Chapter 13 Opener: Weaver ants form superbly cooperative societies
This chapter
is about the
evolution of
social
behavior.
13.1 The energy budget of “helpers” in Neolamprologus pulcher (Part 2)
This species of fish is a type of cichlid (not the variety discussed earlier, but
very similar), and will display a wide range of biparental care behaviors.
In the above scenario, we are seeing an even more complex grouping whereby
some non-reproductive fish become “helpers” at the nest site.
13.1 The energy budget of “helpers” in Neolamprologus pulcher (Part 1)
The role of the helper is primarily to perform
“submissive” behaviors around the nesting
site.
13.2 Effect of removal of the top-ranked subordinate helper in a cooperatively breeding group
In this, another cichlid
species, the change in
patterns seen in helper fish
where the head subordinate
(HS) is removed is shown.
The HS removal changes
dramatically the boundaries
traveled by the other five
“helper” fish.
13.3 Reproductive interference in a social animal
The acorn
woodpecker is a
bird species that
lives in a
communal nesting
site. Here we
have
REPRODUCTIVE
INTERFERENCE
being shown
where the bird
removes a
nestmate’s egg.
13.5 Effect of parasites on cliff swallow nestlings
From a nest infested with
swallow bugs… note
small size.
From a nest
treated with
insecticide.
13.6 Social living with defensive benefits?
Schooling of fish (these are striped catfish) can reduce predation
pressures and increase survivability of individuals.
13.8 The different categories of helping behavior
Fitness consequences of
different helping behaviors.
13.10 Cooperative courtship of the long-tailed manakin
Alpha male mates with all females.
Beta male mates with none.
Other subordninates mate with none.
13.11 Cooperation with an eventual payoff
13.12 A meerkat sentinel on the alert for approaching predators
Reciprocity hypothesis – the
idea that there is reciprocal
altruism in which a helpful
action is repaid at a later date
by the recipient of the
assistance.
13.13 Reciprocity in a social primate
Grooming is one example of a relatively low cost form of reciprocity.
13.14 Experimental demonstration of reciprocity in cotton-top tamarins (Part 1)
Tamarin helper (right)
can drag food to its
partner. Or the Tamarin
helper may be nonresponsive.
13.15 The prisoner’s dilemma
Aka: Game Theory
Direct fitness – fitness gained through
reproduction
Indirect fitness – fitness gained by helping “kin”
Inclusive fitness – the combination of direct and
indirect fittness
Hamilton’s rule – a rare altruistic allele can
become more common in a population only if the
indirect fitness gained by the altruist is greater
than the direct fitness it loses as a result of the
self-sacrificing actions.
13.18 Altruism and relatedness in pied kingfishers
Primary helpers are
related to the
breeders whereas the
secondary helpers are
not.
13.23 Haplodiploid sex determination in Hymenoptera (Part 2)
13.23 Haplodiploid sex determination in Hymenoptera (Part 3)
13.24 Conflict within ant colonies over reproduction
The center ant is
covered with the
sting scent of the
queen to identify
her as becoming
reproductive.
The three worker
ants hold her in
position to
prevent
reproduction.
A single ant
iimpobolizes another
ant whose ovaries
have begun to
mature.
13.27 Eusocial insects have sterile castes
Many social insects like honeybees
and ants have a sterile caste.
13.28 Suicidal sacrifice by a worker bee
13.30 Haplodiploidy and the evolution of eusociality in the Hymenoptera (Part 1)
13.30 Haplodiploidy and the evolution of eusociality in the Hymenoptera (Part 2)
13.31 A sterile thrips soldier (right) next to a reproductive foundress female (left)
Note the larger
forelimbs on the
sterile worker.
13.34 A mammal with an effectively sterile caste