Insect flight

Environmental factors play a key role in the expression of phenotypic traits and life-history decisions, specifically when they act during early development. In birds, brood size is such an important environmental factor affecting development. Experimental manipulation of brood sizes can result in reduced offspring condition, indicating that conditions during development in enlarged broods have consequences within the affected generation. But it is unclear whether stress during early development can have fitness consequences extending into the offspring of the next generation. To study such trans-generational fitness effects, a team of researchers from the University of Bielefeld, Germany, and the Museum of Natural Sciences in Madrid, report a breeding experiment with zebra finches (Taeniopygia guttata) in which mothers had been raised in different experimental brood sizes (Proceedings of the Royal Society, series B, published online). The researchers, led by Marc Naguib, found that adult females were smaller as experimental brood sizes in which their mother had been raised increased. Hatching and fledging success of daughters decreased with increasing maternal brood size. These results illustrate that early developmental stress can have long-lasting effects on reproductive success of future generations. “Such trans-generational effects can be life-history responses adapted to environmental conditions experienced in early life,” the authors report.