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Phylogenetic relationships in Lefua sp. 2 based on the 825-bp mitochondrial D-loop sequences. The NJ tree was constructed based on genetic distances calculated with Kimura's two-parameter model using a total of 85 samples including Lefua sp. 1 from Hidaka and L. echigonia from Ouchi as the outgroup. The scale bar indicates 0.01 substitutions per site. Statistical supports of tree topologies are specified with NJ (left) and MP (middle) bootstrap values and BA posterior probabilities (right) in the vicinity of corresponding nodes. Simbols denote river systems: ▲, Yahagi; ▽, Mito; ▼, Nishida; △, Otowa; ○, Toyo; •, Sana; ■, Tenryu; □, Miyakoda; ◆, Oota.
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Two species Lefua echigonia and Lefua sp. 2 of the eight-barbel loach inhabit the Tokai region of Honshu, Japan. We determined sequences of the mitochondrial D-loop region to elucidate intraspecific phylogenetic relationships and variation in these two species. Lefua sp. 2 represented high intraspecific genetic similarity and complicated haplotype...
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Context 1
... Phylogenic relationships in Lefua sp. 2 and L. echigonia from the Tokai re- gion To determine phylogenetic relationships of 83 specimens in Lefua sp. 2, the NJ tree was constructed based on 825-bp sequences using Lefua sp. 1 from Hidaka and L. echigonia from Ouchi as the outgroup (Figure 2). There were 58 variable sites and 29 parsimony informative sites. ...
Citations
... This species has been designated as endangered (high risk of extinction in the wild) (MOE, 2017) with habitat loss resulting from urbanization identified as the major threat (De-Miguel-Gallo et al., 2019;Mitsuo et al., 2009). L. echigonia is usually found in slow-flowing streams including irrigation channels (Miyazaki et al., 2017). However, most remaining habitats are severely fragmented and the surviving populations are extremely small and isolated (Mitsuo et al., 2009). ...
The lateral line system allows fish to sense the surrounding hydrodynamics via changes in the pressure, acceleration and velocity fields, providing additional information about physical habitat structure. Relations between fish and habitat preference have been traditionally inferred using the parameters of water depth, time-averaged velocity, substrate and vegetation to predict their abundance or presence. However, current methods rely on time-averaged point observations, ignoring the fluid-body interactions used by fish to sense the local flow environment. Here we present the first study to explore the use of artificial lateral lines as tools for aquatic habitat assessment. Relations are explored between conventional physical habitat variables in conjunction with measurements from a pressure sensor-based artificial lateral line probe (LLP). Comparisons are performed using field data of an endangered species, Lefua echigonia, in the Yagawa River (Japan). Random forest presence/absence models were created using habitat variables and the pressure-based LLP variables. Results show that the pressure-based variables were strongly correlated with the habitat variables, indicating that the LLP is able to capture the complex multivariate information encoded in the conventional variables with a single time-averaged measurement. In addition, presence/absence models of L. echigonia based on pressure-based variables marginally outperformed models based on the habitat variables. The major findings of this work are: i) LLP-based habitat models are capable of providing similar or better results than when using conventional habitat variables with considerably less field sampling effort, and ii) the probe-based method removes the subjective bias from observations and reduces model dimensionality. The results of this study indicate that fish habitat models can be efficiently and accurately carried out using a lateral line probe instead of traditional multivariate models based on the water depth, flow velocity, substrate and vegetation.
... At Loc. 9, the distribution of the Mikawa-Shizuoka sub-lineage overlapped with that of the Ise Bay sub-lineage. Similar results were reported by Miyazaki et al. (2017) using the CR sequences of L. echigonia. These results suggest that they dispersed owing to river captures in the region or the connection of paleo-river systems. ...
We examined the genetic population structure of Lefua echigonia in the Ise Bay region based on the nucleotide sequences of the mitochondrial DNA cytochrome b region. Previous phylogeographic studies reported that only the Tokai lineage is distributed in this region; however, the present study revealed that the native Kinki lineage (Kuwana sub-lineage) is also distributed here. Moreover, the Tokai lineage was separated into three sub-lineages—Ise Bay, Mikawa-Shizuoka, and Nakatsugawa—with the Ise Bay and Mikawa-Shizuoka sub-lineages further subdivided into six and two local lineages, respectively. We revealed that L. echigonia has clear geographic differentiation within a single paleo-river basin.
The ecological characteristics of the eight-barbel loach Lefua tokaiensis Ito, Hosoya, and Miyazaki were elucidated. Ecological field research was conducted at two localities: the montane stream of Houraiji and the Arao River of the Toyo River system in the Tokai region of Japan. The two localities showed high population density of L. tokaiensis, consisting of young-to-aged individuals. Loaches were likely to reproduce and migrate both upstream and downstream throughout year. Their lifespan was over 10 years, and loaches of more than ten generations simultaneously lived together. Growth rates slowed down strikingly with increasing age. The montane stream of Houraiji was suitable for the population of L. tokaiensis. The results of this study contribute to the protection of this endangered species.
Considering conservation measures for Lefua echigonia populations inhabiting planned areas of the development project in valley-bottom paddy fields in two river basins of midwestern Aichi Prefecture in Japan, the genetic diversity was analyzed for seven sites in this region and one site in another region using their mitochondrial DNA (mtDNA) D-loop and microsatellite DNA. All specimens were found to have the same sequence among seven sites, and they belonged to the previously known populations identified in the Tokai region. Microsatellite analysis revealed that each site was genetically coherent for each river basin, and there was a difference in the degree of genetic divergence between the two river basins in the same water system based on the calculated genetic differentiation (FST) and STRUCTURE analysis. One site affected by the project and another neighboring site had very low genetic diversity and middle-range genetic divergence was observed between them. However, it was due to fragmentation and miniaturization of the habitat caused by the paddy field development, and these two sites were identified as belonging to the same genetic group. Therefore, it is considered effective to ensure habitat and genetic exchange by treating both sites as one.
