Geographic Variation in Advertisement Calls in a Tree Frog Species: Gene Flow and Selection Hypotheses

Abstract

BackgroundIn 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.MethodologyWe 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.ResultsThe 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.ConclusionsGeographic 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. japoinca. 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.

Morphometrics of two sympatric species of tree frogs in Korea: a morphological key for the critically endangeredHyla suweonensisin relation toH. japonica

“…The samples used for this study were drawn from Jang et al (2011). We included samples from seven sympatric localities in the Republic of Korea for a morphometrical analysis (Table 1).…”

“…The total number of males for this study was 41 H. japonica and 47 H. suweonensis and is representative of the entire distribution of H. suweonensis. Tree frogs have been identified through molecular analysis of the cytochrome c oxidase subunit I mitochondrial gene (Jang et al 2011;Jeong et al 2013), and only individuals with positive species identification were used for this study. After photographing and sample collection, all tree frogs were released at the sampling site.…”

“…Kuramoto (1980) distinguished H. suweonensis from the cryptically diverse Hyla genus (Bryson et al 2010;Funk et al 2012;Stock et al 2012), based on advertisement calls and morphological variations. Studies on call characteristics (Kuramoto 1980;Matsui 2004;Jang et al 2011;Yoo & Jang 2012) and mitochondrial and nuclear genes (Yang et al 1981;Yang & Park 1988;Yu & Lee 1990;Lee & Park 1992;Yang et al 1997;Lee et al 1999) validated the species status of H. suweonensis.…”

First record of Pseudopaludicola boliviana Parker, 1927 (Anura, Leptodactylidae, Leiuperinae) in the Brazilian state of Amapá, with comments on its advertisement call and distribution

“…This might be explained due to different analytic procedures. We measured note period (from beginning of one note to beginning of the next; see Jang et al 2011 for definition) instead of note duration (beginning to end of one note) given that intervals between notes were often barely identified or inexistent in our sample, whereas inter-note intervals in calls analyzed by Duré et al (2004) seemed to be more discernible based on their Figure 3B. With respect to call frequency, minimum and dominant frequencies had quite similar values, but maximum frequency of their calls presented an expressive lower value range (< 6000 Hz) compared to ours (6966 to 7390 Hz).…”

Evolution under unpredictable environmental conditions: quantitative genetics of larval life-history traits in a myobatrachid frogCrinia georgiana

“…Pair formation in this species is characterized by male acoustic signaling and female phonotaxis (Gerhardt et al 2000;Jang et al 2011;Yoo and Jang 2012). However, polyandrous matings often occur when intruding males *Corresponding author.…”