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Leavell BC, Pantoja-Sánchez H, Vélez V, Hemingway CT, Wilhite K, Halfwerk W, Bernal XE. Ripple effects in a communication network: anti-eavesdropper defence elicits elaborated sexual signals in rival males. Proc Biol Sci 2023; 290:20231910. [PMID: 38113943 PMCID: PMC10730286 DOI: 10.1098/rspb.2023.1910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023] Open
Abstract
Emitting conspicuous signals into the environment to attract mates comes with the increased risk of interception by eavesdropping enemies. As a defence, a commonly described strategy is for signallers to group together in leks, diluting each individual's risk. Lekking systems are often highly social settings in which competing males dynamically alter their signalling behaviour to attract mates. Thus, signalling at the lek requires navigating fluctuations in risk, competition and reproductive opportunities. Here, we investigate how behavioural defence strategies directed at an eavesdropping enemy have cascading effects across the communication network. We investigated these behaviours in the túngara frog (Engystomops pustulosus), examining how a calling male's swatting defence directed at frog-biting midges indirectly affects the calling behaviour of his rival. We found that the rival responds to swat-induced water ripples by increasing his call rate and complexity. Then, performing phonotaxis experiments, we found that eavesdropping fringe-lipped bats (Trachops cirrhosus) do not exhibit a preference for a swatting male compared to his rival, but females strongly prefer the rival male. Defences to minimize attacks from eavesdroppers thus shift the mate competition landscape in favour of rival males. By modulating the attractiveness of signalling prey to female receivers, we posit that eavesdropping micropredators likely have an unappreciated impact on the ecology and evolution of sexual communication systems.
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Affiliation(s)
- Brian C. Leavell
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Hoover Pantoja-Sánchez
- Department of Electronic Engineering, University of Antioquia, Medellín, Antioquia, Colombia
| | - Viviana Vélez
- Program of Study and Control of Tropical Diseases, University of Antioquia, Medellín, Antioquia, Colombia
| | - Claire T. Hemingway
- Department of Ecology & Evolutionary Biology and Department of Psychology, University of Tennessee, Knoxville, TN, USA
- Department of Integrative Biology, University of Texas, Austin, TX, USA
| | - Kyle Wilhite
- Department of Integrative Biology, University of Texas, Austin, TX, USA
| | - Wouter Halfwerk
- Department of Ecological Science, VU University, Amsterdam, The Netherlands
| | - Ximena E. Bernal
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
- Smithsonian Tropical Research Institute, Apartado, Balboa, Ancón, Panamá
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DuVal EH, Fitzpatrick CL, Hobson EA, Servedio MR. Inferred Attractiveness: A generalized mechanism for sexual selection that can maintain variation in traits and preferences over time. PLoS Biol 2023; 21:e3002269. [PMID: 37788233 PMCID: PMC10547189 DOI: 10.1371/journal.pbio.3002269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/22/2023] [Indexed: 10/05/2023] Open
Abstract
Sexual selection by mate choice is a powerful force that can lead to evolutionary change, and models of why females choose particular mates are central to understanding its effects. Predominant mate choice theories assume preferences are determined solely by genetic inheritance, an assumption still lacking widespread support. Moreover, preferences often vary among individuals or populations, fail to correspond with conspicuous male traits, or change with context, patterns not predicted by dominant models. Here, we propose a new model that explains this mate choice complexity with one general hypothesized mechanism, "Inferred Attractiveness." In this model, females acquire mating preferences by observing others' choices and use context-dependent information to infer which traits are attractive. They learn to prefer the feature of a chosen male that most distinguishes him from other available males. Over generations, this process produces repeated population-level switches in preference and maintains male trait variation. When viability selection is strong, Inferred Attractiveness produces population-wide adaptive preferences superficially resembling "good genes." However, it results in widespread preference variation or nonadaptive preferences under other predictable circumstances. By casting the female brain as the central selective agent, Inferred Attractiveness captures novel and dynamic aspects of sexual selection and reconciles inconsistencies between mate choice theory and observed behavior.
