Phylogeographic analysis of the threatened and endangered superconglutinate‐producing mussels of the genus Lampsilis (Bivalvia: Unionidae)

Abstract

Several species of freshwater unionid mussels in the genus Lampsilis exhibit a remarkable reproductive strategy. Female mussels of these species enclose their larvae in a minnow-like lure, called a 'superconglutinate', to attract piscivorous fishes. When a fish attempts to ingest the superconglutinate the lure ruptures and the larvae are released to parasitize the fish. Of the four species of mussel which exhibit this strategy and are endemic to the Gulf Coast drainages of the southeastern United States, three are protected under the Endangered Species Act, and one is recognized as imperiled. Phylogenetic analysis of nucleotide sequences of the mitochondrial 16S ribosomal RNA and the first subunit of the cytochrome oxidase c genes was conducted on 18 individual specimens representing these four species and six outgroup taxa. Phylogenetic analyses of these data support the monophyly of the superconglutinate-producing mussels, and indicates a strong geographical component to the data. The zoogeographic patterns of the four taxa included in the study are congruent with those seen in freshwater vertebrates, and are consistent with a vicariant pattern resulting from fluctuations in sea level during the Pleistocene. Despite the strong geographical structuring of the data, only one species, Lampsilis subangulata, was recovered as monophyletic. The authors attribute the lack of support for the monophyly of the remaining species to insufficient sequence variation and the recent origin of the ancestor of these taxa. Based on these data, any future captive breeding projects aimed at augmenting or re-establishing populations should do so only from the appropriate source populations so as to maintain the genetic integrity of these nascent species.

Population genetic structure of a rare unionid (Lampsilis cariosa) in a recently glaciated landscape

“…Only a few studies have specifically examined genetic variation at the population level for freshwater mussels (Berg et al 1998;King et al 1999), with a view towards recommending management units for conservation (Berg et al 1998;Roe and Lydeard 1998a,b;Roe et al 2001). In general, allozymes have provided little resolution below the species level (Kat 1983a;Nagel et al 1996;Berg et al 1998;Johnson et al 1998), whereas studies using DNA markers have revealed substantial population genetic structure (King et al 1999;Mock et al 2004).…”

Freshwater bivalve (Unioniformes) diversity, systematics, and evolution: status and future directions

“…The most commonly used genes in unioniform analyses have been: 1) cytochrome c oxidase subunit 1 (CO1) (e.g., Hoeh et al 1998, Roe and Lydeard 1998, Graf 2000, Graf and O'Foighil 2000a, Lydeard et al 2000, Hoeh et al 2002, Huff et al 2004, Mock et al 2004, Campbell et al 2005, Graf and Cummings 2006, Walker et al 2006a; 2) cytochrome c oxidase II (CO2) (e.g., Kocher 2005, Walker et al 2006b); 3) histone (H3) (Huff et al 2004); NADH dehydrogenase (ND1) (e.g., , Campbell et al 2005, Serb 2006); 4) 18S rRNA (Huff et al 2004); 5) 16S rRNA (e.g., Lydeard et al 1996, Mulvey et al 1997, Lydeard et al 2000, Kandl et al 2001, Campbell et al 2005; and 6) 28S ribosomal DNA (rDNA) domain 6 (Rosenberg et al 1994) and domain 2 (e.g., Graf and O'Foighil 2000b, Graf 2002, Huff et al 2004. Some authors also have used a combination of gene sequences to test hypotheses about unioniform relationships (e.g., Roe et al 2001, Campbell et al 2005, Graf and Cummings 2006, Serb 2006, and a few have combined morphological data with DNA sequence data (e.g., Hoeh et al 2001, Roe and Hoeh 2003, Graf and Cummings 2006. Only one study of mitochondrial gene order has been published for a freshwater mussel.…”

“…The Gondwanan distribution of several major lineages (Hyriidae, Iridinidae, and Mycetopodidae) and largely Laurasian distribution of the remaining families (Unionidae, Margaritiferidae) imply that the breakup of Pangea at the close of the Jurassic included several vicariant events that are reflected in the current distribution of the Unioniformes. Some work has been conducted on zoogeography using freshwater mussels at smaller scales in Europe (e.g., Machordom et al 2003) and North America (Roe et al 2001, Kelly and Rhymer 2005, Elderkin et al 2007), but much additional work remains to done.…”

Universal primers for the specific amplification of the male mitotype of the Unionoidea (Bivalvia)

“…Studies of population structure, phylogeography and systematics using molecular markers have bolstered conservation efforts (White et al 1994;Lydeard et al 1996;White et al 1996;Mulvey et al 1997;Roe and Lydeard 1998;King et al 1999;Roe et al 2001;Buhay et al 2002;Machordom et al 2003;Serb et al 2003). In particular, genetic tools have been identified as important for elucidation of taxonomic boundaries and evolutionary relationships which have long been a problem due to the extensive phenotypic plasticity exhibited by these mussels Lydeard and Roe 1998).…”

“…Phylogeographic and systematic studies of unionoids have relied upon ''universal'' metazoan primers (e.g. HCO/LCO, 16sar/16sbr) (Lydeard et al 1996;Mulvey et al 1997;Roe and Lydeard 1998;King et al 1999;Roe et al 2001;Machordom et al 2003). The design of new primers specific for the unionoid male mitotype provides several potential advantages: a large contiguous region of mtDNA from an independent genome evolving at a different rate (Curole and Kocher 2002;Hoeh et al 2002), elimination of potential cross amplification of non-orthologous sequences (i.e.…”