also tested for their ability to switch floral scent preferences in
response to rewards. Flower-naive butterflies demonstrated a preference
for the floral scent of the butterfly-favourable plants C.
arvense and K. arvensis over the floral scent of the non-favourable
plants Achillea millefolium (Asteraceae), and Philadelphus
coronarius cv. (Hydrangiaceae). Most of the butterflies that were
conditioned to floral scents of either C. arvense, K. arvensis,
or B. davidii readily switched theirfloral scent preferences to
the one most recently associated with reward, thus demonstrating that
floral scent constancy is a result from learning. These findings suggest
that these butterflies use floral scent as an important cue signal to
initially identify and subsequently recognize and distinguish among
rewarding plants.
Received 2 September 2001; accepted 9 September 2002. 相似文献
6.
Individual-level variation in resource use occurs in a broad array of vertebrate and invertebrate taxa and may have important
ecological and evolutionary implications. In this study, we measured the degree of individual-level variation in prey preference
of the hunting wasp Trypoxylon albonigrum, which inhabits the Atlantic Forest in southeastern Brazil. This wasp captures several orb-weaving spider genera to provision
nests. Individuals consistently specialized on a narrow subset of the prey taxa consumed by the population, indicating the
existence of significant individual-level variation in prey preferences. The population niche was broader in the wet season
in terms of both prey size and taxa. In the case of prey size, the population niche expansion was achieved via increased individual
niche breadths, whereas in the case of prey taxa, individual niches remained relatively constrained, and the population niche
expanded via increased interindividual variation. The observed pattern suggests the possibility of functional trade-offs associated
with the taxon of the consumed prey. The nature of the trade-offs remains unknown, but they are likely related to learning
in searching and/or handling prey. We hypothesize that by specializing on specific prey taxa, individuals increase foraging
efficiency, reducing foraging time and ultimately increasing reproductive success. 相似文献
7.
Echinoderms are major predators of anemones in temperate ecosystems. The fate of two algae, zooxanthellae and zoochlorellae, after their host anemone (Anthopleura elegantissima Brandt) was consumed by the leather star Dermasterias imbricata Grube was determined in experiments conducted in July and August 2004. Productivity, photosynthetic pigments, and mitotic index (percent of cells dividing) were used as indicators of algal health; algae released after leather stars consumed their host were compared with algae freshly isolated from anemones. Two types of waste products contained algae: pellets resulting from extraoral digestion, and feces. Zooxanthellae and zoochlorellae isolated from these waste products were photosynthetic, although to different extents. For algae from feces and pellets, light-saturated photosynthetic rates (P
max) were 85 and 13%, respectively, of P
max of freshly isolated zooxanthellae; and were 20 and 46%, respectively, for zoochlorellae. The photosynthetic pigments and mitotic index (percent of dividing cells) were not altered by the feeding activities of the leather star. These results show that algae released by seastar predation on their hosts remain viable, and are hence available for establishing symbioses in A. elegantissima and other potential hosts. 相似文献
8.
The mineralisation of iron in the major lateral teeth of the chiton Acanthopleura echinata has been examined using light and electron microscopy, together with energy dispersive and Raman spectroscopy. The deposition of magnetite in the posterior region of the tooth cusp has been shown to occur simultaneously on two fronts, from both the anterior and posterior sides. In contrast, in the lepidocrocite region, the mineral is formed by aggregation over the whole region. In addition, evidence is presented for the existence of a thin veneer of ferrihydrite over the surface of the magnetite region. The veneer preserves this region from oxidation prior to use in the mature tooth. Data also suggest that the junction zone plays a vital role in the overall biomineralisation process, contributing large amounts of iron at critical stages of development. 相似文献
9.
