共查询到20条相似文献,搜索用时 15 毫秒
1.
In order to assess diet composition and niche breadth of this species, we analysed the stomach content of 182 specimens collected
monthly along the eastern coast of Sicily (Central Mediterranean Sea). Overall, 50 prey taxa belonging to five major groups
(algae, gastropods, crustaceans, polychaetes, fishes) were identified in 102 full stomachs. Benthic or epibenthic crustaceans,
such as decapods, amphipods and isopods were the most important prey, whereas algae, gastropods, polychaetes and fishes were
only occasionally ingested. In terms of composition by species, the diet of Scorpaena maderensis was characterized by a variety of rare or unimportant prey, which was consumed by few individuals only, although sometimes
in large amount. As a result, S. maderensis can be considered a generalized and opportunistic feeder. The feeding intensity followed roughly a seasonal trend, with a
minimum food intake in summer. The individual fish size was the most important factor affecting diet. According to the observed
ontogenetic shift, small-sized individuals fed primarily on small crustaceans (i.e. amphipods and isopods), whereas large-sized
specimens consumed preferably bigger and more vagile prey, such as walking and swimming decapods. No significant differences
in diet were observed in relation to sex of predator and sampling season. 相似文献
2.
Brooke L. Sargeant Aaron J. Wirsing Michael R. Heithaus Janet Mann 《Behavioral ecology and sociobiology》2007,61(5):679-688
Because behavioral variation within and among populations may result from ecological, social, genetic and phenotypic differences,
identifying the mechanism(s) responsible is challenging. Observational studies typically examine social learning by excluding
ecological and genetic factors, but this approach is insufficient for many complex behaviors associated with substantial environmental
variation. Indian Ocean bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia show individual differences in foraging tactics, including possible tool use with marine
sponges and social learning may be responsible for this diversity. However, the contributions of ecological factors to the
development of these foraging tactics were not previously investigated. Here, we determined the relationship between ecological
variables and foraging tactics and assessed whether differences in habitat use could explain individual differences in foraging
tactics. We monitored 14 survey zones to identify how foraging tactics were spatially distributed and matched behavioral data
to the ecological variables within each zone. Three of four foraging tactics were significantly correlated with ecological
characteristics such as seagrass biomass, water depth, presence of marine sponges and season. Further, individual differences
in habitat use were associated with some tactics. However, several tactics overlapped spatially and previous findings suggest
demographic and social factors also contribute to the individual variation in this population. This study illustrates the
importance of environmental heterogeneity in shaping foraging diversity and shows that investigating social learning by ruling
out alternative mechanisms may often be too simplistic, highlighting the need for methods incorporating the relative contributions
of multiple factors. 相似文献
3.
The venomous striped eel catfish Plotosus
lineatus was first recorded in the Mediterranean in 2002. Within 1–3 years, it has spread throughout the entire Israeli coast. We
have studied its spatiotemporal distribution patterns via trawl surveys in order to determine the scale and extent of this
invasion. Findings indicate that a population explosion has occurred, and the catfish now inhabits all sandy and muddy substrates
up to ca 80 m. P. lineatus was found to recruit in autumn in the Mediterranean and displays similar or improved growth patterns and condition factor
compared to those found in its native habitat. We discuss the possible ecological mechanisms responsible for its success:
Benthic invaders are among its main prey items, suggesting an invasional meltdown process. We also point to the decline of
indigenous species using its trophic and behavioral–ecological niche and hypothesize that they might be outcompeted and displaced
by the catfish. 相似文献
4.
