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Sex-Biased Hatching Order and Adaptive Population Divergence in a Passerine Bird
Alexander V. Badyaev,12*Geoffrey E. Hill,2Michelle L. Beck,2Anne A. Dervan,2Renée A. Duckworth,3Kevin J. McGraw,4Paul M. Nolan,2Linda A. Whittingham5
Most species of birds can lay only one egg per day until a clutch
is complete, and the order in which eggs are laid oftenhas strong and
sex-specific effects on offspring growth and survival.In two recently
established populations of the house finch (Carpodacusmexicanus) in Montana and Alabama, breeding females simultaneouslyadjusted the sex and growth of offspring in relation to theirposition
in the laying order, thereby reducing the mortality ofsons and
daughters by 10 to 20% in both environments. We showexperimentally
that the reduction in mortality is produced bypersistent and
sex-specific maternal effects on the growth andmorphology of
offspring. These strong parental effects may havefacilitated the rapid
adaptive divergence among populations ofhouse finches.
1 Division of Biological Sciences, University
of Montana, Missoula, MT 59812, USA.
2 Department of
Biological Sciences, Auburn University, Auburn, AL 36849, USA.
3 Biology Department, Duke University, Box 90338, Durham, NC 27708, USA.
4 Department of Neurobiology
and Behavior, Cornell University, Ithaca, NY 14853, USA.
5 Department of Biological Sciences, University of
Wisconsin, Milwaukee, WI 53201, USA.
*
Present address: Department of Ecology and Evolutionary Biology,
University of Arizona, Tucson, AZ 85721, USA.
To whom correspondence should be addressed. E-mail:
abadyaev{at}selway.umt.edu