Fleur E. Champion de Crespigny Nina Wedell 《Behavioral ecology and sociobiology》2007,61(8):1229-1235
The maternally inherited bacterium Wolbachia pipientis generates strong reproductive incompatibilities between uninfected females and infected males (cytoplasmic incompatibility),
significantly reducing both female and male reproductive success. Such fitness costs are thought to place selective pressure
on hosts to evolve pre-copulatory preferences for mating with compatible mates, thereby enabling them to avoid the reproductive
incompatibilities associated with Wolbachia. Therefore, uninfected females are predicted to prefer mating with uninfected males, whereas infected males are predicted
to prefer mating with infected females. Despite these predictions, previous investigations of pre-copulatory mate preferences
in Wolbachia-manipulated Drosophila have not found evidence of female preference for uninfected or compatible males. However, none of these studies utilised
a design where focal individuals are provided with a simple choice in a relatively non-competitive situation. We examined
both female and male pre-copulatory mate preference based on mate infection status in Drosophila simulans and D. melanogaster using simple choice assays involving between 30–50 replicates per treatment. Although we found no evidence of female pre-copulatory
mate preferences in either species, male D. simulans exhibited some preference for mating with females of the same infection status. However, this preference was not evident
when we repeated the experiment to confirm this finding. Consequently, we conclude that neither male nor female D. melanogaster and D. simulans exhibit significant Wolbachia-associated pre-copulatory mate preferences. 相似文献
10.
Phylogenetic analyses have demonstrated that nonfeeding larvae have evolved from feeding larvae many times among marine invertebrates.
In light of this observation, it is surprising that an intermediate strategy, a larva that can feed but is provisioned with
enough energy to metamorphose without acquiring exogenous food (i.e., facultative planktotrophy), is rare. A hypothesis for
the lack of facultative planktotrophic species among marine invertebrates is that the transition from feeding to nonfeeding
is rapid due to this intermediate stage being evolutionarily unstable. Evidence that would support this hypothesis is if species
with facultative planktotrophy have reduced food assimilation when compared with obligate planktotrophs. We studied a species
with facultative planktotrophic larvae, Clypeaster rosaceus, that is very near the boundary between facultative and obligatory planktotrophy, to answer two questions: (1) does feeding
during the larval stage result in energy gains in larval or juvenile stages and (2) if not, are larvae capable of assimilating
exogenous food at all. Our measurements of energetics in larval and juvenile stages show that C. rosaceus larvae accumulate very little if any energy when fed, but stable isotope data indicate that larvae are able to assimilate
some food. Our results are consistent with similar studies on facultative planktotrophic larvae suggesting poor food assimilation
and rapid loss of larval feeding after a population evolves the ability to reach metamorphosis without feeding (lecithotrophy). 相似文献
11.
Structure and complexity of the substrate are important habitat characteristics for benthic epifauna. The specific growth and mortality rates and inducible defence characters on medium-sized blue mussels (Mytilus edulis L.) exposed to shore crabs (Carcinus maenas L.) were examined on three different substrate types in combined field and laboratory experiments. The experiments showed that complexity of the substrate increased blue mussel survival significantly, through a decrease in predation pressure. However, increased intraspecific competition for food on the complex substrate resulted in significantly lower growth rates of the mussels. Inducible defence characters were also influenced by substrate type. Blue mussels were more affected by predators on the structurally simple substrate, where they developed thicker shells and a larger posterior adductor muscle. 相似文献
12.
Y. P. Kartavtsev T.-J. Park K. A. Vinnikov V. N. Ivankov S. N. Sharina J.-S. Lee 《Marine Biology》2007,152(4):757-773
Mitochondrial DNA (mtDNA) at Cyt-b gene region was sequenced for six flatfish species (in total nine sequences of at least 1,117 bp) from the Far East of Russia
and compared with other sequences of Pleuronectiformes comprising altogether 34 species and 3 outgroup species (Perciformes).
