Biology Reference
In-Depth Information
thrips (Chapman et al ., 2008), shrimps (Duffy, 2003) and mole-rats (Bennett & Faulkes,
2000). Currie et al . (2010) show how the comparative method can be used to examine
the evolution of complexity of human societies.
Hölldobler and Wilson (1990) give a grand tour of ant biology, whilst Helantera et al .
(2009) discuss the ecology and evolution of unicolonial ants, where populations can
consist of a single 'supercolony'. Gordon (1996) discusses variation in the tasks
performed by workers, at both the individual and colony level. Powell and Franks (2007)
show how individual ants sacrifice themselves for the good of others, even in their
foraging behaviour. Mueller et al . (2005) review the behavioural ecology of agriculture
in the fungus growing social insects.
Trivers and Hare (1976) is a tour de force blend of theory and data, that founded one
of the most quantitatively successful areas of behavioural ecology - sex ratio conflict in
the social insects. Boomsma's (2007, 2009) papers provide an excellent exposition of
the importance of monogamy, and played a key role in simplifying our understanding of
how eusociality evolved. Ratnieks et al . (2006) review how a number of conflicts are
resolved in the social insects, including the sex ratio, rearing of queens, production of
males, caste and breeding conflicts between queens. Sex ratio conflict in the social
hymenoptera is reviewed in chapter nine of West (2009).
TOPICS FOR DISCUSSION
1. Discuss whether polyembryonic wasps and flatworms are eusocial (Grbic et al ., 1992;
Crespi & Yanega, 1995; Hechinger et al ., 2011)? Could you test your ideas?
2. Why are all workers female in the hymenoptera?
3. Discuss the implications of there being a genetic component to caste determination in a
eusocial species (Hughes et al ., 2003).
4. Given what we know about mating systems in natural populations, has the monogamy
hypothesis made it too easy to explain eusociality?
5. Would worker production of sons help or hinder the way to eusociality (Charnov, 1978)?
6. Extended parental care can favour the evolution of eusociality through 'insurance benefits'.
But why should extended parental care have evolved in the first place (Field & Brace, 2004)?
7. Why would the replacement of lost queens by one of her daughters lead to split sex ratios
(Boomsma, 1991; Mueller, 1991)?
8. Split sex ratios lead to some colonies where only male reproductives (drones) are produced.
This means that the males that mated with the queen gain no reproductive success
(haplodiploidy means they only pass genes to daughters). Can the males do anything
about this (Boomsma, 1996; Sundström & Boomsma, 2000)?
9. Worker policing occurs in some hymenopteran species where the workers are equally
related to their nephews and their sons. Why would this have evolved? How would you
test your ideas?
10. Compare the factors that have favoured the evolution of eusociality and multicellularity
(Queller, 2000; Grosberg and Strathmann, 2007; Herron and Michod, 2008; Boomsma,
2009).
11. How would you test empirically whether haplodiploidy has favoured the evolution of
eusociality?
12. Nowak et al . (2010) suggest that kin selection theory delivers only 'hypothetical explanations'
and 'does not deliver any additional biological insight' into the social insects. Discuss.
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