Experimental demonstration of the insurance value of extra eggs in an obligately siblicidal seabird
| Autor: | David J. Anderson, L. D. Clifford |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Avian clutch size
biology Reproductive success Ecology Offspring food and beverages Nazca booby biology.organism_classification Brood Siblicide embryonic structures behavior and behavior mechanisms Animal Science and Zoology Clutch Hatchling reproductive and urinary physiology Ecology Evolution Behavior and Systematics |
| Zdroj: | Behavioral Ecology. 12:340-347 |
| ISSN: | 1465-7279 |
| DOI: | 10.1093/beheco/12.3.340 |
| Popis: | A variety of organisms regularly produce more offspring than they raise. Despite the apparent energetic waste of such a reproductive tactic, overproduction may be favored by natural selection in some cases. One such case is when surplus offspring can serve as replacements, or insurance, for failed siblings. We tested the Insurance Egg Hypothesis (IEH) as an explanation for the overproduction of offspring in an obligately siblicidal seabird, the Nazca booby (Sula granti), which fledges a maximum of one nestling regardless of its clutch size. We manipulated clutch sizes within the range of natural variation encountered in this species (one–two eggs). The IEH predicts that parents with two-egg clutches should have higher reproductive success than those with one-egg clutches because the second egg can provide a nestling when the first egg fails to hatch, or when the first chick dies young. Consistent with the IEH, natural one-egg clutches that were enlarged to two eggs produced more hatchlings and fledglings than control one-egg clutches did, and natural two-egg clutches that were reduced to one egg produced fewer hatchlings and fledglings than control two-egg clutches did. We also evaluated aspects of the Individual Optimization Hypothesis, which proposes that individual optimal clutch sizes differ, as an explanation for clutch size variation in this species. In Nazca boobies, selection driven by replacement value appears to favor clutches larger than one even though final brood size is invariably one. One-egg clutches may be produced by parents experiencing some proximate limitation, such as a lack of food. Key words: clutch size, Individual Optimization Hypothesis, Insurance Egg Hypothesis, Nazca booby, siblicide, Sula granti, surplus offspring. [Behav Ecol 12:340–347 (2001)] |
| Databáze: | OpenAIRE |
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