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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. Varied female and male courtship behavior facilitated the evolution of a novel sexual signal

   https://doi.org/10.1093/beheco/arac049  

   Fitzgerald, Sophia L; Anner, Sophia C; Tinghitella, Robin M (June 2022, Behavioral Ecology)

   Jennions, Michael D (Ed.)

   Abstract Sexual selection can contribute to speciation when signals and preferences expressed during mate choice are coupled within groups, but come to differ across groups (generating assortative mating). When new sexual signals evolve, it is important to investigate their roles in both mate location and courtship contexts, as both signaling functions are critical in mate choice. In previous work, researchers identified two new male morphs (silent and purring) in Hawaiian populations of the Pacific field cricket, Teleogryllus oceanicus. These morphs likely evolved because they protect males from an acoustically orienting parasitoid, yet still obtain some reproductive success. But, it remains unknown how the purring morph functions in close courtship encounters. We compared the relative success of the very recently evolved purring morph to that of the ancestral and silent morphs during courtship encounters. Purring males produce a novel courtship song and were not as successful in courtship as the ancestral type, but were mounted by females as often and as quickly as the obligately silent morph that arose and spread ~20 years ago. Purring males initiate courtship more quickly than other morphs, and females from populations where purring is common exhibit higher overall mounting rates. Thus, differences in the behavior of purring males and of females from populations where purring is common may have facilitated the origin of this novel sexual signal. We found no assortative mating between males of a given morph and females from their own population, and so we hypothesize that multiple male types will be maintained within the species because each achieves fitness in different ways. 

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3. Life-Long Experience with Male Mating Tactics Shapes Spatial Cognition and Coercion Evasion in Female Swordtails

   https://doi.org/10.3390/fishes8110562  

   Queller, Philip S; Adams, Elena_R M; Cummings, Molly E (November 2023, Fishes)

   Social experiences can shape adult behavior and cognition. Here, we use El Abra swordtails (Xiphophorus nigrensis) to assess how life-long experience with different male mating tactics shapes coercion evasion ability and female spatial cognition. We raised females from birth to adulthood in environments that varied by male mating tactic: coercers only, courtship displayers only, coercers and displayers together, mixed-strategists, and female only. In adulthood, we tested females’ behavioral responses to a coercive male and spatial cognition in a maze. Females reared with only displayers were significantly worse at distancing themselves from the coercive male than females raised with coercers and displayers and females raised with only coercers. Females raised with a single mating tactic (either courtship display or coercion) exhibited significantly higher accuracy in the spatial maze than females from other rearing groups, and showed significant reduction in total errors (courtship display group) or latency to reward (coercion group) over successive trials. These more predictable environments (one tactic), and not the more complex environments (two tactics), showed evidence for spatial learning. The results are discussed in light of the existing literature on two components of environmental change (environmental predictability and the certainty with which cues predict the best behavioral response) and their effect on the development of cognitive abilities. 

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4. Cryptic Mate Preference in Male Bicyclus anynana Butterflies

   https://doi.org/10.1007/s10905-023-09814-x  

   Siebenmorgen, Jacob P.; Tibbs, Taryn L.; Robertson, Deonna N.; Westerman, Erica L. (March 2023, Journal of Insect Behavior)

   While male mate choice has received sparse attention in comparison to female choice, it occurs often in insects. In addition, male insects may preferentially allocate sperm and ejaculate in response to female quality. Previous research indicates that male Bicyclus anynana butterflies can learn mate preference through prior exposure to females, though naïve males mate randomly. It is unclear whether this preference learning may also influence male sperm and ejaculate allocation after mate selection, or whether males have cryptic mate preference for female wing patterns independent of preference learning. Here we test whether B. anynana males adjust their sperm and ejaculate allocation in response to a learned preference. We also assess whether males exhibit an innate cryptic preference and adjust their sperm and ejaculate in response to female wing pattern. We compared number of eggs laid by females and spermatophore (male butterfly ejaculate) weight in four no-choice treatments: naïve male butterflies (having no prior exposure to females), paired with a 2 or 0-spot female, and experienced male butterflies (having a previous three-hour interaction with a 0-spot female), paired with a 2 or 0-spot female. All females used were naturally 2-spot females, 0-spot females had artificially blocked spots. We found that 0-spot females laid significantly more eggs than 2-spot females, independent of male experience. There was no effect of female phenotype or male experience on spermatophore weight. Our findings suggest that male B. anynana have an innate cryptic preference for 0-spot females, which has been shown in other studies to only be seen as a pre-copulatory preference when enhanced by early experience. 

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5. Little evidence for color- or size-based mating preferences by male strawberry poison frogs (Oophaga pumilio)

   https://doi.org/10.1007/s00265-024-03436-9  

   Lehman, Mik R; González-Santoro, Marco; Richards-Zawacki, Corinne L (February 2024, Behavioral Ecology and Sociobiology)

   AbstractWhile there are many studies documenting female mating preferences across taxa, male mate choice remains relatively understudied. Male mate choice often develops when there is variation in female quality and thus the fitness benefits of mating with particular females. Specifically, males tend to prefer females with traits that confer direct fitness benefits such as large body size, which may be linked with high fecundity. Prior work has shown that females of the strawberry poison frog,Oophaga pumilio, prefer males bearing certain coloration (most often the female’s own color), and that this preference can be learned through maternal imprinting. Females have been shown to prefer larger males as well. Here we test whether similar mate preferences for color and size exist in males of this species using two-way choice tests on captive bred maleO. pumilio. In each test focal males were placed in an arena with two stimulus females: either both of the same size but differing in color, or both of the same color but differing in size. We found only weak evidence for behavioral biases toward particular colors and no evidence for biases toward larger females, suggesting that males ofO. pumiliodo not predictably choose mates based on these female traits. Despite several aspects of their natural history that suggest males have reasons to be choosy, our findings suggest that the cost of mate rejection may outweigh any fitness benefits derived from being selective of mates. Studies of additional populations, ideally conducted on wild individuals, are needed to better understand the range of conditions under which males may exhibit mate choice and the types of traits on which they base these choices. Significance statementTo fully understand the fitness landscapes and evolutionary trajectories that result from sexual selection, we need to understand when and how the mate preferences of the two sexes act and interact. While female mate choice has been widely studied, male mate choice remains poorly understood. To help bridge this gap, we studied male mate preferences in the strawberry poison frogOophaga pumilio, a small brightly colored frog for which female preferences for male color and size have been well-documented. We found no evidence that maleO. pumilioexhibit mate preferences based on female size and little evidence for male mate preferences based on female color. This is surprising given that larger females are often more fecund, maleO. pumilioare known to exhibit color-based behavioral biases in the context of male-male competition, and both sexes provide parental care. 

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