Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are character...Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are characterized by a high level of morphological plasticity during development, and the few species that have been tested do exhibit defensive behaviors when exposed to alarm cues released from the damaged skin of conspecifics. We utilized young juvenile Nicaragua cichlids Hypsophrys nicaraguensis to test if the perception of predation risk from alarm cue （conspecific skin extract） alone induces an increased relative body depth which is a defense against gape-limited predators. After two weeks of exposure, siblings that were exposed to conspecific alarm cue increased their relative body depth nearly double the amount of those exposed to distilled water （control） and zebrafish Danio rerio alarm cue. We repeated our measurements over the last two weeks （12 and 14） of cue exposure when the fish were late-stage juveniles to test if the rate of increase was sustained; there were no differences in final dimensions between the three treatments. Our results show that 1） the Nicaragua cichlid has an innate response to conspecific alarm cue which is not a generalized response to an injured fish, and 2） this innate recognition ultimately results in developing a deeper body at a stage of the life history where predation risk is high [Current Zoology 56 （1）： 36-42, 2010].展开更多
Prey adjust their antipredator behavioral tactics to minimize the risk of an encounter with predators.Spatiotemporal responses of prey to pred-ators have been reported,but the nature of antipredator response is not ub...Prey adjust their antipredator behavioral tactics to minimize the risk of an encounter with predators.Spatiotemporal responses of prey to pred-ators have been reported,but the nature of antipredator response is not ubiquitous and it is the object of increasing interest,especially consid-ering the recent recovery of large carnivores in Europe,and the potential for behavioral antipredator responses to elicit consequences at the ecosystem level.We have tested multiple antipredator responses by fallow deer Dama dama to wolf Canis lupus in a Mediterranean protected area recently recolonized by this apex predator.Through intensive camera trapping,we tested for temporal and spatial association between predator and prey,and we have also studied deer vigilance in forest habitats where focal observations are usually impossible.Wolf detection rates were spatially associated with those of fallow deer.Accordingly,no evidence was found for fallow deer avoiding sites with higher predator detection rates.Temporal activity patterns were significantly different between the 2 species,with the wolf being mainly nocturnal whereas fallow deer was active especially during daylight.A comparison with a preliminary study strongly suggests an increase in the diurnal activity of fallow deer along with the stabilization of wolf presence in the area.Both the rate and the duration of vigilance of female fallow deer increased with the local frequency of wolf activity.We suggest an antipredator response based on temporalrather than spatialavoidance,as well as increasedvigilance.展开更多
Factors related to the invasion process, such as high abundance of invaders, residence time, and functional distinctiveness, are well documented, but less attention has been given to the effects of antipredator strate...Factors related to the invasion process, such as high abundance of invaders, residence time, and functional distinctiveness, are well documented, but less attention has been given to the effects of antipredator strategy of invasive species during colonization. In this study, we explored the antipredator strategy of an introduced species by comparing the predator avoidance behaviors of two native anuran species and one introduced （“exotic”） species in the presence of different predators. The two native anuran species used in the study were Black-spotted Pond FrogRana nigromaculata and Terrestrial Frog Rana limnocharis. The introduced （invasive） species used was American bullfrogLithobates catesbeianus. Chinese pond turtleChinemys reevesii, Red-backed rat snakeElaphe rufodorsata, and Big-headed turtle Platysternon megacephalum were used as predator species. Chinese pond turtles and Red-backed rat snakes are native predators of Black-spotted Pond Frogs and Terrestrial Frogs, while Big-headed turtles are novel （“unfamiliar”） to the two frogs. All three predator species are novel （“unfamiliar”） to the American bullfrog. The results show that tadpoles of the two native species displayed behaviors of recognizing the two native predators, but did not display the capability of identifying the novel predator. Results from our study also suggest that American bullfrog tadpoles exhibited strong antipredator behavioral responses by displaying the capability of identifying “unfamiliar” predators without cohabitation history and prior exposure to them. Such antipredator behavioral responses could have resulted in more favorable outcomes for an invading species during the invasive introductory process.展开更多
Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators （threat-s...Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators （threat-sensitive avoidance） or they have safe but costly general wariness avoiding all potential predators. The level of threat may depend on the predator＇s foraging ecology and distri- bution with the prey with sympatric and specialist species being the most dangerous. We used 2 choice trials to investigate antipredatory behavior of captive born and wild-caught leopard geckos confronted with different snake predators from 2 families （Colubridae, Boidae） varying in foraging ecology and sympatric/allopatric distribution with the geckos. Predator-na＇ive subadult individuals have general wariness, explore both chemically and visually, and perform antipredatory postures toward a majority of snake predators regardless of their sympatry/allopatry or food specialization. The most exaggerated antipredatory postures in both subadult and adult geckos were toward 2 sympatric snake species, the spotted whip snake Hemorrhois ravergieri, an active forager, and the red sand boa Eryxjohnii, a subterranean snake with a sit-and-wait strategy. In contrast, also subter- ranean but allopatric the Kenyan sand boa Eryx colubrinus did not elicit any antipredatory reaction. We conclude that the leopard gecko possesses an innate general antipredatory reaction to different species of snake predators, while a specific reaction to 2 particular sympatric species can be observed. Moreover, adult wild caught geckos show lower reactivity compared with the captive born ones, presumably due to an experience of a real predation event that can hardly be simulated under laboratory conditions.展开更多
Aposematism is an antipredator strategy in which conspicuous coloration acts as a warning of chemical defenses to potential predators.Evidence suggests that aposematism largely functions under positive frequency-depen...Aposematism is an antipredator strategy in which conspicuous coloration acts as a warning of chemical defenses to potential predators.Evidence suggests that aposematism largely functions under positive frequency-dependent selection,which is thought to maintain uniformity of aposematic signals.Many studies of aposematic organisms have found evidence that color signals and defenses are positively correlated,indicating a quantitatively honest aposematic signal.Dendrobatid poison frogs represent a well-studied group of aposematic organisms that in addition to exhibiting a diversity of color signals also display unique defensive behaviors.Few studies have examined if both behavior and coloration act as quantitative honest signals of alkaloid defenses in poison frogs.We aimed to determine if coloration and behavior are quantitatively honest signals in the green and black poison frog(Dendrobates auratus)among 6 populations from Costa Rica.We(1)evaluated antipredator displays by using behavioral assays in the field,(2)assessed frog conspicuousness and pattern using digital images,and(3)quantified alkaloid profiles from frog skin secretions.We found that Pacific populations are less conspicuous in coloration,had greater quantities of alkaloids,and more frequently performed body-raising defensive behaviors when compared with Caribbean populations.Our results do not support the hypothesis that aposematic traits in D.auratus are quantitatively honest.Rather,our results suggest that phenotypic differences among populations may represent different phenotypic optima for advertising unprofitability to predators based on local environmental conditions,leading to the diversification of aposematic signals in this species.展开更多
