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We observed female beaugregory damselfish (Stegastes leucostictus) as they interacted with males to see whether their movements fit the predictions of different mate-search models. We established
high-quality and low-quality groups with low variance in breeding site quality and a medium-quality, high-variance breeding
site group and compared focal observations of female nonforaging forays in each group. Only 8% of 137 forays monitored resulted
in spawning events. Eighty-nine percent of the forays were less than 240 s and were within 7 m of the focal female’s territory.
Average foray times and straight-line foray distances did not differ for females traveling between males in each group. Females
entered high-quality breeding sites at a higher rate than low-quality sites and round-trip distances were also greatest in
high-quality groups, indicating that females were following a more convoluted path. We interpret these results to mean that
(a) female beaugregories separate the tasks of mate assessment and mate choice by conducting information-gathering forays
between mating events, (b) forays are energetically costly and therefore usually short in duration and overall distance traveled,
(c) information collection takes approximately the same time for high-quality and low-quality mates, but (d) females will
alter their foray patterns in high-quality areas to collect additional information. These data are also consistent with the
hypothesis that females optimize their search by employing a tiered process of assessment during information-gathering forays,
first using an adjustable threshold to accept or reject each male based on his courtship and subsequently a fixed threshold
to assess the quality of each breeding site. 相似文献
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Great white sharks are protected by national legislation in several countries, making this species the most widely protected
elasmobranch in the world. Although the market demand for shark fins in general has continued to grow, the value and extent
of utilization of white shark fins in trade has been controversial. We combine law enforcement with genetic profiling to demonstrate
that illegal trade in fins of this species is occurring in the contemporary international market. Furthermore, we document
the presence of fins from very young white sharks in the trade, suggesting a multiple-use market (food to trophies) exists
for fins of this species. The presence of small fins in the trade contradicts the view that white shark fins have market value
only as large display trophies, and not as food. Our findings indicate that effective conservation of protected shark species
will require international management regimes that include monitoring of the shark fishery and trade on a species-specific
basis. 相似文献
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Lori A. Ortega Michelle R. Heupel Philip Van Beynen Philip J. Motta 《Environmental Biology of Fishes》2009,84(4):361-373
Acoustic telemetry was used to examine the size of daily activity space, small-scale movement patterns, and water quality
preferences of juvenile bull sharks in the Caloosahatchee River, Florida. Movement pattern analysis included rate of movement,
swimming depth, linearity, direction, tidal influence, diel pattern, and correlation with environmental variables. Manual
tacking occurred before and after a large freshwater influx which divided the sharks into two groups based on movement patterns.
The first group displayed increased rate of movement, distance traveled, and space utilization at night, and movements correlated
with salinity, temperature, and dissolved oxygen. The second group had an increased rate of movement, distance traveled, and
space utilization during the day, and movements correlated with temperature, dissolved oxygen, turbidity and pH. These juvenile
bull sharks displayed distinct diel movement patterns that were influenced by physical factors, which may account for the
distribution of this top-level predator in the Caloosahatchee River. 相似文献
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Michael G. Boegle Susanne Schneider Beate Mannschreck Arnulf Melzer 《Hydrobiologia》2007,586(1):155-166
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Bourguyia hamata females oviposit almost exclusively inside the rosette formed by the curled leaves of the epiphytic bromeliad Aechmea nudicaulis. We investigated whether the architecture of the individual bromeliads influences oviposition site selection by this harvestman
species. We collected data on the presence of clutches inside bromeliads, rosette length, rosette slope in relation to tree
trunks, and the amount of debris inside the rosette. Additionally, we measured the water volume inside the rosettes as well
as the variation in the humidity inside and outside bromeliads with long and short rosettes. Longer rosettes were preferred
as oviposition site possibly because they accumulate more water and maintain lower internal humidity variation than the external
environment. Although the slope of the rosettes did not influence the occurrence of oviposition, the probability of debris
accumulation inside the rosettes increased with their slope, and the frequency of clutches was greater in bromeliads with
small amounts of debris. A field experiment showed that bromeliads with water inside the rosette were more frequently used
as oviposition sites than bromeliads without water. In conclusion, females oviposit predominantly in bromeliads that accumulate
more water and have small amounts of debris inside the rosettes, probably because these characteristics promote a more adequate
microhabitat for egg development. 相似文献
8.
Esterases are known for their involvement in several physiological processes and high degree of polymorphism, in many organisms.
