Parents are expected to invest more in the sex that benefits most from the local environment. When the quality of breeding sites varies spatially and natal dispersal of males and females differs, parents in high-quality habitats should skew their progeny sex ratio in favor of the less dispersing sex. We tested this prediction in the barn swallow (Hirundo rustica L.), by relating the proportion of male offspring around fledging (secondary sex ratio) of first and second broods to the ecological quality (presence of livestock farming and relative surface of hayfields in the foraging range) and local demographic trends of the farms where the colonies were located. Consistent with our predictions, the proportion of male offspring, which are more philopatric than females, increased with the extent of hayfields, which are high quality, preferred foraging habitats. Moreover, the proportion of male offspring in second broods was smaller in colonies with positive demographic trends, possibly indicating density-dependent effects on sex ratio. Independent of the mechanism generating uneven sex ratio (zygote sex ratio adjustment or sex-related pre-fledging mortality), barn swallows breeding under favorable conditions overproduced the sex that is more likely to benefit from such conditions.

Romano, A., Ambrosini, R., Caprioli, M., Bonisoli Alquati, A., Saino, N. (2012). Secondary sex ratio covaries with demographic trends and ecological conditions in the barn swallow. EVOLUTIONARY ECOLOGY, 26, 1041-1053 [10.1007/s10682-011-9543-1].

Secondary sex ratio covaries with demographic trends and ecological conditions in the barn swallow

AMBROSINI, ROBERTO;
2012

Abstract

Parents are expected to invest more in the sex that benefits most from the local environment. When the quality of breeding sites varies spatially and natal dispersal of males and females differs, parents in high-quality habitats should skew their progeny sex ratio in favor of the less dispersing sex. We tested this prediction in the barn swallow (Hirundo rustica L.), by relating the proportion of male offspring around fledging (secondary sex ratio) of first and second broods to the ecological quality (presence of livestock farming and relative surface of hayfields in the foraging range) and local demographic trends of the farms where the colonies were located. Consistent with our predictions, the proportion of male offspring, which are more philopatric than females, increased with the extent of hayfields, which are high quality, preferred foraging habitats. Moreover, the proportion of male offspring in second broods was smaller in colonies with positive demographic trends, possibly indicating density-dependent effects on sex ratio. Independent of the mechanism generating uneven sex ratio (zygote sex ratio adjustment or sex-related pre-fledging mortality), barn swallows breeding under favorable conditions overproduced the sex that is more likely to benefit from such conditions.
Articolo in rivista - Articolo scientifico
Sex allocation, Natal dispersal, Demographic trend, Habitat quality, Julliard’s model
English
2012
26
1041
1053
none
Romano, A., Ambrosini, R., Caprioli, M., Bonisoli Alquati, A., Saino, N. (2012). Secondary sex ratio covaries with demographic trends and ecological conditions in the barn swallow. EVOLUTIONARY ECOLOGY, 26, 1041-1053 [10.1007/s10682-011-9543-1].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/39119
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