The function of passive debris cloaking in tiny beetles (Coleoptera: Zopheridae)

Of all the antipredator adaptations currently known, camouflage has perhaps received the most interest. However, there has been a strong focus on larger animals that reside out in the open, but empirical evidence of camouflage in smaller litter dwelling invertebrates is lacking. Some species in these environments have been found covered in a thick layer of environmental debris, termed here as ‘passive debris cloaking’. Passive debris cloaking is widespread amongst many different and unrelated taxa globally. It is suspected to be a form of crypsis, but there is very little evidence supporting this. Here, I used beetles of the family Zopheridae as a model to assess the function of passive debris cloaking. Zopheridae are global in distribution, but unusually diverse in Aotearoa New Zealand. Passive debris cloaking is highly variable between genera, making them an ideal family to further study the trait. Firstly, I used behavioural experimentation with ecologically relevant predators, and image analysis with vision modelling to determine that passive debris cloaking functions as both visual and non-visual camouflage. Additionally, I found that texturally complex backgrounds reduce detection of stationary zopherid beetles even when background colour matching is poor. I also found camouflage isn’t broken during movement to a jumping spider predator, but instead provides prey with additional time to either escape or hide. To investigate the relationship between flight loss, micro-habitat and diversification within the family, I used phylogenetic methodologies. I ran a correlated evolution analysis between wing state and micro-habitat type on a zopherid phylogeny, and assessed the effects of flight loss on Zopheridae diversification in New Zealand. I found flight loss is partly driven by exposed habitat types, and diversification is faster when wings are retained, both previously undocumented findings in the field of insect flight loss. Finally, I consider results from all chapters to infer evolutionary pressures that have contributed to the prevalence of passive debris cloaking and speculate on its additional functions. This thesis offers a baseline for future research on passive debris cloaking.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Biology

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2025

Author dc:creator

• Greig, Kelly Jade

Advisors dc:contributor.advisor

• Holwell, Greg
• Leschen, Rich
• Buckley, Thomas

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/73940

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/73940