Mouth dimorphism in scale-eating cichlid fish from Lake Tanganyika advances individual fitness

Indermaur, Adrian and Theis, Anya and Egger, Bernd and Salzburger, Walter. (2018) Mouth dimorphism in scale-eating cichlid fish from Lake Tanganyika advances individual fitness. Evolution; international journal of organic evolution, 72 (9). pp. 1962-1969.

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Official URL: https://edoc.unibas.ch/67916/

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Random asymmetry, that is the coexistence of left- and right-sided (or -handed) individuals within a population, is a particular case of natural variation; what triggers and maintains such dimorphisms remains unknown in most cases. Here, we report a field-based cage experiment in the scale-eating Tanganyikan cichlid Perissodus microlepis, which occurs in two morphs in nature: left-skewed and right-skewed individuals with respect to mouth orientation. Using underwater cages stocked with scale-eaters and natural prey fish, we first confirm that, under semi-natural conditions, left-skewed scale-eaters preferentially attack the right flank of their prey, whereas right-skewed individuals feed predominantly from the left side. We then demonstrate that scale-eaters have a higher probability for successful attacks when kept in dimorphic experimental populations (left- and right-skewed morphs together) as compared to monomorphic populations (left- or right-skewed morphs), most likely because prey fishes fail to accustom to strikes from both sides. The significantly increased probability for attacks appears to be the selective agent responsible for the evolution and maintenance of mouth dimorphism in P. microlepis, lending further support to the hypothesis that negative frequency-dependent selection is the stabilizing force balancing the mouth dimorphism at quasi-equal ratios in scale-eating cichlids.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Integrative Biologie > Evolutionary Biology (Salzburger)
UniBasel Contributors:Salzburger, Walter
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Apr 2020 22:22
Deposited On:22 Apr 2020 22:22

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