An agonistic display by a white shark was observed and photographed during a cage dive at Guadalupe Island in November 2015. Exhibiting exaggerated pectoral fin depression, agonistic behaviors have been previously obs...An agonistic display by a white shark was observed and photographed during a cage dive at Guadalupe Island in November 2015. Exhibiting exaggerated pectoral fin depression, agonistic behaviors have been previously observed and described in several shark species. This account may be the first record of a white shark in close proximity to a caged diver, exhibiting strong pectoral fin depression significantly dipped, in the mid-agonistic display. Such displays should be considered as aggressive and potentially life-threatening by those using the ocean for recreational or professional purposes.展开更多
Visual signals, including changes in coloration and color patterns, are frequently used by animalsto convey information. During contests, body coloration and its changes can be used to assess anopponent＇s state or mo...Visual signals, including changes in coloration and color patterns, are frequently used by animalsto convey information. During contests, body coloration and its changes can be used to assess anopponent＇s state or motivation. Communication of aggressive propensity is particularly importantin group-living animals with a stable dominance hierarchy, as the outcome of aggressive inter-actions determines the social rank of group members. Neolamprologus pulcher is a cooperativelybreeding cichlid showing frequent within-group aggression. Both sexes exhibit two vertical blackstripes on the operculum that vary naturally in shape and darkness. During frontal threat displaysthese patterns are actively exposed to the opponent, suggesting a signaling function. To investi-gate the role of operculum stripes during contests we manipulated their darkness in computeranimated pictures of the fish. We recorded the responses in behavior and stripe darkness of testsubjects to which these animated pictures were presented. Individuals with initially darker stripeswere more aggressive against the animations and showed more operculum threat displays.Operculum stripes of test subjects became darker after exposure to an animation exhibiting a paleoperculum than after exposure to a dark operculum animation, highlighting the role of the dark-ness of this color pattern in opponent assessment. We conclude that （i） the black stripes on theoperculum of N. pulcherare a reliable signal of aggression and dominance, （ii） these markings playan important role in opponent assessment, and （iii） 2D computer animations are well suited to elicitbiologically meaningful short-term aggressive responses in this widely used model system ofsocial evolution.展开更多
Aggression is a common behavioral strategy employed by animals to secure limited resources, but must be applied with restraint to limit potential costs including injury. How animals make the adap- tive decision to fig...Aggression is a common behavioral strategy employed by animals to secure limited resources, but must be applied with restraint to limit potential costs including injury. How animals make the adap- tive decision to fight or flee is barely known. Here, we review our work on crickets that reveals the roles of biogenic amines, primarily octopamine （the insect analog of noradrenaline） and nitric oxide （NO）. Using aminergic drugs, we found that amines are not essential for actually initiating aggres- sion. However, octopamine is necessary for mediating the aggression-promoting effects of poten- tially rewarding experiences including stimulation with a male antenna, physical exertion, winning, and resource possession. Hence, octopamine can be considered as the motivational component of aggression. Imposed handicaps that impede aggressive signaling revealed that the agonistic actions of an opponent perceived during fighting act to reduce aggression, and that crickets make the deci- sion to flee the moment the accumulated sum of such aversive experiences exceeds some critical level. Treatment with nitridergic drugs revealed that the impact of the opponent＇s aggressive actions is mediated by NO. NO acts to suppress aggression by promoting the tendency to flee and is primarily responsible for the depressed aggressiveness of subordinates after social defeat. Octopamine and dopamine can each restore aggression in subordinates, but only dopamine is necessary for normal recovery. The role of serotonin remains unclear, and is discussed. We conclude that octopamine and NO control the decision to fight or flee by mediating the effects of potentially rewarding and aversive experiences, respectively.展开更多
Predation is an important ecological constraint that influences communication in animals.Fish respond to predators by adjusting their visual signaling behavior,but the responses in calling behavior in the presence of ...Predation is an important ecological constraint that influences communication in animals.Fish respond to predators by adjusting their visual signaling behavior,but the responses in calling behavior in the presence of a visually detected predator are largely unknown.We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator.To test this we investigated dyadic contests in female croaking gouramis(Trichopsis vittata,Osphronemidae)in the presence and absence of a predator(Astronotus ocella-tus,Cichlidae)in an adjoining tank.Agonistic behavior in T.vittata consists of lateral(visual)displays,antiparallel circling,and production of croaking sounds and may escalate to frontal displays.We analyzed the number and duration of lateral display bouts,the number,duration,sound pressure level,and dominant frequency of croaking sounds as well as contest outcomes.The number and duration of lateral displays decreased significantly in predator when compared with nopredator trials.Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics.In the presence of a predator,dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays.The gouramis showed approaching behavior toward the predator between lateral displays.This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish.Sound properties,in contrast,did not change.Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat.展开更多
