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1.
In species with restricted dispersal, traits may become genetically fixed leading to local adaptations. Therefore, predator
avoidance in a prey species may differ between populations experiencing different predator regimes, but also between sexes
within a population due to different vulnerability to predators. In this study we used male and female Gammarus pulex from two different predator regimes: fishless ponds, where invertebrates are the dominant predators and ponds with predatory
fish. In the laboratory we examined refuge use, mortality, leaf decomposition rate and pair-formation in G. pulex when exposed to predator cues from either invertebrate predators or fish. Individuals from fish ponds spent more time in
refuge and had a higher mortality than those from fishless ponds independent of predator cues. There was no effect of pond
predator regime or predator cues on leaf decomposition rates. Further, fewer individuals formed pairs in G. pulex from fish ponds than from fishless ponds. Male G. pulex had a higher mortality and a higher decomposition rate than females independent of predator cues. However, there was no difference
in refuge use between sexes. Our study shows that there are general differences in behaviour traits, both between predator
regimes and sexes in G. pulex. 相似文献
2.
Recent findings suggest that grouping with conspecifics is part of the behavioural defences developed by amphipod crustaceans to face predation risk by fish. Amphipods commonly serve as intermediate hosts for trophically transmitted parasites. These parasites are known for their ability to alter intermediate host phenotype in a way that promotes predation by definitive hosts, where they reproduce. If aggregation in amphipods dilutes the risk to be preyed on by fish, then it may dilute the probability of transmission for the parasite using fish as definitive hosts. Using experimental infections, we tested whether infection with the fish acanthocephalan Pomphorhynchus laevis alters attraction to conspecifics in the amphipod intermediate host Gammarus pulex. We also measured G. pulex's activity and reaction to light to detect potential links between changes in aggregation and changes in other behaviours. The attraction to conspecifics in the presence of predator cue, a behaviour found in uninfected gammarids, was cancelled by the infection, while phototaxis was reversed and activity unchanged. We found no correlation between the three behaviours in infected amphipods, while activity and aggregation were negatively correlated in uninfected individuals after the detection of predation cue. The physiological causes and the adaptive value of aggregation suppression are discussed in the context of a multidimensional manipulation. 相似文献
3.
Parasites can fundamentally alter the cost–benefit ratio of living in a group, e.g. if infected individuals increase the predation
risk of shoal mates. Here, the effect of an infection with a trematode, Uvulifer sp. (Diplostomatidae) on the shoaling behaviour of female western mosquitofish, Gambusia affinis, was investigated. The parasite examined causes a direct phenotypical change of the host by forming black spots on its body
surface. When given a choice between a stimulus shoal and no shoal, we found shoaling tendencies to be significantly reduced
in infected focal fish. In another experiment, we tested for association preferences relative to the infection status of the
stimulus fish. Given the choice between an infected and a healthy stimulus fish, both infected and healthy focal fish preferred
to associate with non-infected stimulus fish. Our results suggest that (1) the cost–benefit ratio of shoaling might be different
for infected and non-infected individuals. Infected fish may be more affected by competition for food within a shoal. (2)
Associating with infected conspecifics appears to be costly for female mosquitofish, maybe due to increased predation risk. 相似文献
4.
We compared the shoaling behaviour of three-spined sticklebacks, Gasterosteus aculeatus, infected with the microsporidian, Glugea anomala, to that of non-infected conspecifics. Infected fish lost significantly more weight than non-infected fish during a period of food deprivation, suggesting a metabolic cost to parasitism. In binary shoal choice tests, non-infected test fish showed an association preference for a shoal of non-infected over a shoal of infected conspecifics; infected test fish displayed no preference. Infected fish, however, showed a higher overall tendency to shoal than non-parasitised fish. Furthermore, infected fish occupied front positions within a mixed school. We consider the behavioural differences between infected and uninfected fish in the context of their potential benefits to the fish hosts and the parasites. 相似文献
5.
As compared to other aquatic invertebrates, relatively little is known about the ecology of predaceous, pelagic water mites.
