The role of nocturnal vision in mate choice: females prefer conspicuous males in the European tree frog ( Hyla arborea )

104

SUMMARYAlthough variation in the color of light in terrestrial diurnal and twilight environments has been well documented, relatively little work has examined the color of light in nocturnal habitats. Understanding the range and sources of variation in nocturnal light environments has important implications for nocturnal vision, particularly following recent discoveries of nocturnal color vision. In this study, we measured nocturnal irradiance in a dry forest/woodland and a rainforest in Madagascar over 34 nights. We found that a simple linear model including the additive effects of lunar altitude, lunar phase and canopy openness successfully predicted total irradiance flux measurements across 242 clear sky measurements (r0.85, P<0.0001). However, the relationship between these variables and spectral irradiance was more complex, as interactions between lunar altitude, lunar phase and canopy openness were also important predictors of spectral variation. Further, in contrast to diurnal conditions, nocturnal forests and woodlands share a yellow-green-dominant light environment with peak flux at 560nm. To explore how nocturnal light environments influence nocturnal vision, we compared photoreceptor spectral tuning, habitat preference and diet in 32 nocturnal mammals. In many species, long-wavelength-sensitive cone spectral sensitivity matched the peak flux present in nocturnal forests and woodlands, suggesting a possible adaptation to maximize photon absorption at night. Further, controlling for phylogeny, we found that fruit/flower consumption significantly predicted short-wavelength-sensitive cone spectral tuning in nocturnal mammals (P0.002). These results suggest that variation in nocturnal light environments and species ecology together influence cone spectral tuning and color vision in nocturnal mammals. Supplementary material available online at

Section: Introductionmentioning

confidence: 96%

Nocturnal light environments and species ecology: implications for nocturnal color vision in forests

Veilleux

Cummings

2012

104

“…Females express a strong preference for the complex call (Ryan, 1985;Rand et al, 1992;Ryan and Rand, 2003a). Several studies have shown that visual cues are also used in the courtship behaviors of anurans (Summers et al, 1999;Hödl and Amézquita, 2001;Amézquita and Hödl, 2004;Taylor et al, 2007;Vasquez and Pfennig, 2007;Gomez et al, 2009). As with most anurans, the male túngara frog vocalization is accompanied by a conspicuous, simultaneous inflation of the vocal sac (Pauly et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Multimodal signal variation in space and time: how important is matching a signal with its signaler?

Taylor

Klein

Stein³

et al. 2011

SUMMARY Multimodal signals (acoustic+visual) are known to be used by many anuran amphibians during courtship displays. The relative degree to which each signal component influences female mate choice, however, remains poorly understood. In this study we used a robotic frog with an inflating vocal sac and acoustic playbacks to document responses of female túngara frogs to unimodal signal components (acoustic and visual). We then tested female responses to a synchronous multimodal signal. Finally, we tested the influence of spatial and temporal variation between signal components for female attraction. Females failed to approach the isolated visual cue of the robotic frog and they showed a significant preference for the call over the spatially separate robotic frog. When presented with a call that was temporally synchronous with the vocal sac inflation of the robotic frog, females did not show a significant preference for this over the call alone; when presented with a call that was temporally asynchronous with vocal sac inflation of the robotic frog, females discriminated strongly against the asynchronous multimodal signal in favor of the call alone. Our data suggest that although the visual cue is neither necessary nor sufficient for attraction, it can strongly modulate mate choice if females perceive a temporal disjunction relative to the primary acoustic signal.

“…We based our experimental design on the findings of several previous video playback studies in anurans that females attend to characteristics of male vocal sacs, which are inflated concurrently with sound production (Gomez et al, 2009;Richardson et al, 2010;Rosenthal et al, 2004). The large size and rapid inflation of vocal sacs may improve females' abilities to localize potential mates (Preininger et al, 2013;Rosenthal et al, 2004;Taylor et al, 2008).…”

mentioning

confidence: 99%

Female gray treefrogs, Hyla versicolor, are responsive to visual stimuli but unselective of stimulus characteristics

Reichert

Galante

Höbel

2014

The visual ecology of nocturnal anurans is poorly understood, but there is growing evidence that vision plays a role in important behaviors such as mate choice. While several recent studies have demonstrated that females are responsive to visual cues when selecting mates, the forces responsible for these preferences are unknown. We investigated the responsiveness of female gray treefrogs, Hyla versicolor, to video playbacks of calling conspecific males in which we varied attributes of the vocal sac, a conspicuous visual characteristic of calling males and a target of female choice in other species. Females responded surprisingly strongly to the video playbacks, but did so indiscriminately with respect to variation in vocal sac characteristics. We followed up on these results with a series of additional tests that examined female responses to abstract stimuli. Females continued to respond to such stimuli, leading us to conclude that their behavior was related to a generalized phototactic response. Because of this, we were unable to make conclusions regarding female preferences for vocal sac characteristics. Nonetheless, our results are significant in two respects. First, we illustrate that despite much effort into improving video playback methodologies, challenges remain, and we offer our experimental design as a method to ensure that appropriate conclusions can be drawn from such studies. Second, we argue that the female phototactic response has potentially significant behavioral implications and in general the consequences of anuran visual preferences deserve further investigation.