Intra and in terspecific competiti on for n ectar play an imports nt role in hummingbird communities. Larger sized species usually exclude smaller species from the rich floral resources. However, it has been recently ...Intra and in terspecific competiti on for n ectar play an imports nt role in hummingbird communities. Larger sized species usually exclude smaller species from the rich floral resources. However, it has been recently postulated that the competitive advantages of a large body size decline as the evolutionary distance between the contending species in creases. In this study, we analyzed dominance hierarchy dynamics in a hummingbird assemblage in central Mexico. By monitoring hummingbird territories established in three plant species through 1 year, we assessed the effects of energy within territories and the territory owners identity in the frequency of inter and intraspecific encounters. We also evaluated if these factors affect the dominance of larger species when they compete against smaller distantly related contenders. Our results show that their frequency of intraspecific encounters was related with the identity of the territory's owner. On the contrary, the frequency of interspecific encounters was related with both the territory and the identity of the territory's owner. We did not find a significant difference between the number of encounters dominated by larger and smaller species and their conte nders. However, the in crease in genetic dista nee between contenders was positively associated with a higher frequency of encounters dominated by small hummingbirds.Our results showed that the ecological factors and evolutionary relationships among contenders play important roles in the dominance hierarchy dynamics.展开更多
In many species, agonistic interactions result in social relationships that are stable over time. In Syrian hamsters, two unfamiliar males that are placed together will fight vigorously and a clear winner/loser relati...In many species, agonistic interactions result in social relationships that are stable over time. In Syrian hamsters, two unfamiliar males that are placed together will fight vigorously and a clear winner/loser relationship is usually established. In subsequent interactions, the loser will flee soon after detecting the familiar winner. Here we tested the hypothesis that losing a fight with a conspecific will affect future agonistic interactions not only toward that individual （i.e., the familiar winner） but also toward unfamiliar conspecifics. To test this hypothesis we paired two Syrian hamster males in three trials on one day in which the loser had tile opportunity to escape the winner. The next day the loser was paired with an unfarniliar male, also for three trials. If he lost again, he was tested on a third day with a third unfamiliar male. Subjects were those males that were losers on all three days. The latency to escape on the first trial on Days 2 and 3 was significantly shorter than on the first trial on Day l, indicating that losing against the first male affected the response toward unfamiliar males. However, the latency to escape on the first trial on Days 2 and 3 was significantly longer than that on the third trial on the preceding day, indicating that a loser treats unfamiliar males differently than a familiar winner. These results suggest that a defeat during an interaction with one male affects later agonistic behavior towards other, unfamiliar males [Current Zoology 57 （4）： 449-452, 2011].展开更多
We investigated how the parasitoid Torymus sp. (Hymenoptera: Torymidae) attacking galls of Schismatodiplosis lantanae (Diptera: Cecidomyiidae) on Lantana camara (Verbenaceae) behaves in the presence of a conspecific f...We investigated how the parasitoid Torymus sp. (Hymenoptera: Torymidae) attacking galls of Schismatodiplosis lantanae (Diptera: Cecidomyiidae) on Lantana camara (Verbenaceae) behaves in the presence of a conspecific female competitor in the patch. Presence of a competitor greatly changed resident exploitation behavior. Wasps alone spent more time in gall exploitation behaviors (walk-antennate and probe) and in post-oviposition behaviors (stationary and groom), and when intruders were present they spent more time walking. The attack strategy was through threatening: raising wings and pointing the antennae towards the opponent. Different from theoretical expectations, residents were not always the attacker. Number of galls in the patch and female wasp size did not affect contest outcomes, although gall exploitation time and time on leaf were significant factors for the probability of having attacks. Overall, the study highlights the fact that intruder interest in the host was the main cause of contests and also this is a unique report both in terms of the target species and the nature of the disputed resource, a gall-inducer inside a singular spatial unit, the gall.展开更多
文摘An agonistic display by a white shark was observed and photographed during a cage dive at Guadalupe Island in November 2015. Exhibiting exaggerated pectoral fin depression, agonistic behaviors have been previously observed and described in several shark species. This account may be the first record of a white shark in close proximity to a caged diver, exhibiting strong pectoral fin depression significantly dipped, in the mid-agonistic display. Such displays should be considered as aggressive and potentially life-threatening by those using the ocean for recreational or professional purposes.
