MDPI AG Acta Medica Okayama 2076-2615 16 3 2026 Impact of the July 2018 Heavy Rain Disaster on the Endangered Nagoya Daruma Pond Frog (Pelophylax porosus brevipodus) in Rice Fields of Mabi Town, Kurashiki City, Western Japan: Changes in Population Structure over Five Years 369 EN Ryo Nakajima Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Daisuke Azumi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Masakazu Tada Okayama Prefectural Public Interest Incorporated Foundation for Environmental Conservation Junya Nakaichi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Koki R. Katsuhara Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Kazuyoshi Nakata Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Rice paddy fields (referred to below as rice fields) are important not only for food production, but also as habitats for various species. The Nagoya Daruma Pond Frog (Pelophylax porosus brevipodus) is an endangered frog species endemic to Japan, mainly living in and around rice field areas. In July 2018, heavy rainfall caused severe flooding in Mabi Town of Okayama Prefecture, western Japan, submerging numerous rice fields and affecting local frog populations, including P. porosus brevipodus. To clarify whether the population structure of P. porosus brevipodus changed following the flood disaster in the rice fields of Mabi Town, we conducted quantitative field surveys in a rice fallow field in mid-October before (2017) and after (2018, 2020–2022, excluding 2019) the flood. The number of frogs declined sharply after the 2018 flood, reaching only a few individuals by 2020, but showed a substantial recovery in 2021 following the resumption of rice cultivation, although numbers decreased again in 2022. This recovery, despite fluctuations, indicates that habitat restoration through rice farming played a key role in enabling the population to rebound. Our findings underscore the importance of maintaining and restoring rice field environments after natural disasters for the survival and long-term recovery of P. porosus brevipodus. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0022-0477 109 11 2021 The eco]evolutionary dynamics of prior selfing rates promote coexistence without niche partitioning under conditions of reproductive interference 3916 3928 EN Koki Katsuhara Graduate School of Human Development and Environment, Kobe University Kobe Yuuya Tachiki Department of Biological Sciences Tokyo Metropolitan University Tokyo Japan Ryosuke Iritani Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) RIKEN Wako Saitama Japan Atushi Ushimaru Graduate School of Human Development and Environment Kobe University Kobe Japan 1. Pollinator-mediated reproductive interference can occur when two or more plant species share the same pollinators. Recent studies have suggested that prior autonomous selfing mitigates reproductive interference, potentially facilitating coexistence even in the absence of pollination niche partitioning (i.e. the pre-emptive selfing hypothesis). However, whether the evolution of prior selfing promotes coexistence, in the context of the eco-evolutionary dynamics of population size, selfing rates and inbreeding depression, remains poorly understood.<br> 2. We constructed an individual-based model to examine the conditions under which the evolution of prior selfing promotes coexistence in the context of mutual reproductive interference. In the model, two plant species compete by way of mutual reproductive interference, and both have the potential to evolve the capacity for prior autonomous selfing. We expected that purging of deleterious mutations might result in evolutionary rescue, assuming that the strength of inbreeding depression declines as the population selfing rate increases; this would enable inferior competitors to maintain population density through the evolution of prior selfing.<br> 3. Our simulation demonstrated that evolution of prior selfing may promote coexistence, whereas reproductive interference in the absence of such evolution results in competitive exclusion. We found that lower pollinator availability is likely to favour rapid evolutionary shifts to higher prior selfing rates, thereby neutralising the negative effects of reproductive interference in both species. When the strength of inbreeding depression decreased with an increase in the population-level selfing rate, moderate pollinator availability resulted in long-term coexistence in which relative abundance-dependent selection on the prior selfing rate served to intermittently maintain the population density of the inferior competitor.<br> 4. Synthesis. We demonstrate that the evolution of prior selfing may increase population growth rates of inferior competitors and may consequently promote long-term coexistence via an evolutionary rescue. This constitutes a novel mechanism explaining the co-evolutionary coexistence of closely related plant species without niche partitioning, and is consistent with recent studies reporting that closely related species with mixed mating systems can co-occur sympatrically, even under conditions of mutual reproductive interference. No potential conflict of interest relevant to this article was reported.