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1. Extreme Duty Cycles in the Acoustic Signals of Tiger Moths: Sexual and Natural Selection Operating in Parallel

   https://doi.org/10.1093/iob/obaa046  

   Fernández, Y ; Dowdy, N J ; Conner, W E ( January 2020 , Integrative Organismal Biology)

   null (Ed.)

   Synopsis Sound production in tiger moths (Erebidae: Arctiinae) plays a role in natural selection. Some species use tymbal sounds as jamming signals avoiding bat predation. High duty cycle signals have the greatest efficacy in this regard. Tiger moth sounds can also be used for intraspecific communication. Little is known about the role of sound in the mating behavior of jamming species or the signal preferences underlying mate choice. We recorded sound production during the courtship of two high duty cycle arctiines, Bertholdia trigona and Carales arizonensis. We characterized variation in their acoustic signals, measured female preference for male signals that vary in duty cycle, and performed female choice experiments to determine the effect of male duty cycle on the acceptance of male mates. Although both species produced sound during courtship, the role of acoustic communication appears different between the species. Bertholdia trigona was acoustically active in all intraspecific interactions. Females preferred and ultimately mated with males that produced higher duty cycles. Muted males were never chosen. In C. arizonensis however, sound emissions were limited during courtship and in some successful matings no sound was detected. Muted and clicking males were equally successful in female mate-choice experiments, indicating that acoustic communication is not essential for mating in C. arizonensis. Our results suggest that in B. trigona natural and sexual selection may work in parallel, to favor higher duty cycle clicking. 

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2. Substrate-borne vibration in Pacific field cricket courtship displays

   https://doi.org/10.3897/jor.30.47778  

   Broder, E Dale ; Wikle, Aaron W. ; Gallagher, James H. ; Tinghitella, Robin M. ( May 2021 , Journal of Orthoptera Research)

   While thought to be widely used for animal communication, substrate-borne vibration is relatively unexplored compared to other modes of communication. Substrate-borne vibrations are important for mating decisions in many orthopteran species, yet substrate-borne vibration has not been documented in the Pacific field cricket Teleogryllus oceanicus . Male T. oceanicus use wing stridulation to produce airborne calling songs to attract females and courtship songs to entice females to mate. A new male morph has been discovered, purring crickets, which produce much quieter airborne calling and courtship songs than typical males. Purring males are largely protected from a deadly acoustically orienting parasitoid fly, and they are still able to attract female crickets for mating though typical calling song is more effective for attracting mates. Here, we document the first record of substrate-borne vibration in both typical and purring male morphs of T. oceanicus . We used a paired microphone and accelerometer to simultaneously record airborne and substrate-borne sounds produced during one-on-one courtship trials in the field. Both typical and purring males produced substrate-borne vibrations during courtship that temporally matched the airborne acoustic signal, suggesting that the same mechanism (wing movement) produces both sounds. As previously established, in the airborne channel, purring males produce lower amplitude but higher peak frequency songs than typical males. In the vibrational channel, purring crickets produce songs that are higher in peak frequency than typical males, but there is no difference in amplitude between morphs. Because louder songs (airborne) are preferred by females in this species, the lack of difference in amplitude between morphs in the substrate-borne channel could have implications for mating decisions. This work lays the groundwork for investigating variation in substrate-borne vibrations in T. oceanicus , intended and unintended receiver responses to these vibrations, and the evolution of substrate-borne vibrations over time in conjunction with rapid evolutionary shifts in the airborne acoustic signal. 

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3. Midbrain node for context-specific vocalisation in fish

   https://doi.org/10.1038/s41467-023-43794-y  

   Schuppe, Eric R. ; Ballagh, Irene ; Akbari, Najva ; Fang, Wenxuan ; Perelmuter, Jonathan T. ; Radtke, Caleb H. ; Marchaterre, Margaret A. ; Bass, Andrew H. ( January 2024 , Nature Communications)

