Abstract
Space use including territoriality and spatial arrangement within a population can reveal important information on the nature, dynamics, and evolutionary maintenance of alternative strategies in color polymorphic species. Despite the prevalence of color polymorphic species as model systems in evolutionary biology, the interaction between space use and genetic structuring of morphs within populations has rarely been examined. Here, we assess the spatial and genetic structure of male throat color morphs within a population of the tawny dragon lizard, Ctenophorus decresii. Male color morphs do not differ in morphology but differ in aggressive and antipredator behaviors as well as androgen levels. Despite these behavioral and endocrine differences, we find that color morphs do not differ in territory size, with their spatial arrangement being essentially random with respect to each other. There were no differences in genetic diversity or relatedness between morphs; however, there was significant, albeit weak, genetic differentiation between morphs, which was unrelated to geographic distance between individuals. Our results indicate potential weak barriers to gene flow between some morphs, potentially due to nonrandom pre‐ or postcopulatory mate choice or postzygotic genetic incompatibilities. However, space use, spatial structure, and nonrandom mating do not appear to be primary mechanisms maintaining color polymorphism in this system, highlighting the complexity and variation in alternative strategies associated with color polymorphism.
Highlights
This was performed for the whole population and within each color morph to test whether the genetic distribution of morphs within a population is affected by geographic distance, which could be due to dispersal behavior based on genetic similarity
Likewise, when we considered geo‐ graphic and genetic distance within each morph, there was no evi‐ dence for correlation indicating that differentiation of color morphs was not due to their spatial arrangement in either year and that morphs do not differ in dispersal distance (Supporting Information Appendix S1: Table S3)
The combined evidence of behavioral (Yewers et al, 2016) and en‐ docrinological differences (Yewers et al, 2017), morph heritability (Rankin et al, 2016), and microsatellite genetic differentiation to‐ gether suggest a genetic polymorphism in C. decresii with a suite of correlated phenotypic traits
Summary
The tawny dragon lizard, Ctenophorus decresii, is a small, sexually dimorphic agamid lizard found on rocky outcrops of the southern Flinders Ranges, Mt Lofty Ranges, and Kangaroo Island in South Australia (Houston, 1974). We performed Mantel tests of matrix correspondence in GenAlEx with a linear genetic distance matrix of individual‐by‐indi‐ vidual pairwise comparisons as the independent variable following the established protocol of Smouse, Long, and Sokal (1986) and geographic distances generated by calculating the Euclidean dis‐ tance between the centroid of territories as the dependent variable. This was performed for the whole population and within each color morph to test whether the genetic distribution of morphs within a population is affected by geographic distance, which could be due to dispersal behavior based on genetic similarity. Likewise, when we considered geo‐ graphic and genetic distance within each morph, there was no evi‐ dence for correlation indicating that differentiation of color morphs was not due to their spatial arrangement in either year and that morphs do not differ in dispersal distance (Supporting Information Appendix S1: Table S3)
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