Fine-scale movement patterns in penaeid prawns are rarely observed in situ, but are essential in understanding habitat use,
foraging, and anti-predator behaviour. Acoustic telemetry was applied to examine the activity, space utilization, and habitat
use of the eastern king prawn Penaeus (Melicertus) plebejus, at small temporal and spatial scales. Tracking of sub-adult P. plebejus (n = 9) in Wallagoot Lake (36.789°S, 149.959°E; 23 April–12 May 2009) and calculation of a minimum activity index (MAI) revealed high variation in activity rates across diel periods and in different habitats. Elevated activity rates and movement
indicated foraging in unvegetated habitats during the night. Areas within the 95 and 50% space utilization contours averaged
2,654.1 ± 502.0 and 379.9 ± 103.9 m2, respectively, and there was a significant negative relationship between these areas and prawn activity rates in unvegetated
habitats. This study provides the first estimates of prawn activity rates and space utilization in the field. Application
of acoustic telemetry can increase knowledge of prawn movements and their interactions with other marine species in different
habitats. 相似文献
5.
While qualitative observations of jellyfish intraguild predation abound in the literature, there are only few rate measurements
of these interactions. We quantified predation rates among two common jellyfish in northern boreal waters, Cyanea capillata and its prey Aurelia aurita, both of which also feed on crustacean zooplankton and fish larvae. A series of incubation experiments using a wide range
of prey concentrations (0.38–3.8 m−3) in large containers (2.6 m3) was carried out. By replenishing the prey continuously as they were captured we maintained a nearly constant prey concentrations.
Ingestion rates increased linearly up to prey concentrations of 1.92 m−3, yielding maximum clearance rates of ∼2.37 ± 0.39 m3 predator−1 h−1 for C. capillata predators 16 ± 2.3 cm in diameter. Mean ingestion rate at saturated prey concentrations (1.92–3.85 m−3) was 4.01 ± 0.78 prey predator−1 h−1. Behavioral observations suggested that predators did not alter their swimming behavior during meals, and thus that feeding
rates were generally handling limited rather than encounter limited. Predators captured more prey than needed, and semi-digested
prey was often discarded when fresh prey was encountered. 相似文献
6.
Stefan Garthe William A. Montevecchi Gilles Chapdelaine Jean-Francois Rail April Hedd 《Marine Biology》2007,151(2):687-694
In order to forage and to provision offspring effectively, seabirds negotiate a complex of behavioural, energetic, environmental
and social constraints. In first tests of GPS loggers with seabirds in North America, we investigated the foraging tactics
of free-ranging northern gannets (Sula bassana) at a large and a medium-sized colony that differed in oceanography, coastal position and prey fields. Gannets at Low Arctic
colony (Funk Island) 50 km off the northeast coast of Newfoundland, Canada provisioned chicks almost entirely with small forage
fish (capelin Mallotus villosus, 89%), while at boreal colony (Bonaventure Island) 3 km from shore in the Gulf of St. Lawrence, Quebec, Canada, large pelagic
fish dominated parental prey loads (Atlantic mackerel Scomber scombrus 50%, Atlantic herring Clupea harengus 33%). Mean foraging range and the total distance travelled per foraging trip were significantly greater at the larger inshore
colony (Bonaventure) than at the smaller offshore colony (Funk Island; 138 and 452 km vs. 64 and 196 km, respectively). Gannets
from Funk Island consistently travelled inshore to forage on reproductive capelin shoals near the coast, whereas foraging
flights of birds from Bonaventure were much more variable in direction and destination. Birds from the Low Arctic colony foraged
in colder sea surface water than did birds from the boreal colony, and dive characteristics differed between colonies, which
is concordent with the difference in prey base. Differences between the colonies reflect oceanographic and colony-size influences
on prey fields that shape individual foraging tactics and in turn generate higher level colony-specific foraging “strategies”. 相似文献
7.