Eyespots have been shown to perform an anti-predator function by intimidating predators.However,whether predators are deterred by the eyespots’mimicking eyes of higher-order predators,or by the conspicuousness of the...Eyespots have been shown to perform an anti-predator function by intimidating predators.However,whether predators are deterred by the eyespots’mimicking eyes of higher-order predators,or by the conspicuousness of the spots,is still being debated.The anti-predator mechanism of eyespots,which involves the predator’s visual perception and cognition,urges to be examined.To explore the“eye mimicry hypothesis”and“conspicuous signal hypothesis,”we designed prey with deceptive eyespots eliciting 2-dimensional(2D)or 3-dimensional(3D)visual illusions for domestic chicks(as predators).For 2D visual illusion,we provided prey with occluded eyespots for chicks.Chicks can“complete”the occluded eyespots into a full 2D concentric circle by the amodal completion mechanism,that is,one of visual illusion.For 3D visual illusion,we created the crescent-shaped sparkles on the eyespots to simulate a visually 3D eye.Our result indicated that(1)2D:chicks hesitated more when facing preys with occluded eyespots than facing preys with broken eyespots and(2)3D:compared to prey with no-sparkle eyespots,chicks spent more time approaching prey with sparkle eyespots and were more likely to approach them tangentially.Thus,the visual illusion perceived by chicks would impact the anti-predation effectiveness of eyespots.Eyespots that more closely resemble the real eyes,especially those with 3-dimensionality,provided more effective protection.Our study supported the eye mimicry hypothesis from the perspective of visual illusion.展开更多
Paternal predation risk can program offspring phenotypes via maternal responses and epigenetic marks of spermatozoa.However,the processes and consequences of this experience in biparental species are unknown.Here,we e...Paternal predation risk can program offspring phenotypes via maternal responses and epigenetic marks of spermatozoa.However,the processes and consequences of this experience in biparental species are unknown.Here,we examined how preconception and postconception paternal cat odor(CO)exposure affects anxiety-like behavior and antipredator response in Brandt’s voles(Lasiopodomys brandtii).We found that preconception paternal CO exposure inhibited maternal investment when offspring were raised by mothers alone,while postconception exposure increased paternal investment towards the offspring raised by both parents.The increased paternal behavior may be associated with an increasing grooming behavior received from their mates,which alleviated the anxiety-like behavior in CO-exposed males.Both paternal experiences increased the levels of anxiety-like behavior in adolescent offspring but differentially altered adult phenotypes.Specifcally,adult females from preconception CO-exposed fathers spent less time in defensive concealing,whereas the offspring of postconception CO-exposed fathers showed more in response to acute cat urine exposure.Correspondingly,baseline corticosterone levels were decreased and increased in these offspring,respectively.Our results indicate that in biparental species,paternal predation risk exposure affects offspring phenotypes in pathway-dependent and age-specifc manners and that only the presence of both parents can elicit adaptive responses to a high predation-risk environment.展开更多
Functional constraints between different types of antipredator behavior should be common,especially if they are on the opposite sides of the behavioral spectrum such as flight and post-capture immobility.We examined a...Functional constraints between different types of antipredator behavior should be common,especially if they are on the opposite sides of the behavioral spectrum such as flight and post-capture immobility.We examined a potential compromise between post-capture immobility displays and sprint speed in dice snakes(Natrix tessellata),using a field-based approach.We sampled snakes(N=238)from two populations:from a dense island population free of mammal predators,and from a less dense mainland population,preyed upon by both bird and mammal predators.We explored the effects of sexual maturity,temperature,body size,presence of palpable food in the gut,and injuries on the occurrence and duration of post-capture immobility as well as sprint speed.Our results confirm the existence of functional constraints between locomotor performance and post-capture immobility in dice snakes.Faster dice snakes start escaping promptly after release,while slower individuals utilize more passive antipredator behaviors such as death feigning.Local adaptations seem to have great influence on behavioral compromise,since the mammal-free island population exhibited a higher incidence of post-capture immobility and a significantly lower sprint speed,compared to the less dense mainland population.Additionally,immature individuals tended to avoid death feigning and their post-capture immobility lasted shorter compared to adult individuals.It remains to be seen how individuals adjust their behavior to accomodate locomotor constraints,and in which specific phases of the predator-prey interaction these adjustments occur.展开更多
Animals deploy diverse color-based defenses against predators,including crypsis,mimicry,aposematism,and masquerade.While crypsis,mimicry,aposematism have been extensively studied,the strategy of masquerade-where organ...Animals deploy diverse color-based defenses against predators,including crypsis,mimicry,aposematism,and masquerade.While crypsis,mimicry,aposematism have been extensively studied,the strategy of masquerade-where organisms imitate inedible or inanimate objects such as leaves,twigs,stones,and bird droppings-remains comparatively underexplored,particularly in adult butterflies.The Indian oakleaf butterfly(Kallima inachus)exemplifies this phenomenon,with its wings resembling dead leaves,providing a classic example of natural selection.Although it has long been postulated that these butterflies evade predation by being misidentified as dead leaves,direct experimental evidence is lacking.In the current study,using domestic chicks as predators,we manipulated their prior experience with dead leaves(model objects)while maintaining constant exposure to butterflies to test whether dead-leaf masquerade provides a protective advantage by preventing recognition.Results showed a marked delay in the initiation of attacks by chicks familiar with dead leaves compared to those with no prior exposure or those exposed to visually altered leaves.Chicks with prior dead-leaf experience required a similar amount of time to attack the butterflies as they did to attack dead leaves.These findings provide the first empirical demonstration of dead-leaf masquerade in Kallima butterflies,shedding light on its evolutionary significance.Our study highlights the effectiveness of masquerade in inducing the misclassification of butterflies as inanimate objects,showcasing the precise mimicry achieved by these organisms when viewed in isolation from the model objects.This study advances our understanding of the evolution of masquerade and its role as a potent antipredator strategy in nature.展开更多
Visual cues are important in both interspecific and intraspecific communication.The species confidence hypothesis proposes that animals are more attracted to conspecific colors and repelled by colors,not on their bodi...Visual cues are important in both interspecific and intraspecific communication.The species confidence hypothesis proposes that animals are more attracted to conspecific colors and repelled by colors,not on their bodies.Studies on terrestrial lizards and birds have tested the species confidence hypothesis and shown that conspecific colors elicit reduced antipredator behavior.To date,the species confidence hypothesis has not been tested in the marine environment,specifically on coral reefs where color communication is of vital importance.We addressed this knowledge gap by measuring flight initiation distance(the distance an individual moves away from an approaching threat)in dusky damselfish(Stegastes nigricans)in response to an approaching disc of 1 of 4 different color treatments:conspecific,blue,yellow,and black.If the species confidence hypothesis explained variation in damselfish flight initiation distance,then we expected individuals to tolerate closer approaches when approached by a conspecific color.In addition,we calculated the color difference between each stimulus and its corresponding back-ground as a potential alternative explanation for flight responses.Damselfish tolerated the closest approach from the conspecific color stimulus;there were no significant differences between other colors and there was no support for the alternative color difference hypothesis.As with similar terrestrial studies,these results are relevant to ecotourists'choice of swimsuit and wetsuit colors because color choice may modify naturalantipredatorbehavior.展开更多
