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Seesamut T, Oba Y, Jirapatrasilp P, Martinsson S, Lindström M, Erséus C, Panha S. Global species delimitation of the cosmopolitan marine littoral earthworm Pontodrilus litoralis (Grube, 1855). Sci Rep 2024; 14:1753. [PMID: 38243053 PMCID: PMC10799051 DOI: 10.1038/s41598-024-52252-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/16/2024] [Indexed: 01/21/2024] Open
Abstract
The marine littoral earthworm Pontodrilus litoralis (Grube, 1855) is widely distributed and is reported as a single species. This study utilized an integrative taxonomic approach based upon morphological examination, phylogenetic reconstruction, and molecular species delimitation, to test whether the taxon is a single species or a species complex. For this, a total of 114 P. litoralis specimens collected from North America, Africa, Australia and Oceania, Europe and Asia were used. The phylogenetic analyses revealed deeply divergent mitochondrial lineages and a high level of genetic diversity among P. litoralis populations. Both single and multi-locus species delimitation analyses yielded several molecular operational taxonomic units. Therefore, due to the homogeneity of morphological characteristics, it is likely that the morphospecies P. litoralis is a complex of four or more cryptic species, suggesting that more sampling is required and that the population structure genetic data and gene flow need to be investigated.
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Affiliation(s)
- Teerapong Seesamut
- Department of Biology, Faculty of Science, Rangsit University, Pathumthani, 12000, Thailand
| | - Yuichi Oba
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan
| | - Parin Jirapatrasilp
- Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Svante Martinsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30, Göteborg, Sweden
| | - Maria Lindström
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30, Göteborg, Sweden
| | - Christer Erséus
- Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, 405 30, Göteborg, Sweden.
| | - Somsak Panha
- Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
- Academy of Science, The Royal Society of Thailand, Bangkok, 10300, Thailand.
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Seesamut T, Ng B, Sutcharit C, Chanabun R, Panha S. Responses to salinity in the littoral earthworm genus Pontodrilus. Sci Rep 2022; 12:22304. [PMID: 36566279 PMCID: PMC9789941 DOI: 10.1038/s41598-022-26099-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 12/09/2022] [Indexed: 12/25/2022] Open
Abstract
The cosmopolitan littoral earthworm Pontodrilus litoralis is distributed in tropical and sub-tropical coastal habitats, whereas P. longissimus is reported only in the Thai-Malay coastal line. In the present study, we examined the difference in salinity effect on the survival rate, wet weight (hereafter weight) change, behaviour, and osmolality of these two Pontodrilus species. A 28 d exposure to varying salinity concentration (0-50 ppt) revealed that P. litoralis is able to survive over a wide salinity range than P. longissimus, with the latter species exhibiting a low survival rate over the same salinity range. During short-term exposure (0-96 h) to a salinity of less than 30 ppt, P. litoralis exhibited weight gain and this was significant in the first 12 h of exposure. However, P. longissimus gained weight when exposed to salinity at under 10 ppt in the first 72 h of exposure. The two species of Pontodrilus behaved differently when exposed to different salinities. The coelomic fluid osmolarity of Pontodrilus was related to the exposure medium and was mostly maintained as hyperosmotic to the external medium over the range of salinities tested. This study shows how two different species of the littoral earthworm genus Pontodrilus respond to a change in salinity, which may explain their dispersal pattern and shape their distribution pattern throughout Southeast Asia.