Analysis of the protein-coding Cyt-b gene revealed a statistically substantiated bias in (T + C):(A + G) content, supporting earlier findings. Values of P-distances, as summarized for different scales of the evolutionary history at Cyt-b gene, revealed a clear pattern of increased nucleotide diversity at four different phylogenetic levels: (1) intraspecies,
(2) intragenus, (3) intrafamily, and (4) intraorder. Scores of average P-distances of the four categories of comparison in flatfishes were (1) 0.46 ± 0.19%, (2) 11.74 ± 2.26%, (3) 17.51 ± 3.13%,
and (4) 25.60 ± 0.42%, respectively (mean ± SE). These data support the concept that speciation in the order Pleuronectiformes,
in most cases, follows a geographic mode through the accumulation of numerous small genetic changes over a long period of
time. A phylogenetic tree for 64 sequences of flatfishes and 3 other fishes belonging to ray-finned fishes (Actinopterigii)
was developed using Cyt-b gene and four different analytical approaches: neighbour-joining (NJ), Bayesian (BA), maximum parsimony (MP), and maximum
likelihood (ML). The analysis revealed a monophyletic origin for the representatives of Pleuronectidae, which is the principal
flatfish family investigated (99% repetition level in our BA analysis). A well supported property of the phylogenetic tree
was the monophyletic placement of all the five flatfish families and the order Pleuronectiformes among other representatives
of ray-finned fishes of the class Actinopterigii. Species identification on per individual basis (barcoding tagging) was generally
high. However, there were taxonomic complications that arose during analysis, and they are discussed. Major outcomes of this
discussion are the necessity of synonymy acceptance for Hippoglossoides elassodon, and H. robustus, and for Pseudopleuronectes yokohamae and P. schrenki. Priority considerations suggest H. elassodon and P. yokohamae as valid species names. 相似文献
13.
Adult rock hyrax (Procavia capensis) and bush hyrax (Heterohyrax brucei) allocate much of their surface activity to being vigilant for vertebrate predators. Individuals of the two species associate for thermoregulatory basking on rock outcrops (koppies) and, in the Matobo National Park, Zimbabwe, frequently constitute heterospecific groups that produce offspring synchronously. Exposure to predators during basking is thought to put a high premium on vigilance, particularly during the presence of dependent offspring in nurseries. We predicted, therefore, an increase in the association of the two species of hyraxes when offspring were present because this would lead to larger groups, thus enhancing the ability to detect predators. Koppie aggregations of hyraxes were classified as homospecific or heterospecific according to basking group composition. Heterospecific association increased when offspring were present, and heterospecific groups were larger than homospecific ones. Fifty-one percent of nurseries were heterospecific for adults/subadults. During the pre-weaning phase (<2 months after birth), 85% of P. capensis and 65% of H. brucei juveniles were in nurseries of heterospecific basking groups. Heterospecific groups had more offspring than homospecific groups. Juvenile mortality is most evident after young are weaned and heterospecific associations break down. Heterospecific aggregation, through increased group size, may result in a higher probability of avoiding predators, thereby reducing the vulnerability of young. 相似文献
14.
Susanna Andersson 《Chemoecology》2003,13(1):13-20
Summary. To better understand the biological role of floral scents for
butterflies, electrophysiological responses to floral scents were
investigated using combined gas chromatography and electroantennographic
detection (GC-EAD). The antennal responses of three butterfly species,
Aglais urticae L. (Nymphalidae), Inachis io L. (Nymphalidae), and
Gonepteryx rhamni L. (Pieridae) to floral scent compounds from both
natural and synthetic mixtures were examined. Floral scents were
collected from the butterfly nectar plants Cirsium arvense (L.)
(Asteraceae), and Buddleja davidii Franchet cv. (Loganicaeae) with
dynamic head-space methods on Tenax-GR and eluted with pentane. These
eluates, composed of natural floral scent blends, represent an array of
compounds in their natural state. In the GC-EAD analyses eleven
compounds were identified from C. arvense with the benzenoid compound
phenylacetaldehyde in highest abundance. Seventeen compounds were
identified from B. davidii with the irregular terpene oxoisophorone in
highest abundance. Thirty-nine synthetic floral scent compounds were
mixed in pentane, in equal amounts; about 35 ng were allowed to reach
the antennae. The butterflies showed antennal responses to most of the
floral scent compounds from both natural and synthetic blends except to
the highly volatile monoterpene alkenes. Certain benzenoid compounds
such as phenylacetaldehyde, monoterpenes such as linalool, and irregular
terpenes such as oxoisophorone, were emitted in relatively large amounts
from C. arvense and B. davidii, and elicited the strongest antennal
responses. These compounds also elicited strong antennal responses when
present in the synthetic scent blends. Thus, the butterflies seem to
have many and /or sensitive antennal receptors for these compounds,
which points to their biological importance. Moreover, these compounds
are exclusively of floral scent origin. For B. davidii, which depends
highly on butterflies for pollination, the exclusive floral scent
compounds emitted in high abundance could be the result of an adaptive
pressure to attract butterflies.