文摘Visual signals, including changes in coloration and color patterns, are frequently used by animalsto convey information. During contests, body coloration and its changes can be used to assess anopponent＇s state or motivation. Communication of aggressive propensity is particularly importantin group-living animals with a stable dominance hierarchy, as the outcome of aggressive inter-actions determines the social rank of group members. Neolamprologus pulcher is a cooperativelybreeding cichlid showing frequent within-group aggression. Both sexes exhibit two vertical blackstripes on the operculum that vary naturally in shape and darkness. During frontal threat displaysthese patterns are actively exposed to the opponent, suggesting a signaling function. To investi-gate the role of operculum stripes during contests we manipulated their darkness in computeranimated pictures of the fish. We recorded the responses in behavior and stripe darkness of testsubjects to which these animated pictures were presented. Individuals with initially darker stripeswere more aggressive against the animations and showed more operculum threat displays.Operculum stripes of test subjects became darker after exposure to an animation exhibiting a paleoperculum than after exposure to a dark operculum animation, highlighting the role of the dark-ness of this color pattern in opponent assessment. We conclude that （i） the black stripes on theoperculum of N. pulcherare a reliable signal of aggression and dominance, （ii） these markings playan important role in opponent assessment, and （iii） 2D computer animations are well suited to elicitbiologically meaningful short-term aggressive responses in this widely used model system ofsocial evolution.
文摘Aggression is a common behavioral strategy employed by animals to secure limited resources, but must be applied with restraint to limit potential costs including injury. How animals make the adap- tive decision to fight or flee is barely known. Here, we review our work on crickets that reveals the roles of biogenic amines, primarily octopamine （the insect analog of noradrenaline） and nitric oxide （NO）. Using aminergic drugs, we found that amines are not essential for actually initiating aggres- sion. However, octopamine is necessary for mediating the aggression-promoting effects of poten- tially rewarding experiences including stimulation with a male antenna, physical exertion, winning, and resource possession. Hence, octopamine can be considered as the motivational component of aggression. Imposed handicaps that impede aggressive signaling revealed that the agonistic actions of an opponent perceived during fighting act to reduce aggression, and that crickets make the deci- sion to flee the moment the accumulated sum of such aversive experiences exceeds some critical level. Treatment with nitridergic drugs revealed that the impact of the opponent＇s aggressive actions is mediated by NO. NO acts to suppress aggression by promoting the tendency to flee and is primarily responsible for the depressed aggressiveness of subordinates after social defeat. Octopamine and dopamine can each restore aggression in subordinates, but only dopamine is necessary for normal recovery. The role of serotonin remains unclear, and is discussed. We conclude that octopamine and NO control the decision to fight or flee by mediating the effects of potentially rewarding and aversive experiences, respectively.
基金This study was funded by the Austrian Science Fund[FWF Grant No.P31045 to F.L.].