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Affiliation(s)
- Teerapong Seesamut
- grid.7922.e0000 0001 0244 7875Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330 Thailand
| | - Beewah Ng
- grid.7922.e0000 0001 0244 7875Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330 Thailand ,Freecap Resource Sdn Bhd, Lot T-5, Lumut Port Industrial Park, KG Acheh Mukim Lumut, 32000 Sitiawan, Perak Malaysia
| | - Chirasak Sutcharit
- grid.7922.e0000 0001 0244 7875Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330 Thailand
| | - Ratmanee Chanabun
- grid.444149.80000 0001 0370 0609Program in Animal Science, Faculty of Agricultural Technology, Sakon Nakhon Rajabhat University, Sakon Nakhon, 47000 Thailand
| | - Somsak Panha
- grid.7922.e0000 0001 0244 7875Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok, 10330 Thailand ,grid.512985.2Academy of Science, The Royal Society of Thailand, Bangkok, 10300 Thailand
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Chen SY, Hsu CH, Soong K. How to cross the sea: testing the dispersal mechanisms of the cosmopolitan earthworm Pontodrilus litoralis. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202297. [PMID: 34430039 PMCID: PMC8355663 DOI: 10.1098/rsos.202297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
Dispersal capability often decides the geographical distribution and long-term success of a species. In this investigation, Pontodrilus litoralis, a widely distributed species along shores throughout mid- and low latitudes of the world, was investigated. We tested three hypotheses explaining its dispersal: helped by humans, transported by birds and carried by currents. Although the earthworms seemed to be associated with artificially planted wind-breaking woods and mangroves along the west coast of Taiwan, they were also found on isolated beaches in the Pescadores Islands without such plantings. They are approximately 2 mm wide, making them too small for use as fishing bait. These two mechanisms invoking human help were not supported. In a laboratory experiment, we moved the earthworms to the plumage of various body parts of pigeons, and they dropped off or died within a short time, a result incompatible with the bird hypothesis. The earthworms stayed alive and grew when immersed in freshwater or seawater for at least a month. They also survived on floating wood in an in situ experiment lasting approximately two months. Thus, the current hypothesis was the only one we were unable to falsify; driftwood and perhaps wooden vessels could provide both food and transport on long journeys. Wood boats exist for a short time on an evolutionary time scale, but it may be long enough to disperse the earthworm around the world. The phase-out of wood boats, thus, may start the divergence of P. litoralis populations around the world.
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Affiliation(s)
- Shiao-Yin Chen
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Chia-Hsuan Hsu
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Keryea Soong
- Department of Oceanography, National Sun Yat-sen University, Kaohsiung, Taiwan
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Seesamut T, Yano D, Paitio J, Kin I, Panha S, Oba Y. Occurrence of bioluminescent and nonbioluminescent species in the littoral earthworm genus Pontodrilus. Sci Rep 2021; 11:8407. [PMID: 33863974 PMCID: PMC8052329 DOI: 10.1038/s41598-021-87984-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 04/05/2021] [Indexed: 01/02/2023] Open
Abstract
Pontodrilus litoralis is a cosmopolitan littoral earthworm known to exhibit bioluminescence. Recently, a congeneric species, Pontodrilus longissimus, from Thailand was described. These species are sympatric, but their burrowing depths on Thai beaches are different. In this study, we examined the in vivo and in vitro bioluminescent properties of P. longissimus and P. litoralis. Mechanical stimulation induced in vivo luminescence in P. litoralis, as reported previously, but not in P. longissimus. In vitro cross-reaction tests between these species revealed the absence of luciferin and luciferase activities in P. longissimus. The coelomic fluid of P. litoralis had strong fluorescence that matched the spectral maximum of its bioluminescence, but the same result was not observed for P. longissimus. These results suggest that P. litoralis has luminescence abilities due to the creation of bioluminescent components (i.e., luciferin, luciferase, and light emitters). The presence of both luminous and nonluminous species in a single genus is likely widespread, but only a few examples have been confirmed. Our findings provide insight into the possible functions of bioluminescence in earthworms, such as avoiding predation by littoral earwigs.
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Affiliation(s)
- Teerapong Seesamut
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan
| | - Daichi Yano
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan
| | - José Paitio
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan
| | - Ikuhiko Kin
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan
| | - Somsak Panha
- Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.,Academy of Science, The Royal Society of Thailand, Bangkok, 10300, Thailand
| | - Yuichi Oba
- Department of Environmental Biology, Chubu University, Kasugai, 487-8501, Japan.
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