Migrating birds often alternate between flight steps, when distance is covered and energy consumed, and stopover periods,
when energy reserves are restored. An alternative strategy is fly-and-forage migration, useful mainly for birds that hunt
or locate their prey in flight, and thus, enables birds to combine foraging with covering migration distance. The favourability
of this strategy in comparison with the traditional stopover strategy depends on costs of reduced effective travel speed and
benefits of offsetting energy consumption during migration flights. Evaluating these cost-benefit effects, we predict that
fly-and-forage migration is favourable under many conditions (increasing total migration speed), both as a pure strategy and
in combination with stopover behaviour. We used the osprey (Pandion haliaetus) as test case for investigating the importance of this strategy during spring and autumn migration at a lake in southern
Sweden. The majority, 78%, of passing ospreys behaved according to the fly-and-forage migration strategy by deviating from
their migratory track to visit or forage at the lake, while 12% migrated past the lake without response, and 10% made stopovers
at the lake. Foraging success of passing ospreys was almost as good as for birds on stopover. Timing of foraging demonstrated
that the birds adopted a genuine fly-and-forage strategy rather than intensified foraging before and after the daily travelling
period. We predict that fly-and-forage migration is widely used and important among many species besides the osprey, and the
exploration of its occurrence and consequences will be a challenging task in the field of optimal migration. 相似文献
8.
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
9.
Shallow-water octopuses have been reported as major predators of motile species in benthonic marine communities, capturing
their prey by different foraging techniques. This study assessed for the first time the feeding ecology, foraging behavior,
and defensive strategy during foraging, including the use of body patterns, to construct a general octopus foraging strategy
in a shallow water-reef system. Octopus insularis was studied in situ using visual observations and video recordings. The diet included at least 55 species of crustaceans
(70%), bivalves (17.5%), and gastropods (12.5%); however, only four species accounted for half of the occurrences: the small
crabs Pitho sp. (26.8%) and Mithrax forceps (23.9%), the bivalve Lima lima (5.3%), and the gastropod Pisania pusio (4.9%). Poke and crawl were most frequent foraging behaviors observed in the video recordings. The foraging behaviors were
associated with environmental variables and octopus body size. The sequences of foraging behavior showed characteristics of
a tactile saltatory searching predator, as well as a visual opportunist. Body patterns showed a relationship with foraging
behavior, habitat variables, and octopus body size. Mottle was the most frequent pattern, especially during poke and crawl,
in shallower depths. Dorsal light–ventral blue green was more frequent during swimming at mid-water, and Blotch was the normal
pattern during web-over by large animals. The large proportion of two species of small crabs in den remains, the intense search
for food during short hunting trips, and the intense use of cryptic body patterns during foraging trips, suggest that this
species is a ‘time-minimizing’ forager instead of a ‘rate-maximizer’. 相似文献
10.
Halictine bees exhibit a wide range of social behaviour that varies both inter- and intraspecifically. Although previous studies
suggested that the intraspecific variation might be attributed to temperature differences, there was no direct evidence to
detect the relationships between temperature and socialities. Lasioglossum (Evylaeus) baleicum exhibited solitary behaviour in a cooler locality (Kawakita) because of the shorter breeding season; in a warmer locality
(Nishioka Park), however, this bee species exhibited eusociality at sunny site and solitary behaviour at shady site, whereas
a molecular phylogeny confirms that all of these colonies are evidently conspecific. Therefore, we examined the effect of
degree-day accumulation on the sympatric social variation of L. baleicum by rearing the bees to calculate the threshold temperature. Whereas they showed high mortality, the threshold temperature
was estimated to be 10.33°C and the expected degree-day accumulation was 340 degree days. When we use this value of a degree-day
accumulation to estimate the expected eclosion date, the estimated dates were always consistent with observed eclosion dates.
In any sites where the bees were solitary, the degree-day accumulation was not enough for the second eclosion by the end of
the bee-active season. In Nishioka Park, sex ratio of the first brood was female biased, and daughters were smaller than mothers;
in Kawakita, however, there was no sex bias, and daughters were as large as their mothers indicating that the foundresses
seem to produce gyne-sized females in Kawakita but worker-sized females in Nishioka though these females do not become workers
at shady site. 相似文献
11.
