The fatal plane crash that upended one of the nation's tightest and most aggressive contests for the United States Senate has also frozen the remarkable race to replace Gov. Jesse Ventura, the professional wrestler who was elected four years ago after an iconoclastic run against the political system.
For each trial we recorded the duration of the aggressive contest – from first contact until the contest ended (one male retreated from its opponent following a break in the aggressive contest) – and the contest victor, determined as the individual that tremulated or stridulated, and chased its opponent.
Each male took part in only one aggressive contest.
In 27 of 39 (69%) aggressive contests with a clear winner, the male that scored higher on PC1 won significantly more aggressive contests than expected by chance (binomial p = 0.024).
In painted buntings Passerina ciris, males even engage in aggressive contests to take over the best territories from their previous-year owners (Lanyon and Thompson 1986).
The most aggressive contests occurred between old wasps competing for large hosts and the least aggressive between young wasps competing for small hosts (figures 1 and 2).
All males were handled and marked as in experiment 1, except that we weighed males several hours before the aggressive contests and then matched pairs of males for similar body mass but different head width.
To test whether relative head/mouthpart size has an effect on the outcome of male-male aggressive contests, we formed pairs of males matched for age and body size (pronotum length), but differing in head width, and staged a series of male-male contests.
In fact, previous laboratory research has shown that males' mating experience is expressed only during aggressive contests (Brown et al. 2007), whereas for females to benefit from mate choice, there must be detectable differences among males in the benefits they offer or the costs they impose (Pitnick and García-González 2002).
For instance, in Melittobia australica males engage in aggressive contests where the majority of competitors are killed; males possess mandibles which they use only for fighting (they do not feed after emergence; Abe, Kamimura & Shimada, 2005).
The link between agonistic interactions and access to resources may be direct, as when individuals engage in aggressive competition for access to food (Janson 1985a), or indirect, as when individuals avoid engaging in contests with individuals they perceive as likely to win the interaction (Thouless 1990; Vogel 2005).
