Distribution patterns of two sympatric Japanese dojo loach species within a wetland as revealed by direct collection and environmental DNA surveys
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1
Faculty of Agriculture, Kindai University, Japan
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2
Graduate School of Science and Technology, Ryukoku University, Japan
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3
Department of Plant Science, Faculty of Agriculture, Ryukoku University, Japan
A recent genetic study revealed that Japanese populations of the dojo loach (Cypriniformes: Cobitidae: Misgurnus anguillicaudatus species complex) included a cryptic species distributed in discontinuous restricted areas in certain parts of northeastern Japan (Misgurnus sp. Type I, hereafter called as Type I loach), as well as a common species of dojo loach widely distributed throughout the Japanese Archipelago (Misgurnus anguillicaudatus, hereafter called as Type II loach). In the Naka-ikemi wetland in Fukui prefecture, sympatric distribution of Type I and Type II loaches was reported. Ecological differences between closely related sympatric species, especially in the breeding ecology, are more likely to cause development of new coexistence mechanisms. In order to investigate the ecological difference between two sympatric dojo loach species, we performed direct collection and environmental DNA (eDNA) surveys. Using a quantitative survey by direct capture of dojo loaches - covering their breeding period in 2016 - indicated that occurrences of the two loaches differed among the three sampling sites; however, seasonal migrations were not observed. The following eDNA surveys using species-specific real-time PCR conducted in 2017 by increasing the number of sampling sites (12 sites) supported the direct capture survey result and elucidated the overall distribution patterns of both species: Type I loach has a limited distribution, inhabiting the northern part of the wetland; Type II loach is widely distributed across the central to southern parts of the wetland. Both loaches occurred sympatrically in some areas throughout the sampling periods, indicating incomplete segregation with respect to habitats. Since no hybrid species between the two loach species are found so far in this wetland, it is likely that the two species developed mechanisms to prevent inter-specific mating or a post-zygotic isolation system between them such as hybrid breakdown.The results also revealed that Type I loach is rare compared to Type II loach in the wetland. If specific environmental factors are involved in the establishment of Type I loach populations in a limited area of the wetland, environmental changes may result in habitat loss of Type I loach. Therefore, favorable environment characteristics involved in Type I loach population establishment should be identified for conservation purposes.
Keywords:
Misgurnus,
Real-Time PCR,
Habitat segregation,
cryptic species,
Breeding season
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Oral
Topic:
ECOLOGY AND LIFE CYCLES
Citation:
Okada
R,
Tsuji
S,
Shibata
N,
Morita
K,
Yamanaka
H and
Kitagawa
T
(2019). Distribution patterns of two sympatric Japanese dojo loach species within a wetland as revealed by direct collection and environmental DNA surveys.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00010
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Received:
20 Jul 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Dr. Tadao Kitagawa, Faculty of Agriculture, Kindai University, Nara, Nara, Japan, tkitagaw@nara.kindai.ac.jp