Elizabeth A. Tibbetts 《Behavioral ecology and sociobiology》2007,61(12):1877-1883
Social insects are popular models for studying the evolution of cooperation. Casteless taxa where individuals have the flexibility
to either nest alone or cooperate are particularly valuable for understanding the causes and consequences of cooperative behavior.
For example, some ‘workers’ from Polistes paper wasp nests disappear from their natal colony soon after pupal emergence and nest independently. However, little is
known about dispersal behavior. In this paper, I compare predispersal behavior of wasps who leave their natal colony soon
after emergence with behavior of individuals who remain on the natal colony as true workers. I found that P. dominulus females with short nest tenure behave much like gynes (reproductive-destined offspring produced at the end of the season),
as wasps with short nest tenure are behaviorally selfish while on the natal colony. They spend a smaller proportion of their
time foraging and a larger proportion of their time resting than workers with long nest tenure. In addition, I assessed the
factors that may favor early dispersal. Nest environment strongly influenced dispersal; large colonies had a smaller proportion
of females with short nest tenure. Queen turnover also increased dispersal behavior perhaps because queen turnover reduces
relatedness between a colony’s current and future offspring, thereby reducing the kin-selected benefits of cooperation. Therefore,
casteless social insects exhibit a surprising degree of reproductive flexibility. Individuals may use information about their
internal state and nest environment to optimize their behavioral strategies. 相似文献
12.
Ana Catarina Ferreira Silva Sónia Brazão Steve J. Hawkins Richard C. Thompson Diana M. Boaventura 《Marine Biology》2009,156(12):2591-2599
Wave action is known to influence the abundance and distribution of intertidal organisms. Wave action will also determine
the duration and suitability of various foraging windows (high-tide and low-tide, day and night) for predation and can also
affect predator behaviour, both directly by impeding prey handling and indirectly by influencing prey abundance. It remains
uncertain whether semi-terrestrial mobile predators such as crabs which can access intertidal prey during emersion when the
effects of wave action are minimal, are influenced by exposure. Here, we assessed the effect of wave action on the abundance
and population structure (size and gender) of the semi-terrestrial intertidal crab Pachygrapsus marmoratus on rocky shores in Portugal. The activity of P. marmoratus with the tidal cycle on sheltered and exposed shores was established using baited pots at high-tide to examine whether there
was activity during intertidal immersion and by low-tide searches. Because prey abundance varies along a wave exposure gradient
on most Portuguese shores and because morphology of crab chelipeds are known to be related to diet composition, we further
tested the hypothesis that predator stomach contents reflected differences in prey abundance along the horizontal gradient
in wave exposure and that this would be correlated with the crab cheliped morphology. Thus, we examined phenotypic variation
in P. marmoratus chelipeds across shores of differing exposure to wave action. P. marmoratus was only active during low-tide. Patterns of abundance and population structure of crabs did not vary with exposure to wave
action. Stomach contents, however, varied significantly between shores of differing exposure with a higher consumption of
hard-shelled prey (mussels) on exposed locations, where this type of prey is more abundant, and a higher consumption of barnacles
on sheltered shores. Multivariate geometric analysis of crab claws showed that claws were significantly larger on exposed
shores. There was a significant correlation between animals with larger claws and the abundance of mussels in their stomach.
Variation in cheliped size may have resulted from differing food availability on sheltered and exposed shores. 相似文献
13.
