Beyond temperature coupling: Effects of temperature on ectotherm signaling and mate choice and the implications for communication in multispecies assemblages

Abstract

Many organisms share communication channels, generating complex signaling environments that increase the risk of signal interference. Variation in abiotic conditions, such as temperature, may further exacerbate signal interference, particularly in ectotherms. We tested the effects of temperature on the pulse rate of male signals in a community of Oecanthus tree crickets, and for one focal species we also assessed its effect on female pulse rate preferences and motivation to seek mates. We confirm prior findings of temperature‐dependent signals that result in increasing signal similarity at lower temperatures. Temperature also affected several aspects of female preferences: The preferred pulse rate value was temperature dependent, and nearly perfectly coupled with signal pulse rate; the range of pulse rate values that females found attractive also increased with temperature. By contrast, the motivation of females to perform phonotaxis was unaffected by temperature. Thus, at lower temperatures the signals of closely related species were more similar and females more discriminating. However, because signal similarity increased more strongly than female discrimination, signal interference and the likelihood of mismating may increase as temperatures drop. We suggest that a community approach will be useful for understanding the role of environmental variability in the evolution of communication systems.

Listening in the bog: I. Acoustic interactions and spacing between males of Sphagniana sphagnorum

“…Temperature has a strong effect on the parameters of the calling songs of ectothermic insects (Walker 1962 ; Doherty 1985 ; Gerhardt and Huber 2002 ; Symes et al 2017 ). Our measurements of air temperatures under conditions of steady sunshine at different heights within the bog vegetation revealed a strong warming effect on the sphagnum surface (Fig.…”

“…Our experimental results support the hypothesis that song rate is an important parameter in agonistic interactions. However, temperature has also been demonstrated to have a profound effect on acoustic signalling in these ectotherm insects, and specifically on the rate with which song elements are produced (Walker 1962 ; Doherty 1985 ; Gerhardt and Huber 2002 ; Symes et al 2017 ). As our measurements in the bog showed (Fig.…”

Temperature alters multimodal signaling and mating success in an ectotherm

“…In systems like H. clypeatus, females only mate once; thus, there are potentially large fitness consequences for females that choose mates with misleading signals. In most species in which this has been studied, animals have been shown to use signal-preference coupling to coordinate signaling changes a b c d in temperature (Gerhardt 1978;Doherty 1985;Pires and Hoy 1992;Symes et al 2017). Signal-preference coupling predicts that across temperatures, mating rates should be similar, as the same quality males would be selected even as signaling behavior shifts.…”

“…Studies examining signal-preference coupling have primarily focused on acoustic/vibratory modalities (Gerhardt 1978;Doherty 1985;Ritchie et al 2001;Greenfield and Medlock 2007;Symes et al 2017), with fewer studies evaluating visual (Michaelidis et al 2006;Allen and Levinton 2014), and electric (Dunlap et al 2000) modalities. However, many animals communicate using signals that involve more than one signaling modality (Partan and Marler 1999) and there has been a dearth of studies that investigate how temperature impacts these multimodal systems (but see Conrad et al 2017).…”

“…Field activity information is necessary to interpret laboratory data in many instances. For example, studies conducted on temperate species have demonstrated that signals, preferences, and mate choice may shift across temperatures, but animals may be active only within a narrow range of temperatures, e.g., tree frogs (Gerhardt 1978), fruit flies (Ritchie et al 2001), and tree crickets (Symes et al 2017). Information about the temperatures that animals naturally experience, and their activity patterns across temperatures, is therefore critical to understanding the relationship between temperature and behavior.…”