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Within-shoal phenotypic homogeneity affects shoaling preference in a killifish
Silvia Cattelan1, Matteo Griggio2
1Department of Biology, University of Padova, Padova, Italy silvia.cattelan@unipd.it.
Biology Letters
|August 10, 2018
Summary
Fish prefer to join groups with similar body patterns to enhance anti-predator benefits. This study shows that phenotypic homogeneity in pigmentation influences shoaling preferences in fish.
Area of Science:
- Behavioral Ecology
- Evolutionary Biology
- Ichthyology
Background:
- Group living in fish provides anti-predator advantages, such as the confusion effect, where predators struggle to target individuals in dense shoals.
- Phenotypic homogeneity within shoals is theorized to enhance the confusion effect, but research has primarily focused on body size, neglecting pigmentation.
Purpose of the Study:
- To investigate whether within-shoal homogeneity in body pigmentation influences shoaling preferences in the Mediterranean killifish (Aphanius fasciatus).
- To determine if fish preferentially associate with shoals exhibiting greater uniformity in phenotypic characteristics, specifically body pigmentation patterns.
Main Methods:
- The study utilized the Mediterranean killifish, Aphanius fasciatus, a species known for its distinct vertical bars.
- Individual females were presented with a choice between two artificial shoals differing in their degree of homogeneity (high vs. low) in the number of bars.
Main Results:
- Individual females demonstrated a clear preference for associating with the shoal that exhibited higher phenotypic homogeneity in terms of bar patterns.
- This preference for homogeneity in body pigmentation was observed irrespective of the individual female's own phenotype.
Conclusions:
- Fish shoaling behavior can be influenced by a preference for phenotypic homogeneity in body pigmentation, not just body size.
- Maximizing within-shoal phenotypic homogeneity in pigmentation may be a strategy employed by fish to enhance survival through improved anti-predator benefits.
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