Between and within clutch variation of egg size in greater rheas
We describe egg characteristics, and analyze between and within clutch variation in egg size and mass in a natural population of Greater Rheas (Rhea americana). We assess the effect of this variation on nesting success and egg success. Yolk represented 29.5% of egg mass whereas albumen was 63.9%. Yo...
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| Autores principales: | , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_15594491_v120_n4_p674_Fernandez |
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| Sumario: | We describe egg characteristics, and analyze between and within clutch variation in egg size and mass in a natural population of Greater Rheas (Rhea americana). We assess the effect of this variation on nesting success and egg success. Yolk represented 29.5% of egg mass whereas albumen was 63.9%. Yolk mass increased with egg width but not with egg length, while mass of albumen increased mainly with egg length. The largest and smallest eggs were 10.3% larger and 25.3% smaller, respectively than mean intra-clutch values. The widest egg was 11.9% wider while the narrowest egg was 20.5% narrower than mean intra-clutch values. There was a significant decrease in egg size between clutches during the breeding season as a result of a decrease in egg length. There was no effect of laying order on intra-clutch variation in egg size, but we detected an increase in the variation of egg length within clutches with clutch size. We did not detect a relationship between egg size and nesting success, and between egg size and egg success. The relatively low intra-clutch variation in egg size and lack of effect of egg size on hatching success do not support the hypothesis that females invest in eggs according to expected chick fitness. |
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