Hatching asynchrony as a bet‐hedging strategy – an offspring diversity hypothesis

Laaksonen, Toni

doi:10.1111/j.0030-1299.2004.12858.x

Cited by 47 publications

(42 citation statements)

References 43 publications

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“…Size hierarchy is unrelated to hatching asynchrony but to egg size In many birds, hatching asynchrony is the key factor establishing intra-brood size hierarchies (Magrath 1992;Stokland and Amundsen 1988;Viñuela 2000;Laaksonen 2004). In Giant Babaxes, the size hierarchy is largely the result of variation in egg size that varies with laying order.…”

Section: Discussionmentioning

confidence: 99%

Giant Babaxes mix brood reduction and brood survival strategies

Liu

Guan

et al. 2011

J Ornithol

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Altricial birds may vary their relative reproductive investment at the egg versus nestling stages as an adaptive strategy to deal with variable or unpredictable food availability between stages. We investigated the parental investment strategies of Giant Babax (Babax waddelli) breeding in a harsh, high-altitude environment on the Tibetan plateau. In the modal clutch size of three, egg size declined strongly with laying order, resulting in an intra-brood size hierarchy throughout the nestling period. However, provisioners counteracted the initial handicapping of smaller, last-hatching young by two means: (1) preventing siblings from competing over a predictable feeding site; and (2) preferentially feeding the smallest nestling. Consequently, nestling growth curves differed near significantly by hatching order. We suggest this contrasting investment during the egg and nestling stages may be a strategy to maximize reproductive success in a harsh and unpredictable, high-altitude environment. The handicapping of last-laid eggs provides the opportunity for more efficient brood reduction in unfavorable conditions, but can be counteracted by preferential feeding under favorable conditions.Keywords Babax waddelli Á Parental investment strategy Á Brood reduction Á Brood survival Á Size hierarchy Zusammenfassung Riesenbabaxe (Babax waddelli) vermischen Strategien zum Brutverkleinern und Brutü berlebenNesthocker variieren ihre relativen Fortpflanzungs-Investitionen während der Ei-und Nestlings-Phasen als eine Anpassungsstrategie, um das wechselnde, oder nicht vorhersagbare, Nahrungsangebot in den unterschiedlichen Stadien in den Griff zu bekommen. Wir untersuchten die elterlichen Investitionsstrategien des in einer rauen Umgebung auf dem Tibetischen Hochplateau brütenden Riesenbabax. Bei einer modalen Gelegegröße von drei Eiern nahm die Größe der Eier stark mit der Reihenfolge, in der sie gelegt wurden, ab, was in einer brutinternen Größen-Hierarchie während der gesamten Nestlingszeit resultierte. Die Fütternden wirkten diesem anfänglichen Handicap der kleineren, später geschlüpften Jungen aber auf zwei Arten entgegen, indem sie: (1) die Jungen davon abhielten, an einem Futterplatz miteinander zu konkurrieren und (2) die kleineren Nestlinge beim Füttern bevorzugten. Die Wachstumskurven der Nestlinge unterschieden sich beinahe signifikant entsprechend der Reihenfolge des Schlüpfens. Unserer Meinung nach könnte dieses sich voneinander abhebende Investieren während der Ei-und Schlüpf-Stadien eine Strategie zur Maximierung des Fortpflanzungserfolgs in einer rauen, unberechenbaren und hoch gelegenen Umwelt sein. Diese Benachteiligung der später gelegten Eier bietet eine Gelegenheit für eine effizientere Brutverkleinerung bei ungünstigen Bedingungen, der aber bei günstigen Bedingungen durch eine Bevorzugung beim Füttern entgegengesteuert werden kann. Communicated by T.