Bearded vultures (<Emphasis Type="Italic">Gypaetus barbatus</Emphasis>) prefer fatty bones 总被引:1,自引:0,他引:1
Antoni Margalida 《Behavioral ecology and sociobiology》2008,63(2):187-193
In animal species, prey processing and the provisioning of nutrients are subject to several constraints related with finding,
ingesting and processing food. In most bird species, these constraints are obvious as a consequence of food morphology. In
the case of the bearded vulture (Gypaetus barbatus), in comparison with other species, its behavioural and physiological adaptations apparently allow this vulture to ingest
bone remains irrespective of their morphology. Here, by comparing bones delivered to the nest to be consumed (selected) and
remains found at an experimental feeding station and at bone-breaking sites or ossuaries (rejected), I tested whether bearded
vultures are capable of choosing from among the various anatomical parts of an animal carcass in relation to their fatty acid
content (nutrient concentration hypothesis), their size (width-reduction hypothesis) or both. The results suggest that bearded
vultures prefer the fatty anatomical parts (with a high percentage of oleic acid) of an animal carcass regardless of bone
length, although bone morphology as a consequence of handling efficiency or the ingestion process may also play a secondary
role in food selection. The close association between the bones selected and their high fat value implies an optimisation
of foraging time and of the increased energy gained from the food. This is in line with selective foraging to redress specific
nutritional imbalances (nutrient concentration hypothesis) and, secondarily, the width-reduction hypothesis. 相似文献
14.
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
15.
Most research on animal contests has focused on the factors that influence the intensity and outcome of aggressive contests
within nonsocial species, while relatively little is known about contests in social taxa. Here, we examine contests among
queens of the social paper wasp, Polistes dominulus. Queens use multiple reproductive strategies, including nesting alone, usurping established colonies, and cooperatively joining
other queens. We stage contests between a nesting queen and a challenger to test how resource value (RV) and resource holding
potential (RHP) influence (a) who occupies the nest at the end of the contest and (b) the extent of conflict between the queen
and challenger. We found that RHP, as measured by individuals’ facial patterns and body size, influenced the outcome of the
contest. Challengers with high RHP were more likely to successfully usurp the nest than challengers with low RHP. Interestingly,
queens with relatively high RHP were more likely to form a cooperative association with the challenger than queens with lower
RHP, suggesting that queens may evict individuals that are an aggressive threat. RV influenced the intensity of conflict.
There was more aggressive conflict over large nests than over small nests. Overall, social taxa have complex contest dynamics
with important parallels to contests in nonsocial taxa. Studying contests in social taxa provides an important perspective
on the factors that influence individual decisions about conflict versus cooperation. 相似文献
16.
On many sea shores of the Niedersachsen coast, the polychaete Scolelepis squamata is the dominant animal species living in the sediment of exposed beaches.The population of the predatory species Eteone longa, with a main distribution in more sheltered intertidal and subtidal habitats, has a certain overlap with S. squamata. In these restricted areas, S. squamata suffers from a permanent pursuit by E. longa during low tide. Field and laboratory studies have revealed that this predator-prey relationship follows a distinct behavioural pattern and is an exploitation of surviving animals: the predator does not ingest the whole prey individual but only feeds on regenerable parts of the body. Both species draw characteristic tracks on the sediment surface that illustrate the phases of the chase, the attempts at defence and the mutilation of the prey species.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
17.
As intermediaries, some heterotrophic protists can enhance the content of the long chain n-3 essential fatty acids (LCn-3EFAs),
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), of low food quality algae for subsequent use at higher trophic
levels. However, the mechanisms that produce LCn-3EFAs are presently unknown, although LCn-3EFA production by heterotrophic
protists at the phytoplankton–zooplankton interface may potentially affect the nutritional status of the pelagic system. We
investigated whether the heterotrophic protists, Oxyrrhis marina and Gyrodinium dominans, produce LCn-3EFAs via elongation and desaturation of dietary LCn-3EFA precursors and/or synthesize LCn-3EFAs de novo by:
(1) feeding the two heterotrophic protists with a prey deficient in n-3 fatty acids, (2) incubating them in medium containing
13C-labeled sodium acetate, and (3) feeding the two protists gelatin acacia microspheres (GAMs) containing a deuterium-labeled
LCn-3EFA precursor, linolenic acid [18:3(n-3)-d4]. Both O. marina and G. dominans synthesized EPA and DHA when fed the n-3 fatty acid-deficient prey, Perkinsus marinus, a parasitic protozoan. O. marina, but not G. dominans utilized 13C-labeled acetate from the medium to produce uniformly labeled fatty acids, including DHA. Both heterotroph species consumed
GAMs containing 18:3(n-3)-d4 and catabolized 18:3(n-3)-d4 to 16:3(n-3)-d4 and 14:3(n-3)-d4, while no 20 or 22 carbon metabolites
of 18:3(n-3)-d4 were detected. These results suggest that O. marina and G. dominans do not elongate and desaturate dietary LCn-3EFA precursors to produce LCn-3EFAs, but rather they produce LCn-3EFAs de novo,
possibly via a polyketide synthesis pathway. 相似文献
18.
