Investigating allometric scaling and trade-off between sensory organs in European butterflies
(2025) BION02 20242Degree Projects in Biology
- Abstract
- Understanding how organisms allocate limited resources among competing traits is a central issue in evolutionary biology. In this thesis, I test whether butterflies have an energetic trade-off between the high-cost sensory traits, compound eyes and antennae. Such a trade-off would be predicted by the Expensive Tissue Hypothesis. We used high-resolution 3D micro-CT data from 233 museum specimens (representing 59 species of European butterflies) to quantify the trait sizes of sensory (eyes and antennae) and various somatic traits (thorax, abdomen and forewing). Allometric analyses revealed that eyes and antennae exhibited negative allometric scaling with different body size proxy, suggesting that individuals with larger body sizes invest... (More)
- Understanding how organisms allocate limited resources among competing traits is a central issue in evolutionary biology. In this thesis, I test whether butterflies have an energetic trade-off between the high-cost sensory traits, compound eyes and antennae. Such a trade-off would be predicted by the Expensive Tissue Hypothesis. We used high-resolution 3D micro-CT data from 233 museum specimens (representing 59 species of European butterflies) to quantify the trait sizes of sensory (eyes and antennae) and various somatic traits (thorax, abdomen and forewing). Allometric analyses revealed that eyes and antennae exhibited negative allometric scaling with different body size proxy, suggesting that individuals with larger body sizes invest relatively lower in sensory organs. Contrary to predictions, eyes and antennae show significant positive correlations after controlling for body size and phylogenetic relatedness, with no trade-offs found between the two. My analyses also suggests that the choice of body size proxy metrics slightly affected slope estimates and body size corrected eye and antenna size, suggesting consideration should be given to the which body size metric is used when doing allometry. In future, testing of trade-off between brain and sensory structure, as well as other expensive tissues such as the gut (as expected by the Expensive Tissue Hypothesis), will be interesting. Finally, identifying ecological drivers mediating trade-offs or morphological diversification of sensory traits would provide deeper understanding on the evolution of these key expensive traits. (Less)
- Popular Abstract
- Just as people can’t spend all their money on luxury homes and cars, animals can’t equally invest in every trait they possess. This idea, known as the “expensive tissue hypothesis,” holds that if one trait is biologically expensive, then less investment may be made in another equally expensive trait. Eyes and antennae are two key sensory organs in butterflies or generally in insects, and both are metabolically expensive. So, are butterflies forced to choose between better eyesight and better smell?
To find out, I used high-resolution 3D scans of museum specimens of 59 European butterfly species. I measured the size of their eyes, antennae, and bodies, and analyzed how these traits change in proportion to overall body size, and whether... (More) - Just as people can’t spend all their money on luxury homes and cars, animals can’t equally invest in every trait they possess. This idea, known as the “expensive tissue hypothesis,” holds that if one trait is biologically expensive, then less investment may be made in another equally expensive trait. Eyes and antennae are two key sensory organs in butterflies or generally in insects, and both are metabolically expensive. So, are butterflies forced to choose between better eyesight and better smell?
To find out, I used high-resolution 3D scans of museum specimens of 59 European butterfly species. I measured the size of their eyes, antennae, and bodies, and analyzed how these traits change in proportion to overall body size, and whether investment in one sensory organ (e.g. eyes) comes at the expense of another (e.g. antennae).
I found that both eyes and antennae do not scale proportionally to body size, meaning that larger butterflies don’t necessarily invest more in sensory traits. Further, surprisingly, I found no evidence of a trade-off between investment in eyes and antenna. In fact, butterflies with larger eyes tend to have larger antennae.
This shows that the sensory organs of butterflies are not necessarily competing for energy resources, at least based on my study, they may have co-evolved to meet ecological needs (such as migration and habitat complexity). If future studies can use fresh samples, they can further test whether butterflies also have trade-offs between "expensive organs " such as the brain, intestines or reproductive systems, so as to have a more comprehensive understanding of how animals allocate limited energy resources. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9212853
@misc{9212853,
abstract = {{Understanding how organisms allocate limited resources among competing traits is a central issue in evolutionary biology. In this thesis, I test whether butterflies have an energetic trade-off between the high-cost sensory traits, compound eyes and antennae. Such a trade-off would be predicted by the Expensive Tissue Hypothesis. We used high-resolution 3D micro-CT data from 233 museum specimens (representing 59 species of European butterflies) to quantify the trait sizes of sensory (eyes and antennae) and various somatic traits (thorax, abdomen and forewing). Allometric analyses revealed that eyes and antennae exhibited negative allometric scaling with different body size proxy, suggesting that individuals with larger body sizes invest relatively lower in sensory organs. Contrary to predictions, eyes and antennae show significant positive correlations after controlling for body size and phylogenetic relatedness, with no trade-offs found between the two. My analyses also suggests that the choice of body size proxy metrics slightly affected slope estimates and body size corrected eye and antenna size, suggesting consideration should be given to the which body size metric is used when doing allometry. In future, testing of trade-off between brain and sensory structure, as well as other expensive tissues such as the gut (as expected by the Expensive Tissue Hypothesis), will be interesting. Finally, identifying ecological drivers mediating trade-offs or morphological diversification of sensory traits would provide deeper understanding on the evolution of these key expensive traits.}},
author = {{Li, Min}},
language = {{eng}},
note = {{Student Paper}},
title = {{Investigating allometric scaling and trade-off between sensory organs in European butterflies}},
year = {{2025}},
}