Studies to date do, however, show that water mites can be important components of aquatic food webs. Here, we used manipulative
field experiments to better understand the trophic ecology of a predaceous water mite (Piona carnea). Three experiments were conducted that examined (i) the effect of P. carnea density on the per-capita interaction strength (PCIS) of P. carnea preying on zooplankton; (ii) how the effects of P. carnea predation change with prey productivity; and (iii) how P. carnea interacts with another pelagic predator (Chaoborus americanus) to affect a shared prey species (Daphnia pulex). Results from the first experiment showed that P. carnea can strongly impact D. pulex populations, and that the PCIS of P. carnea decreases with an increase in P. carnea density. The second experiment showed that the effects of P. carnea on D. pulex populations depend on bottom-up factors that influence D. pulex population biomass and the reproductive potential of a D. pulex population relative to its size. The third experiment uncovered a non-additive interaction between P. carnea and C. americanus that resulted in a risk reducing situation for D. pulex in the presence of both predators. Together these experiments show that P. carnea imposes a strong negative impact on D. pulex, that the magnitude of this negative impact is dependent on the P. carnea density and the productivity of the system, and that the trophic ecology of P. carnea is modified by coexisting predator species. 相似文献
6.
Joachim G. Frommen Fabian Herder Leif Engqvist Marion Mehlis Theo C. M. Bakker Julia Schwarzer Timo Thünken 《Evolutionary ecology》2011,25(3):641-656
Predation risk is one of the major forces affecting phenotypic variation among and within animal populations. While fixed
anti-predator morphologies are favoured when predation level is consistently high, plastic morphological responses are advantageous
when predation risk is changing temporarily, spatially, or qualitatively. Three-spined sticklebacks (Gasterosteus aculeatus) are well known for their substantial variability in morphology, including defensive traits. Part of this variation might
be due to phenotypic plasticity. However, little is known about sticklebacks’ plastic ability to react morphologically to
changing risks of predation and about the proximate cues involved. Using a split-clutch design we show that odour of a predatory
fish induces morphological changes in sticklebacks. Under predation risk, i.e., when exposed to odour of a predator, fish
grew faster and developed a different morphology, compared to fish reared under low predation risk, i.e., exposed to odour
of a non-predatory fish, or in a fish-free environment. However, fast growing comes at cost of increased body asymmetries
suggesting developmental constraints. The results indicate that sticklebacks are able to distinguish between predatory and
non-predatory fishes by olfactory cues alone. As fishes were fed on invertebrates, this reaction was not induced by chemical
cues of digested conspecifics, but rather by predator cues themselves. Further, the results show that variation in body morphology
in sticklebacks has not only a strong genetical component, but is also based on plastic responses to different environments,
in our case different predation pressures, thus opening new questions for this model species in ecology and evolution. 相似文献
7.
Eric P. Caragata Kathryn M. Real Myron P. Zalucki Elizabeth A. McGraw 《Symbiosis (Philadelphia, Pa.)》2011,54(1):55-60
Wolbachia pipientis is a commonly occurring endosymbiont with well-characterised effects on host reproductive biology associated with its infection
of the gonads. Wolbachia infections are also widespread in somatic tissues and consequently they have the potential to play a much broader role in
host biology. Recently, Wolbachia was shown to alter the locomotion of Drosophila melanogaster in response to food cues in the laboratory. To determine whether this laboratory-based phenotype might translate to real
differences for insects in the field, we performed a simple mark-release-recapture experiment with Wolbachia-infected D. melanogaster in a forested habitat. We demonstrate that infected flies are recaptured at twice the rate of uninfected flies, although
infection does not affect the distance traveled by those flies recaptured. The differences in recapture could be explained
by infection-induced changes in physiology or behavior. If generalizable, such changes may affect the interpretation of behavioral
studies for Wolbachia-infected insects and have potential implications for the dynamics of Wolbachia infections in natural populations, including situations where Wolbachia-infected insects are being released for biological control. 相似文献
8.