Many birds join cooperative mobbing aggregations and collectively harass predators. Individuals participating in these ephemeral associations benefit by deterring the predator, but also incur energetic costs and incre...Many birds join cooperative mobbing aggregations and collectively harass predators. Individuals participating in these ephemeral associations benefit by deterring the predator, but also incur energetic costs and increased risk of predation. Ex- plaining the evolution of mobbing is challenging because individuals could prevail by selfishly seeking safety while allowing others to mob. An important step in understanding the evolution of mobbing is to identify factors affecting its expression. The ecological constraints model suggests that animals are more likely to cooperate under adverse environmental conditions, such as when local predation pressure is high. We tested this prediction by comparing the mobbing responses of several species of birds to the local abundance of their primary predator, the ferruginous pygmy-owl Glaucidium brasilianum. We used acoustic playback to elicit mobbing responses in environments where owls were common, uncommon, or rare. Stimuli were either the song of a fer- ruginous pygmy-owl or the mobbing calls of three of the owl＇s common prey species. During each playback, we characterized mobbing responses by noting the number of species and individuals that approached the loudspeaker, as well as the closest ap- proach by any bird. Mobbing responses to both stimuli were strong in locations where Ferruginous Pygmy-owls were common, intermediate where owls were uncommon, and weak where they were rare. This pattern persisted even after controlling for dif- ferences in species richness and composition among the three environments. Results support the ecological constraints model and provide strong evidence that intense predation pressure increases the expression of cooperative mobbing in tropical birds [Cur- rent Zoology 58 （5）： 781-790, 2012].展开更多
After being kept in captivity and isolated from natural predators for more than 1,200 years, P6re David＇s deer has been reintroduced in China and now occurs in a reserve where human activity is the only potential thr...After being kept in captivity and isolated from natural predators for more than 1,200 years, P6re David＇s deer has been reintroduced in China and now occurs in a reserve where human activity is the only potential threat. Antipredator vigilance i~ an important component of survival for many prey animals in their natural habitat. Do deer still adjust vigilance as a function of risk after such a long period of relaxed predation pressure？ Here, we examined vigilance levels in P6re David＇s deer groups as a function of group size, sex and level of human disturbance. The results showed that individual vigilance significantly decreased with group size in all-female groups but not in all-males or mixed-sex groups. In rutting season, males compete with one another and harass females, and we argue that vigilance is partly aimed at threatening males and that such vigilance increases with group size. This explains why overall vigilance did not vary with group size for males in general and for females in mixed-sex groups. Vigilance increased in more disturbed areas but in in male deer only. The results indicate that despite relaxed predation pressure over centuries, P6re David＇s deer can still adjust antipredator responses as a function of perceived risk. Such information may become useful in the rewilding programme now under way for this species in China [Current Zoology 59 （2）： 265-270, 2013].展开更多
In many vertebrates,the brain's right hemisphere which is connected to the left visual field specializes in the processing of information about threats while the left hemisphere which is connected to the right vis...In many vertebrates,the brain's right hemisphere which is connected to the left visual field specializes in the processing of information about threats while the left hemisphere which is connected to the right visual field specializes in the processing of information about conspecifics.This is referred to as hemispheric lateralization.But individuals that are too predictable in their response to predators could have reduced survival and we may expect selection for somewhat unpredictable responses.We studied hemispheric lateralization in yellow-bellied marmots Marmota flaviventer,a social rodent that falls prey to a variety of terrestrial and aerial predators.We first asked if they have lateralized responses to a predatory threat.We then asked if the eye that they used to assess risk influenced their perceptions of risk.We recorded the direction marmots were initially looking and then walked toward them until they fled.We recorded the distance that they responded to our experimental approach by looking,the eye with which they looked at us,and the distance at which they fled (i.e.,flight initiation distance;FID).We found that marmots had no eye preference with which they looked at an approaching threat.Furthermore,the population was not comprised of individuals that responded in consistent ways.However,we found that marmots that looked at the approaching person with their left eye had larger FIDs suggesting that risk assessment was influenced by the eye used to monitor the threat.These findings are consistent with selection to make prey less predictable for their predators,despite underlying lateralization.展开更多
Camouflage is ubiquitous in the natural world and benefits both predators and prey. Amongst the range of conceal- ment strategies, disruptive coloration is thought to visually fragment an animal＇s＇ outline, thereby ...Camouflage is ubiquitous in the natural world and benefits both predators and prey. Amongst the range of conceal- ment strategies, disruptive coloration is thought to visually fragment an animal＇s＇ outline, thereby reducing its rate of discovery. Here, I propose two non-mutually exclusive hypotheses for how disruptive camouflage functions, and describe the visual me- chanisms that might underlie them. （1） The local edge disruption hypothesis states that camouflage is achieved by breaking up edge information. （2） The global feature disruption hypothesis states camouflage is achieved by breaking up the characteristic features of an animal （e.g., overall shape or facial features）. Research clearly shows that putatively disruptive edge markings do increase concealment; however, few tests have been undertaken to determine whether this survival advantage is attributable to the distortion of features, so the global feature disruption hypothesis is under studied. In this review the evidence for global feature disruption is evaluated. Further, I address if object recognition processing provides a feasible mechanism for animals＇ features to influence concealment. This review concludes that additional studies are needed to test if disruptive camouflage operates through the global feature disruption and proposes future research directions [Current Zoology 61 （4）： 708-717, 2015].展开更多