Received 2 Septemter 2001; accepted 9 September 2002. 相似文献
15.
J. D. Salierno J. D. Shields A. Z. Murphy G. E. Hoffman A. S. Kane 《Marine Biology》2007,152(4):835-843
To better understand sublethal effects of harmful algal blooms (HABs) on fish, mummichog, Fundulus heteroclitus (L.), were exposed in the laboratory to varying, environmentally relevant densities of Pfiesteria shumwayae (Glasgow et Burkholder, CCMP 2089, dinoflagellate) and Chaetoceros concavicornis (Mangin, CCMP 169, diatom). Two experiments were conducted during the spring of 2003 and 2004 to quantitatively examine the
effects of acute (2 h) P. shumwayae and C. concavicornis algal exposure on mummichog brain activity using c-Fos expression as a marker of altered neuronal activity. Brains from HAB-exposed
fish were removed, sectioned, and stained using immunocytochemistry prior to quantifying neuronal c-Fos expression. Fish exposed
to P. shumwayae and C. concavicornis showed increased c-Fos expression compared to unexposed control fish. A significant dose-response relationship was observed,
with increased labeling in brains of fish exposed to higher cell densities for both HAB species tested (P ≤ 0.01). Increased labeling was found in the telencephalon, optic lobes, midbrain, and portions of the medulla. The greatest
increases in expression were observed in the telencephalon of P. shumwayae-exposed fish, and in the telencephalon and optic lobes of C. concavicornis-exposed fish (P ≤ 0.01). These increases in c-Fos expression are consistent with other physical and chemical stress exposures observed in
fish. Neuronal stress, evidenced by c-Fos expression, demonstrates a sublethal effect of exposure and changes in brain activity
in fish exposed to HAB species. 相似文献
16.
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18.
Bruna Plese Vladislav A. Grebenjuk Heinz C. Schröder Hans J. Breter Isabel M. Müller Werner E. G. Müller 《Marine Biology》2008,153(6):1219-1232
The cDNA sequence coding for tauropine dehydrogenase (TaDH) [belonging to the family of opine dehydrogenases] has been determined.
Using the demosponge Suberites domuncula, we describe for the first time the tauropine dehydrogenase gene (of length 2,992 kb) from a eukaryote, consisting of two
introns flanked by three exons. Moreover, two allelic variants have been identified, which are present in the different specimens
either in a homozygotic or in a heterozygotic way; the data suggest an intermediary type of heritance. Phylogenetic analyses
indicate that S. domuncula TaDH is only distantly related to the opine dehydrogenases from marine invertebrates; rather it comprises high sequence similarity
to bacterial ornithine cyclodeaminases (OCD). In addition, expression studies revealed that the steady-state level of TaDH
dropped drastically in animals, which had been exposed to elevated aeration. Antibodies raised against the recombinant sponge
TaDH were used to demonstrate that S. domuncula expresses high levels of this enzyme in almost all cells. If tissue samples were kept under additional aeration no immuno-signals
could be identified. A strong accumulation of the enzyme was seen around the bacteria, existing in bacteriocytes, indicating
that under aerobic conditions the bacteria might produce taurine. These data suggest involvement of the sponge TaDH in the final step of the glycolytic pathway, more specifically, in regeneration of NAD(+) under anaerobic conditions. Furthermore,
potential mutual influences between bacteria and sponge are discussed, claiming a horizontal gene transfer of the gene from
a bacterium to the sponge.
The following sequences from Suberites domuncula have been deposited (EMBL/GenBank): the cDNA encoding the tauropine [(carboxyethyl)-taurine/derived from sulfhydryl-amino
acids] dehydrogenase (SD_TaDH) under AM712888; the corresponding gene under AM712889; and the fragments of the sponge-associated bacteria comprising the
opine dehydrogenase domain: SUBDO_BAC1 (AM712890), SUBDO_BAC2 (AM712891), SUBDO_BAC3 (AM712892), SUBDO_BAC5 (AM712894), SUBDO_BAC6
(AM712895), SUBDO_BAC7 (AM712896), SUBDO_BAC8 (AM712897) and SUBDO_BAC9 (AM712898). 相似文献
19.