Anti-predator behaviour often represents a trade-off between the benefits of reducing predation risk and the drawbacks of
limiting access to resources (e.g. food availability, mating and nesting sites). The effectiveness of avoidance behaviour
relies on the ability to detect predator cues, which may provide reliable information on predation risk. Using controlled
laboratory experiments, we studied the relative importance of visual and chemical cues in the triggering of anti-predator
responses in Galaxias maculatus, where Oncorhyncus mykiss was used as the predator. Metabolic cost was also estimated, measured as oxygen consumption. Exposure to different types
of predator cue induced diverse behavioural responses in G. maculatus. Detection of the exotic predator, using both visual and chemical stimuli, resulted in reduced G. maculatus swimming activity and changes in respiratory rate. 相似文献
9.
Selection on traits conferring reduced predation may be opposed by selection on other traits associated with reproduction.
Here, we examined the hypothesis that traits associated with reproduction in Gammarus pulex are driven by predation. We studied G. pulex originating from ponds with two different kinds of predator regimes: (1) ponds with fish—often large, non-gap-limited predators
and (2) ponds without fish where invertebrates are the dominant predators—often small, gap-limited predators with a much more
restricted prey size range. We examined the body size of males and females in G. pulex amplexus pairs originating from fish and fishless ponds. We also examined, in the laboratory, their mating success, the number
of offspring per female and offspring mortality under different rearing conditions, with or without fish cue. Mating success,
defined as the percentage of amplexus pairs that produced live offspring, was higher for G. pulex from fishless ponds independent of rearing condition. Individuals from fish ponds were larger and they produced a higher
number of offspring which tended to be related to female body size. Offspring mortality was higher in populations from fish
ponds compared to populations from fishless ponds. Despite the higher offspring mortality, females from fish ponds had a higher
number of offspring alive after 13 weeks, which is the approximate time it takes for G. pulex to reach maturity. Our data imply that no trade-off between reducing body size to reduce mortality caused by fish and maximising
reproductive success exist in G. pulex from fish ponds. The strategy with many offspring may be the correct strategy in fishponds where predation pressure generally
is higher than in fishless ponds. 相似文献
10.
Trophically-transmitted parasites often change the phenotype of their intermediate hosts in ways that increase their vulnerability to definitive hosts, hence favouring transmission. As a “collateral damage”, manipulated hosts can also become easy prey for non-host predators that are dead ends for the parasite, and which are supposed to play no role in transmission strategies. Interestingly, infection with the acanthocephalan parasite Polymorphus minutus has been shown to reduce the vulnerability of its gammarid intermediate hosts to non-host predators, whose presence triggered the behavioural alterations expected to favour trophic transmission to bird definitive hosts. Whilst the behavioural response of infected gammarids to the presence of definitive hosts remains to be investigated, this suggests that trophic transmission might be promoted by non-host predation risk. We conducted microcosm experiments to test whether the behaviour of P. minutus-infected gammarids was specific to the type of predator (i.e. mallard as definitive host and fish as non-host), and mesocosm experiments to test whether trophic transmission to bird hosts was influenced by non-host predation risk. Based on the behaviours we investigated (predator avoidance, activity, geotaxis, conspecific attraction), we found no evidence for a specific fine-tuned response in infected gammarids, which behaved similarly whatever the type of predator (mallard or fish). During predation tests, fish predation risk did not influence the differential predation of mallards that over-consumed infected gammarids compared to uninfected individuals. Overall, our results bring support for a less sophisticated scenario of manipulation than previously expected, combining chronic behavioural alterations with phasic behavioural alterations triggered by the chemical and physical cues coming from any type of predator. Given the wide dispersal range of waterbirds (the definitive hosts of P. minutus), such a manipulation whose efficiency does not depend on the biotic context is likely to facilitate its trophic transmission in a wide range of aquatic environments. 相似文献
11.
