The song systems of oscine passerines(songbirds)are complex and diverse.Because songs are used for both mate attraction and territory defense and are therefore important signals for survival and reproduction,comprehen...The song systems of oscine passerines(songbirds)are complex and diverse.Because songs are used for both mate attraction and territory defense and are therefore important signals for survival and reproduction,comprehensive knowledge of within and among species song structure and distribution is informative for understanding the evolution of song repertoires and vocal behaviour.In this study,we explored variation in the song structure of the Ovenbird(Seiurus aurocapilla),a widespread warbler(Family Parulidae)found in North American forests.We analyzed recordings from the 2021 breeding season to assess song type variation at a local(n=158 birds;Sault Ste.Marie,ON)and breeding range scale(n=512 birds;eBird).We characterized the local song types and tested whether Ovenbirds share song types with their neighbors more often than expected by chance.We then characterized song types of Ovenbirds across the breeding range to determine whether any geographic pattern of song clustering exists(i.e.,macro-dialects).We found 10 distinct song types and some evidence for song type clustering at the local study site(i.e.,song neighborhoods).We found 7 of those 10 song types throughout the breeding range and identified an additional 24 types that were not recorded in our local population.We found no evidence for song dialects across the Ovenbird breeding range.This study contributes to our understanding of Ovenbird song while simultaneously adding to our understanding of geographic structuring of warbler repertoires.Our work contributes to delineating a more comprehensive understanding of factors affecting dialect development for this diverse group of songbirds.展开更多
Many recent studies of ecological speciation have focused on ＂magic trait＂ scenarios, in which divergent selection on viability traits leads inextricably to corresponding divergence in mechanisms, especially mate re...Many recent studies of ecological speciation have focused on ＂magic trait＂ scenarios, in which divergent selection on viability traits leads inextricably to corresponding divergence in mechanisms, especially mate recognition systems, that facilitate assortative mating. Speciation however may also proceed via other scenarios, such as when populations experience directly se- lected or random divergence in mate recognition systems. The relative contributions of magic trait versus other scenarios for speciation remain virtually unexplored. The present study aims to test the relative contribution of the magic trait scenario in the divergence of populations of the medium ground finch Geospiza fortis of Santa Cruz Island, Galapagos. First, we assess differ- ences in G. fortis song between a northern population （Borrero Bay） and a southeastern population （El Garrapatero）, differences that we propose （along with other within-island geographic song variations） have arisen via scenarios that do not involve a magic trait scenario. Pairwise comparisons of raw and composite （PC） song parameters, as well as discriminant functions analyses, re- veal significant patterns of song divergence between sites. Second, we test the ability of territorial males at Borrero Bay to dis- criminate songs from the two sites. We find that G. fortis males can discriminate within-island song variants, responding more strongly to local than to ＂foreign＂ songs, along 3 raw and 1 composite response measures. Third, we compare these findings to prior data sets on song divergence and discrimination in Santa Cruz G. fortis. These comparisons suggest that song divergence and discrimination are shaped less strongly by geographic sources than by morphological （beak-related） sources. We thus argue that interpopulation song divergence and discrimination, fundamental elements of assortative mating in Darwin＇s finches, can be fos- tered in early stages of divergence under magic trait as well as alternative scenarios for speciation, but with more emphasis on the magic trait scenario, at least for this species on this island [Current Zoology 59 （1）： 8-19, 2013].展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)Canadian Foundation for Innovation(CFI)+1 种基金Ontario Ministry of Research and Innovation(OMRI)Northern Ontario Heritage Fund Corporation(NOHFC)。
文摘The song systems of oscine passerines(songbirds)are complex and diverse.Because songs are used for both mate attraction and territory defense and are therefore important signals for survival and reproduction,comprehensive knowledge of within and among species song structure and distribution is informative for understanding the evolution of song repertoires and vocal behaviour.In this study,we explored variation in the song structure of the Ovenbird(Seiurus aurocapilla),a widespread warbler(Family Parulidae)found in North American forests.We analyzed recordings from the 2021 breeding season to assess song type variation at a local(n=158 birds;Sault Ste.Marie,ON)and breeding range scale(n=512 birds;eBird).We characterized the local song types and tested whether Ovenbirds share song types with their neighbors more often than expected by chance.We then characterized song types of Ovenbirds across the breeding range to determine whether any geographic pattern of song clustering exists(i.e.,macro-dialects).We found 10 distinct song types and some evidence for song type clustering at the local study site(i.e.,song neighborhoods).We found 7 of those 10 song types throughout the breeding range and identified an additional 24 types that were not recorded in our local population.We found no evidence for song dialects across the Ovenbird breeding range.This study contributes to our understanding of Ovenbird song while simultaneously adding to our understanding of geographic structuring of warbler repertoires.Our work contributes to delineating a more comprehensive understanding of factors affecting dialect development for this diverse group of songbirds.
文摘Many recent studies of ecological speciation have focused on ＂magic trait＂ scenarios, in which divergent selection on viability traits leads inextricably to corresponding divergence in mechanisms, especially mate recognition systems, that facilitate assortative mating. Speciation however may also proceed via other scenarios, such as when populations experience directly se- lected or random divergence in mate recognition systems. The relative contributions of magic trait versus other scenarios for speciation remain virtually unexplored. The present study aims to test the relative contribution of the magic trait scenario in the divergence of populations of the medium ground finch Geospiza fortis of Santa Cruz Island, Galapagos. First, we assess differ- ences in G. fortis song between a northern population （Borrero Bay） and a southeastern population （El Garrapatero）, differences that we propose （along with other within-island geographic song variations） have arisen via scenarios that do not involve a magic trait scenario. Pairwise comparisons of raw and composite （PC） song parameters, as well as discriminant functions analyses, re- veal significant patterns of song divergence between sites. Second, we test the ability of territorial males at Borrero Bay to dis- criminate songs from the two sites. We find that G. fortis males can discriminate within-island song variants, responding more strongly to local than to ＂foreign＂ songs, along 3 raw and 1 composite response measures. Third, we compare these findings to prior data sets on song divergence and discrimination in Santa Cruz G. fortis. These comparisons suggest that song divergence and discrimination are shaped less strongly by geographic sources than by morphological （beak-related） sources. We thus argue that interpopulation song divergence and discrimination, fundamental elements of assortative mating in Darwin＇s finches, can be fos- tered in early stages of divergence under magic trait as well as alternative scenarios for speciation, but with more emphasis on the magic trait scenario, at least for this species on this island [Current Zoology 59 （1）： 8-19, 2013].
