ARTHUR, Wallace; CHIPMAN, Ariel; National University of Ireland, Galway; University of Cambridge: Genetic, developmental and environmental aspects of variation in centipede segment numbers

In some groups of centipedes, the number of segments is fixed. In others, notably the order Geophilomorpha, it is variable. The variation in this particular group has both within and between species components. The former has both within and between population components. There is also sexual dimorphism, with females typically having more segments than males. This multi-faceted variation provides a unique opportunity to investigate both developmental and evolutionary aspects of how segment number is determined. Here, we look specifically at variation in a ‘model species’ of geophilomorph, concentrating on the following: the geographic pattern of variation; possible heritable and plastic components of this; selective scenarios; the developmental genetic basis of segment number; and the interaction between the developmental and populational processes. We conclude by asking what our studies on this model system can tell us about the evolution of arthropod segment number more generally.