Clément Lagrue Nicolas Kaldonski Sébastien Motreuil Thierry Lefèvre Olivier Blatter Philippe Giraud Loïc Bollache 《Biological invasions》2011,13(6):1409-1421
“Drifting” is known to subject aquatic invertebrates to intense predation by drift feeding fish. Consequently, interspecific
variations in drifting behaviour could lead to differences in predation pressure between coexisting prey species. Predation
being an important factor determining the success of invaders, differences in drift patterns could advantage either native
or exotic invertebrates through differential predation by native fish predators. The exotic freshwater amphipod (Gammarus roeseli) has now largely colonized Western Europe where it is often found in sympatry with a native species (Gammarus pulex). Here we documented interspecific differences in drifting behaviour that might have favored the invader’s success through
differential predation. Benthic and drifting amphipods were sampled three times at the same site to compare the proportion
of each species within and between sample types (benthos or drift) across time. Compared with the benthos, where the invader
(G. roeseli) was significantly less abundant than the native (G. pulex), G. roeseli was proportionally overrepresented in the drift but displayed a very different drifting pattern. While G. pulex drift rates remained roughly constant over a 24 h period, G. roeseli showed a marked diel periodicity with low diurnal and high nocturnal drift rates. Such drifting behaviour could procure this
species with a competitive advantage regarding predation as most drift feeding fish are diurnal. As a result, the native appears
more disadvantaged with respect to drift. This may partly explain the ability of G. roeseli to coexist with G. pulex in a habitat more suitable to the native. 相似文献
12.
In the present study, the effect of chemical cues from two fish species (mosquitofish and pumpkinseed), at different concentrations,
was tested in life history experiments with Daphnia longispina. The two fish species used represent the most abundant planktivores of many Mediterranean shallow lakes (SW Europe), where
the indigenous fish communities have been replaced by such exotic assemblages. Results have shown a similar response of D. longispina to both fish species: kairomones stimulated daphnids to produce more offspring, which resulted in higher fitness (r), relatively to a fishless control. Fish presence also induced an earlier first reproduction, a smaller size at maturity
of daphnids, and the production of smaller-sized neonates. Significant correlations with fish concentration (indirect measure
of fish kairomone concentration) were found for size at maturity and neonate size, for both fish species. These results are
in accordance to the “positive response” observed by other authors, which represents a defence mechanism to face losses caused
by fish predators. The chemically mediated size reduction of mature females and neonates is an adaptive response to the size-selective
predation exerted by fish. Pumpkinseed introduction is very recent in the lake of origin of the daphnids used in the experiments
and its kairomone produced similar effects to mosquitofish in the life history of D. longispina. These results are contrary to the existence of a species-specific kairomone and support the hypothesis of a general fish
kairomone.
Guest editor: Piet Spaak
Cladocera: Proceedings of the 7th International Symposium on Cladocera 相似文献
13.
Predators often have nonconsumptive effects (NCEs) on prey. For example, upon detection of predator cues, prey can reduce feeding activities to hamper being detected by predators. Previous research showed that waterborne chemical cues from green crabs (Carcinus maenas, predator) limit the dogwhelk (Nucella lapillus, prey) consumption of barnacles regardless of dogwhelk density, even though individual predation risk for dogwhelks decreases with conspecific density. Such NCEs might disappear with dogwhelk density if dogwhelks feed on mussels, as mussel stands constitute better antipredator refuges than barnacle stands. Through a laboratory experiment, we effectively found that crab chemical cues limit the per-capita consumption of mussels by dogwhelks at low dogwhelk density but not at high density. The combination of tactile and chemical cues from crabs, however, limited the dogwhelk consumption of mussels at both dogwhelk densities. The occurrence of such NCEs at both dogwhelk densities could have resulted from tactile cues indicating a stronger predation risk than chemical cues alone. Overall, the present study reinforces the notions that prey evaluate conspecific density when assessing predation risk and that predator cue type affects their perception of risk. 相似文献
14.
The predation potential of the indigenous leech Glossiphonia weberi on the snail Pomacea bridgesii, introduced in India, was evaluated in the laboratory. Snails used belonged to the size-classes ≤‰3.0, 3.1–5.0, 5.1–7.0 and
7.1–9.0 mm in shell height, using them both separately and together (mixed) in combinations. In each experiment lasting 24 h
a single leech belonging to the size-classes 2.0–3.9, 4.0–5.9, 6.0–7.9, 8.0–9.9 and 10.0–11.9 mm in length was used. Except
the 4.0–5.9 mm size-class, leeches were able to capture and kill P. bridgesii irrespective of latter’s size; the predation, however, was confined to snails ≤3.0 mm. The rate of predation varied with
the size of the predator and the prey, and a leech was able to kill a maximum of three snails per day. In India, in nature
G. weberi feeds mostly on the pulmonate snail, Lymnaea (Radix) luteola. Experimental studies, however, revealed that G. weberi prefers the snails P. bridgesii and L. (R) luteola at the same rate from amongst the many other either less or not-preferred native operculate and non-operculate snails. 相似文献
15.
