Parapatric distributions of closely related species are common in many taxonomic groups. However, habitat overlap in sympatric areas within both species’ ranges is complex and driven by the nature of the interactions between species as well as each species’ ecological requirements. We therefore investigated the distribution of breeding habitats for two congeneric frogs, Pelophylax nigromaculatus and Pelophylax porosus brevipodus , in a region of Japan where these species co-occur, based on observation of mating calls as an index of the abundance of males engaging in reproductive activities. Among a total of 381 surveyed sites, P. nigromaculatus and P. porosus brevipodus were found at 171 and 229 sites, respectively. Pelophylax porosus brevipodus was widely distributed throughout the study area and was more abundant than P. nigromaculatus in sympatric sites. Analysis using cumulative link mixed models revealed that the abundance of calling males was negatively affected by the presence of calling males of the other species and by landscape factors. Interspecific differences in this negative effect appear to favor P. porosus brevipodus over P. nigromaculatus in our study area. Due to differences in the primary habitat preferences of the two species during the non-breeding season, habitat partitioning during the breeding season is likely driven by negative interspecific interactions during the reproductive process (i.e., reproductive interference).

中文翻译：

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两种密切相关的池塘青蛙，黑斑斑斑蛙和 Pelophylax porosus brevipodus 在繁殖季节的栖息地划分

在许多分类群中，密切相关物种的准地区分布很常见。然而，两个物种范围内同域地区的栖息地重叠是复杂的，并且是由物种之间相互作用的性质以及每个物种的生态要求驱动的。因此，我们根据对交配叫声的观察作为参与繁殖活动的雄性丰度的指标，调查了两种同系青蛙 Pelophylax nigromaculatus 和 Pelophylax porosus brevipodus 在这些物种共同出现的地区的繁殖栖息地分布. 在共调查的 381 个地点中，P. nigromaculatus 和 P. porosus brevipodus 分别在 171 个和 229 个地点被发现。Pelophylax porosus brevipodus 广泛分布于整个研究区，比 P. nigromaculatus 在同域部位。使用累积链接混合模型的分析表明，呼叫雄性的丰度受到其他物种呼叫雄性的存在和景观因素的负面影响。在我们的研究区域，这种负面影响的种间差异似乎有利于 P. porosus brevipodus 而不是 P. nigromaculatus。由于两个物种在非繁殖季节的主要栖息地偏好存在差异，繁殖季节期间的栖息地划分可能是由繁殖过程中的负面种间相互作用（即繁殖干扰）驱动的。在我们的研究区域，这种负面影响的种间差异似乎有利于 P. porosus brevipodus 而不是 P. nigromaculatus。由于两个物种在非繁殖季节的主要栖息地偏好存在差异，繁殖季节期间的栖息地划分可能是由繁殖过程中的负面种间相互作用（即繁殖干扰）驱动的。在我们的研究区域，这种负面影响的种间差异似乎有利于 P. porosus brevipodus 而不是 P. nigromaculatus。由于两个物种在非繁殖季节的主要栖息地偏好存在差异，繁殖季节期间的栖息地划分可能是由繁殖过程中的负面种间相互作用（即繁殖干扰）驱动的。