Ecotourism encourages an environmentally friendly exploration of the world＇s natural habitats. Tourists often engage in wildlife photography, an activity that is generally not considered disturbing to animals. We inv...Ecotourism encourages an environmentally friendly exploration of the world＇s natural habitats. Tourists often engage in wildlife photography, an activity that is generally not considered disturbing to animals. We investigated the effects of cam- era-related stimuli to determine whether shutter noise and/or flash affected the immediate behavior of female crested anoles Ano- lis cristaellus. Anoles decreased their display rate following stimuli that included shutter noises, but did not change their behavior in response to flash or silence treatments. To determine the relative importance of this response, we observed anole behavior fol- lowing playbacks of calls from kestrels Falco sparverius, a predator, and bananaquits Coereba flaveola, a non-predator. Anoles decreased display rates following kestrel calls when compared to their response to bananaquit calls. Furthermore, anoles spent a greater proportion of time displaying following bananaquit calls compared to both kestrel calls and silence. The magnitude of response to shutter noises was about the same as that to predator calls. This demonstrates that photography may not be as benign as commonly believed, and we should consider whether restrictions on camera noises should be implemented to reduce ani- mal disturbance展开更多
Age and body size can influence predation risk and hence habitat use. Many species undergo ontogenetic shifts in habitat use as individuals grow larger and have different age-specific predation pressures. On coral ree...Age and body size can influence predation risk and hence habitat use. Many species undergo ontogenetic shifts in habitat use as individuals grow larger and have different age-specific predation pressures. On coral reefs, a number of fish species are more tolerant of threats in structurally complex habitats that contain more refuges than in less structurally complex habitats. However, we do not know how risk perception varies with age, and whether age interacts with habitat complexity. Adults and juveniles, because of their size, may face different risks in structurally simple versus complex habitats. We used flight initiation distanee as a metric to analyze perceptions of risk in a species of damselfish Stegastes nigricans. All else being equal, fish fleeing at greater distances are inferred to perceive higher risk. We targeted juvenile and adult damselfish to assess whether there are ontogenetic shifts in perceptions of safety in relation to structural complexity, inferred based on percent coral cover and rugosity. We found that adult damselfish tolerated closer approach in more complex habitats as measured by percent coral cover, but not rugosity, whereas juvenile fish always allowed closer approach than adult fish regardless of complexity. This ontogenetic shift in habitat use may result from juvenile fish taking bigger risks to maximize growth, whereas older animals, who are closer to their maximum body size, can afford to take fewer risks and protect their assets.展开更多
There is growing evidence that individual animals show consistent differences in behavior. For example, individual threespined stickleback fish differ in how they react to predators and how aggressive they are during ...There is growing evidence that individual animals show consistent differences in behavior. For example, individual threespined stickleback fish differ in how they react to predators and how aggressive they are during social interactions with con- specifics. A relatively unexplored but potentially important axis of variation is parental behavior. In sticklebacks, fathers provide all of the parental care that is necessary for offspring survival; therefore paternal care is directly tied to fitness. In this study, we assessed whether individual male sticklebacks differ consistently from each other in parental behavior. We recorded visits to nest, total time fanning, and activity levels of 11 individual males every day throughout one clutch, and then allowed the males to breed again. Half of the males were exposed to predation risk while parenting during the first clutch, and the other half of the males ex- perienced predation risk during the second clutch. We detected dranlatic temporal changes in parental behaviors over the course of the clutch： for example, total time fanning increased six-fold prior to eggs hatching, then decreased to approximately zero. De- spite these temporal changes, males retained their individually-distinctive parenting styles within a clutch that could not be ex- plained by differences in body size or egg mass. Moreover, individual differences in parenting were maintained when males re- produced for a second time. Males that were exposed to simulated predation risk briefly decreased fanning and increased activity levels. Altogether, these results show that individual sticklebacks consistently differ from each other in how they behave as parents [Current Zoology 58 （1）： 45-52, 2012].展开更多
The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessin...The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessing highly detectable external coloration are unknown. We tested whether variation in the degree of plumage vividness in birds explained variation in flight-initiation distance. After controlling for body mass, the distance at which the experimental approach began, and phylogenetic relatedness, plumage vividness was not a predictor of FID. Contrary to the expectation that vividness affects risk, and therefore risk assess- ment, these results suggest that birds do not compensate for greater visual conspicuousness by fleeing sooner from approaching threats [Current Zoology 61 （4）： 773-780, 2015].展开更多
Biological invasions threaten biodiversity worldwide,and therefore,understanding the traits of successful invaders could mitigate their spread.Many comm only invasive species do well in disturbed habitats,such as urba...Biological invasions threaten biodiversity worldwide,and therefore,understanding the traits of successful invaders could mitigate their spread.Many comm only invasive species do well in disturbed habitats,such as urban environments,and their abilities to effectively respond to disturbarices could con tribute to their invasiveness.Yet,there are non invasive species that also do well in disturbed habitats.The question remains whether urban invaders behave differently in urban environments than noninvaders,which could suggest an"urban-exploiting"phenotype.In Southern California,the co-occurrence of in vasive Italia n wall lizards Pod arc is siculus,brown anoles Anolis sagrei,and green anoles A.carolinensis,and native western fence lizards Sceloporus occidentalis offers an opportunity to test whether invasives exhibit consistent differences in risk-taking within human-altered habitats compared with a native species.We predicted that invasive lizards would exhibit more bold behavior by having shorter flight-initiation distances(FIDs)and by being found farther from a refuge(behaviors that would presumably maximize foraging in low-risk environments).Invasive populations had similar or longer FIDs,but were consistently found at distances closer to a refuge.Collectively,invasive lizards in urban habitats were not bolder than a native species.Relianee on nearby refuges might help species successfully invade urban habitats,and if a general pattern,may pose an added challenge in detecting or eliminating them.展开更多
基金provided by the Undergraduate Research Opportunities Program of Boston University
文摘Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are characterized by a high level of morphological plasticity during development, and the few species that have been tested do exhibit defensive behaviors when exposed to alarm cues released from the damaged skin of conspecifics. We utilized young juvenile Nicaragua cichlids Hypsophrys nicaraguensis to test if the perception of predation risk from alarm cue （conspecific skin extract） alone induces an increased relative body depth which is a defense against gape-limited predators. After two weeks of exposure, siblings that were exposed to conspecific alarm cue increased their relative body depth nearly double the amount of those exposed to distilled water （control） and zebrafish Danio rerio alarm cue. We repeated our measurements over the last two weeks （12 and 14） of cue exposure when the fish were late-stage juveniles to test if the rate of increase was sustained; there were no differences in final dimensions between the three treatments. Our results show that 1） the Nicaragua cichlid has an innate response to conspecific alarm cue which is not a generalized response to an injured fish, and 2） this innate recognition ultimately results in developing a deeper body at a stage of the life history where predation risk is high [Current Zoology 56 （1）： 36-42, 2010].
