Tick parasitism impairs contest behavior in the western fence lizard (Sceloporus occidentalis)

Natural parasites in conjunction with behavioral and color traits explain male agonistic behaviors in a lizard

“…Although previous studies failed to find a significant relationship between the blue coloration and male aggression indices in S. occidentalis ( Seddon and Hews 2016 ; Lanser et al 2021 ), blue chroma in the genus Sceloporus increases with increasing melanin in the skin ( Quinn and Hews 2003 ), which in turn, increases with testosterone levels ( Cox et al 2008 but see Zúñiga-Vega et al 2021 ). As in other animals, testosterone levels and melanin are positively associated with aggression and physical performance in lizards ( Huyghe et al 2005 ; Raia et al 2010 ; Abalos et al 2016 , but also see Seddon and Hews 2016 ).…”

“…Lizards infested by ticks performed more pushups. Moderate to severe infestations by black-legged ticks can impair physiological and behavioral traits of S. occidentalis ( Dunlap and Mathies 1993 ; Megía-Palma et al 2020 ; Lanser et al 2021 ). However, infestations of 5–7 nymphal ticks may have only a moderate impact on the lizards ( Dunlap and Mathies 1993 ; Megía-Palma et al 2020 ).…”

“…Although cryptic and photoprotective colorations are expected to evolve in ecological contexts of high predation and/or solar radiation (e.g., Reguera et al 2014 ; Dunn et al 2015 ; Marshall et al 2015 ), sexual selection can promote the evolution of conspicuous color patches and complex display behaviors ( Emlen and Oring 1977 ; Andersson 1994 ; Ord et al 2001 ; Stuart-Fox and Ord 2004 ; Griffith and Pryke 2006 ; Pérez i de Lanuza et al 2013 ). In this sense, color and behavioral traits in lizards may broadcast health status and quality to conspecifics ( Swierk and Langkilde 2013 ; Assis et al 2018 , 2021 ) because physical displays and color patch production are energetically demanding processes ( Martins 1993 ; Megía-Palma et al 2018 ; Lanser et al 2021 ). Thus, contest behavior in lizards conforms to a cost–benefit model; fights increase mating opportunities for dominant lizards, but may also result in injuries, energy imbalance, and greater exposure to both predators and some parasites ( Christenson and Goist 1979 ; Lane et al 2010 ).…”

“…Parasites draw resources from their hosts and some parasitic infections may thus reduce traits contributing to male reproductive success (e.g., Mulvey and Aho 1993 ), including agonistic behavior ( Innocenti et al 2003 ; Lanser et al 2021 ). Thus, parasitic infections can have a negative effect on the host physical performance (reviewed in McElroy and Buron 2014 ).…”

“…This effect has been more profusely studied in fish hosts; however, the available evidence is mixed ( Hamilton and Poulin 1995 ; Barber 2002 ; Mikheev et al 2010 ). Malarial parasites and ticks can impair the male agonistic behaviors of lizards ( Schall and Dearing 1987 ; Lanser et al 2021 ). Nevertheless, positive relationships between parasite load and both pigmentation of color patches and aggression, 2 correlates of reproductive effort in lizards, also suggest that reproductive investment can increase the susceptibility of male lizards to some parasites ( Megía-Palma et al 2021 ; Payne et al 2021 ).…”