Examination of unidentifiable spined loach individuals found in overlapping zones of two tetraploid species within a single river in Japan
Examination of unidentifiable spined loach individuals found in overlapping zones of two tetraploid species within a single river in Japan
复制标题
在日本一条河流内两个四倍体物种重叠区域中发现的无法识别的有刺泥鳅个体的检查
DOI：
10.1111/jai.14081
复制
发表时间：
2020
影响因子：
0.9
通讯作者：
T. Kitagawa
中科院分区：
文献类型：
--
作者：
M. Ishihara;K. Morita;Y. Iguchi;K. Takaku;K. Takata;T. Kitagawa
竹野鳅（Cobitis takenoi，Cypriniformes：Cobitidae;以下简称Tangoloach）是一种濒危的四倍体刺鳅，仅栖息在日本京都县的一条河流中。由于Tangoloach是最近发现的，在2010年，直到2016年才被描述，它的形态，生态和遗传学都没有得到很好的研究。另一种四倍体刺鳅属物种Cobitissp. A型（以下称为Ohshimaloach）生活在同一条河流中。据报道，这两种泥鳅在形态上彼此可区分。虽然这两个物种在河流中的栖息地是分离的（Ohshimaloach和Tangoloach分别栖息在上游和下游），但它们在边界区域有很小程度的重叠。最近，在重叠区发现了一些形态特征介于两种之间的个体。由于两个物种的繁殖季节重叠，因此怀疑这两个物种之间产生了杂交。为了调查这两个物种是否产生杂交种，我们对无法识别的个体进行了线粒体和核DNA分析。对2017年至2018年期间在河流中收集的8种无法识别的物种进行了检查，并与Tango和Ohshimaloach物种进行了比较。线粒体DNA细胞色素分析结果表明，有6个个体的线粒体DNA类型与Tangoloach相同，2个个体的线粒体DNA类型与Ohshimaloach相同。此外，核重组激活基因1（RAG-1）的测序分析显示，每个物种都有物种特异性等位基因。系统发育分析表明，Tangoloach的等位基因可分为两个簇，Ohshimaloach的等位基因形成一个簇。在每个标本中，mtDNA和核DNA物种类型之间的组合没有差异。DNA指纹分析（AFLP）结果表明，这两个物种的个体具有明显的遗传分化，分别属于Tango和Ohshimaloches。总之，在本研究中检查的任何无法识别的个体中均未检测到杂种。由于这两种泥鳅之间没有严格的形态学特征，因此，本文建立的鉴别这两种泥鳅的新的常规遗传学方法可以作为Tangoloach保护的有效工具。
An endangered tetraploid spined loach species,Cobitis takenoi(Cypriniformes: Cobitidae; hereafter calledTangoloach) is known to inhabit only a single river in Kyoto Prefecture, Japan. SinceTangoloach was discovered recently, in 2010, and only described in 2016, its morphology, ecology, and genetics are not well studied. Another tetraploid spined loach speciesCobitissp. BIWAE type A (hereafter, calledOhshimaloach) inhabits the same river. The two loaches are reported as morphologically distinguishable from each other. Although the habitats of the two species in the river are segregated (Ohshimaloach andTangoloach inhabit the upper and lower reaches, respectively), they overlap to a small degree in the boundary area. Recently, some individuals with morphological characteristics that are intermediate between the two species were found in the overlap zone. It was suspected that hybrids between the two species were produced since breeding seasons of the two species overlapped. To investigate whether the two species produce hybrids, we performed mitochondrial and nuclear DNA analyses on the unidentifiable individuals. Eight individuals unidentifiable to the species level collected in the river between 2017 and 2018 were examined and compared with theTangoandOhshimaloach species. Using mitochondrial DNA (mtDNA) cytochromebanalysis, we found that six individuals had mtDNA types identical toTangoloach and two individuals had mtDNA types identical toOhshimaloach. Furthermore, sequencing analysis of nuclear recombination activating gene 1 (RAG‐1) revealed that each species had species‐specific alleles. The phylogenetic analysis indicated that alleles inTangoloach were divided into two clusters and those fromOhshimaloach formed a single cluster. There were no discrepancies in the combination between mtDNA and nuclear DNA species types within each specimen. DNA fingerprinting analysis (AFLP) showed that the species‐unidentifiable individuals exhibited distinctly segregated genetic groups corresponding withTangoandOhshimaloaches. In summary, no hybrids were detected from among any unidentifiable individual examined in this study. New conventional genetic method for discriminating the two sympatric loach species developed here can be effective tool for the conservation of theTangoloach since there was no strict diagnostic morphological character between them.