Quantifying ecological constraints on motion signaling

The environment in which animal signals are generated has the potential to affect transmission and reliable detection by receivers. To understand such constraints, it isimportant to quantify both signals and noise in detail. Investigations of acoustic and colorsignals now utilize established methods, but quantifying motion-based visual signals andnoise remains rudimentary. In this paper, we encourage a more complete consideration of motion signaling environments and describe an approach to quantifying signal and noise in detail. Signals are reconstructed in three-dimensions, microhabitats are mapped and the noise environment quantified in a standardized manner. Information on signal and noise is combined to consider signal contrast from multiple viewpoints, and in any of the habitats we map. We illustrate our approach by examining signals andnoise for two allopatric populations of the Australian mallee military dragon Ctenophorusfordi. By “placing” signals in different microhabitats we observed similar signal contrast results within populations, but clear differences when considered in microhabitats ofthe other population. These preliminary results are consistent with the hypothesis that habitat structure has affected display structure in these populations of lizards. Our novel methodology will facilitate the examination of habitat-dependent convergence anddivergence in motion signal structure in a variety of taxonomic groups and habitats. Furthermore, we anticipate application of our approach to consider the visual ecology of animals more broadly.
Ramos JA,Peters RA(2017) Quantifying ecological constraints on motion signalling. Frontiers in Ecology and Evolution5:9

FIGURE | (A) The environment where motion signaling takes place includes plants (a, b, c) that could mask motion-based signals generated by lizards (L). (B) Schematic representation of the scene depicted in (A) showing the lizard and three main plants, as well as four different viewing positions (1–4). (C), The perspective for viewers positioned at each of the four locations differs and serves to illustrate how viewing position will determine the noise environment. Viewing positions 1, 2,and 3 are at a similar distance from the signaler, while 4 is further away. The lizard is completely blocked by plant “c” for a viewer located at viewing position 2 and as such the signal is completely masked by noise. For the other viewing positions, plant “a” is relevant for positions 1, 3, and 4, but its apparent size and masking potential increases when positioned in front of the lizard (viewing position 1) and decreases when behind (viewing position 3, 4). Plant “b” is outside the field of viewfrom viewing position 1, but is relevant from viewing positions 3 and 4. Plant “c” is relevant for viewing positions 1, 3, and 4, and is at the same depth plane as thelizard in each case.