1 The evolution of territoriality in butterflies Preface In The descent of man, and selection in relation to sex (1871) Charles Darwin devoted a chapter to butterflies and moths in order to build up a body of facts and cases to support the theory of evolution through sexual selection. He gave plenty of examples of differences in coloration between males and females, and explained this by intersexual selection via female choice, but he also reflected on intrasexual selection through male-male conflicts: “Although butterflies are such weak and fragile creatures, they are pugnacious, and an Emperor butterfly has been captured with the tips of its wings broken from a conflict with another male.” -Charles Darwin (1871) Darwin was not only one of the first to describe male-male contests in butterflies, but was also the first to give a possible explanation for the origin and maintenance of such peculiar behaviour. In fact, Darwin refers to the naturalist Cuthbert Collingwood who described frequent contests between butterfly males in Borneo, on a scientific voyage in 1866-1867. Collingwood (1868) expresses his frustration over the troubles to capture unharmed specimens as he writes: “Another source of disappointment arose from the fact that not infrequent, when one thought oneself fortunate in capturing a fine insect, after carefully disentangling it from the net, its wings turned out to be so torn and rubbed as to render it almost useless, except indeed as a decoy. This circumstance is due, I imagine, partly to their frequent battles with one another, in which they whirl round each other with the greatest rapidity, and appear to be incited by the greatest ferocity...” -Cuthbert Collingwood (1868) Ever since Darwin‟s and Collingwood‟s time, researchers and naturalists have recorded and studied interactions between males of butterflies. A noticeable part of their behaviour is also that males often are exceptionally faithful to specific patches, which they frequently guard from intruding males via aerial flight disputes, just like the ones described by Collingwood (1868). But despite numerous publications and excellent field studies over decades, there are a number of parts concerning the evolution of territorial behaviour in butterflies that have never been thoroughly investigated. There are also parts of territorial behaviour in butterflies that have received a lot of scientific attention, but that still puzzle researchers today. The aim of this thesis is to investigate the parts of territorial behaviour in butterflies that are still largely unknown, and thereby to shed new light on the questions that despite earlier studies, remain unanswered.