Biology Reference
In-Depth Information
equivalent form of lifetime
monogamy, where the queen mates
a single male, who then dies before
colony foundation. In these species,
the queen continues to use the
sperm of this single male for her
entire lifetime, in some cases for
periods of over 30 years. However, it
is also true that multiple mating
occurs in some social insects, such
as honeybees, where females will
mate with 10-20 males on their
nuptial flight, and, ideally, we would
thus like a more formal test of
Boomsma's monogamy hypothesis.
Bill Hughes and colleagues did
exactly this by collecting data on
female mating frequency for 267
hymeopteran species. Amongst
these species, most were mono-
gamous, but about a quarter showed
some levels of multiple mating
(polyandry). Hughes
et al
. (2008)
then mapped these data onto a
0.7
0.6
Many social
insects are
monogamous …
0.5
0.4
Sisters
…but not all
0.3
0.2
Brothers
0.1
5
10
15
20
Number of males mated (
m
)
Fig. 13.4
The relatedness of a worker to
her sisters and brothers, plotted against the
number of times that her mother (the queen)
has mated. The relatedness of a worker to
her sisters declines from 0.75 to 0.25,
whereas the relatedness to a brother is
always 0.25 (Boxes 13.1 and 13.2).
(a)
Haplodiploidy hypothesis
(b)
Monogamy
(c)
Polyandry
Offspring
r = 0.5
Siblings
r > 0.5
Offspring
r = 0.5
Siblings
r = 0.5
Offspring
r = 0.5
Siblings
r < 0.5
Fig. 13.5
Monogamy paves the way to eusociality. (a) The haplodiploidy hypothesis relies
on individuals being more related to siblings than offspring, making siblings worth more than
offspring. As originally envisioned, this appears to have mostly been a red herring. (b) The
monogamy hypothesis emphasizes that if an individual is equally related to its siblings and its
offspring, even a very slight but consistent efficiency benefit for raising siblings translates into
a continuous selective advantage for helping. (c) Without strict monogamy, individuals are
more related to their offspring than they are to their siblings, so that a large efficiency benefit
is required in order for rearing siblings to be favoured. From West and Gardner (2010).
