Samreen Munim, MSc Candidate
Department of Biology, Martin Lab, Queen's University Do acoustic signals diverge or converge where geographic ranges overlap? Closely related bird species often have similar acoustic mating signals because of their shared recent ancestry, which can affect their reproductive isolation and ability to live together when they overlap in range. Mating signals are mostly used to attract mates and interact with competitors of the same species, but closely related species can also respond to these signals, which can lead to costs of co-occurrence, both direct (e.g., hybridization, aggression) and indirect (e.g., as a by-product of ecological divergence). As a result, where closely related species overlap in range, we expect mating signals to diverge to minimize these costs. However, the opposite can also occur: signals may converge in sympatry (i.e., range overlap) because of similar selective pressures from the environment, or from introgression or cultural drift. Moreover, selection to reduce aggressive encounters can also lead to convergence. Whether signals more often diverge or converge when species overlap in range is poorly understood, particularly for acoustic signals. To address this gap, I used a comparative framework wherein each comparison involves a pair of closely related sister lineages that differ in whether they overlap in range with a third, more distant lineage within the same genus. For each comparison, I found recordings of birds and compared the signals of the sympatric pair of species to the allopatric (i.e., no range overlap) pair to see if acoustic signals more often diverge or converge when closely related species overlap in range. The results of this study will help us better understand signal evolution and the maintenance of species barriers in sympatry, with consequences for the broad patterns of biodiversity we see in nature. Comments are closed.
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