基金supported by the Maremma Regional Park Agency.Additional financial support was provided by the German Society for Mammalian Biology(DGS Project Funding 2018)BE was supported by a grant from the Ministry of Agriculture of the Czech Republic(Institutional support MZE-RO0718)and by an Erasmus+scholarship from the Czech University of Life Sciences Prague.
文摘Prey adjust their antipredator behavioral tactics to minimize the risk of an encounter with predators.Spatiotemporal responses of prey to pred-ators have been reported,but the nature of antipredator response is not ubiquitous and it is the object of increasing interest,especially consid-ering the recent recovery of large carnivores in Europe,and the potential for behavioral antipredator responses to elicit consequences at the ecosystem level.We have tested multiple antipredator responses by fallow deer Dama dama to wolf Canis lupus in a Mediterranean protected area recently recolonized by this apex predator.Through intensive camera trapping,we tested for temporal and spatial association between predator and prey,and we have also studied deer vigilance in forest habitats where focal observations are usually impossible.Wolf detection rates were spatially associated with those of fallow deer.Accordingly,no evidence was found for fallow deer avoiding sites with higher predator detection rates.Temporal activity patterns were significantly different between the 2 species,with the wolf being mainly nocturnal whereas fallow deer was active especially during daylight.A comparison with a preliminary study strongly suggests an increase in the diurnal activity of fallow deer along with the stabilization of wolf presence in the area.Both the rate and the duration of vigilance of female fallow deer increased with the local frequency of wolf activity.We suggest an antipredator response based on temporalrather than spatialavoidance,as well as increasedvigilance.
基金provided by the Doctor’s Start-up Foundation of Anhui Normal University and the National Natural Science Foundation of China
文摘Factors related to the invasion process, such as high abundance of invaders, residence time, and functional distinctiveness, are well documented, but less attention has been given to the effects of antipredator strategy of invasive species during colonization. In this study, we explored the antipredator strategy of an introduced species by comparing the predator avoidance behaviors of two native anuran species and one introduced （“exotic”） species in the presence of different predators. The two native anuran species used in the study were Black-spotted Pond FrogRana nigromaculata and Terrestrial Frog Rana limnocharis. The introduced （invasive） species used was American bullfrogLithobates catesbeianus. Chinese pond turtleChinemys reevesii, Red-backed rat snakeElaphe rufodorsata, and Big-headed turtle Platysternon megacephalum were used as predator species. Chinese pond turtles and Red-backed rat snakes are native predators of Black-spotted Pond Frogs and Terrestrial Frogs, while Big-headed turtles are novel （“unfamiliar”） to the two frogs. All three predator species are novel （“unfamiliar”） to the American bullfrog. The results show that tadpoles of the two native species displayed behaviors of recognizing the two native predators, but did not display the capability of identifying the novel predator. Results from our study also suggest that American bullfrog tadpoles exhibited strong antipredator behavioral responses by displaying the capability of identifying “unfamiliar” predators without cohabitation history and prior exposure to them. Such antipredator behavioral responses could have resulted in more favorable outcomes for an invading species during the invasive introductory process.
文摘Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators （threat-sensitive avoidance） or they have safe but costly general wariness avoiding all potential predators. The level of threat may depend on the predator＇s foraging ecology and distri- bution with the prey with sympatric and specialist species being the most dangerous. We used 2 choice trials to investigate antipredatory behavior of captive born and wild-caught leopard geckos confronted with different snake predators from 2 families （Colubridae, Boidae） varying in foraging ecology and sympatric/allopatric distribution with the geckos. Predator-na＇ive subadult individuals have general wariness, explore both chemically and visually, and perform antipredatory postures toward a majority of snake predators regardless of their sympatry/allopatry or food specialization. The most exaggerated antipredatory postures in both subadult and adult geckos were toward 2 sympatric snake species, the spotted whip snake Hemorrhois ravergieri, an active forager, and the red sand boa Eryxjohnii, a subterranean snake with a sit-and-wait strategy. In contrast, also subter- ranean but allopatric the Kenyan sand boa Eryx colubrinus did not elicit any antipredatory reaction. We conclude that the leopard gecko possesses an innate general antipredatory reaction to different species of snake predators, while a specific reaction to 2 particular sympatric species can be observed. Moreover, adult wild caught geckos show lower reactivity compared with the captive born ones, presumably due to an experience of a real predation event that can hardly be simulated under laboratory conditions.
基金funded by 2 grants awarded to KPB(Animal Behavior Society,Student Research Grant and Sigma Xi,Grants-in-Aid of Research)funding from John Carroll University.
文摘Aposematism is an antipredator strategy in which conspicuous coloration acts as a warning of chemical defenses to potential predators.Evidence suggests that aposematism largely functions under positive frequency-dependent selection,which is thought to maintain uniformity of aposematic signals.Many studies of aposematic organisms have found evidence that color signals and defenses are positively correlated,indicating a quantitatively honest aposematic signal.Dendrobatid poison frogs represent a well-studied group of aposematic organisms that in addition to exhibiting a diversity of color signals also display unique defensive behaviors.Few studies have examined if both behavior and coloration act as quantitative honest signals of alkaloid defenses in poison frogs.We aimed to determine if coloration and behavior are quantitatively honest signals in the green and black poison frog(Dendrobates auratus)among 6 populations from Costa Rica.We(1)evaluated antipredator displays by using behavioral assays in the field,(2)assessed frog conspicuousness and pattern using digital images,and(3)quantified alkaloid profiles from frog skin secretions.We found that Pacific populations are less conspicuous in coloration,had greater quantities of alkaloids,and more frequently performed body-raising defensive behaviors when compared with Caribbean populations.Our results do not support the hypothesis that aposematic traits in D.auratus are quantitatively honest.Rather,our results suggest that phenotypic differences among populations may represent different phenotypic optima for advertising unprofitability to predators based on local environmental conditions,leading to the diversification of aposematic signals in this species.
