Inconsistent inbreeding effects during lizard ontogeny

Badreddine Bererhi,Tonia S. Schwartz,Mats Olsson,Erik Wapstra

doi:10.1007/s10592-019-01180-6

Badreddine Bererhi, Tonia S. Schwartz + Show 2 more

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https://doi.org/10.1007/s10592-019-01180-6

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Abstract

Reported effects of inbreeding vary among taxa and may depend on a number of factors, including what trait is measured, temporal variability, parental effects, or life history stage. To understand the effects of inbreeding during early life history stages, we estimated the effects of individual-level heterozygosity on hatching success and first year survival in a Swedish population of sand lizards (Lacerta agilis) over a period of almost a decade, using over 4000 eggs, 400 clutches, and over 3000 juveniles. Heterozygosity had a positive effect on hatching success, in standardized laboratory conditions, but no effect on first year survival. Also, both of these measures of viability varied across the years of the study, demonstrating the importance of temporal heterogeneity in pre and post-hatching conditions. Finally, we identified both paternal and maternal identity effects on hatching success. Thus, we show that selection on heterozygosity was not consistent across developmental life stages, emphasizing the need of considering a number of ontogenic stages, as well as potential parental and environmental effects, when studying the effects of heterozygosity on viability in natural populations.

Highlights

IntroductionInbreeding–mating between genetically similar individuals—is an important phenomenon in evolutionary and conservation biology (Darwin 1868; Charlesworth and Charlesworth 1987), as it occurs in a wide range of animal and plant populations, and may lead to inbreeding depression with potentially severe fitness consequences (Keller et al 1994; Olsson et al 1996a; Crnokrak and Roff 1999; Slate et al 2000; Amos et al 2001; Keller and Waller 2002; Huisman et al 2016)
Our aim was to test the effects of inbreeding at two key life history stages in the sand lizard population of Asketunnan, Sweden
No such effect was found on first year survival

Summary

Introduction

Inbreeding–mating between genetically similar individuals—is an important phenomenon in evolutionary and conservation biology (Darwin 1868; Charlesworth and Charlesworth 1987), as it occurs in a wide range of animal and plant populations, and may lead to inbreeding depression with potentially severe fitness consequences (Keller et al 1994; Olsson et al 1996a; Crnokrak and Roff 1999; Slate et al 2000; Amos et al 2001; Keller and Waller 2002; Huisman et al 2016). Such increase in homozygosity can affect fitness negatively through two proposed mechanisms, over-dominance or partial dominance. With over-dominance, inbreeding depression occurs due to the superiority of heterozygous individuals relative to homozygous individuals at fitness-related loci. Partial dominance can cause inbreeding depression when inbred individuals become homozygous for recessive or partially recessive deleterious alleles at fitness-related loci (Charlesworth and Charlesworth 1987). In conservation biology, considering genetic factors is important for the success of conservation efforts in small populations with a reduced genetic variation (Lacy 1997; Whiteley et al 2015)

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