Meryem Beklioglu Ayse Gul Gozen Feriha Yıldırım Pelin Zorlu Sertac Onde 《Hydrobiologia》2008,614(1):321-327
Vertical migration of Daphnia represents the best-studied predator-avoidance behaviour known; yet the mechanisms underlying the choice to migrate require
further investigation to understand the role of environmental context. To investigate the optimal habitat choice of Daphnia under fish predation pressure, first, we selected the individuals exhibiting strong migration behaviour. The animals collected
from the hypolimnion during the daytime were significantly larger, being more conspicuous, and in turn performed stronger
diel vertical migration (DVM) when exposed to fish cue. We called them strong migrants. Second, we provided the strong migrant
D. pulex with food at high and intermediate (1 and 0.4 mg C l−1, respectively) levels, which were well above the incipient limiting level and of high quality. They traded the benefits of
staying in the warm water layer and moved down to the cold water in response to fish cue indicating fish predation. The availability
of food allowed the animals to stay in the cold hypolimnion. However, at the low food level (0.1 mg C l−1), which is an additional constraint on fitness, Daphnia moved away from the cold hypolimnion. Poor food condition resulted in strong migrant Daphnia to cease migration and remain in the upper warmer water layer. Although temperature is known to be a more important cost
factor of DVM than food, our results clearly show that this is only true as long as food is available. It becomes clear that
food availability is controlling the direction of vertical positioning when daphnids experience a dilemma between optimising
temperature and food condition while being exposed to fish cue. Then they overlook the predation risk. Thus, the optimal habitat
choice of Daphnia appears to be a function of several variables including temperature, food levels and fish predation.
Handling editor: S. I. Dodson 相似文献
16.
Previous studies confirmed the presence of melatonin in Daphnia magna and demonstrated diurnal fluctuations in its concentration. It is also known that in several invertebrate species, melatonin
affects locomotor activity. We tested the hypothesis that this hormone is involved in the regulation of Daphnia diel vertical migration (DVM) behaviour that is well recognized as the adaptive response to predation threat. Using ‘plankton
organs’, we studied the effect of three concentrations of exogenous melatonin (10−5, 10−7, 10−9 M) on DVM of both female and male D. magna in the presence or absence of chemical cue (kairomone) of planktivorous fish. Depth distribution was measured six times a
day, using infrared-sensitive closed circuit television cameras. Our results showed a significant effect of melatonin on the
mean depth of experimental populations, both males and females, but only when melatonin was combined with fish kairomone.
Females stayed, on average, closer to the surface than males, both responding to the presence of kairomone by descending to
deeper strata. In the presence of exogenous melatonin and with the threat of predation, Daphnia stayed closer to the surface and their distribution was more variable than that of individuals, which were exposed to the
kairomone alone. Approaching the surface in the presence of predation threat seems to be maladaptive. We postulate the role
of melatonin as a stress signal inhibitor in molecular pathways of response to predation threat in Cladocera. 相似文献
17.
