Evolution of Growth Rates in Eagles: Sibling Competition Vs. Energy Considerations

摘要: Nestlings of birds that raise only one young (B1 species) grow slower than those more (B2 species). B2 species may be fast growing because sibling competition exerts a strong selective force for rapid growth. Other hypothesis have been proposed to explain the slow growth B1's. To overcome problem inherent in previous investigations comparing widely divergent ecology and phylogeny, I analyzed patterns variation group only: eagles world. fitted curves data obtained from literature some species, but most were compared using length nestlings period as an indicator rate. also collected on wild Bald Eagle (Haliaeetus leucocephalus) nestlings. investigated how postnatal related brood size, clutch mortality, body prenatal B1 found eagles. Differences foraging ecology, diet, mode development are unlikely account observed variability rate form Contrary hypothesis, was not correlated with intensity competition. Eagles regularly lay two eggs always lose chick (obligate fratricide) which such mortality or occur (facultative fratricide). Species characterized by facultative fratricide at expected their adult whereas do not. early inflection points The shape rates contrary predictions instead resulted selection reduce peak energy requirements present model effect hatching interval, species—specific rate, relative siblings, probability fratricide, suggests is important factor selecting