基金financially supported by the National Natural Science Foundation of China(Grant No.32471564)。
文摘Eyespots have been shown to perform an anti-predator function by intimidating predators.However,whether predators are deterred by the eyespots’mimicking eyes of higher-order predators,or by the conspicuousness of the spots,is still being debated.The anti-predator mechanism of eyespots,which involves the predator’s visual perception and cognition,urges to be examined.To explore the“eye mimicry hypothesis”and“conspicuous signal hypothesis,”we designed prey with deceptive eyespots eliciting 2-dimensional(2D)or 3-dimensional(3D)visual illusions for domestic chicks(as predators).For 2D visual illusion,we provided prey with occluded eyespots for chicks.Chicks can“complete”the occluded eyespots into a full 2D concentric circle by the amodal completion mechanism,that is,one of visual illusion.For 3D visual illusion,we created the crescent-shaped sparkles on the eyespots to simulate a visually 3D eye.Our result indicated that(1)2D:chicks hesitated more when facing preys with occluded eyespots than facing preys with broken eyespots and(2)3D:compared to prey with no-sparkle eyespots,chicks spent more time approaching prey with sparkle eyespots and were more likely to approach them tangentially.Thus,the visual illusion perceived by chicks would impact the anti-predation effectiveness of eyespots.Eyespots that more closely resemble the real eyes,especially those with 3-dimensionality,provided more effective protection.Our study supported the eye mimicry hypothesis from the perspective of visual illusion.
基金supported by grants from the National Natural Science Foundation of China(31770422 and 31900334)Natural Science Foundation of Jiangsu Province(BK20190910)+2 种基金Postdoctoral Science Foundation of China(2018M630610 and 2019T120468)Students’Project for Innovation and Entrepreneurship Training Program of Yangzhou University(XCX20230796)Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Paternal predation risk can program offspring phenotypes via maternal responses and epigenetic marks of spermatozoa.However,the processes and consequences of this experience in biparental species are unknown.Here,we examined how preconception and postconception paternal cat odor(CO)exposure affects anxiety-like behavior and antipredator response in Brandt’s voles(Lasiopodomys brandtii).We found that preconception paternal CO exposure inhibited maternal investment when offspring were raised by mothers alone,while postconception exposure increased paternal investment towards the offspring raised by both parents.The increased paternal behavior may be associated with an increasing grooming behavior received from their mates,which alleviated the anxiety-like behavior in CO-exposed males.Both paternal experiences increased the levels of anxiety-like behavior in adolescent offspring but differentially altered adult phenotypes.Specifcally,adult females from preconception CO-exposed fathers spent less time in defensive concealing,whereas the offspring of postconception CO-exposed fathers showed more in response to acute cat urine exposure.Correspondingly,baseline corticosterone levels were decreased and increased in these offspring,respectively.Our results indicate that in biparental species,paternal predation risk exposure affects offspring phenotypes in pathway-dependent and age-specifc manners and that only the presence of both parents can elicit adaptive responses to a high predation-risk environment.
基金supported by the Prespa-Ohrid Nature Trust and the Aage V.Jensen Foundation via PrespaNet's"Prespa Project(2021-2024)"the Rufford Foundation(grant number 30090-1)the Ministry of Science,Technological Development and Innovation of the Republic of Serbia(grant numbers451-03-0133012020-14/2627,451-03-47/2023-01/200178,451-03-47/2023-01/200007).
文摘Functional constraints between different types of antipredator behavior should be common,especially if they are on the opposite sides of the behavioral spectrum such as flight and post-capture immobility.We examined a potential compromise between post-capture immobility displays and sprint speed in dice snakes(Natrix tessellata),using a field-based approach.We sampled snakes(N=238)from two populations:from a dense island population free of mammal predators,and from a less dense mainland population,preyed upon by both bird and mammal predators.We explored the effects of sexual maturity,temperature,body size,presence of palpable food in the gut,and injuries on the occurrence and duration of post-capture immobility as well as sprint speed.Our results confirm the existence of functional constraints between locomotor performance and post-capture immobility in dice snakes.Faster dice snakes start escaping promptly after release,while slower individuals utilize more passive antipredator behaviors such as death feigning.Local adaptations seem to have great influence on behavioral compromise,since the mammal-free island population exhibited a higher incidence of post-capture immobility and a significantly lower sprint speed,compared to the less dense mainland population.Additionally,immature individuals tended to avoid death feigning and their post-capture immobility lasted shorter compared to adult individuals.It remains to be seen how individuals adjust their behavior to accomodate locomotor constraints,and in which specific phases of the predator-prey interaction these adjustments occur.
基金supported by the National Natural Science Foundation of China(32270531,32370530)Singapore Ministry of Education AcRF Tier 1 Grants(A-0008615-00,A-8001085-00-00)。
文摘Animals deploy diverse color-based defenses against predators,including crypsis,mimicry,aposematism,and masquerade.While crypsis,mimicry,aposematism have been extensively studied,the strategy of masquerade-where organisms imitate inedible or inanimate objects such as leaves,twigs,stones,and bird droppings-remains comparatively underexplored,particularly in adult butterflies.The Indian oakleaf butterfly(Kallima inachus)exemplifies this phenomenon,with its wings resembling dead leaves,providing a classic example of natural selection.Although it has long been postulated that these butterflies evade predation by being misidentified as dead leaves,direct experimental evidence is lacking.In the current study,using domestic chicks as predators,we manipulated their prior experience with dead leaves(model objects)while maintaining constant exposure to butterflies to test whether dead-leaf masquerade provides a protective advantage by preventing recognition.Results showed a marked delay in the initiation of attacks by chicks familiar with dead leaves compared to those with no prior exposure or those exposed to visually altered leaves.Chicks with prior dead-leaf experience required a similar amount of time to attack the butterflies as they did to attack dead leaves.These findings provide the first empirical demonstration of dead-leaf masquerade in Kallima butterflies,shedding light on its evolutionary significance.Our study highlights the effectiveness of masquerade in inducing the misclassification of butterflies as inanimate objects,showcasing the precise mimicry achieved by these organisms when viewed in isolation from the model objects.This study advances our understanding of the evolution of masquerade and its role as a potent antipredator strategy in nature.
