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Graham Thompson
The phylogenetics of social evolution
To study the phylogenetics of social evolution I identify clades showing variation
in social characteristics, and then reconstruct over them the ancestral states
of these characteristics through comparative and transformational mapping. This
part of my research program is concerned with determining the macroevolutionary
patterns of social life histories, thus permitting the development and testing
of macroevolutionary scenarios. For example, the application of phylogeny to
developing and testing models of termite social evolution has hitherto been
minimal, despite the significant impact that phylogenetics could have towards
resolving their widely-disputed social origins.
To this end, my collaborators and I have used molecular data from multiple
genes in combination with likelihood-based models of molecular evolution to
infer the phylogenetic relationships among various termite groups. First, we
have demonstrated using Australian lineages of drywood termite an evolutionary
correlation between social (defensive behaviour) and ecological (nest type)
variables (Mol. Phylog. Evol. 17:419-429).
Second, an order-wide phylogeny derived by us suggests, controversially, that the traditional interpretation of termite phylogeny may be out-of-date, and so too may several well-established phylogeny-dependent hypotheses concerning the evolutionary history of termite social systems (J. evol. Biol 13:869-881 and J. evol. Biol 17:217-220).
We have also re-visited the age-old question of how many times eusociality
itself has evolved in the corbiculate bees (Mol.
Phyl. Evol. 33:452-456). Surprisingly, no single topology can yet be accepted
to the exclusion of all others, despite a large amount of molecular and morphological
data. Moreover, the question of whether eusociality evolved 'once' or 'twice'
depends not just on the topology, as the question has commonly been presented,
but also on assumptions regarding how eusociality can evolve. The age-old
question of how many times eusociality has evolved in the corbiculate bees has
not yet solved.
Future objectives under this research heading will be to expand the range of characters mapped onto phylogenies to include not only phenotypic life-history polymorphisms but also, ultimately, the genotypic expression-patterns that underlie these polymorphisms.
