Biology Reference
In-Depth Information
BOX 13.2 COEFFICIENTS OF RELATEDNESS,
r
, IN HAPLODIPLOID
SPECIES WHEN FEMALES MATE MULTIPLY
When haplodiploid queens mate multiple males, this reduces the relatedness of
her daughters to their sisters, but not to their brothers. The methods are as in
Box 13.1, with the only difference being that females are assumed to have mated
a large number of males, such that offspring are half-siblings, who only share
genes through their mother.
Examples
(a) Sister-sister
Half of a female's genes comes from the father; the
probability that a copy of one of these is shared with the
sister is zero because the sister has another father. The
other half comes from the mother; the probability that
a copy of one of these is shared is 0.5.
+
½
½
+
+
Via mother
=
(0.5
×
0.5)
+
Via father
=
(0.5
×
0);
r
=
0.25
(b) Sister-brother
A female is linked to her brother only via her mother, as her
brother develops from an unfertilized egg. Half of her genes
come from her mother; the probability that a copy of one of
these is shared is 0.5. The other half come from her father;
the probability that a copy of one of these is shared is zero.
+
½
½
½
+
Via mother (0.5
×
0.5)
+
Via father (0.5
×
0); r
=
0.25
The relatedness of brothers to their sisters and brother is
unchanged from that in Box 13.1 (part b) because males
obtain all of their genes from their mothers.
(c) Sister-nephew (or niece)
A female shares 0.25 of her genes with her sister, who
passes on one half of her genes to her son.
+
½
½
½
+
+
½
½
+
Via reproduction of sister
=
(0.25
×
0.5);
r
=
0.125
population cannot even get started on the road to eusociality, although looser forms
such as cooperative breeding can be maintained.
A possible role of monogamy is supported by the observation of lifetime monogamy in
many eusocial species (Boomsma, 2007). In most termites physical lifetime monogamy
is the default option, with a queen committing to a single male when founding a nest,
after which they remain together. Many ants, bees and wasps have a functionally
