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Hensley NM, Rivers TJ, Gerrish GA, Saha R, Oakley TH. Collective synchrony of mating signals modulated by ecological cues and social signals in bioluminescent sea fireflies. Proc Biol Sci 2023; 290:20232311. [PMID: 38018106 PMCID: PMC10685132 DOI: 10.1098/rspb.2023.2311] [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: 10/12/2023] [Accepted: 11/06/2023] [Indexed: 11/30/2023] Open
Abstract
Individuals often employ simple rules that can emergently synchronize behaviour. Some collective behaviours are intuitively beneficial, but others like mate signalling in leks occur across taxa despite theoretical individual costs. Whether disparate instances of synchronous signalling are similarly organized is unknown, largely due to challenges observing many individuals simultaneously. Recording field collectives and ex situ playback experiments, we describe principles of synchronous bioluminescent signals produced by marine ostracods (Crustacea; Luxorina) that seem behaviorally convergent with terrestrial fireflies, and with whom they last shared a common ancestor over 500 Mya. Like synchronous fireflies, groups of signalling males use visual cues (intensity and duration of light) to decide when to signal. Individual ostracods also modulate their signal based on the distance to nearest neighbours. During peak darkness, luminescent 'waves' of synchronous displays emerge and ripple across the sea floor approximately every 60 s, but such periodicity decays within and between nights after the full moon. Our data reveal these bioluminescent aggregations are sensitive to both ecological and social light sources. Because the function of collective signals is difficult to dissect, evolutionary convergence, like in the synchronous visual displays of diverse arthropods, provides natural replicates to understand the generalities that produce emergent group behaviour.
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Affiliation(s)
- Nicholai M. Hensley
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9620, USA
| | - Trevor J. Rivers
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66405, USA
| | - Gretchen A. Gerrish
- Center for Limnology, Trout Lake Station, University of Wisconsin, Boulder Junction, Madison, WI 54512, USA
| | - Raj Saha
- Roux Institute, Northeastern University, Portland, ME 04101, USA
| | - Todd H. Oakley
- Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9620, USA
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Harrison LM, Melo GC, Perez DM, Backwell PRY. Why signal if you are not attractive? Courtship synchrony in a fiddler crab. Behav Ecol 2021. [DOI: 10.1093/beheco/arab088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Synchronized male courtship signals are puzzling because males generally compete with each other for females. Male Austruca mjoebergi fiddler crabs wave in synchrony to attract females, but, all else being equal, females have a strong preference for “leader” males that can produce waves before other males (“followers”). So why do followers participate in synchrony? Here, we experimentally investigate three explanations for why followers might wave in synchrony: 1) followers obtain a small proportion of matings, 2) followers are more likely than a leader to attract females if they are positioned closer to her than is the leader, and 3) synchrony functions as a long-distance visual signal that attracts females so there is a net benefit to synchrony for all males. Using robotic male crabs, we found that females show a strong preference for leading males, but followers obtain a “better-than-nothing” proportion of mates. We also showed that closer proximity of a follower to the female did not affect her preference for leaders, although being a leader increased a male’s success when he was further from the female than were rival males. Finally, females were more likely to approach a distant group if there was a leader present, suggesting that followers do benefit from participating in synchrony.
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Affiliation(s)
- Lauren M Harrison
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
| | - Gabriela C Melo
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, VIC, 3800, Australia
| | - Daniela M Perez
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
- Graduate Program in Ecology and Conservation, Universidade Federal do Paraná, Caixa Postal 19031, Curitiba, PR, 81531-990, Brazil
| | - Patricia R Y Backwell
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, Canberra, ACT, 2601, Australia
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