17Liolaemus fabiani is a lizard that lives in the Salar de Atacama, located in the center of the 18 Atacama Desert, northern Chile, one of the driest places on the planet. Likely due to the extreme 19 environmental conditions of their habitat, L. fabiani has colonized all watercourse shores of the 20 Puilar pond where the primary source of food, flies, are confined. By 'owning' these shores, they 21 can retain resources, explaining their natural sense of territory and their world-renowned 22 aggressive territorial behavior. From the perspective of the lizard, the battlefield is a narrow 23 stretch between mountains of halite salt and the water, which leads to a winner-take-all type 24 territory. The winning lizard is rewarded with control of the food supply, access to females and 25 a privileged space to survive. This modern gladiator faces his opponent with an unmatched 26 ferocity, although there are rarely, if ever, deaths between the contenders. Like other vertebrates, 27 the defense of the territory is a cooperative job with the alpha female. She releases pheromone 28 compounds, conferring an advantage to her partner to proceed ruthlessly to attack the intruder, 29 on land or in water, in order to obtain victory. and then plummet to below 0 °C at night. Rainfall is sparse and falls in intermittent cycles 37 generated by the austral Andean winter (Ortlieb, 1995). The desert covers approximately 2,800 38 km 2 and its altitude ranges between 2400 and 2500 meters elevation above sea level (Marquet et 39 al., 1998). This unique environment is home to various animals living in this extreme area, 40offering diverse examples of successful survival strategies (Pincheira-Donoso, 2012). One such 41 creature is Liolaemus fabiani, (Yáñez & Núñez, 1983), a lizard known to dwell around San Pedro 42 de Atacama. L. fabiani is probably one of few animals in the Salar de Atacama whose survival 43 strategy includes agonistic skills (Veloso et al. 1982; Núñez y Fox 1985, Núñez y Veloso, 2001. 44
45Although initially described in the northern salt flats (26°46'S, 68°14'W), L. fabiani has been 46 reported in vegetative patches and waterways such as the wide lagoons of Cejar and Chaxa, and 47 the smaller lagoons of Puilar and Punta Brava (Labra et al., 2001). In this report, the agonistic 48 behavior is described in the shores of the Agua de Quelana lagoon (Fig. 1). Only one other lizard, 49Liolaemus constanzae is known to inhabit this area. L. fabiani can be spotted darting over the 50 salt crust; its orange, red, yellow, green, and blue skin flashing as it dashes over the rough, manner that facilitates its identification (Pough et al, 1998; Labra, 2011). Liolaemus lizards use 58 chemoreception (odors, feces, skin and precloacal secretions) for various social and sensory 59 purposes (Labra et al., 2002; Labra, 2008). This has allowed individuals to develop self-60 recognition (i.e., to discriminate between their own odors and those of other members of the 61 species) and to evaluate the sex of other lizards (Labra, 20...