Pang-Ching Joshua M, Paxton Kristina L, Paxton Eben H, Pack Adam A, Hart Patrick J
Tropical Conservation Biology and Environmental Science University of Hawaii at Hilo Hilo HI USA.
Department of Biology University of Hawaii at Hilo Hilo HI USA.
Ecol Evol. 2018 Jan 18;8(4):2076-2087. doi: 10.1002/ece3.3820. eCollection 2018 Feb.
Little is known about how important social behaviors such as song vary within and among populations for any of the endemic Hawaiian honeycreepers. Habitat loss and non-native diseases (e.g., avian malaria) have resulted in isolation and fragmentation of Hawaiian honeycreepers within primarily high elevation forests. In this study, we examined how isolation of Hawai'i 'amakihi () populations within a fragmented landscape influences acoustic variability in song. In the last decade, small, isolated populations of disease tolerant 'amakihi have been found within low elevation forests, allowing us to record 'amakihi songs across a large elevational gradient (10-1800 m) that parallels disease susceptibility on Hawai'i island. To understand underlying differences among populations, we examined the role of geographic distance, elevation, and habitat structure on acoustic characteristics of 'amakihi songs. We found that the acoustic characteristics of 'amakihi songs and song-type repertoires varied most strongly across an elevational gradient. Differences in 'amakihi song types were primarily driven by less complex songs (e.g., fewer frequency changes, shorter songs) of individuals recorded at low elevation sites compared to mid and high elevation populations. The reduced complexity of 'amakihi songs at low elevation sites is most likely shaped by the effects of habitat fragmentation and a disease-driven population bottleneck associated with avian malaria, and maintained through isolation, localized song learning and sharing, and cultural drift. These results highlight how a non-native disease through its influence on population demographics may have also indirectly played a role in shaping the acoustic characteristics of a species.
对于夏威夷本土蜜旋木雀而言，诸如鸣叫等社会行为在种群内部和种群之间的重要性，我们所知甚少。栖息地丧失和外来疾病（如禽疟）导致夏威夷蜜旋木雀在主要为高海拔森林的区域内出现隔离和碎片化分布。在本研究中，我们探究了在破碎化景观中，夏威夷绿雀（）种群的隔离如何影响其鸣叫的声学变异性。在过去十年里，在低海拔森林中发现了少量对疾病具有耐受性的、隔离的绿雀种群，这使我们能够在与夏威夷岛疾病易感性平行的较大海拔梯度（10 - 1800米）上记录绿雀的鸣叫。为了解种群之间的潜在差异，我们研究了地理距离、海拔和栖息地结构对绿雀鸣叫声学特征的作用。我们发现，绿雀鸣叫的声学特征和鸣叫类型库在海拔梯度上变化最为强烈。绿雀鸣叫类型的差异主要是由低海拔地区记录的个体所发出的较简单鸣叫（例如，频率变化较少、鸣叫较短）与中高海拔种群相比导致的。低海拔地区绿雀鸣叫复杂性的降低很可能是由栖息地破碎化的影响以及与禽疟相关的疾病驱动的种群瓶颈所塑造的，并通过隔离、局部鸣叫学习和共享以及文化漂变得以维持。这些结果凸显了一种外来疾病如何通过其对种群统计学的影响，可能也间接地在塑造一个物种的声学特征方面发挥了作用。