Such polymorphism has been used to characterize species and species groups and to study genetic changes occurred in their
evolutionary history. In the present study, the esterase patterns of 19 strains from 10 species representative of the five
subgroups of the saltans species group were analyzed using polyacrylamide gel electrophoresis and α- and β- naphthyl acetates as substrates. Fifty-one
esterase bands were detected and classified as 31 α-esterases, 18 β-esterases and two α/β-esterases. On the basis of the inhibition
patterns using Malathion and eserine sulfate, 34 bands were classified as carboxylesterases, 14 as acethylesterases and three
as cholinesterases. Ten gene loci were tentatively established on the basis of data on band position in the gel, substrate
preference and inhibition pattern. Twenty bands were species-specific, the remaining being shared by species from the same
or different subgroups. Bands detected exclusively in males and bands with a different frequency or degree of expression between
sexes were also detected. In the gels prepared for analysis of gene expression in the body parts (head, thorax and abdomen),
the degree of expression of the β-esterases was higher in the thorax, while the α-esterases were expressed predominantly in
the abdomen and thorax. A global view of the data available at present on the esterases of the species from the saltans group and their degree of polymorphism are presented, as well as the possibility of using some β-esterases, because of their
characteristics in the gels, as markers for species identification. 相似文献
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Oliver J. D. Jewell Ryan L. Johnson Enrico Gennari Marthán N. Bester 《Environmental Biology of Fishes》2013,96(7):881-894
Previous work on white sharks indicate the species show seasonally limited movement patters, at certain aggregation sites small areas may play vital roles in the life history of a large amount of the population. Acoustic telemetry was used to estimate habitat use of white sharks, Carcharodon carcharias, while aggregating at Mossel Bay, South Africa. Total range of all shark tracks combined accumulated 782 h and covered an area of 93.5 km2 however, within this range, sharks were found to highly utilise a core habitat (50 % Kernel, K50) of just 1.05 km2 over a reef system adjacent to a river mouth. Individual tracks revealed additional core habitats, some of which were previously undocumented and one adjacent to a commercial harbor. Much was found to be dependent on the size of the shark, with larger sharks (>400 cm) occupying smaller activity areas than subadult (300–399 cm) and juvenile (<300 cm) conspecifics, while Index of Reuse (IOR) and Index of Shared Space (IOSS) were both found to increase with shark size. Such results provide evidence that larger white sharks are more selective in habitat use, which indicates they have greater experience within aggregation sites. Furthermore, the focused nature of foraging means spatially restricted management strategies would offer a powerful tool to aid enforcement of current protective legislation for the white shark in similar environments of limited resources and capacity. 相似文献
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Parrots are the most threatened group of birds in the world, mainly because of the reduction and fragmentation of their natural
habitats. However, few studies have investigated the dynamics of parrot populations in disturbed landscapes on a broad scale.
In this paper, we studied the ecological interactions of the vulnerable blue-winged macaw (Primolius maracana) in a fragmented landscape surrounding a large protected park in southeastern Brazil. We sampled 36 forest fragments that
varied in size, characteristics, degree of isolation and type of surrounding matrix in order to assess the importance of habitat
features on the maintenance of these birds. Blue-winged macaws were recorded in 70% of the satellite remnants that were sampled,
which included large and small blocks of forest. These areas were used as sites for feeding, nesting or overnight rests, and
also provided connectivity for birds’ displacements. However, the frequency of macaw visits varied among the remnants, and
this was related to habitat features such as patch size, human use of surrounding land, and the proximity to the protected
park, to urban areas and to the birds’ roosting areas. In general, landscape-scale parameters explained more of the variation
in the frequency of visits by macaws than did patch-scale parameters. These results demonstrate the importance of landscape
mosaics for the survival of blue-winged macaws. 相似文献
11.
There are three most important bacterial causative agents of serious infections that could be misused for warfare purposes:
Bacillus anthracis (the causative agent of anthrax) is the most frequently mentioned one; however, Fracisella tularensis (causing tularemia) and Yersinia pestis (the causative agent of plague) are further bacterial agents enlisted by Centers for Disease Control and Prevention into the category A of potential biological weapons. This review intends to summarize basic information about these bacterial
agents. Military aspects of their pathogenesis and the detection techniques suitable for field use are discussed. 相似文献
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The life cycle and developmental stages of Aylax hypecoi (Trotter, 1913, Hymenoptera: Cynipidae: Aylacini) were studied in detail. Aylax hypecoi is known to induce galls in fruits of two Hypecoum species — H. imberbe and H. geslini (Papaveraceae) and the larva develops in host plant fruits. The morphology and development of egg, larva and pupa were investigated, which
has previously not been done. The shape and size of terminal-instar larvae and associated galls are sex-specific. Overwintering
stage, adult emergence and flying periods, and egg productivity were studied also. 相似文献
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Summary. The paper describes two methods of the synthesis of ethyl (3R,4S)- and (3S,4S)-4-[(benzyloxycarbonyl)amino]-5-[(tert-butyloxycarbonyl)amino]-3-hydroxypentanoates, useful for the syntheses of edeine analogs. Differently N-protected (S)-2,3-diaminopropanoic acid was used as a substrate in both procedures. The absolute configuration of newly generated asymmetric
carbon atoms C-3 in β-hydroxy-γ,δ-diamino products was assigned by means of 1H NMR spectroscopy after their transformation into corresponding piperidin-2-ones.