文摘Predation is an important ecological constraint that influences communication in animals.Fish respond to predators by adjusting their visual signaling behavior,but the responses in calling behavior in the presence of a visually detected predator are largely unknown.We hypothesize that fish will reduce visual and acoustic signaling including sound levels and avoid escalating fights in the presence of a predator.To test this we investigated dyadic contests in female croaking gouramis(Trichopsis vittata,Osphronemidae)in the presence and absence of a predator(Astronotus ocella-tus,Cichlidae)in an adjoining tank.Agonistic behavior in T.vittata consists of lateral(visual)displays,antiparallel circling,and production of croaking sounds and may escalate to frontal displays.We analyzed the number and duration of lateral display bouts,the number,duration,sound pressure level,and dominant frequency of croaking sounds as well as contest outcomes.The number and duration of lateral displays decreased significantly in predator when compared with nopredator trials.Total number of sounds per contest dropped in parallel but no significant changes were observed in sound characteristics.In the presence of a predator,dyadic contests were decided or terminated during lateral displays and never escalated to frontal displays.The gouramis showed approaching behavior toward the predator between lateral displays.This is the first study supporting the hypothesis that predators reduce visual and acoustic signaling in a vocal fish.Sound properties,in contrast,did not change.Decreased signaling and the lack of escalating contests reduce the fish's conspicuousness and thus predation threat.
文摘Intra and in terspecific competiti on for n ectar play an imports nt role in hummingbird communities. Larger sized species usually exclude smaller species from the rich floral resources. However, it has been recently postulated that the competitive advantages of a large body size decline as the evolutionary distance between the contending species in creases. In this study, we analyzed dominance hierarchy dynamics in a hummingbird assemblage in central Mexico. By monitoring hummingbird territories established in three plant species through 1 year, we assessed the effects of energy within territories and the territory owners identity in the frequency of inter and intraspecific encounters. We also evaluated if these factors affect the dominance of larger species when they compete against smaller distantly related contenders. Our results show that their frequency of intraspecific encounters was related with the identity of the territory's owner. On the contrary, the frequency of interspecific encounters was related with both the territory and the identity of the territory's owner. We did not find a significant difference between the number of encounters dominated by larger and smaller species and their conte nders. However, the in crease in genetic dista nee between contenders was positively associated with a higher frequency of encounters dominated by small hummingbirds.Our results showed that the ecological factors and evolutionary relationships among contenders play important roles in the dominance hierarchy dynamics.
文摘In many species, agonistic interactions result in social relationships that are stable over time. In Syrian hamsters, two unfamiliar males that are placed together will fight vigorously and a clear winner/loser relationship is usually established. In subsequent interactions, the loser will flee soon after detecting the familiar winner. Here we tested the hypothesis that losing a fight with a conspecific will affect future agonistic interactions not only toward that individual （i.e., the familiar winner） but also toward unfamiliar conspecifics. To test this hypothesis we paired two Syrian hamster males in three trials on one day in which the loser had tile opportunity to escape the winner. The next day the loser was paired with an unfarniliar male, also for three trials. If he lost again, he was tested on a third day with a third unfamiliar male. Subjects were those males that were losers on all three days. The latency to escape on the first trial on Days 2 and 3 was significantly shorter than on the first trial on Day l, indicating that losing against the first male affected the response toward unfamiliar males. However, the latency to escape on the first trial on Days 2 and 3 was significantly longer than that on the third trial on the preceding day, indicating that a loser treats unfamiliar males differently than a familiar winner. These results suggest that a defeat during an interaction with one male affects later agonistic behavior towards other, unfamiliar males [Current Zoology 57 （4）： 449-452, 2011].
文摘We investigated how the parasitoid Torymus sp. (Hymenoptera: Torymidae) attacking galls of Schismatodiplosis lantanae (Diptera: Cecidomyiidae) on Lantana camara (Verbenaceae) behaves in the presence of a conspecific female competitor in the patch. Presence of a competitor greatly changed resident exploitation behavior. Wasps alone spent more time in gall exploitation behaviors (walk-antennate and probe) and in post-oviposition behaviors (stationary and groom), and when intruders were present they spent more time walking. The attack strategy was through threatening: raising wings and pointing the antennae towards the opponent. Different from theoretical expectations, residents were not always the attacker. Number of galls in the patch and female wasp size did not affect contest outcomes, although gall exploitation time and time on leaf were significant factors for the probability of having attacks. Overall, the study highlights the fact that intruder interest in the host was the main cause of contests and also this is a unique report both in terms of the target species and the nature of the disputed resource, a gall-inducer inside a singular spatial unit, the gall.
