The size of signal detection and emission organs in a synchronous firefly: sexual dimorphism, allometry and assortative mating

Abstract

The size of the organs responsible for emitting and detecting sexual communication signals is a likely target for selection. Communication via bioluminescent signals in synchronous fireflies is a promising model to test hypotheses regarding differences between males and females in the effect of the size of signal emission and detection organs on fitness components. Synchronous firefly species congregate in large numbers during the mating season, displaying bioluminescent signals aimed at potential mates during relatively short nightly periods. Operational sex ratios are male-biased and, thus, the so-called typical sex roles (indiscriminate males and choosy females) are expected to evolve. We studied the synchronous firefly Photinus palaciosi, a species that during the mating season congregates in forests of central Mexico offering a magnificent natural show that attracts numerous tourists. P. palaciosi females have reduced wings (brachyptery) and cannot fly. Our field study tested the hypothesis that the male-biased operational sex ratio and the short daily mating period result in strong male-male competition that selects for males with larger lanterns and larger eyes, and against male mate choice, whereas female-female mate competition is absent and, thus, no selection on lantern or eye size is expected. Even though lantern, eye or body size do not predict the probability of being found in copula for either sex, sexual dimorphism in these features, along with allometric slopes of lantern size and assortative mating in terms of relative lantern size, support not only the hypothesis of intense sexual selection among males, but the possibility of subtle mechanisms of sexual selection among females. Trade-offs between investment in signaling (lanterns) versus detection (eyes) structures, or with pressures different from sexual selection such as those imposed by predators, are also likely to be important in shaping the evolution of sexual signaling in these fireflies.

Signal detection shapes ornament allometry in functionally convergent Caribbean Anolis and Southeast Asian Draco lizards

“…These patterns were reasonably attributed to developmental costs that effectively cap the maximum size weapons can reach. However, there have yet to be any substantial attempts to empirically determine the extent to which signal detection might contribute towards allometric scaling patterns in sexual display structures (but see Lopez‐Palafox et al, 2020 for a rare example). Doing so could potentially reveal why some ornaments or structures used in sexual display exhibit different allometric relationships across closely related taxa (e.g.…”

Deceptive Seduction by Femme Fatale Fireflies and Its Avoidance by Males of a Synchronous Firefly Species (Coleoptera: Lampyridae)

“…P. palaciosi (Photinus hereafter), a synchronous firefly, is a protandrous species (females appear around a week after the first males) whose females cannot fly because they have reduced wings (i.e., they are brachypterous) [31]. The mating season of this species starts between the first and second week of June, so males appear approximately when Photuris females start hunting.…”

“…In this paper, we report field measurements of rates of attraction and capture for male Photinus palaciosi, a synchronous firefly from the mountains of Central Mexico [31], by Photuris lugubris femmes fatales [29]. This study is part of a broader project aimed at understanding the evolution of the femme fatale behavior of Photurinae fireflies.…”

Bioluminescence and Photoreception in Unicellular Organisms: Light-Signalling in a Bio-Communication Perspective

“…It turns out that many species of dinoflagellates have both a “social” and sexual life [ 429 , 430 , 431 , 432 ] that may require an animal-like “language”. One hypothesis could be, for example, that dinoflagellate bioluminescence displays some analogies with light-emission strategies used by various bioluminescent animal species to communicate [ 433 , 434 , 435 , 436 , 437 , 438 , 439 , 440 , 441 ]. Interestingly, complex collective behaviours involving communication for mating have been observed in other unicellular organisms such as ciliates [ 442 , 443 , 444 ].…”