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Affiliation(s)
- Emily H. DuVal
- Department of Biological Sciences, Florida State University, Tallahassee, Florida, United States of America
| | - Courtney L. Fitzpatrick
- Department of Biology, Texas A&M University, College Station, Texas, United States of America
| | - Elizabeth A. Hobson
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, United States of America
- Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Maria R. Servedio
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
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Reichert MS, Bolek MG, McCullagh EA. Parasite effects on receivers in animal communication: Hidden impacts on behavior, ecology, and evolution. Proc Natl Acad Sci U S A 2023; 120:e2300186120. [PMID: 37459523 PMCID: PMC10372545 DOI: 10.1073/pnas.2300186120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023] Open
Abstract
Parasites exert a profound effect on biological processes. In animal communication, parasite effects on signalers are well-known drivers of the evolution of communication systems. Receiver behavior is also likely to be altered when they are parasitized or at risk of parasitism, but these effects have received much less attention. Here, we present a broad framework for understanding the consequences of parasitism on receivers for behavioral, ecological, and evolutionary processes. First, we outline the different kinds of effects parasites can have on receivers, including effects on signal processing from the many parasites that inhabit, occlude, or damage the sensory periphery and the central nervous system or that affect physiological processes that support these organs, and effects on receiver response strategies. We then demonstrate how understanding parasite effects on receivers could answer important questions about the mechanistic causes and functional consequences of variation in animal communication systems. Variation in parasitism levels is a likely source of among-individual differences in response to signals, which can affect receiver fitness and, through effects on signaler fitness, impact population levels of signal variability. The prevalence of parasitic effects on specific sensory organs may be an important selective force for the evolution of elaborate and multimodal signals. Finally, host-parasite coevolution across heterogeneous landscapes will generate geographic variation in communication systems, which could ultimately lead to evolutionary divergence. We discuss applications of experimental techniques to manipulate parasitism levels and point the way forward by calling for integrative research collaborations between parasitologists, neurobiologists, and behavioral and evolutionary ecologists.
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Affiliation(s)
- Michael S. Reichert
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK74078
| | - Matthew G. Bolek
- Department of Integrative Biology, Oklahoma State University, Stillwater, OK74078
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Bernal XE, Leavell BC, Page RA. Assessing patterns of eavesdropper risk on sexual signals and the use of meta-analysis in behavioural ecology: a comment on: 'The exploitation of sexual signals by predators: a meta-analysis' White et al. (2022). Proc Biol Sci 2023; 290:20221866. [PMID: 37161325 PMCID: PMC10170210 DOI: 10.1098/rspb.2022.1866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Affiliation(s)
- Ximena E Bernal
- Department of Biological Sciences, Purdue University, 915 W State Street, West Lafayette, IN 47907, USA
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panamá
| | - Brian C Leavell
- Department of Biological Sciences, Purdue University, 915 W State Street, West Lafayette, IN 47907, USA
| | - Rachel A Page
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panamá
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Bernal XE, Page RA. Tactics of evasion: strategies used by signallers to deter eavesdropping enemies from exploiting communication systems. Biol Rev Camb Philos Soc 2023; 98:222-242. [PMID: 36176190 DOI: 10.1111/brv.12904] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/03/2022] [Accepted: 09/06/2022] [Indexed: 01/12/2023]
Abstract
Eavesdropping predators, parasites and parasitoids exploit signals emitted by their prey and hosts for detection, assessment, localization and attack, and in the process impose strong selective pressures on the communication systems of the organisms they exploit. Signallers have evolved numerous anti-eavesdropper strategies to mitigate the trade-off between the costs imposed from signal exploitation and the need for conspecific communication. Eavesdropper strategies fall along a continuum from opportunistic to highly specialized, and the tightness of the eavesdropper-signaller relationship results in differential pressures on communication systems. A wide variety of anti-eavesdropper strategies mitigate the trade-off between eavesdropper exploitation and conspecific communication. Antagonistic selection from eavesdroppers can result in diverse outcomes including modulation of signalling displays, signal structure, and evolutionary loss or gain of a signal from a population. These strategies often result in reduced signal conspicuousness and in decreased signal ornamentation. Eavesdropping enemies, however, can also promote signal ornamentation. While less common, this alternative outcome offers a unique opportunity to dissect the factors that may lead to different evolutionary pathways. In addition, contrary to traditional assumptions, no sensory modality is completely 'safe' as eavesdroppers are ubiquitous and have a broad array of sensory filters that allow opportunity for signal exploitation. We discuss how anthropogenic change affects interactions between eavesdropping enemies and their victims as it rapidly modifies signalling environments and community composition. Drawing on diverse research from a range of taxa and sensory modalities, we synthesize current knowledge on anti-eavesdropper strategies, discuss challenges in this field and highlight fruitful new directions for future research. Ultimately, this review offers a conceptual framework to understand the diverse strategies used by signallers to communicate under the pressure imposed by their eavesdropping enemies.
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Affiliation(s)
- Ximena E Bernal
- Department of Biological Sciences, Purdue University, 915 W State Street, West Lafayette, IN, 47907, USA.,Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
| | - Rachel A Page
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
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