Abstract:
The lateral line system of aquatic vertebrates is composed of neuromast mechanoreceptors along
the head and body that detect movement through vibration and pressure gradients in the water. Although
mechanosensory information has been shown to be important in the contexts of predator escape and
foraging, little is known about the role of the lateral line in intraspecific interactions such as reproduction.
Many species of fish have complex courtship and aggressive repertoires that involve movement of the
body and fins, resulting in local displacement of the surrounding water. This displacement has the
potential to function as a signal that contains information about the sender. In this study, I conducted two
behavioral experiments using fathead minnows (Pimephales promelas) to test the hypothesis that the
outcomes of male-male contests and male-female courtship interactions are influenced by animalgenerated
hydrodynamic flows. In my first experiment, I pitted control males against those with ablated
lateral lines and assessed both overall aggression and the likelihood of territory acquisition. In my second
experiment, I conducted dual-choice, female mate-choice experiments to determine whether control
females and those without access to mechanosensory information (ablated females) differed in
discriminatory ability and use of courtship as a criterion of choice. In experiment 1, control males won a
significantly greater proportion of territorial contests than expected by chance and were more likely to use
non-contact threat displays during aggressive interactions compared with ablated males. In experiment 2,
females with access to the mechanosensory information channel showed enhanced mate discrimination
compared to ablated females. These data are some of the first to show that mechanosensory signals are an
important criterion of territorial and reproductive success in fishes and contribute to multimodal
communication in this group.
