Biology Reference
In-Depth Information
Polistes chenesis
30
Dolichovespula saxonica
10
Vespula rufa
D. sylvestris
D. norwegica
D. media
5
Vespa crabro
Vespula germanica
Vespula vulgaris
Apis melifera
0
30 50
70
80
90
95
98
99
100
Effectiveness of policing (%)
Fig. 13.16 Policing enforces altruism. Lower levels of worker reproduction are observed
in wasp and bee species where worker policing is more effective. From Wenseleers and
Ratnieks (2006). With permission of the University of Chicago Press. Photograph shows
the common wasp Vespula vulgaris , which has highly effective worker policing (queens
mate multiply) and low levels of worker reproduction. Photo © Tom Wenseleers.
conflicts within colonies but the importance of these can be reduced by policing.
Furthermore, many traits, such as foraging, waste removal and so on, can be completely
understood from the perspective of the good of the colony (i.e. as if workers were trying
to maximize colony productivity). However, this concept of a superorganism sounds
dangerously like Wynne-Edwards' idea of group selection, that we explained was wrong
in Chapter 2. How can we reconcile this apparent contradiction?
Andy Gardner and Alan Grafen (2009) addressed this problem theoretically, by
asking when natural selection would lead to individuals behaving in a way that
maximizes the fitness of the colony or group. They found that this could occur, but only
in the restrictive conditions where either relatedness within colonies was sufficiently
high (as would be the case with monogamous mating) or policing was so effective that
it completely removed any benefit of more selfish behaviour such as worker reproduction
within colonies (as would be the case with high levels of policing). So, given the high
relatedness and/or effective policing that can occur in many of the eusocial insects
(especially those that are obligately eusocial), it does seem valid to think of colonies of
species such as the honey bee as a superorganism! The key point here is that behaving
for the good of the colony can be selected for under restrictive conditions, but it is not a
general evolutionary principle - the general principle is that individuals should
maximize their inclusive fitness.
Can we think of
social insect
colonies as a
superorganism?
Comparison of vertebrates with insects
With the possible exception of naked mole-rats, there are no known examples of sterile
castes in vertebrates, but in other respects there are some close parallels between the
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