Support for maternal manipulation of developmental nutrition in a facultatively eusocial bee, Megalopta genalis (Halictidae)

One of the hallmarks of eusociality is that workers forego their own reproduction to assist their mother in raising siblings. This seemingly altruistic behaviour may benefit workers if gains in indirect fitness from rearing siblings outweigh the loss of direct fitness. If worker presence is advantageous to mothers, however, eusociality may evolve without net benefits to workers. Indirect fitness benefits are often cited as evidence for the importance of inclusive fitness in eusociality, but have rarely been measured in natural populations. We compared inclusive fitness of alternative social strategies in the tropical sweat bee, Megalopta genalis , for which eusociality is optional. Our results show that workers have significantly lower inclusive fitness than females that found their own nests. In mathematical simulations based on M. genalis field data, eusociality cannot evolve with reduced intra-nest relatedness. The simulated distribution of alternative social strategies matched observed distributions of M. genalis social strategies when helping behaviour was simulated as the result of maternal manipulation, but not as worker altruism. Thus, eusociality in M. genalis is best explained through kin selection, but the underlying mechanism is likely maternal manipulation.

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A review of deviant phenotypes in bees in relation to brood parasitism, and a gynandromorph of Megalopta genalis (Hymenoptera: Halictidae)

Journal of Natural History ◽

10.1080/0022293031000155322</doi> ◽

2004 ◽

Vol 38 (11) ◽

pp. 1443-1457 ◽

Cited By ~ 1

Author(s):

W. T. WCISLO ◽

V. H. GONZALEZ ◽

ARNESON L.

Keyword(s):

Brood Parasitism ◽

Megalopta Genalis

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Juvenile hormone levels reflect social opportunities in the facultatively eusocial sweat bee Megalopta genalis (Hymenoptera: Halictidae)

Hormones and Behavior ◽

10.1016/j.yhbeh.2012.08.012 ◽

2013 ◽

Vol 63 (1) ◽

pp. 1-4 ◽

Cited By ~ 31

Author(s):

Adam R. Smith ◽

Karen M. Kapheim ◽

Betzi Pérez-Ortega ◽

Colin S. Brent ◽

William T. Wcislo

Keyword(s):

Juvenile Hormone ◽

Sweat Bee ◽

Hormone Levels ◽

Megalopta Genalis ◽

Social Opportunities

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Stable eusociality via maternal manipulation when resistance is costless

10.1101/019877 ◽

2015 ◽

Author(s):

Mauricio González-Forero

Keyword(s):

Mathematical Model ◽

Resource Allocation ◽

Maternal Care ◽

Honest Signaling ◽

Queen Pheromones ◽

Honest Signals ◽

Long Run ◽

Maternal Manipulation ◽

Selection For ◽

Eusocial Species

In many eusocial species, queens use pheromones to influence offspring to express worker phenotypes. While evidence suggests that queen pheromones are honest signals of the queen's reproductive health, here I show that queen's honest signaling can result from ancestral maternal manipulation. I develop a mathematical model to study the coevolution of maternal manipulation, offspring resistance to manipulation, and maternal resource allocation. I assume that (1) maternal manipulation causes offspring to be workers against offspring's interests; (2) offspring can resist at no direct cost, as is thought to be the case with pheromonal manipulation; and (3) the mother chooses how much resource to allocate to fertility and maternal care. In the coevolution of these traits, I find that maternal care decreases, thereby increasing the benefit that offspring obtain from help, which in the long run eliminates selection for resistance. Consequently, ancestral maternal manipulation yields stable eusociality despite costless resistance. Additionally, ancestral manipulation in the long run becomes honest signaling that induces offspring to help. These results indicate that both eusociality and its commonly associated queen honest signaling can be likely to originate from ancestral manipulation.

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