A. Sawada, T. Iwasaki, T. Matsuo, Kana Akatani, M. Takagi
{"title":"Reversed Sexual Size Dimorphism in the Ryukyu Scops Owl Otus elegans on Minami-Daito Island","authors":"A. Sawada, T. Iwasaki, T. Matsuo, Kana Akatani, M. Takagi","doi":"10.2326/osj.20.15","DOIUrl":null,"url":null,"abstract":"Abstract One of the consequences of selections acting on body size is the difference in body size between the sexes or sexual size dimorphism. Although many hypotheses have been proposed for reversed sexual size dimorphism (RSD) in raptors, ornithologists have rarely paid attention to temporal aspects of RSD when testing their hypotheses. Because selection pressures may vary temporally, describing temporal variation in RSD is a first step towards understanding evolutionary mechanism which shape and maintain the dimorphism. Here, we describe RSD in the population of Ryukyu Scops Owls Otus elegans on Minami-daito Island using a dataset of the external measurements of 770 individuals obtained during a 17-year long-term population monitoring project. Females were larger than males in body mass, culmen length, bill depth, bill width, tail length and flattened wing length, whereas males were larger than females in tarsus and head lengths. Among these traits, the degree and direction of RSD of body mass, tarsus length, bill depth and flattened wing length varied across years. There were neither increasing nor decreasing trends in RSD. This is a rare study which addressed temporal variation in RSD in a raptor species.","PeriodicalId":49009,"journal":{"name":"Ornithological Science","volume":"20 1","pages":"15 - 26"},"PeriodicalIF":0.5000,"publicationDate":"2021-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"6","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ornithological Science","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.2326/osj.20.15","RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ORNITHOLOGY","Score":null,"Total":0}
引用次数: 6
Abstract
Abstract One of the consequences of selections acting on body size is the difference in body size between the sexes or sexual size dimorphism. Although many hypotheses have been proposed for reversed sexual size dimorphism (RSD) in raptors, ornithologists have rarely paid attention to temporal aspects of RSD when testing their hypotheses. Because selection pressures may vary temporally, describing temporal variation in RSD is a first step towards understanding evolutionary mechanism which shape and maintain the dimorphism. Here, we describe RSD in the population of Ryukyu Scops Owls Otus elegans on Minami-daito Island using a dataset of the external measurements of 770 individuals obtained during a 17-year long-term population monitoring project. Females were larger than males in body mass, culmen length, bill depth, bill width, tail length and flattened wing length, whereas males were larger than females in tarsus and head lengths. Among these traits, the degree and direction of RSD of body mass, tarsus length, bill depth and flattened wing length varied across years. There were neither increasing nor decreasing trends in RSD. This is a rare study which addressed temporal variation in RSD in a raptor species.
期刊介绍:
Ornithological Science publishes reviews, original articles, short communications and comments covering all aspects of ornithology. Manuscripts are judged on the basis of their contribution of original data and ideas or interpretation. All articles are peer-reviewed by at least two researchers expert in the field of the submitted paper. Manuscript are edited where necessary for clarify and economy. Ornithological Science aims to publish as rapidly as is consistent with the requirements of peer-review and normal publishing constraints.