Maternal effects due to male attractiveness affect offspring development in the zebra finch

Abstract

Maternal effects occur when offspring phenotype is influenced by environmental factors experienced by the mother. Mothers are predicted to invest differentially in offspring in ways that will maximize offspring fitness depending on the environment she expects them to encounter. Here, we test for maternal effects in response to mate attractiveness on offspring developmental traits in the zebra finch Taeniopygia guttata. We controlled for parental genetic quality by manipulating male attractiveness using coloured leg rings and by randomly assigning mating pairs. The potential confounding effect of differential nestling care was controlled for by cross-fostering clutches and by allowing for variance due to foster father attractiveness in general linear models. We found a difference in egg mass investment between attractiveness groups and, importantly, we found that all of the offspring traits we measured varied with the attractiveness of the father. This provides strong evidence for maternal effects in response to mate attractiveness. Furthermore, due to the experiment design, we can conclude that these effects were mediated by differential investment of egg resources and not due to genetic differences or differences in nestling care.

Differential allocation in relation to mate song quality in the Bengalese finch

“…In accordance with predictions of the differential allocation hypothesis (Sheldon, 2000), many previous studies in birds have reported that females paired with attractive or preferred males increased their reproductive investment by laying larger clutches or heavier eggs (e.g., peahen, Pavo cristatus: Petrie & Williams, 1993; Chinese quail, Coturnix chinensis: Uller et al, 2005; mallard, Anas platyrhynchos: Cunningham & Russell, 2000; zebra finch, Taeniopygia guttata: Balzer & Williams, 1998;Gilbert et al, 2006;Holveck & Riebel, 2010; canary, Serinus canaria: Leitner et al, 2006). In addition, it has been revealed that the attractiveness of mates affects the concentration of egg yolk components thought to contribute to the early physical development of offspring, such as testosterone (Gil et al, 1999;Gil et al, 2004; but see Mazuc et al, 2003;Michl et al, 2005) and immune factors (Saino et al, 2002b).…”

Compensatory investment in zebra finches: females lay larger eggs when paired to sexually unattractive males

“…(b) Previous studies Two previous studies have found interaction effects of male attractiveness on female investment patterns over the egg laying sequence of a clutch (Gilbert et al 2006;Williamson et al 2006). Caution is required when assessing the statistical significance of such interaction effects (see §2 and Schielzeth & Forstmeier in press).We found no interaction between male attractiveness and female investment over the lay order.…”

“…unattractive) males . Four studies have looked at effects of natural or manipulated male attractiveness on egg size and found no consistent trends (Balzer & Williams 1998;Rutstein et al 2004;von Engelhardt 2004;Gilbert et al 2006).…”

“…(i) Interaction effects on allocation Two previous studies looking at female investment in relation to male manipulated attractiveness found different investment patterns over the egg laying sequence for attractive versus unattractive males (Gilbert et al 2006;Williamson et al 2006). We therefore tested for interactions between treatment and lay order, using linear mixed effect models.…”

“…Three of these studies used artificial ornaments (i.e. colour rings) to manipulate male attractiveness and found no significant main effects, but rather two-or three-way interactions with different investment patterns for attractive versus unattractive males, either with respect to egg laying sequence (Gilbert et al 2006;Williamson et al 2006) or with respect to female mass (Rutstein et al 2004). The biological interpretation of these interactions is not straightforward.…”