In dense mating
aggregations, such as insect and anuran choruses, signals produced at the same
time can overlap and interfere with one another, reducing the ability of
receivers to discriminate between individual signals. Thus, evolution by sexual
selection is expected to result in mating signal timing strategies that avoid
overlap. Patterns of signal alternation between competing males are commonly
observed in leks and choruses across taxa. In some species, however, signalers
instead deliberately overlap, or ‘synchronize’, their mating signals with
neighboring conspecifics. Given the assumed high cost of reduced mate
attraction when signals overlap, mating signal synchronization has remained an
evolutionary puzzle. Synchronization may be beneficial, however, if overlapping
signals reduce the attraction of nontarget receivers (predator avoidance
hypothesis). Synchronized signals could also constructively interfere,
increasing female attraction to the mating aggregation (the beacon effect
hypothesis). I investigate these functions of synchronized signaling in two
species of tree frogs that synchronize their mating calls: the pug-nosed tree
frog (<i>Smilisca sila</i>) and the Ryukyu Kajika frog (<i>Buergeria japonica</i>).
To examine the trade-offs imposed by call synchronization in each species, I
conduct a series of field and laboratory playback experiments on target (female
frogs) and nontarget (eavesdropping predators) receivers of frog calls. Results
from these experiments support both hypotheses, suggesting that synchronized
frog calls can reduce the attraction of predators and attract mates to the
chorus. In addition, I found reduced preferences for fine-scale call timings in
female <i>S. sila</i> and <i>B. japonica</i>, deviating from the expected
preferences observed in many other anuran and non-anuran species. Thus, while
males may enjoy multiple benefits from synchronized mating signals, relaxed
sexual selection for non-synchronous signals may be key to the evolution and
maintenance of mating signal synchrony.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12252857 |
| Date | 06 May 2020 |
| Creators | Henry D Legett (8803115) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/THE_FUNCTION_OF_FINE-SCALE_SIGNAL_TIMING_STRATEGIES_SYNCHRONIZED_CALLING_IN_STREAM_BREEDING_TREE_FROGS/12252857 |
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