Filer Alannah, Burchardt Lara S, van Rensburg Berndt J
Centre for Biodiversity and Conservation Science School of Biological Sciences The University of Queensland St Lucia Qld Australia.
Museum für Naturkunde - Leibniz Institute for Evolution and Biodiversity Science Berlin Germany.
Ecol Evol. 2021 May 27;11(13):8814-8830. doi: 10.1002/ece3.7713. eCollection 2021 Jul.
Male frog advertisement calls are species-specific vocalizations used to attract females for breeding. However, it is possible for environmental or biological sounds to overlap these calls in both frequency and duration resulting in signal confusion, influencing female decision and/or location abilities. It is therefore important for vocal species competing for the same acoustic space to partition their calls either spatially or temporally (via call alternation or suppression). However, frog species previously isolated from each other may not have developed appropriate adaptive behaviors, resulting in acoustic competition. This study applied rhythm analysis to track changes in calling behavior, namely changes in calling frequency (as in beats per second), of the wallum sedgefrog and the eastern sedgefrog when vocalizing alone versus in the presence of each other to assess potential acoustic competition. Our main findings demonstrated that both species significantly altered their calling behavior when exposed to each other. While we expected the increased calling activity of one species to inhibit the activity of the other to avoid signal confusion, we instead found that both species greatly increased the beat frequency of their calls when calling in the presence of each other. We also found evidence of beat frequency development in the wallum sedgefrog whereby there was always a strong initial increase in call frequency in reaction to the first vocal interruption by the eastern sedgefrog. These results support the hypothesis that the eastern sedgefrog and the wallum sedgefrog are in competition for the acoustic space in habitats where they occur together. This highlights a new threat to the vulnerable wallum sedgefrog species and may serve to inform future management practices. Using rhythm analyses to track changes in acoustic behavior can help inform on important population dynamics such as health, trajectory, and response to management, and therefore be of great benefit to the conservation of vocal species.
雄性青蛙的求偶叫声是特定物种的发声，用于吸引雌性进行繁殖。然而，环境声音或生物声音在频率和时长上都有可能与这些叫声重叠，从而导致信号混淆，影响雌性的决策和/或定位能力。因此，对于在同一声学空间中竞争的发声物种来说，在空间或时间上（通过叫声交替或抑制）划分它们的叫声很重要。然而，以前彼此隔离的青蛙物种可能没有形成适当的适应性行为，从而导致声学竞争。本研究应用节奏分析来追踪沃勒姆泽蛙和东部泽蛙在单独鸣叫以及相互存在时鸣叫行为的变化，即鸣叫频率（每秒的节拍数）的变化，以评估潜在的声学竞争。我们的主要发现表明，当两种青蛙相互接触时，它们的鸣叫行为都发生了显著变化。虽然我们预计一个物种增加的鸣叫活动会抑制另一个物种的活动以避免信号混淆，但相反，我们发现当两种青蛙相互存在时鸣叫，它们的叫声节拍频率都大幅增加。我们还发现了沃勒姆泽蛙叫声节拍频率发展的证据，即东部泽蛙第一次发声干扰后，其鸣叫频率总是会有强烈的初始增加。这些结果支持了这样的假设，即东部泽蛙和沃勒姆泽蛙在它们共同出现的栖息地中争夺声学空间。这凸显了对脆弱的沃勒姆泽蛙物种的一种新威胁，可能有助于为未来的管理实践提供信息。使用节奏分析来追踪声学行为的变化有助于了解重要的种群动态，如健康状况、发展轨迹和对管理的反应，因此对发声物种的保护非常有益。
