Sex-Specific Correlations of Individual Heterozygosity, Parasite Load, and Scalation Asymmetry in a Sexually Dichromatic Lizard

Abstract

Heterozygosity-fitness correlations (HFCs) provide insights into the genetic bases of individual fitness variation in natural populations. However, despite decades of study, the biological significance of HFCs is still under debate. In this study, we investigated HFCs in a large population of the sexually dimorphic lizard Takydromus viridipunctatus (Lacertidae). Because of the high prevalence of parasitism from trombiculid mites in this lizard, we expect individual fitness (i.e., survival) to decrease with increasing parasite load. Furthermore, because morphological asymmetry is likely to influence individuals' mobility (i.e., limb asymmetry) and male biting ability during copulation (i.e., head asymmetry) in this species, we also hypothesize that individual fitness should decrease with increasing morphological asymmetry. Although we did not formally test the relationship between morphological asymmetry and fitness in this lizard, we demonstrated that survival decreased with increasing parasite load using a capture-mark-recapture data set. We used a separate sample of 140 lizards to test the correlations between individual heterozygosity (i.e., standardized mean d2 and HL based on 10 microsatellite loci) and the two fitness traits (i.e., parasite load and morphological asymmetry). We also evaluated and excluded the possibility that single-locus effects produced spurious HFCs. Our results suggest male-only, negative correlations between individual heterozygosity and parasite load and between individual heterozygosity and asymmetry, suggesting sex-specific, positive HFCs. Male T. viridipunctatus with higher heterozygosity tend to have lower parasite loads (i.e., higher survival) and lower asymmetry, providing a rare example of HFC in reptiles.

Tail regeneration after autotomy revives survival: a case from a long-term monitored lizard population under avian predation

“…For all individuals, we recorded their sex, age class, and tail autotomy index (see below) before uniquely tagging them by toe clipping, which is thought to be the most efficient and least stressful method for marking this kind of small lizard [43]. Our previous study suggested that there was no systematic bias in the capture procedure [41].…”

“…This behaviour is believed to prevent predation by rodents, shrews, and serpents from the ground at night. These lizards are usually non-territorial, forming extremely high population densities in suitable microhabitats with no pronounced male-male competition [39][40][41], limiting the potential for intraspecific interactions to result in tail loss. Finally, sympatric owls (Otus spp.)…”

Pairing patterns in relation to body size, genetic similarity and multilocus heterozygosity in a tropical monogamous bird species

“…We first used GLMs to analyze the relationship between wing chord and tarsus length, as well as the relationship between each morphometric variable and MLH, using each time sex as covariate (Husseneder and Simms 2008;Shaner et al 2013). We then used logistic regressions to test for the effects of tarsus length, wing chord and MLH, and those of all the interactions between these three variables, on social status (coded as a binomial variable, i.e.…”

Age‐dependent, negative heterozygosity–fitness correlations and local effects in an endangered Caribbean reptile, Iguana delicatissima

“…Many studies report significant positive HFCs (reviewed in Hansson & Westerberg, 2002; in reptiles, Shaner, Chen, Lin, Kolbe, & Lin, 2013; Phillips, Jorgenson, Jolliffe, & Richardson, 2017). However, the hypothesized reasons for these correlations are varied, and not all HFCs lend insight into inbreeding (Chapman et al., 2009).…”