Parental care and adaptive brood sex ratio manipulation in birds.
Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against non-significant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex-differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.
Hasselquist
Dennis
D
Department of Animal Ecology, Lund University, Ecology Building, 223 62, Sweden. dennis.hasselquist@zooekol.lu.se
Kempenaers
Bart
B
D000367:Age Factors; D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000502:physiology*; D004734:Energy Metabolism; D005247:Feeding Behavior; D005260:Female; D008297:Male; D008425:Maternal Behavior; D008954:Models, Biological; D009425:Nesting Behavior; D010152:Pair Bond; D010332:Paternal Behavior; D012737:Sex Factors; D012744:Sex Ratio