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Section: Discussionmentioning

confidence: 99%

Giant Babaxes mix brood reduction and brood survival strategies

Liu

Guan

et al. 2011

J Ornithol

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“…when food is limited (Lack 1947; Amundsen & Slagsvold 1998). However, when food is abundant and parents can rear the full brood, hatching asynchrony reduces phenotypic quality of late‐hatching nestlings (Forbes 1994; but see Laaksonen 2004). In our study, the positive effect of yolk testosterone on body mass was found mainly in nestlings at the end of the size hierarchy.…”

Section: Discussionmentioning

confidence: 99%

Maternal yolk testosterone does not modulate parasite susceptibility or immune function in great tit nestlings

Tschirren

Saladin

Fitze

et al. 2005

Journal of Animal Ecology

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Summary 1.Maternal yolk hormones can enhance the development and phenotypic quality of nestling birds. Nevertheless, within species large differences in yolk androgen concentrations among clutches are observed. This differential allocation of maternal yolk hormones might be explained by a trade-off between beneficial effects of yolk androgens and their associated costs. 2. Potential costs include an increased susceptibility to parasites in nestlings exposed to high concentrations of yolk androgens during embryonic development, weaker immune response or increased levels of circulating corticosterone that indirectly reduce immune function. 3. In a field study, we manipulated yolk testosterone in great tit ( Parus major ) eggs and tested the nestling's susceptibility to ectoparasites as measured by the parasites' effect on growth, the cellular immune response, and the levels of circulating corticosterone. 4. At the end of the nestling period, nestlings originating from testosterone-injected eggs were heavier than control nestlings. This effect was strongest in nestlings at the end of the size hierarchy, as shown by a significant interaction between hormone treatment and the nestlings' size rank within nests. 5. High levels of yolk testosterone promoted growth of the nestling's body mass similarly in parasite-infested and parasite-free nests, and neither affected the levels of plasma corticosterone, nor the nestling's cell-mediated immune response. 6. In summary, our results do not show negative short-term effects of high concentrations of yolk testosterone on immune function or parasite susceptibility, but emphasize that maternal investment via deposition of yolk testosterone can promote fitnessrelated growth and development of nestlings.

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“…Polymorphic dispersal profiles have been argued to be adaptive for mothers, ensuring that offspring are spread throughout a range of habitats, ameliorating risk and mitigating intraspecific competition (Raimondi and Keough, 1990;Strathmann, 1974). Similarly, Laaksonen (Laaksonen, 2004) argues that hatching asynchrony is an adaptive strategy in birds that maximizes parental fitness by reducing variation in the success of their offspring (i.e. bet-hedging).…”

Section: Implications For Dispersalmentioning

confidence: 99%

Larval size and age affect colonization in a marine invertebrate

Marshall

Steinberg

2014

Journal of Experimental Biology

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The relationship between offspring size and performance determines the optimal trade-off between producing many small offspring or fewer large offspring and the existence of this relationship has become a central tenet of life-history theory. For organisms with multiple life-history stages, the relationship between offspring size and performance is determined by the effects of offspring size in each life-history stage. Marine invertebrates have long been a model system for examining the evolutionary ecology of offspring size, and whilst offspring size effects have been found in several life-history stages, the crucial stage of colonization has received less attention. We examined the effect of offspring size on the settlement response of sea-urchin larvae (Heliocidaris erythrogramma) to preferred and less preferred host plants, how these effects changed over the larval period and estimated the success of juveniles in the field on preferred and less-preferred host plants. We found that smaller larvae became competent to respond to preferred host plant cues sooner than larger larvae but larger larvae rejected less-preferred host plants for longer than smaller larvae. Overall, smaller H. erythrogramma larvae are likely to have less dispersal potential and are more likely to settle in less-preferred habitats whereas larger larvae appear to have an obligately longer dispersal period but settle in preferred habitats. Our results suggest that marine invertebrates that produce non-feeding larvae may have the potential to affect the dispersal of their offspring in previously unanticipated ways and that offspring size is subject to a complex web of selection across life-history stages.

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Hatching asynchrony as a bet‐hedging strategy – an offspring diversity hypothesis

Cited by 47 publications

References 43 publications

Giant Babaxes mix brood reduction and brood survival strategies

Giant Babaxes mix brood reduction and brood survival strategies

Maternal yolk testosterone does not modulate parasite susceptibility or immune function in great tit nestlings

Larval size and age affect colonization in a marine invertebrate

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