Alien plant species, such as Caulerpa racemosa var. cylindracea, that invade Mediterranean marine vegetated habitats can affect habitat structure. In turn, changes in habitat structure
may affect the associated invertebrate assemblages, either through changes in habitat selection or as a result of altered
predation efficiency. In order to test for effects of changes in habitat structure resulting from colonization by C. racemosa on prey availability for predators, the importance of amphipods as a trophic resource in natural vegetated habitat was first
assessed, and later experiments were undertaken to assess the effects of the alien alga on predation by Thalassoma pavo of two dominant amphipods: Elasmopus brasiliensis (Gammaridea) and Caprella dilatata (Caprellidea). Laboratory experiments were conducted in separate aquaria with five vegetation habitat types: Halopteris scoparia, Jania rubens, C. racemosa without detritus, C. racemosa with detritus, Cymodocea nodosa, together with controls. The vegetation was first defaunated, and then 30 amphipods were introduced to each aquarium and
exposed to a single Thalassoma pavo individual for 1 h, after which the fish’s gut contents were examined. Consumption (per fish per hour) of caprellids (11.7 ± 1.4)
was higher overall than that of gammarids (8.7 ± 1.5) and likely reflects different microhabitat use by amphipods, which affects
susceptibility to predators. Consumption of amphipods also varied by habitat type. The highest predation rate was found in
the C. nodosa habitat (12.7 ± 2.19) and the lowest in the C. racemosa habitats with detritus (4.1 ± 1.78) and without detritus (5.2 ± 0.55), which did not differ. The pattern of predation across
habitats, however, was similar for both caprellid and gammarid amphipods, indicating a more general effect of habitat on amphipod
predation. Our findings showed that invasive species such as C. racemosa can decrease feeding by predators such as T. pavo. Changes in predator–prey interactions could have consequences for food web support in the Mediterranean. 相似文献
18.
Yuki Nakamura Fumiko Yukuhiro Masaya Matsumura Hiroaki Noda 《Applied Entomology and Zoology》2012,47(3):273-283
Cytoplasmic incompatibility (CI) is a reproductive phenotype induced by bacterial endosymbionts in arthropods. Measured as a reduction in egg hatchability resulting from the crossing of uninfected females with bacteria-infected males, CI increases the frequency of bacteria-infected hosts by restricting the fertilization opportunities of uninfected hosts in populations. Wolbachia, a type of alpha-proteobacteria, is well known as a CI inducer in a wide range of arthropod species, while Cardinium, a member of the phylum Bacteroidetes, is known to cause CI in one wasp and three spider mite species. In this study, dual infection with Cardinium and Wolbachia induced strong CI in a single host, Sogatella furcifera (Horváth), a planthopper species that is naturally infected with both bacteria. Specifically, infection with Cardinium alone was found to cause a 76 % reduction in egg development, and dual infection with Cardinium and Wolbachia a 96 % reduction, indicating that Cardinium induces CI and the dual infection raises the CI level. This study was the first to document reproductive alteration by Cardinium in a diploid host species. 相似文献
19.
Cayelan C. Carey Moana P. Ching Sarah M. Collins Angela M. Early William W. Fetzer David Chai Nelson G. HairstonJr. 《Aquatic Ecology》2011,45(1):35-41
Diel migration is a common predator avoidance mechanism commonly found in temperate water bodies and increasingly in tropical
systems. Previous research with only single day and night samples suggested that the endemic shrimp, Halocaridina rubra, may exhibit diel migration in Hawaiian anchialine pools to avoid predation by introduced mosquito fish, Gambusia affinis, and perhaps reverse migration to avoid the predatory invasive Tahitian prawn, Macrobrachium lar. To examine this phenomenon in greater detail, we conducted a diel study of H. rubra relative abundance and size at 2-h intervals in three anchialine pools that varied in predation regime on the Kona-Kohala
Coast of Hawai‘i Island. We found two distinct patterns of diel migration. In two pools dominated by visually feeding G. affinis, the abundance of H. rubra present on the pool bottom or swimming in the water column was very low during the day, increased markedly at sunset and
remained high until dawn. In contrast, in a pool dominated by the nocturnal predator M. lar, H. rubra density was significantly lower during the night than during the day (i.e., a pattern opposite to that of shrimp in pools
containing fish). In addition, we observed that the mean body size of the shrimp populations varied among pools depending
upon predator type and abundance, but did not vary between day and night in any pools. Our results are consistent with the
hypothesis that H. rubra diel migratory behavior and size distributions are influenced by predation regime and suggest that diel migration may be
a flexible strategy for predator avoidance in tropical pools where it may be a significant adaptive response of endemic species
to introduced predators. 相似文献
20.