Heliconius butterflies exhibit Müllerian mimicry, in which two or more unpalatable species share a mutual advantage from having a common conspicuous colour pattern. These tropical butterflies have impressive visual signals, which are under conflicting selection pressures, as they are used in choosing potential mates and defending against visual predators through aposematic coloration. As both selection pressures are likely to be strong, different elements of the signal might be adapted for different receivers. Here, I combine sensory ecology with behavioural ecology to explain Heliconius colours signals of different co-mimic pairs. I explore how mimicry in Heliconius is perceived both from the perspective of predators and conspecifics, using visual abilities of both butterflies and birds. The different visual sensitivities of avian predators, H. erato females and males make them to perceive Heliconius coloration in different ways. My work suggests that having the ability to see in the ultra-violet light range enables higher discrimination between co-mimics both for birds and butterflies. Heliconius warning colours transmit a consistent signal across time of the day and habitat in a tropical forest for avian vision. In contrast through Heliconius vision there is evidence that patterns are more conspicuous in their own habitats. All these traits could facilitate communication between co-mimics and reduce the cost of confusion in courtship while still maintaining the advantages of Müllerian mimicry against predation. I conducted a field experiment to show that attack rates on a novel distasteful butterfly reduced over time, suggesting that Heliconius wing colouration can enhance aversion among predators. Finally, I have shown that Heliconius butterflies use leaf shape as a cue to approach their host plants, demonstrating the potential for Heliconius to drive negative frequency dependent selection on the leaf shape of their Passiflora host plants. Overall these results highlight ecological interactions between Heliconius butterflies, their predators and host plants.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:725509 |
| Date | January 2016 |
| Creators | Dalbosco Dell'Aglio, Denise |
| Contributors | Jiggins, Chris |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.repository.cam.ac.uk/handle/1810/267756 |
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