Maternal Inheritance and Rapid Evolution of Sexual Size Dimorphism: Passive Effects or Active Strategies?

Abstract

Adaptive evolution is often strongly influenced by maternal inheritance that transfers the parental strategies across generations. The consequences of maternal effects for the offspring generation depend on the between-generation similarity in environments and on the evolved sensitivity of the offspring's ontogeny to maternal effects. When these factors differ between sons and daughters, maternal effects can influence the evolution of sexual dimorphism. The establishment of house finch populations across western Montana during the last 30 years was accompanied by rapid evolutionary change in sexual size dimorphism. Here I show that traits that changed the most across generations were most influenced by maternal effects in males but not females. Maternal effects differentially affected sons' and daughters' survival; greater maternal effects were commonly associated with higher survival of sons, especially when maternal and offspring environments were similar. Stronger maternal effects extended preselection phenotypic variance in morphological traits of males, thereby producing some locally adaptive phenotypes and lessening juvenile mortality. Thus, the observed sex-specific maternal effects and their contribution to the evolution of sexual size dimorphism are likely a passive consequence of the distinct sensitivity of sons and daughters to maternal adaptations to breeding in ecologically distinct parts of the house finch's expanding range.

Heritability of dispersal rate and other life history traits in the Glanville fritillary butterfly

“…Recent studies on birds have shown that maternal effects can be strongly sex-specific and apparently play an important role in the evolution of sexual dimorphism (Badyaev, 2005;Badyaev et al, 2005Badyaev et al, , 2006. Sex-specific maternal effects can arise by for example, mothers allocating variable amounts of nutrients or hormones to sons and daughters in relation to their own condition (Badyaev et al, , 2006.…”

The beak of the other finch: coevolution of genetic covariance structure and developmental modularity during adaptive evolution

“…Pairing and nesting affiliations of breeding adults were reliably determined with observations, filming on the nests, and confirmed with genotyping (Oh & Badyaev 2006). Complete census of marked individuals, strong fidelity of adult house finches to the location of previous breeding and the isolation of the study site allowed us to follow individual birds from hatching to up to 10 years of age, monitor population size precisely and construct accurate pedigrees (references in Badyaev 2005). Breeding resident population (breeding pairs and single adults between nesting attempts) averaged n ¼ 324 birds per year and varied from n ¼ 218 birds during the fifth generation to n ¼ 628 birds in the 11th generation.…”

Maternal effects and range expansion: a key factor in a dynamic process?

“…The house finch, a species that is native to the southwestern deserts of the US, has recently expanded its range to encompass the entire continental US and parts of southern Canada. Badyaev (2005a) have shown that maternal effects are crucial to population persistence by enabling this passerine bird to survive under novel climactic conditions at the extremes of its range. In particular, breeding females modify the onset of incubation in each population differently depending on ambient temperatures during breeding, and, in turn, this produces sex biases in the laying order that ultimately act to increase variance in offspring morphology (Badyaev et al 2003).…”