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

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.

2021 ◽  
Author(s):  
Neil Robert Caton ◽  
Barnaby Dixson

Sexual selection via male-male contest competition has shaped the evolution of agonistic displays, weaponry, and fighting styles, and is further argued to have shaped human psychological mechanisms to detect, process, and respond appropriately to cues of fighting ability. Drawing on the largest fight-specific dataset to date across the sports and biological sciences (N = 2,765), we examined how different indicators of fighting ability in humans reflect unique paths to victory and indicate different forms of perceived and actual resource-holding power (RHP). Overall, we discovered that: (1) both striking skill and vigour, and grappling skill and vigour, individually and collectively predict RHP; (2) different RHP indicators are distinguished by a unique path to victory (e.g., striking skill is a knockout-typical strategy, whereas grappling vigour is a submission-typical strategy); and (3) third-party observers accurately track fighting skill and vigour along their unique paths to victory. Our argument that different measures of RHP are associated with unique paths to victory, and third-party observers accurately track fighting vigour and skill along their unique paths to victory, advance our understanding not only of human contest competition, but animal contest theory more broadly.


2020 ◽  
Vol 181 ◽  
pp. 104251
Author(s):  
Jorge Vázquez ◽  
Juan A. Fargallo ◽  
Nallely Jiménez ◽  
Fernando Aguilar-Montiel ◽  
Luisa Rodríguez-Martínez

2017 ◽  
Vol 126 ◽  
pp. 17-22 ◽  
Author(s):  
Christopher Moser-Purdy ◽  
Elizabeth A. MacDougall-Shackleton ◽  
Daniel J. Mennill

Behaviour ◽  
2012 ◽  
Vol 149 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Satoshi Awata ◽  
Masanori Kohda ◽  
Haruki Ochi

AbstractAn algivorous cichlid, Variabilichromis moorii( Vm), defends permanent territories in Lake Tanganyika, Africa. A zoobenthivorous cichlid, Neolamprologus mustax( Nm), spends 60% of daylight hours foraging in Vmterritories, from which other zoobenthivorous fishes are chased out and consequently which are much richer in prey animals than areas outside of Vmterritories. We conducted a field experiment to examine whether Nmresidents and non-residents received different degrees of attacks from Vm. Nmfish were caught in their territories, released at a point distant from these territories, and followed to observe interactions with Vmfish. The frequency of attacks received by the displaced Nmfish was greater than attacks received by Nmresidents, indicating that Nmresidents had easier access to Vmterritories than non-residents did. A possible mechanism for this is reduced aggression of Vmtowards Nmresidents, as a result of the ‘dear enemy’ effect that has been reported in territorial contests between rivals. An alternative mechanism is that tolerance towards Nmdiffers among Vmfish and Nmresidents selectively visit more tolerant Vmfish due to previous experience while non-residents randomly approach both tolerant and hostile Vmfish. The ability of Vmto discriminate between Nmresidents and non-residents is essential to the former mechanism but not to the latter. To more specifically examine which mechanism works in the Vm– Nmcommensal system, we will need to follow individually identified Vmfish interacting with Nmresidents and non-residents.


2013 ◽  
Vol 63 (1) ◽  
pp. 47-58
Author(s):  
Veena H.F. Ammanna ◽  
Srinivas K. Saidapur ◽  
Bhagyashri A. Shanbhag

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’.


2012 ◽  
Vol 289 (3) ◽  
pp. 189-195 ◽  
Author(s):  
H. B. Cross ◽  
D. T. Blumstein ◽  
F. Rosell

2002 ◽  
Vol 63 (6) ◽  
pp. 1073-1078 ◽  
Author(s):  
Frank Rosell ◽  
Tore Bjørkøyli

Sign in / Sign up

Export Citation Format

Share Document