Endogenous bornavirus-like L (EBLL) elements are inheritable sequences derived from ancient bornavirus L genes that encode a viral RNA-dependent RNA polymerase (RdRp) in many eukaryotic genomes. Here, we demonstrate that bats of the genus Eptesicus have preserved for more than 11.8 million years an EBLL element named eEBLL-1, which has an intact open reading frame of 1,718 codons. The eEBLL-1 coding sequence revealed that functional motifs essential for mononegaviral RdRp activity are well conserved in the EBLL-1 genes. Genetic analyses showed that natural selection operated on eEBLL-1 during the evolution of Eptesicus. Notably, we detected efficient transcription of eEBLL-1 in tissues from Eptesicus bats. To the best of our knowledge, this study is the first report showing that the eukaryotic genome has gained a riboviral polymerase gene from an ancient virus that has the potential to encode a functional RdRp.

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28Water, sediment, and large wood (LW) are the three key components of dynamic 29 river-floodplain ecosystems. We examined variations in sediment and LW discharge with 30 respect to precipitation, the presence of dams, land and river use change, and related channel 31 incision and forest expansion on gravel bars and floodplains across Japan. The results 32 indicated that unit sediment discharge and unit LW discharge were smaller in southern Japan 33 where precipitation intensity is generally much greater. Effective precipitation, an index that 34 takes current and antecedent precipitation into account, was a strong predictor of discharge in 35 small watersheds, but not in larger watersheds. However, precipitation intensities related to 36 unit sediment discharge in intermediate and large watersheds were smaller than those 37 associated with unit LW discharge, which we attribute to differences in particle shape and 38 size and also transport mechanisms. The relationship between river flow and discharge of 39 sediment and LW lead us to posit that discharges of these components are supply limited in 40 southern Japan and transport limited in northern Japan. The cross-sectional mean low-flow 41 bed elevation of gravel-bed and sand-bed rivers in Japan decreased by ~0.71 and 0.74 m on 42 average, respectively, over the period 1960-2000. Forest expansion on bars and floodplains 43 has been prominent since the 1990s, and trees apparently began to colonize gravel bars ~10 to 44 20 years after riverbed degradation began. Forest recovery in headwater basins, dam 45 construction, gravel mining, and channelization over the past half century are likely the 46 dominant factors that significantly reduced downstream sediment delivery, thereby promoting 47 channel incision and forest expansion. Changes in rivers and floodplains associated with 48 channel incision and forest expansion alter the assemblages of aquatic and terrestrial 49 organisms in riverine landscapes of Japan, and climate change may contribute to this change 50 by intensified precipitation. Additionally, regime shifts of water, sediment, and LW may 51 continue or they may reach a dynamic state of quasi-equilibrium in the future. Continued 52 monitoring of these three components, taking into account their geographic variation, is 53 critical for anticipating and managing future changes in river-floodplain systems in Japan and 54 around the world. 55 56 Keywords: regime shift; channel incision; forest expansion; sediment discharge 57 58River and floodplain ecosystems are sustained by water and material flows delivered 60 from contributing watershed areas. Among those flows, water is the most fundamental 61 component because it transports materials that shape heterogeneous structures and various 62 functions of river-floodplain ecosystems. Water transports organic matter, nutrients, and 63 organisms from headwater basins to lowland rivers (Vannote et al., 1980). Among these 64 materials transported by water flows, sediment is an essential component in creating river ...

The meanders and floodplains of the Kushiro River were restored in March 2011. A 1.6-km stretch of the straightened main channel was remeandered by reconnecting the cutoff former channel and backfilling the straightened reach, and a 2.4-km meander channel was restored. Additionally, flood levees were removed to promote river-floodplain interactions. There were four objectives of this restoration project: to restore the in-stream habitat for native fish and invertebrates; to restore floodplain vegetation by increasing flooding frequency and raising the groundwater table; to reduce sediment and nutrient loads in the core wetland areas; to restore a river-floodplain landscape typical to naturally meandering rivers. In this project, not only the natural landscape of a meandering river but also its function was successfully restored. The monitoring results indicated that these goals were likely achieved in the short term after the restoration. The abundance and species richness of fish and invertebrate species increased, most likely because the lentic species that formerly inhabited the cutoff channel remained in the backwater and deep pools created in the restored reach. In addition, lotic species immigrated from neighboring reaches. The removal of flood levees and backfilling of the formerly straightened reach were very effective in increasing the frequency of flooding over the floodplains and raising the water table. The wetland vegetation recovered rapidly 1 year after the completion of the meander restoration. Sediment-laden floodwater spread over the floodplain, and approximately 80-90% of the fine sediment carried by the water was filtered out by the wetland vegetation.

In recent years, we have experienced mega-flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as "grey infrastructure") to protect human lives and assets from floods, but these hard protective measures will not function against mega-floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure as an adaptation strategy for climate change. If we can use abandoned farmlands as green infrastructure, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of green infrastructure and conventional grey infrastructure. In this combination, the fundamental green infrastructure, composed of forests and wetlands in the catchment (GI-1), and additional multilevel green infrastructures such as flood control basins that function when floodwater exceeds the planning level (GI-2) are introduced. We evaluated the flood attenuation function (GI-1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI-2, considering flood risk, biodiversity, and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods, and suitable locations for introducing GI-2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI-1 as a hub and GI-2 as a dispersal site for conservation of the Red-crowned Crane, one of the symbolic species of Japan.