1. The Evolution of Electroreception: An Historical Overview
Bruce A. Carlson and Joseph A. Sisneros
This chapter will provide an historical introduction to the field that focuses on evolutionary diversity. This will include a description of phylogenetic diversity that helps orient readers to the various taxonomic groups that have electroreception. It will also address phenotypic diversity, including differences between tuberous and ampullary electrosensory systems, and the wide variety of tuberous electrosensory systems, and how these differences are adapted to behavioral function.
2. Comparative Genomics Approaches to the Evolution and Development of Electroreceptors
Clare V. Baker
This chapter will review recent advances in our understanding of the evolution and development of electroreceptors. Developmental genetics studies in cartilaginous and bony fishes have confirmed the homology of ampullary electroreceptors in non-teleost jawed vertebrates, and their embryonic origins from lateral line placodes. This review will focus on these important recent discoveries and on remaining questions regarding the evolutionary and developmental origins of teleostean ampullary and tuberous electroreceptors.
3. Comparative Genomics Approaches to the Evolution and Development of Electric Organs
Graciela A. Unguez, Jason R. Gallant, and Harold H. Zakon
This chapter will address the fundamental question of what constitutes a true electric organ, and how to distinguish true electric organs from possible intermediate stages in their evolution from muscle. The focus of this chapter will then be to review recent developments in our understanding of the evolutionary and embryological origins of electric organs. Comparative genetics and genomics studies have revealed the molecular basis for the evolution of electric organs across multiple clades, with implications for better understanding electric organ development.
4. Biophysical Basis of Electric Signal Diversity
Michael R. Markham
This chapter will address the morphological and physiological basis for the generation of electric organ discharges (EODs). The focus will be on specializations in electrocyte morphology and physiology, and how these generate specific features of the EOD waveform. A comparative perspective will relate species differences in morphology and physiology to EOD diversity.
5. Evolutionary Drivers of Electric Signal Diversity
Rüdiger Krahe
This chapter will focus on ecological genetics and the ultimate evolutionary causes of EOD diversification in gymnotiforms and mormyroids, including ecological adaptation, sexual selection, and predation. In addition, this chapter will address the role of electric signaling in species diversification.
6. Sensory Adaptations to Active Sensing and Communication
Eric S. Fortune
This chapter will focus on general principles related to the anatomy and physiology of different tuberous electrosensory systems, and how they are adapted to their particular functions. This overview will highlight shared, independently evolved features of tuberous electrosensory systems that point to fundamental mechanisms, as well as the tremendous diversity of tuberous electrosensory systems and how this reflects adaptations to different functions.
7. Evolution of Time-Coding in Electrosensory and Auditory Systems
Bruce A. Carlson
The focus of this chapter will be on common themes in temporal coding across sensory systems, as well as key differences. It will address both sub-millisecond timing comparisons (interaural time differences, phase comparisons, pulse duration, electric signal waveform) and temporal patterns (call rates, pulse intervals, modulation rates). This topic has the distinct advantage of a common computational problem with clear behavioral relevance having been studied in-depth in a diversity of auditory and electrosensory systems. Thus, this chapter will get at the heart of how we can both uncover shared fundamental mechanisms and seek to determine the ultimate causes for differences between systems.
8. Envelope Coding and Processing
Maurice J. Chacron
Higher-order modulations of sensory stimuli, or envelopes, play a key role in information transmission across sensory modalities (for example, contrast modulation in the visual system, and amplitude modulation in the auditory system). This chapter will focus on recent advances in the coding and processing of envelopes in the electrosensory system of gymnotiform fishes. There will be a particular emphasis on links to auditory processing and behavioral relevance, and how research on these fishes has led to fundamental insights into how envelopes are coded and processed more generally.
9. Spatial Learning and the Telencephalon
Leonard Maler
There have been exciting advances in understanding the neural bases of spatial learning and navigation in recent years, but much of this work is limited in its taxonomic scope. The focus of this chapter will be on recent advances in our understanding of spatial learning in gymnotiform fishes and its neural basis in the telencephalon. There will be a particular emphasis on how the electrosensory system of fishes can be used to identify fundamental aspects of spatial learning and its neural basis across vertebrates.
10. Sensorimotor Integration in the Processing of Reafferent Sensory Input
Nathaniel B. Sawtell
Decades of research on mormyrid electric fishes have provided tremendous insights into sensorimotor integration, filtering of reafferent and exafferent sensory input, and the generation and subtraction of sensory expectations. This chapter will focus on the most recent developments in this field, which have revealed the cellular, synaptic, and circuit bases for generating and subtracting sensory expectations, using a combination of computational and experimental studies. There will be a particular emphasis on links to auditory processing and behavior in mammals, and how research on these fishes has led to fundamental insights into the processing of reafferent sensory input.
11. Hormonal Influences on Social Behavior
Ana Silva
This chapter will address hormonal influences on social behavior through actions on sensory and motor systems. There will be a particular focus on diversity in social behavior, and how hormonal actions differ in species with divergent aggressive behavior.
12. Predatory Behavior of Strongly Electric Fish
Kenneth C. Catania
This chapter will focus on the exciting recent discoveries into the predatory behavior of electric eels. This will include a description of specialized behavioral adaptations for delivering strong discharges to prey items, mechanisms for inducing involuntary twitches in prey items to reveal their location, and the use of strong electric discharges in active electrolocation. These findings will be placed into a broader evolutionary context that relates these findings to the evolution of electrogenesis.
