The habitat saturation hypothesis and sociality in an allodapine bee: cooperative nesting is not "making the best of a bad situation"

Bull, Nicholas J.; Schwarz, Michael P.

doi:10.1007/s002650050289

Cited by 48 publications

(48 citation statements)

References 20 publications

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“…In most primitively eusocial and cooperatively breeding Hymenoptera, it appears that helpers indeed help (e.g. Hogendoorn & Velthuis 1993;Bull & Schwarz 1996), but that colony productivity increases at a decreasing rate as helper number increases (Michener 1964;Kukuk & Sage 1994). In most of these species where reproduction has been quanti¢ed or inferred, the skew appears to be high when the mother queen is present (Packer & Owen 1994; see the review in Reeve & Keller (1995)) and some such species exhibit relatedness levels which are su¤ciently low to draw concession model predictions into question (Strassmann et al , 1994Ross & Carpenter 1991;Hughes et al 1993;Field et al 1998).…”

Section: Discussionmentioning

confidence: 99%

A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

Crespi

Ragsdale

2000

Proc. R. Soc. Lond. B

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Concession-based reproductive skew models predict that social groups can form via persuasion, whereby dominant individuals forfeit some reproduction to subordinates as an incentive to stay and help. We have developed an alternative skew model based on manipulation, whereby dominant individuals coerce subordinates into staying and helping by imposing costs on their independent reproductive prospects. Stable groups can evolve under a much wider range of genetic and ecological conditions under this manipulation model than under concession models. We describe evidence that various forms of preemptive and ongoing manipulation occur in nature and we discuss the implications of the model for the development of a general theory of social evolution.

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Section: Discussionmentioning

confidence: 99%

A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

Crespi

Ragsdale

2000

Proc. R. Soc. Lond. B

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“…Data also suggest that the ¢rst brood to eclose consists almost always of females, and Bull & Schwarz (1997) show that newly eclosed females will rear their sibs in orphaned colonies. In addition, Bull & Schwarz (1996) demonstrate that females nesting alone often fail to produce any brood at all, and they attribute this to predator pressure at the nest as the solitary female forages. The combination of these results supports the predictions of the insurance model, which suggests that females may produce individuals of the alloparental sex before unbiased production of brood as insurance on their brood in the event of their death.…”

Section: Discussionmentioning

confidence: 99%

“…However, this does not represent the frequency of colonies becoming orphaned, as a large number of excavated tunnels were recovered with no occupants at all. It is expected that an orphaned colony would lose its unguarded brood very quickly to ant predators (Bull & Schwarz 1996).…”

Section: (A) Colony Composition and E¤ciencymentioning

confidence: 99%

“…Allodapine bees rear their brood progressively in an unsealed, communal chamber, making brood highly vulnerable to predation and starvation in the event of orphaning (Bull & Schwarz 1996;Schwarz et al 1998). The insurance model hypothesizes that a mother may produce one individual (or more) of the alloparental sex as insurance on the remainder of her brood in the event of her death, followed by a switch to unbiased production of further brood.…”

Section: (A) the Insurance Modelmentioning

confidence: 99%

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Brood insurance via protogyny: a source of female-biased sex allocation

Bull

Schwarz

2001

Proc. R. Soc. Lond. B

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Sex allocation patterns and colony productivity are examined in Exoneura nigrescens, a social allodapine bee. As for previous studies on Australian allodapine bees, numerical sex ratios were strongly female biased in the smallest broods, but neared equality in larger broods. Local ¢tness enhancement has been suggested previously to explain female-biased allocation in allodapine bees. Here, we propose an alternative model, the`insurance model', which predicts protogyny and, as a consequence, female-biased sex allocation in small broods with decreasing bias in larger broods. Because allodapine broods are reared progressively in an open burrow, broods require that adult females be present throughout their development in order to survive to maturity. If mothers invest in daughters (alloparents) ¢rst, these daughters can rear younger, dependent brood in cases in which orphaning occurs. If such daughters behave as surrogate mothers, then investment in them by mothers should not be regarded as investment in female sex allocation per se, giving rise to apparently female-biased broods. The model predicts a pattern of sex ratios as a function of total brood size that very closely match empirical data from E. nigrescens.

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“…All failed nests were excluded from analysis in these studies. If solitary nests have a higher likelihood of complete nest failure, as has been found for other carpenter bees (Stark, 1992a;Bull and Schwarz, 1996), relative reproductive output of social nests might be even higher. Therefore k is larger than 2.0.…”

Section: Parameter Estimatesmentioning

confidence: 99%

Task allocation and reproductive skew in social mass provisioning carpenter bees in relation to age and size

Hogendoorn

Velthuis

1999

Insectes soc.

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SummaryThe mass provisioning carpenter bees comprise two tribes, the Xylocopini and the Ceratinini. Although social nesting occurs in both tribes, no morphological castes have evolved and females are totipotent, which makes the tribe as a whole highly suitable to test predictions of reproductive skew models. We review current information for the two tribes with respect to reproductive competition and reproductive skew and then investigate whether the observed skew fits with predictions from optimal skew theory. Social nests of Xylocopa species include a non-foraging guard and a foraging egg layer who completely dominates reproduction. Reproductive dominance is settled by aggression, and the probability of winning this fight is influenced by both age and size. In Ceratina species, task allocation is also very clear: one female guards the nest, while the other female(s) forage(s). Although the guard is usually the first to produce an egg, her eggs are frequently replaced by those of the forager, and skew is incomplete.Using comparisons between species and genera the impact of ecological constraints on solitary nesting, relative group productivity and relatedness on reproductive partitioning between dominants and subordinates are investigated in a qualitative way. In support of the optimal skew model, strong constraints on solitary nesting coincided with strong skew. However, the predicted effects of relatedness and group productivity on skew were not found. Furthermore, no support was found for the predictions of the optimal skew model that high skew coincides with frequent aggressive testing and risky task performance by subordinates.

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The habitat saturation hypothesis and sociality in an allodapine bee: cooperative nesting is not "making the best of a bad situation"

Cited by 48 publications

References 20 publications

A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

Brood insurance via protogyny: a source of female-biased sex allocation

Task allocation and reproductive skew in social mass provisioning carpenter bees in relation to age and size

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