scholarly journals A test of the dear enemy phenomenon in the Eurasian beaver

2002 ◽  
Vol 63 (6) ◽  
pp. 1073-1078 ◽  
Author(s):  
Frank Rosell ◽  
Tore Bjørkøyli
Keyword(s):  
Dear Enemy ◽  
Eurasian Beaver ◽  
Dear Enemy Phenomenon

Aggression towards unfamiliar intruders by male lizards Eurolophosaurus nanuzae depends on contestant’s body traits: a test of the dear enemy effect

Behaviour ◽  
2017 ◽  
Vol 154 (6) ◽  
pp. 693-708 ◽  
Author(s):  
Eduardo C. Quintana ◽  
Conrado A.B. Galdino
Keyword(s):  
Saving Energy ◽  
Potential Threat ◽  
Dear Enemy ◽  
Holding Power ◽  
Resource Holding Power ◽  
Dear Enemy Phenomenon ◽  
Dear Enemy Effect ◽  
Tail Condition

A reduction of territory owners’ aggression towards their neighbours in relation to the intrusion of strangers characterises the dear enemy phenomenon. Supposedly, the disparity in aggression levels of territory owners is due to a higher threat imposed by strangers compared to the threat imposed by neighbours. To evaluate the occurrence of the phenomenon in males of the small-sized lizard Eurolophosaurus nanuzae we performed a field manipulative study. We considered three models to run intrusions in males’ territories: neighbour, tailed stranger (unfamiliar) and tailless stranger intruders. Our results lend support to the presence of dear enemy for this species as residents acted more aggressively towards strangers than to neighbours. In addition, the information we provide supports the relative threat hypothesis as territory owners were more aggressive towards tailed stranger intruders than to tailless stranger intruders. In this sense, tail condition can represent a trait that signals the ‘resource holding power’ (RHP) of a lizard. Therefore, we show that beyond neighbourhood recognition, residents are able to evaluate the potential threat of stranger intruders in general, thereby extending the evolutionary gains of the dear enemy by saving energy even in the context they are expected to acts with higher costs.

Absence of kin discrimination in the hatchlings of a lizard, Calotes versicolor (Agamidae)

2013 ◽  
Vol 63 (1) ◽  
pp. 47-58
Author(s):  
Veena H.F. Ammanna ◽  
Srinivas K. Saidapur ◽  
Bhagyashri A. Shanbhag
Keyword(s):  
Kin Discrimination ◽  
Visual Displays ◽  
Dear Enemy ◽  
Discrimination Ability ◽  
Dear Enemy Phenomenon ◽  
Calotes Versicolor

Laboratory born Calotes versicolor hatchlings were reared for 15 days in pure or mixed sibships or singly in isolation and then tested for their kin discrimination ability. As C. versicolor orients itself visually, visual displays like push-ups, gular extensions, and distance between the test individuals were used as indicators of arousal/aggression towards the opponents (familiar vs. familiar/unfamiliar sib or non-sib). The hatchlings exhibited aggressiveness towards unfamiliar sibs as well as non-sibs in the form of push-ups and gular extensions; they also remained at a longer distance from each other. In contrast, they did not exhibit such behaviors against familiar individuals regardless of their relatedness, and stayed closer to each other. In tests involving once familiar individuals, sib, or non-sib reared together for 15 d from hatching and then separated for 7 or 30 d, the lizards showed aggressiveness towards each other following 30 d separation. A greater number of push-ups and gular extensions were exhibited by the test individuals after 30 d separation compared to those separated for 7 d. Thus, in this non-social lizard, there is no kin discrimination. An early dispersal of hatchlings in this species may have led to a loss of kin discrimination. However, familiar individuals are recognized as long as they continue to remain familiar thereby suggesting a ‘dear enemy phenomenon’.

Do marmots display a ‘dear enemy phenomenon’ in response to anal gland secretions?

2012 ◽  
Vol 289 (3) ◽  
pp. 189-195 ◽  
Author(s):  
H. B. Cross ◽  
D. T. Blumstein ◽  
F. Rosell
Keyword(s):  
Anal Gland ◽  
Dear Enemy ◽  
Dear Enemy Phenomenon

scholarly journals Dear Enemy Phenomenon in the Ant Ectatomma brunneum (Formicidae: Ectatomminae): Chemical Signals Mediate Intraspecific Agressive Interactions

Sociobiology ◽  
2019 ◽  
Vol 66 (2) ◽  
pp. 218
Author(s):  
Márlon César Pereira ◽  
Ellen Liciane Barbosa Firmino ◽  
Rafaella Caroline Bernardi ◽  
Luan Dias Lima ◽  
Ingrid De Carvalho Guimarães ◽  
...  
Keyword(s):  
Cuticular Hydrocarbon ◽  
Hydrocarbon Composition ◽  
Chemical Signals ◽  
Behavioral Strategies ◽  
Intraspecific Interactions ◽  
Ant Colonies ◽  
Dear Enemy ◽  
Ant Behavior ◽  
Dear Enemy Phenomenon ◽  
Group Members

The integrity of ant colonies depends exclusively on social relationships between their individuals, especially the ability of communication between group members, which is mainly mediated through chemical signals. Another important feature of ant behavior is territory defense, since they need to gather large amounts of food to feed their larvae, males and breeding females. Thereby, ants might display behavioral strategies to defend their territories from intruders. Here we investigated whether Ectatomma brunneum displays the Dear Enemy Phenomenon, what is the relationship between Cuticular Hydrocarbon composition and levels of aggression during their intraspecific interactions and which compounds and/or classes of compounds might be the most important to modulate the level of aggression. To test our hypothesis, we evaluated the levels of aggression through behavioral observations during interactions between 23 pairs of colonies nested in two distinct sites at varied distances. Then, we analyzed the cuticular chemical profile of the individuals involved in the interactions, and compared these results with the levels of aggression displayed between colonies tested. The results allow us to confirm our hypothesis that the DEP occurs in E. brunneum. The higher tolerance between closer colonies can be explained due to their kinship level in addition to sharing the same microhabitats. The results also showed there are significant differences in CHCs profiles, especially between colonies nested at relatively greater distances, and it is likely that differences in content of some branched alkanes are the most important to establish these differences and, therefore, the levels of aggression during the interactions.

