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Hewitt TL, Johnson PD, Buntin M, Moore TY, Ó Foighil D. Polymorphism in the aggressive mimicry lure of the parasitic freshwater mussel Lampsilis fasciola. PeerJ 2024; 12:e17359. [PMID: 38803583 PMCID: PMC11129695 DOI: 10.7717/peerj.17359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 04/18/2024] [Indexed: 05/29/2024] Open
Abstract
Unionoid freshwater mussels (Bivalvia: Unionidae) are free-living apart from a brief, obligately parasitic, larval stage that infects fish hosts, and gravid female mussels have evolved a spectrum of strategies to infect fish hosts with their larvae. In many North American species, this involves displaying a mantle lure: a pigmented fleshy extension that acts as an aggressive mimic of a host fish prey, thereby eliciting a feeding response that results in host infection. The mantle lure of Lampsilis fasciola is of particular interest because it is apparently polymorphic, with two distinct primary lure phenotypes. One, described as "darter-like", has "eyespots", a mottled body coloration, prominent marginal extensions, and a distinct "tail". The other, described as "worm-like", lacks those features and has an orange and black coloration. We investigated this phenomenon using genomics, captive rearing, biogeographic, and behavioral analyses. Within-brood lure variation and within-population phylogenomic (ddRAD-seq) analyses of individuals bearing different lures confirmed that this phenomenon is a true polymorphism. The relative abundance of the two morphs appears stable over ecological timeframes: the ratio of the two lure phenotypes in a River Raisin (MI) population in 2017 was consistent with that of museum samples collected at the same site six decades earlier. Within the River Raisin, four main "darter-like" lure motifs visually approximated four co-occurring darter species (Etheostoma blennioides, E. exile, E. microperca, and Percina maculata), and the "worm-like" lure resembled a widespread common leech, Macrobdella decora. Darters and leeches are typical prey of Micropterus dolomieui (smallmouth bass), the primary fish host of L. fasciola. In situ field recordings of the L. fasciola "darter" and "leech" lure display behaviors, and the lure display of co-occurring congener L. cardium, were captured. Despite having putative models in distinct phyla, both L. fasciola lure morphs have largely similar display behaviors that differ significantly from that of sympatric L. cardium individuals. Some minor differences in the behavior between the two L. fasciola morphs were observed, but we found no clear evidence for a behavioral component of the polymorphism given the criteria measured. Discovery of discrete within-brood inheritance of the lure polymorphism implies potential control by a single genetic locus and identifies L. fasciola as a promising study system to identify regulatory genes controlling a key adaptive trait of freshwater mussels.
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Affiliation(s)
- Trevor L. Hewitt
- Ecology and Evolutionary Biology, University of Michigan—Ann Arbor, Ann Arbor, Michigan, United States
| | - Paul D. Johnson
- Alabama Aquatic Biodiversity Center, Marion, Alabama, United States of America
| | - Michael Buntin
- Alabama Aquatic Biodiversity Center, Marion, Alabama, United States of America
| | - Talia Y. Moore
- Ecology and Evolutionary Biology, University of Michigan—Ann Arbor, Ann Arbor, Michigan, United States
- Robotics Department & Mechanical Engineering Department, University of Michigan—Ann Arbor, Ann Arbor, Michigan, United States
| | - Diarmaid Ó Foighil
- Ecology and Evolutionary Biology, University of Michigan—Ann Arbor, Ann Arbor, Michigan, United States
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Johnson NA, Henderson AR, Jones JW, Beaver CE, Ahlstedt SA, Dinkins GR, Eckert NL, Endries MJ, Garner JT, Harris JL, Hartfield PD, Hubbs DW, Lane TW, McGregor MA, Moles KR, Morrison CL, Wagner MD, Williams JD, Smith CH. Glacial vicariance and secondary contact shape demographic histories in a freshwater mussel species complex. J Hered 2024; 115:72-85. [PMID: 38015800 DOI: 10.1093/jhered/esad075] [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: 06/20/2023] [Revised: 10/16/2023] [Accepted: 11/27/2023] [Indexed: 11/30/2023] Open
Abstract
Characterizing the mechanisms influencing the distribution of genetic variation in aquatic species can be difficult due to the dynamic nature of hydrological landscapes. In North America's Central Highlands, a complex history of glacial dynamics, long-term isolation, and secondary contact have shaped genetic variation in aquatic species. Although the effects of glacial history have been demonstrated in many taxa, responses are often lineage- or species-specific and driven by organismal ecology. In this study, we reconstruct the evolutionary history of a freshwater mussel species complex using a suite of mitochondrial and nuclear loci to resolve taxonomic and demographic uncertainties. Our findings do not support Pleurobema rubrum as a valid species, which is proposed for listing as threatened under the U.S. Endangered Species Act. We synonymize P. rubrum under Pleurobema sintoxia-a common and widespread species found throughout the Mississippi River Basin. Further investigation of patterns of genetic variation in P. sintoxia identified a complex demographic history, including ancestral vicariance and secondary contact, within the Eastern Highlands. We hypothesize these patterns were shaped by ancestral vicariance driven by the formation of Lake Green and subsequent secondary contact after the last glacial maximum. Our inference aligns with demographic histories observed in other aquatic taxa in the region and mirrors patterns of genetic variation of a freshwater fish species (Erimystax dissimilis) confirmed to serve as a parasitic larval host for P. sintoxia. Our findings directly link species ecology to observed patterns of genetic variation and may have significant implications for future conservation and recovery actions of freshwater mussels.
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Affiliation(s)
- Nathan A Johnson
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL, United States
| | - Andrew R Henderson
- U.S. Fish and Wildlife Service, Ecological Services, Asheville, NC, United States
| | - Jess W Jones
- U.S. Fish and Wildlife Service, Virginia Tech University, Blacksburg, VA, United States
| | - Caitlin E Beaver
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL, United States
| | - Steven A Ahlstedt
- McClung Museum of Natural History and Culture, University of Tennessee, Knoxville, TN, United States
| | - Gerald R Dinkins
- McClung Museum of Natural History and Culture, University of Tennessee, Knoxville, TN, United States
| | - Nathan L Eckert
- U.S. Fish and Wildlife Service, Neosho National Fish Hatchery, Neosho, MO, United States
| | - Mark J Endries
- U.S. Fish and Wildlife Service, Ecological Services, Asheville, NC, United States
| | - Jeffrey T Garner
- Alabama Division of Wildlife and Freshwater Fisheries, Florence, AL, United States
| | - John L Harris
- Arkansas State University Museum of Zoology, Jonesboro, AR, United States
| | - Paul D Hartfield
- U.S. Fish and Wildlife Service, Ecological Services, Jackson, MS, United States
| | - Don W Hubbs
- DJH Environmental Services, Camden, TN, United States
| | - Timothy W Lane
- Virginia Department of Wildlife Resources, Marion, VA, United States
| | - Monte A McGregor
- Kentucky Department of Fish and Wildlife Resources, Frankfort, KY, United States
| | - Kendall R Moles
- Arkansas Game and Fish Commission, Benton, AR, United States
| | - Cheryl L Morrison
- U.S. Geological Survey, Eastern Ecological Science Center, Kearneysville, WV, United States
| | - Matthew D Wagner
- U.S. Fish and Wildlife Service, Ecological Services, Jackson, MS, United States
| | - James D Williams
- Florida Museum, University of Florida, Gainesville, FL, United States
| | - Chase H Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, United States
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