   Vocalizations communicate information indicative of behavioural state across divergent social contexts. Yet, how brain regions actively pattern the acoustic features of context-specific vocal signals remains largely unexplored. The midbrain periaqueductal gray (PAG) is a major site for initiating vocalization among mammals, including primates. We show that PAG neurons in a highly vocal fish species (Porichthys notatus) are activated in distinct patterns during agonistic versus courtship calling by males, with few co-activated during a non-vocal behaviour, foraging. Pharmacological manipulations within vocally active PAG, but not hindbrain, sites evoke vocal network output to sonic muscles matching the temporal features of courtship and agonistic calls, showing that a balance of inhibitory and excitatory dynamics is likely necessary for patterning different call types. Collectively, these findings support the hypothesis that vocal species of fish and mammals share functionally comparable PAG nodes that in some species can influence the acoustic structure of social context-specific vocal signals.

    

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4. Communication via Biotremors in the Veiled Chameleon ( Chamaeleo calyptratus ): Part II—Social Contexts

   https://doi.org/10.1093/icb/icad084  

   Denny, Kathryn L. ; Huskey, Steve ; Anderson, Christopher V. ; Smith, Michael E. ( June 2023 , Integrative And Comparative Biology)

   This study extends recent research demonstrating that the veiled chameleon (Chamaeleo calyptratus) can produce and detect biotremors. Chameleons were paired in various social contexts: dominance (male–male; female–female C. calyptratus); courtship (male–female C. calyptratus); heterospecific (C. calyptratus + C. gracilis); and inter-size class dominance (adult + juvenile C. calyptratus). Simultaneous video and accelerometer recordings were used to monitor their behavior and record a total of 398 biotremors. Chamaeleo calyptratus produced biotremors primarily in conspecific dominance and courtship contexts, accounting for 84.7% of the total biotremors recorded, with biotremor production varying greatly between individuals. Biotremors were elicited by visual contact with another conspecific or heterospecific, and trials in which chameleons exhibited visual displays and aggressive behaviors were more likely to record biotremors. Three classes of biotremor were identified—hoots, mini-hoots, and rumbles, which differed significantly in fundamental frequency, duration, and relative intensity. Biotremor frequency decreased with increasing signal duration, and frequency modulation was evident, especially in hoots. Overall, the data show that C. calyptratus utilizes substrate-borne vibrational communication during conspecific and possibly heterospecific interactions.

    

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5. Spiders, microbes and sex: Bacterial exposure on copulatory organs alters mating behaviour in funnel‐web spiders

   https://doi.org/10.1111/eth.12921  

   Spicer, Michelle Elise ; Pruitt, Jonathan N. ; Keiser, Carl N. ; Bertram, ed., S. ( July 2019 , Ethology)

   Environmental microbes have the potential to be involved in nearly all behavioural processes. For example, mating systems where males use intromittent organs to transfer sperm to females represent a means by which environmental microbes collected by males can breach entry into females' body cavities during mating. However, the degree to which the acquisition of environmental microbes onto important sex structures alters courtship behaviours remains unknown. Here, we collected bacteria from the copulatory organs ofAgelenopsis pennsylvanicafunnel‐weaving spiders in situ to test whether exposure to bacteria on copulatory organs can alter hosts' courtship behaviour, reproductive success and survival. We used a standardized assay to repeatedly measure each spider's aggressiveness, a behavioural component of both male courtship and female sexual receptivity. Then, we experimentally altered the bacteria present on male and female spiders' copulatory organs with an application of either (a) a mixture of bacteria collected from conspecifics to increase bacterial presence, (b) an antibiotic to reduce bacterial presence or (c) a procedural control. Each spider was paired with a size‐matched spider of the opposite sex whose copulatory organs were unaltered, and we measured the latency until the onset and the duration of courtship. Spiders were then isolated, and we measured each individual's time until death and female fecundity over the next 40 days. We found that female exposure to bacteria had multiple effects on mating dynamics. Males took over four times longer to begin courting females that had been exposed to bacteria compared to unexposed and antibiotic‐treated females. Only when courting these bacteria‐exposed females, males began courtship sooner when females were more aggressive. Lastly, females whose mate had been exposed to bacteria experienced reduced survival. These data suggest that bacteria present on animals' copulatory organs can alter courtship behaviours, female survivorship, and may potentially play a role in mating dynamics.

    

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