Heidi C. Pearson 《Behavioral ecology and sociobiology》2009,63(10):1437-1446
In societies characterized by a high degree of fission-fusion dynamics, individuals adjust their grouping patterns according
to the shifting balance of costs and benefits associated with grouping. This study examines influences on fission-fusion dynamics
for dusky dolphins (Lagenorhynchus obscurus) in Admiralty Bay, New Zealand. This area is an important foraging habitat for dusky dolphins during the winter and spring.
Admiralty Bay has little predation risk, but nearshore mussel farms may infringe on available habitat. I used generalized
estimating equations to determine the influences of coordinated foraging, predation risk, and presence of mussel farms on
party size, rate of fission-fusion, and behavioral state. I conducted 168 boat-based group focal follows totaling 168 h. The
proportion of individuals observed foraging was positively related to party size and rate of party fusion. Resting had no
effect on party size and did not vary according to location. Near mussel farms, traveling decreased, and rate of party fission
decreased. I conclude that (1) coordinated foraging strategies are a primary influence on fission-fusion dynamics within this
population, (2) dolphins may respond to decreased predation risk by not adjusting party size or location during resting, and
(3) areas near mussel farms are not used for traveling. 相似文献
19.
According to indicator models of sexual selection, mates may obtain indirect, i.e. genetic, benefits from choosing partners indicating high overall genetic quality by honest signals. In the scorpionfly Panorpa vulgaris, both sexes show mating preferences on the basis of the condition of the potential partners. Females prefer males that produce nuptial gifts (i.e. salivary secretions) during copulation, while males invest more nuptial gifts in females of high nutritional status. Both characters, males' ability to produce nuptial gifts and high nutritional status of females, are known to be reliable indicators of foraging ability. Thus, besides possible direct benefits, both sexes might also obtain indirect benefits in terms of “good foraging genes” by their choice and thereby increase the fitness of their offspring. A prerequisite for this possibility is the heritability of the respective trait. In the present study, we estimated the repeatability and the heritability of foraging ability. Our results indicate (1) a significant repeatability of individual foraging efficiencies in males and females and (2) a heritable component of this trait by a significant parent–offspring regression. These findings suggest that genetic benefits in terms of increased offspring foraging ability might contribute to selection for mating preferences in both sexes. 相似文献
20.
Any mechanism that allows animals to increase their foraging efficiency is likely to be selected for, including the ability
to learn to recognise and subsequently discriminate between habitat types based on their profitability. In a series of laboratory
studies, we manipulated prey densities across two different experimental subhabitats and demonstrated that threespine stickleback
(Gasterosteus aculeatus) can develop foraging preferences for subhabitats that have previously yielded prey. Fish were not recalling the spatial
location of prey patches; rather, they were discriminating between subhabitats based on foraging experience there and allocating
foraging effort accordingly. Foraging preferences took around 14 days to develop, and once established, they persisted independently
of experimental prey density, suggesting that fish were using experience rather than real-time sampling to select foraging
grounds. When we presented focal fish with social information cues, we found that they preferentially used local enhancement
and current public information cues when they conflicted with previous experience, but that they did not use prior public
information. This suggests that in the presence of conspecifics, individuals prioritise social conformity over the use of
private information. We discuss our results in the context of optimal foraging and the trade-offs associated with balancing
conflicting private and social information. 相似文献