| Popis: |
Animals use signals to manipulate the behavior of the multiple, distinct audiences they interact with, including predators, prey, and conspecifics. One example of this is Batesian mimicry. Batesian mimics resemble dangerous or unpalatable prey to avoid predators. They also face a unique challenge: being accurate enough mimics to deceive predators, while remaining detectable to potential mates. The tension of meeting the demands of distinct audiences may help explain the evolutionary puzzle of imperfect mimicry. One set of hypotheses explaining imperfect mimicry posits that different audiences exert conflicting selective forces resulting in morphological compromises on the part of the mimic. If these compromises arise from selective pressures originating from distinct vantage points (e.g., potential mates viewing animals head-on or from the side, while larger or aerial predators view animals from above), this creates an opportunity for detection and study of this phenomenon.In my thesis, I investigated the possibility that mimics may have more accurate mimicry when viewed from above to avoid detection from predators, but lower fidelity mimicry when viewed from the side to be visible to prospective mates. I studied the morphology of Synemosyna formica, an ant mimic, from a three-dimensional perspective as viewed by the visual systems of their different audiences. I also studied the movement of S. formica and how this might impact their mimicry. I found that S. formica exhibited higher mimetic fidelity in shape and color when analyzed from an overhead versus a lateral vantage point. This is consistent with the idea that mimicry helps these animals avoid predators that view them from above, while they adopt a less mimetic morphology to attain mates that view them laterally. However, I found mixed evidence for behavioral mimicry.Another example of animals using signals to manipulate the behavior of audiences is male courtship displays. Males of many species evolve signals under selection via female choice. These males face a key challenge: they must capture and hold female attention while performing their displays. In this thesis, I studied Habronattus pyrrithrix, a jumping spider in which the males exhibit courtship displays involving moving orange knees up and down. I evaluated whether the coloration and/or motion of the knees, previously known to be important in attracting female gaze, translated to attention-holding in live interactions. Surprisingly, I found that experimental manipulation of neither knee coloration nor knee movement detectably altered measures of female attention during live courtship. However, I did find that males that courted for longer durations were able to get closer to females and retained more female attention.Taken together, my thesis highlights the importance of audience perception and attentiveness in shaping animal signals. I provide evidence for a novel driver of imperfect mimicry: that imperfect mimicry may be a result of the distinct positions of viewers in the environment. I also demonstrate that female attentional processes may not always translate into differential attention during courtship. This work demonstrates that consideration of how animals are perceived by audiences is critical to understanding the evolution of signals. |
