Biology Reference
In-Depth Information
(1)
The behaviour really is costly to the actor, and
doesn't have some long-term direct benefit
.
Developing as a soldier is clearly costly
because all soldiers are sterile and do not
complete development to adults, paying the
ultimate sacrifice of never being able to
reproduce themselves.
(2)
Harming behaviours are directed towards
relatively unrelated individuals
.
Giron
et al
.
(2004) tested whether kin discrimination
occurred, with harming being preferentially
directed at non-relatives. They varied
relatedness by introducing either clonal
sisters (
r
= 1.0), brothers (
r
relative
Developing as a
soldier is costly,
because soldiers
are sterile
actor
non-
relative
Fig. 11.10
Spiteful harming of
another individual is favoured
when this provides a benefit to
a secondary recipient to whom
the actor is more closely related.
=
0.25) or
unrelated larvae (
r
0) into a host caterpillar
containing a developing female brood of
=
Organism
Trait
Why selfish and
not spiteful
Table 11.3
Not spite: example
behaviours that
have been
suggested as
spiteful, but are
explained much
more easily as
selfish behaviours
that provide a
direct benefit to
the actor (West &
Gardner, 2010).
Birds
Protection of territories
Reduced competition for
resources
Herring gull (
Larus
argentatus
) and western gull
(
L. occidentalis
)
Siblicide at neighbouring
nests
Reduced competition for
resources
Macaques (several species)
Harassing infant and
juvenile daughters of
others
Reduced competition for
own offspring
Macaques (stumptail,
Macaca
arctoides
)
Sexual interference
Increased reproductive
success in long term
Mammals
Infanticide
Reduced competition for
own offspring
Mountain sheep
(
Ovis Canadensis
)
Harassing injured male
Increases chance the
harassed male dies, so
reduces competition for
mates in next breeding
season
Sticklebacks
Egg cannibalism
Reduced competition for
own offspring
