Odom Karan J, Cain Kristal E, Hall Michelle L, Langmore Naomi E, Mulder Raoul A, Kleindorfer Sonia, Karubian Jordan, Brouwer Lyanne, Enbody Erik D, Jones John Anthony, Dowling Jenélle L, Leitão Ana V, Greig Emma I, Evans Christine, Johnson Allison E, Meyers Kimberley K-A, Araya-Salas Marcelo, Webster Michael S
Cornell Lab of Ornithology and Department of Neurobiology and Behavior Cornell University Ithaca New York USA.
Department of Psychology University of Maryland, College Park College Park Maryland USA.
Ecol Evol. 2021 Dec 7;11(24):17901-17919. doi: 10.1002/ece3.8378. eCollection 2021 Dec.
Historically, bird song complexity was thought to evolve primarily through sexual selection on males; yet, in many species, both sexes sing and selection pressure on both sexes may be broader. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high, temperate latitudes. Furthermore, we expect male-female song structure and elaboration to be more similar at lower, tropical latitudes, where longer breeding seasons and year-round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both types of selective pressures and sexes into account. We examined song in both sexes in 15 populations of nine-fairy-wren species (Maluridae), a Southern Hemisphere clade with female song. We compared song elaboration (in both sexes) and sexual song dimorphism to latitude and life-history variables tied to sexual and social selection pressures and sex roles. Our results suggest that song elaboration evolved in part due to sexual competition in males: male songs were longer than female songs in populations with low male survival and less male provisioning. Also, female songs evolved independently of male songs: female songs were slower paced than male songs, although only in less synchronously breeding populations. We also found male and female songs were more similar when parental care was more equal and when male survival was high, which provides strong evidence that sex role similarity correlates with male-female song similarity. Contrary to Northern Hemisphere latitudinal patterns, male and female songs were more similar at higher, temperate latitudes. These results suggest that selection on song can be sex specific, with male song elaboration favored in contexts with stronger sexual selection. At the same time, selection pressures associated with sex role similarity appear to favor sex role similarity in song structure.
从历史上看，鸟鸣的复杂性被认为主要是通过对雄性的性选择而进化的；然而，在许多物种中，两性都会鸣叫，而且对两性的选择压力可能更广泛。先前的研究表明，在短暂、同步的繁殖季节中，对配偶和资源的竞争导致在高纬度温带地区雄性的歌声更加复杂。此外，我们预计在低纬度热带地区，雄性和雌性的歌声结构和复杂性会更相似，因为那里较长的繁殖季节和全年的领地行为会给两性带来相似的社会选择压力。然而，很少有研究同时考虑这两种选择压力和两性因素。我们研究了九种仙女鹩（细尾鹩莺科）15个种群中两性的歌声，这是一个南半球的类群，其中雌性也会鸣叫。我们将歌声的复杂性（两性都有）和歌声的性别二态性与与性选择和社会选择压力以及性别角色相关的纬度和生活史变量进行了比较。我们的结果表明，歌声的复杂性部分是由于雄性的性竞争而进化的：在雄性存活率低且雄性育雏较少的种群中，雄性的歌声比雌性的歌声更长。此外，雌性的歌声是独立于雄性的歌声进化的：雌性的歌声节奏比雄性的歌声慢，尽管只在繁殖不太同步的种群中如此。我们还发现，当亲代抚育更加平等且雄性存活率较高时，雄性和雌性的歌声更相似，这有力地证明了性别角色的相似性与雄性和雌性歌声的相似性相关。与北半球的纬度模式相反，在较高的温带纬度地区，雄性和雌性的歌声更相似。这些结果表明，对歌声的选择可能具有性别特异性，在性选择较强的情况下，雄性歌声的复杂性更受青睐。与此同时，与性别角色相似性相关的选择压力似乎有利于歌声结构上的性别角色相似性。