文摘Visual cues are important in both interspecific and intraspecific communication.The species confidence hypothesis proposes that animals are more attracted to conspecific colors and repelled by colors,not on their bodies.Studies on terrestrial lizards and birds have tested the species confidence hypothesis and shown that conspecific colors elicit reduced antipredator behavior.To date,the species confidence hypothesis has not been tested in the marine environment,specifically on coral reefs where color communication is of vital importance.We addressed this knowledge gap by measuring flight initiation distance(the distance an individual moves away from an approaching threat)in dusky damselfish(Stegastes nigricans)in response to an approaching disc of 1 of 4 different color treatments:conspecific,blue,yellow,and black.If the species confidence hypothesis explained variation in damselfish flight initiation distance,then we expected individuals to tolerate closer approaches when approached by a conspecific color.In addition,we calculated the color difference between each stimulus and its corresponding back-ground as a potential alternative explanation for flight responses.Damselfish tolerated the closest approach from the conspecific color stimulus;there were no significant differences between other colors and there was no support for the alternative color difference hypothesis.As with similar terrestrial studies,these results are relevant to ecotourists'choice of swimsuit and wetsuit colors because color choice may modify naturalantipredatorbehavior.
文摘Many birds join cooperative mobbing aggregations and collectively harass predators. Individuals participating in these ephemeral associations benefit by deterring the predator, but also incur energetic costs and increased risk of predation. Ex- plaining the evolution of mobbing is challenging because individuals could prevail by selfishly seeking safety while allowing others to mob. An important step in understanding the evolution of mobbing is to identify factors affecting its expression. The ecological constraints model suggests that animals are more likely to cooperate under adverse environmental conditions, such as when local predation pressure is high. We tested this prediction by comparing the mobbing responses of several species of birds to the local abundance of their primary predator, the ferruginous pygmy-owl Glaucidium brasilianum. We used acoustic playback to elicit mobbing responses in environments where owls were common, uncommon, or rare. Stimuli were either the song of a fer- ruginous pygmy-owl or the mobbing calls of three of the owl＇s common prey species. During each playback, we characterized mobbing responses by noting the number of species and individuals that approached the loudspeaker, as well as the closest ap- proach by any bird. Mobbing responses to both stimuli were strong in locations where Ferruginous Pygmy-owls were common, intermediate where owls were uncommon, and weak where they were rare. This pattern persisted even after controlling for dif- ferences in species richness and composition among the three environments. Results support the ecological constraints model and provide strong evidence that intense predation pressure increases the expression of cooperative mobbing in tropical birds [Cur- rent Zoology 58 （5）： 781-790, 2012].
基金Acknowledgements Financial support for this work was provided by the National Natural Science Foundation of China （No. 31000174 ＆ No. Jl103512）. We thank Prof. Ding Yuhua and other staff members at Dafeng Milu National Natural Reserve for supporting our field research in the reserve. We also thank Xianlong Li, Rongrong Wang, Jia He, Dameng Li, Ruonan Jia, Yilei Hua, and Long Wang for help with the field work, and Chen Ge and Cheng Huang for useful discussions.
文摘After being kept in captivity and isolated from natural predators for more than 1,200 years, P6re David＇s deer has been reintroduced in China and now occurs in a reserve where human activity is the only potential threat. Antipredator vigilance i~ an important component of survival for many prey animals in their natural habitat. Do deer still adjust vigilance as a function of risk after such a long period of relaxed predation pressure？ Here, we examined vigilance levels in P6re David＇s deer groups as a function of group size, sex and level of human disturbance. The results showed that individual vigilance significantly decreased with group size in all-female groups but not in all-males or mixed-sex groups. In rutting season, males compete with one another and harass females, and we argue that vigilance is partly aimed at threatening males and that such vigilance increases with group size. This explains why overall vigilance did not vary with group size for males in general and for females in mixed-sex groups. Vigilance increased in more disturbed areas but in in male deer only. The results indicate that despite relaxed predation pressure over centuries, P6re David＇s deer can still adjust antipredator responses as a function of perceived risk. Such information may become useful in the rewilding programme now under way for this species in China [Current Zoology 59 （2）： 265-270, 2013].
基金D.T.B.was supported by the National Science Foundation (grant 1557130). A.D.was an NSF REU fellow supported by DBI 1226713(to the Rocky Mountain Biological Laboratory).L.Y.was supported by China Scholarship Counsel and Peking University.
文摘In many vertebrates,the brain's right hemisphere which is connected to the left visual field specializes in the processing of information about threats while the left hemisphere which is connected to the right visual field specializes in the processing of information about conspecifics.This is referred to as hemispheric lateralization.But individuals that are too predictable in their response to predators could have reduced survival and we may expect selection for somewhat unpredictable responses.We studied hemispheric lateralization in yellow-bellied marmots Marmota flaviventer,a social rodent that falls prey to a variety of terrestrial and aerial predators.We first asked if they have lateralized responses to a predatory threat.We then asked if the eye that they used to assess risk influenced their perceptions of risk.We recorded the direction marmots were initially looking and then walked toward them until they fled.We recorded the distance that they responded to our experimental approach by looking,the eye with which they looked at us,and the distance at which they fled (i.e.,flight initiation distance;FID).We found that marmots had no eye preference with which they looked at an approaching threat.Furthermore,the population was not comprised of individuals that responded in consistent ways.However,we found that marmots that looked at the approaching person with their left eye had larger FIDs suggesting that risk assessment was influenced by the eye used to monitor the threat.These findings are consistent with selection to make prey less predictable for their predators,despite underlying lateralization.
文摘Camouflage is ubiquitous in the natural world and benefits both predators and prey. Amongst the range of conceal- ment strategies, disruptive coloration is thought to visually fragment an animal＇s＇ outline, thereby reducing its rate of discovery. Here, I propose two non-mutually exclusive hypotheses for how disruptive camouflage functions, and describe the visual me- chanisms that might underlie them. （1） The local edge disruption hypothesis states that camouflage is achieved by breaking up edge information. （2） The global feature disruption hypothesis states camouflage is achieved by breaking up the characteristic features of an animal （e.g., overall shape or facial features）. Research clearly shows that putatively disruptive edge markings do increase concealment; however, few tests have been undertaken to determine whether this survival advantage is attributable to the distortion of features, so the global feature disruption hypothesis is under studied. In this review the evidence for global feature disruption is evaluated. Further, I address if object recognition processing provides a feasible mechanism for animals＇ features to influence concealment. This review concludes that additional studies are needed to test if disruptive camouflage operates through the global feature disruption and proposes future research directions [Current Zoology 61 （4）： 708-717, 2015].
