Maternal effects on anogenital distance in a wild marmot population

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Maternal effects on anogenital distance in a wild marmot population.

In mammals, prenatal exposure to sex steroid hormones may have profound effects on later behavior and fitness and have been reported under both laboratory and field conditions. Anogenital distance is a non-invasive measure of prenatal exposure to sex steroid hormones. While we know that intra-uterine position and litter sex ratio influence anogenital distance, there are other, heretofore unstudied, factors that could influence anogenital distance, including maternal effects. We capitalized on a long-term study of wild yellow-bellied marmots (Marmota flaviventris) to study the importance of maternal effects on explaining variation in anogenital distance and found significant effects. The strength of these effects varied annually. Taken together, our data highlights the strong variability due to environmental effects, and illustrates the importance of additive genetic and maternal genetic effects on neonatal anogenital distance. We suspect that, as others apply recently popularised quantitative genetic techniques to study free-living populations, such effects will be identified in other systems

Variance ratio and components estimated for random effects from anogenital distance models of juvenile marmots.

<p>The random effects were additive genetic (AG), maternal genetic (MG), maternal environmental (ME), litter (L) and year (Y) effects. N indicates that an effect was not fitted in the model and a 0 indicates that the effect was fitted but estimated as zero. * indicates significant effects.</p

Estimates (with standard error) of the fixed effects on anogenital distance of juvenile yellow-bellied marmots studied at the Rocky Mountain Biological Laboratory.

<p>Estimates significantly different from zero are in bold.</p><p>*: Females taken as reference</p>†<p>: N males: N total</p><p>DF: numerator, denominator degrees of freedom</p><p>F-cond: conditional Wald F-test</p