Received May 24, 2002 Accepted October 10, 2002 Published online December 18, 2002
Acknowledgment The authors are indebted to the Faculty of Chemistry, Technical University of Gdańsk for financial support.
Authors' address: Zbigniew Czajgucki, M. Sc., Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Technical University
of Gdańsk, 11/12 Narutowicza St., 80-952 Gdańsk, Poland, Fax +48 58 347 11 44, E-mail: zmczaj@wp.pl 相似文献
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Swimming and diving abilities of two syntopic species of water shrews, Neomys anomalus and Neomys fodiens, were tested in aquaria using video recordings taken from three views (lateral distant, lateral close and dorsal). The frequency
and total duration of diving, as well as the mean duration of diving and floating bouts, were significantly higher in N. fodiens than in N. anomalus. Frequency of paddling during surface swimming was lower in N. fodiens than in N. anomalus. N. fodiens dived mainly for long distances at the bottom of the aquarium and performed a wider range of dive profiles than N. anomalus, which preferred rather short and shallow dives. The two species differed also significantly in their fineness ratios (describing
how streamlined their bodies are) when diving. When swimming, N. fodiens had a relatively wider body and performed narrower movements with its tail than N. anomalus. These results show quantitatively and qualitatively for the first time that N. fodiens is more proficient at swimming and diving than N. anomalus. The results also help to explain the inter-specific differences in efficiency of underwater foraging, and support the idea
of segregation of ecological niches of these species based on their different foraging modes (diving vs. wading). 相似文献
16.
O. V. Golovanova V. I. Konenkov A. V. Shevchenko M. V. Smolnikova 《Russian Journal of Genetics》2009,45(8):981-986
Based on population analysis of the DRB1, DQA1, DQB1 and TNFA allele frequency distribution patterns, regional features of immunogenetic structure of the population of West Siberia were
investigated. Statistically significant linkage disequilibrium within the HLA class II region, as well as between the TNFA and DRB1, DQA1, and DQB1 was demonstrated. Population frequency distribution patterns of two- and multilocus haplotypes were examined. 相似文献
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S. E. Dawson 《Kew Bulletin》2008,63(3):517-517
Summary The name Pavetta modesta (Hiern) S. E. Dawson is a later homonym of P. modesta Bremek. Pavetta crystalensis is proposed as a new name. 相似文献
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The research on incidence of mistletoe (Viscum album ssp. abietis) on silver fir (Abies alba) was carried out in natural fir stands in Croatia. In the area of Gorski Kotar 32.8 % of the examined dominant fir trees
were infected with mistletoe. The mistletoe incidence was presented according to the damage degrees of silver fir from 0 (healthy
trees) to 4 (dead trees), rated by the crown defoliation and needle discoloration. With the increase of incidence, mistletoe
spreads more onto more vital, i.e. less damaged trees. In the Dinaric Alps 28.6% of the examined fir trees were infected,
this percentage amounting to 27.1% for the mountainous regions between the Sava and Drava rivers.
The site and stand parameters (exposure, elevation, site quality, forest community and crown closure) were analysed in order
to establish whether there was a correlation between these parameters and mistletoe incidence. There was a negative correlation
between the elevation and mistletoe incidence. Among the compartments with a closed stands there were considerably less compartments
with higher mistletoe incidence than among compartments with a sparsely closed and understocked stands. The other analysed
site and stand parameters individually had no significant influence on mistletoe incidence.
The correlation of silver fir mortality in 2004 and mistletoe incidence in 2002/03 was analysed, and their strong correlation
was established. Mistletoe could be considered as a bioindicator of silver fir decline, and probably a significant contributor
to that decline. In the areas where mistletoe incidence is great it can be presumed that silver fir is significantly damaged. 相似文献