title: Geographic variation in advertisement calls in a tree frog species: gene flow and selection hypotheses.
abstract: BACKGROUND
  In a species with a large distribution relative to its dispersal capacity, geographic variation in traits may be explained by gene flow, selection, or the combined effects of both. Studies of genetic diversity using neutral molecular markers show that patterns of isolation by distance (IBD) or barrier effect may be evident for geographic variation at the molecular level in amphibian species. However, selective factors such as habitat, predator, or interspecific interactions may be critical for geographic variation in sexual traits. We studied geographic variation in advertisement calls in the tree frog Hyla japonica to understand patterns of variation in these traits across Korea and provide clues about the underlying forces for variation.
  
  
  METHODS
  We recorded calls of H. japonica in three breeding seasons from 17 localities including localities in remote Jeju Island. Call characters analyzed were note repetition rate (NRR), note duration (ND), and dominant frequency (DF), along with snout-to-vent length.
  
  
  RESULTS
  The findings of a barrier effect on DF and a longitudinal variation in NRR seemed to suggest that an open sea between the mainland and Jeju Island and mountain ranges dominated by the north-south Taebaek Mountains were related to geographic variation in call characters. Furthermore, there was a pattern of IBD in mitochondrial DNA sequences. However, no comparable pattern of IBD was found between geographic distance and call characters. We also failed to detect any effects of habitat or interspecific interaction on call characters.
  
  
  CONCLUSIONS
  Geographic variations in call characters as well as mitochondrial DNA sequences were largely stratified by geographic factors such as distance and barriers in Korean populations of H. japonica. Although we did not detect effects of habitat or interspecific interaction, some other selective factors such as sexual selection might still be operating on call characters in conjunction with restricted gene flow.
authors.affiliation: Division of EcoScience, Ewha Womans University, Seoul, Republic of Korea. jangy@ewha.ac.kr
authors.forename: Yikweon
authors.initials: Y
authors.lastname: Jang
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Hahm
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Lee
authors.forename: Soyeon
authors.initials: S
authors.lastname: Park
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Won
authors.forename: Jae C
authors.initials: JC
authors.lastname: Choe
mesh_terms: D000818:Animals; D001001:Anura / Q000145:classification / Q000235:genetics / Q000502:physiology*; D044822:Biodiversity; D049628:Body Size / Q000502:physiology; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D051456:Gene Flow; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes; D008297:Male; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D012044:Regression Analysis; D056910:Republic of Korea; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013045:Species Specificity; D014828:Vocalization, Animal / Q000502:physiology*
chemical_list: D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV