Male throat colour polymorphism is related to differences in space use and in habitat selection in tree lizards

Abstract

Habitat selection is the disproportionate use of some habitats relative to their availability and is used by animals to maximize fitness. Habitat selection has been the dominant framework for predicting the spatial distribution of animals, but different habitat selection strategies can occur within a population when there are physical or behavioural differences between individuals. Colour polymorphism is often linked to differences in other behavioural and morphological traits, and may therefore affect habitat selection strategy. Male ornate tree lizards (Urosaurus ornatus) exhibit a throat colour polymorphism associated with differences in behaviour and in reproductive strategy. Blue‐throated males are dominant and defend home ranges containing several females; orange‐throated males are either nomadic or sedentary and do not defend territories; and yellow‐ or green‐throated males are reproductive parasites that sneak copulations with females. We tested the hypothesis that throat colour in tree lizards affects habitat selection and space use with mark‐recapture data collected from 10 sites in the Chiricahua Mountains of southeastern Arizona, USA. We found that males with green throats moved more than males with blue throats, and that males with orange throats occupied smaller home ranges. Male ornate tree lizards were closer to the highest quality habitat than if their spatial distribution was random, and green‐throated males had a more marked preference for the highest quality habitat than blue‐throated males. We found no difference in the departures of body temperatures from the preferred body temperature range between males of different throat colours. Survival rates were similar for blue‐, green‐ and orange‐throated males. We demonstrated that throat colour polymorphism in ornate tree lizards is related to habitat selection strategy and this may help maintain the colour polymorphism.

Comparative morphology and trophic ecology in a population of the polymorphic lizard Sceloporus minor (Squamata: Phrynosomatidae) from central Mexico

“…The presence of two or more color morphs (polymorphism) among individuals of the same sex and population is a topic that has received increasing attention from researchers in recent years (Sinervo et al, 2000; Zamudio & Sinervo, 2000; Hamilton & Sullivan, 2005; Bastiaans et al, 2013; Olsson, Stuart-Fox & Ballen, 2013; Lattanzio & Miles, 2016; Scali et al, 2016; McDiarmid et al, 2017; Paterson & Blouin-Demers, 2018). Many of these studies attempt to identify the processes that lead to the evolution and maintenance of links between alternative color morphs and morph-specific behavioral strategies (Sinervo & Lively, 1996; Sinervo et al, 2000; Zamudio & Sinervo, 2000).…”

“…Maintaining the polymorphism requires that each morph achieve equal fitness over a long period of time (Gross, 1996; Taborsky, Oliveira & Brockmann, 2008). This balance can be achieved through two processes, niche partitioning (Skúlason & Smith, 1995; Lattanzio & Miles, 2016; Scali et al, 2016; Paterson & Blouin-Demers, 2018), and frequency-dependent selection (Sinervo & Lively, 1996; Pryke et al, 2007).…”

Space use and genetic structure do not maintain color polymorphism in a species with alternative behavioral strategies

“…Rather, the greater potential territory overlaps in 2011 may reflect environmental conditions with 2012 being much hotter and drier than 2011 (The Bureau of Meterology, ). In tree lizards, orange males are nomadic in drought years but not normal years (Moore et al, ; Paterson & Blouin‐Demers, ). However, we found no evidence that C. decresii color morphs responded differently to the different environmental conditions in the 2 years we sampled.…”

“…For example, in the white‐throated sparrow Zonotrichia albicollis , the promiscuous, aggressive white male morph settles in high‐density areas where the potential to encounter mates is highest, whereas the mate guarding tan male morph is found in low‐density areas where the risk of intruders is lower (Formica, Gonser, Ramsay, & Tuttle, ). Despite the importance of space use in maintaining polymorphism, detailed data on territory size, overlap, and spatial arrangement exist for a limited number of polymorphic systems (but see Calsbeek & Sinervo, , Olsson, Wapstra, Healey, Schwartz, & Uller, , Paterson & Blouin‐Demers, , Sinervo, Chaine, et al, ).…”

“…For example, in side‐blotched lizards ( Uta stansburiana ), dominant orange males control and defend the largest territories (Sinervo & Lively, ; Zamudio & Sinervo, ; Sinervo et al 2000, 2006; Calsbeek & Sinervo, ); whereas in tree lizards ( Urosuarus ornatus ), dominant blue males defend small, defined territories compared to males of the other morphs (Lattanzio & Miles, ; Thompson & Moore, ), and in painted dragons ( Ctenophorus pictus ), the territory size of dominant red males is no bigger than that of yellow males (Olsson et al, ). Furthermore, in tree lizards, the least dominant orange morph may be territorial or nomadic depending on resources, which vary between years (Moore, Hews, & Knapp, ; Paterson & Blouin‐Demers, ). In addition to territory size, we assessed the spatial arrangement of individuals to test whether males of each morph are located in the population in a nonrandom way, indicative of dispersal behaviors or population dynamics.…”