Investigating the ‘dear enemy’ phenomenon in the territory defence of the fiddler crab, Uca mjoebergi

2010 ◽  
Vol 79 (2) ◽  
pp. 419-423 ◽  
Author(s):  
Isobel Booksmythe ◽  
Michael D. Jennions ◽  
Patricia R.Y. Backwell
Keyword(s):  
Fiddler Crab ◽  
Dear Enemy ◽  
Territory Defence ◽  
Dear Enemy Phenomenon

A dear enemy relationship in a territorial cichlid: evidence for the threat-level hypothesis

Behaviour ◽  
2016 ◽  
Vol 153 (4) ◽  
pp. 387-400 ◽  
Author(s):  
Shumpei Sogawa ◽  
Kazutaka Ota ◽  
Masanori Kohda
Keyword(s):  
Cichlid Fish ◽  
Experimental Tank ◽  
Territorial Defence ◽  
Neolamprologus Pulcher ◽  
Dear Enemy ◽  
Threat Level ◽  
Dear Enemy Phenomenon ◽  
Focal Fish ◽  
Boundary Paradigm ◽  
Aggression Level

Despite competing for resources such as space, food and mates, many territorial animals are less aggressive towards neighbours who rarely go beyond their territorial boundaries. This so-called dear enemy phenomenon is advantageous in territorial defence, but it has not been well studied in fish. In this work, we tested the ‘correct–incorrect boundary paradigm’ of the dear enemy phenomenon using the territorial cichlid fishNeolamprologus pulcher, which exhibits dear enemy relationships. When the fish was placed in a small experimental tank, in which fish established its territory, it was initially very aggressive against a neighbouring fish in an adjacent tank, but the aggression level decreased rapidly (within 4 days). When the tank containing the neighbour was shifted to the opposite side, the focal fish was more aggressive than the day before, but it exhibited less aggression than it did against a stranger placed on the shifted side. This lower level of aggression suggested that the focal fish did not regard the shifted neighbour as a stranger. Our observations provide support for the threat-level hypothesis, according to which territory owners will modulate aggression intensity based on the threat level.

The ability of red squirrels (Tamiasciurus hudsonicus) to discriminate conspecific olfactory signatures

2001 ◽  
Vol 79 (7) ◽  
pp. 1296-1300 ◽  
Author(s):  
Marion Vaché ◽  
Jean Ferron ◽  
Patrick Gouat
Keyword(s):  
Boreal Forest ◽  
Vocal Communication ◽  
Tamiasciurus Hudsonicus ◽  
Olfactory Communication ◽  
Red Squirrels ◽  
Dear Enemy ◽  
Dear Enemy Phenomenon

Using a habituation-dishabituation procedure, we investigated the ability of male red squirrels (Tamiasciurus hudsonicus) to discriminate olfactory signatures of different male conspecifics. Our results indicate that they effectively pay attention to odours from unfamiliar male conspecifics and that they invest more time sniffing litter impregnated with these unfamiliar social odours than control litters. They can also habituate themselves to a given social odour and can discriminate olfactory signatures of different male conspecifics. The role of olfactory communication in this territorial species from the boreal forest is discussed with regard to the "dear enemy" phenomenon and to the fact that these squirrels are known to use vocal communication intensively to advertise their territories.

Responses to neighbours and non-neighbours in the buff-banded rail (Gallirallus philippensis): no dear-enemy relationships

2004 ◽  
Vol 52 (4) ◽  
pp. 369 ◽  
Author(s):  
Shelly Lachish ◽  
Anne W. Goldizen
Keyword(s):  
Advertisement Calls ◽  
Dear Enemy ◽  
Territory Defence ◽  
Dear Enemy Phenomenon ◽  
Males And Females ◽  
High Level ◽  
Insular Population

Territorial individuals often respond less aggressively to intrusions by their neighbours than to intrusions by unfamiliar individuals. This commonly observed strategy, the dear-enemy phenomenon, is thought to minimise the costs associated with territory defence. This study determined whether an insular population of territory-holding buff-banded rails (Gallirallus philippensis) exhibits dear-enemy relationships and whether males and females differ in their responses to neighbours and non-neighbours. Playback techniques were used to examine and compare the vocalisations and movements of focal individuals in response to the territorial advertisement calls of their neighbours and of unfamiliar individuals (non-neighbours). Results showed that focal birds did not respond differently to the calls of neighbours and non-neighbours; thus, no evidence for the dear-enemy phenomenon was found in this species. We suggest that this result is due to the significant threats posed by neighbours to territory owners in this territorial system, in addition to a high level of territorial instability in the population. Males and females were shown to differ qualitatively in their general territorial response to intruders but not in their relative responses to neighbours and non-neighbours, suggesting that the relative threats posed by neighbours and non-neighbours do not differ between the sexes.

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