文摘Ecotourism encourages an environmentally friendly exploration of the world＇s natural habitats. Tourists often engage in wildlife photography, an activity that is generally not considered disturbing to animals. We investigated the effects of cam- era-related stimuli to determine whether shutter noise and/or flash affected the immediate behavior of female crested anoles Ano- lis cristaellus. Anoles decreased their display rate following stimuli that included shutter noises, but did not change their behavior in response to flash or silence treatments. To determine the relative importance of this response, we observed anole behavior fol- lowing playbacks of calls from kestrels Falco sparverius, a predator, and bananaquits Coereba flaveola, a non-predator. Anoles decreased display rates following kestrel calls when compared to their response to bananaquit calls. Furthermore, anoles spent a greater proportion of time displaying following bananaquit calls compared to both kestrel calls and silence. The magnitude of response to shutter noises was about the same as that to predator calls. This demonstrates that photography may not be as benign as commonly believed, and we should consider whether restrictions on camera noises should be implemented to reduce ani- mal disturbance
文摘Age and body size can influence predation risk and hence habitat use. Many species undergo ontogenetic shifts in habitat use as individuals grow larger and have different age-specific predation pressures. On coral reefs, a number of fish species are more tolerant of threats in structurally complex habitats that contain more refuges than in less structurally complex habitats. However, we do not know how risk perception varies with age, and whether age interacts with habitat complexity. Adults and juveniles, because of their size, may face different risks in structurally simple versus complex habitats. We used flight initiation distanee as a metric to analyze perceptions of risk in a species of damselfish Stegastes nigricans. All else being equal, fish fleeing at greater distances are inferred to perceive higher risk. We targeted juvenile and adult damselfish to assess whether there are ontogenetic shifts in perceptions of safety in relation to structural complexity, inferred based on percent coral cover and rugosity. We found that adult damselfish tolerated closer approach in more complex habitats as measured by percent coral cover, but not rugosity, whereas juvenile fish always allowed closer approach than adult fish regardless of complexity. This ontogenetic shift in habitat use may result from juvenile fish taking bigger risks to maximize growth, whereas older animals, who are closer to their maximum body size, can afford to take fewer risks and protect their assets.
文摘There is growing evidence that individual animals show consistent differences in behavior. For example, individual threespined stickleback fish differ in how they react to predators and how aggressive they are during social interactions with con- specifics. A relatively unexplored but potentially important axis of variation is parental behavior. In sticklebacks, fathers provide all of the parental care that is necessary for offspring survival; therefore paternal care is directly tied to fitness. In this study, we assessed whether individual male sticklebacks differ consistently from each other in parental behavior. We recorded visits to nest, total time fanning, and activity levels of 11 individual males every day throughout one clutch, and then allowed the males to breed again. Half of the males were exposed to predation risk while parenting during the first clutch, and the other half of the males ex- perienced predation risk during the second clutch. We detected dranlatic temporal changes in parental behaviors over the course of the clutch： for example, total time fanning increased six-fold prior to eggs hatching, then decreased to approximately zero. De- spite these temporal changes, males retained their individually-distinctive parenting styles within a clutch that could not be ex- plained by differences in body size or egg mass. Moreover, individual differences in parenting were maintained when males re- produced for a second time. Males that were exposed to simulated predation risk briefly decreased fanning and increased activity levels. Altogether, these results show that individual sticklebacks consistently differ from each other in how they behave as parents [Current Zoology 58 （1）： 45-52, 2012].
基金We thank Kate Rose for help managing data, the survey participants for judging vividness, C. East- wood for his intellectual contributions, and Bill Cooper and one anonymous reviewer for their constructive comments on a previous version of this MS. NMH was supported by the UC Regents Special Fellowship. JPD was supported by a National Science Foundation （NSF） Graduate Research Fellowship and a fellowship from the UCLA Graduate Division during the course of this study. DTB is supported by NSF-DEB-1119660.
文摘The distance from an approaching threat at which animals initiate flight - flight-initiation distance （FID） -- is a sensitive metric of variation in risk, but the effects on FID associated with the risk of possessing highly detectable external coloration are unknown. We tested whether variation in the degree of plumage vividness in birds explained variation in flight-initiation distance. After controlling for body mass, the distance at which the experimental approach began, and phylogenetic relatedness, plumage vividness was not a predictor of FID. Contrary to the expectation that vividness affects risk, and therefore risk assess- ment, these results suggest that birds do not compensate for greater visual conspicuousness by fleeing sooner from approaching threats [Current Zoology 61 （4）： 773-780, 2015].
基金This work was supported by the Urban Nature Research Center at the Natural History Museum of Los Angeles County,and the National Science Foundation through a Postdoctoral Research Fellowship in Biology(DBI-1611562 to B.J.P.).
文摘Biological invasions threaten biodiversity worldwide,and therefore,understanding the traits of successful invaders could mitigate their spread.Many comm only invasive species do well in disturbed habitats,such as urban environments,and their abilities to effectively respond to disturbarices could con tribute to their invasiveness.Yet,there are non invasive species that also do well in disturbed habitats.The question remains whether urban invaders behave differently in urban environments than noninvaders,which could suggest an"urban-exploiting"phenotype.In Southern California,the co-occurrence of in vasive Italia n wall lizards Pod arc is siculus,brown anoles Anolis sagrei,and green anoles A.carolinensis,and native western fence lizards Sceloporus occidentalis offers an opportunity to test whether invasives exhibit consistent differences in risk-taking within human-altered habitats compared with a native species.We predicted that invasive lizards would exhibit more bold behavior by having shorter flight-initiation distances(FIDs)and by being found farther from a refuge(behaviors that would presumably maximize foraging in low-risk environments).Invasive populations had similar or longer FIDs,but were consistently found at distances closer to a refuge.Collectively,invasive lizards in urban habitats were not bolder than a native species.Relianee on nearby refuges might help species successfully invade urban habitats,and if a general pattern,may pose an added challenge in detecting or eliminating them.
