Intraspecific phylogeography of Lasmigona subviridis (Bivalvia: Unionidae): conservation implications of range discontinuity

Abstract

A nucleotide sequence analysis of the first internal transcribed spacer region (ITS-1) between the 5.8S and 18S ribosomal DNA genes (640 bp) and cytochrome c oxidase subunit I (COI) of mitochondrial DNA (mtDNA) (576 bp) was conducted for the freshwater bivalve Lasmigona subviridis and three congeners to determine the utility of these regions in identifying phylogeographic and phylogenetic structure. Sequence analysis of the ITS-1 region indicated a zone of discontinuity in the genetic population structure between a group of L. subviridis populations inhabiting the Susquehanna and Potomac Rivers and more southern populations. Moreover, haplotype patterns resulting from variation in the COI region suggested an absence of gene exchange between tributaries within two different river drainages, as well as between adjacent rivers systems. The authors recommend that the northern and southern populations, which are reproductively isolated and constitute evolutionarily significant lineages, be managed as separate conservation units. Results from the COI region suggest that, in some cases, unionid relocations should be avoided between tributaries of the same drainage because these populations may have been reproductively isolated for thousands of generations. Therefore, unionid bivalves distributed among discontinuous habitats (e.g. Atlantic slope drainages) potentially should be considered evolutionarily distinct. The DNA sequence divergences observed in the nuclear and mtDNA regions among the Lasmigona species were congruent, although the level of divergence in the COI region was up to three times greater. The genus Lasmigona, as represented by the four species surveyed in this study, may not be monophyletic.

Molecular phylogeny of the Nearctic and Mesoamerican freshwater mussel genus Megalonaias

“…Mantle tissue samples were preserved in 95% ethanol and DNA was isolated from using a DNAeasy Blood and Tissue Extraction Kit (Qiagen, inc). Primers for polymerase chain reaction (PCR) and sequencing were as follows: COI dgLCO-1490-GGTCAACAAATCATAAA-GAYATYGG and COI dgHCO-2198-TAAACTT-CAGGGTGACCAAARAAYCA (Meyer, 2003); ITS-1 18S-AAAAAGCTTCCGTAGGTGAACCTGCG and ITS-1 5.8S-AGCTTGCTGCGTTCTTCATCG (King et al, 1999).…”

Congruence and Conflict Between Molecular and Reproductive Characters When Assessing Biological Diversity in the Western Fanshell Cyprogenia aberti (Bivalvia, Unionidae)1

“…The first two factors appear to play a major role in unionid speciation (Kat, 1984) and may be useful when assessing biological diversity (Roe & Lydeard, 1998;King et al, 1999;Roe et al, 2001). In contrast, mitochondrial genes are often used in phylogenetic reconstruction because most models of mitochondrial DNA (mtDNA) evolution consider neutral evolution and purifying selection as the major processes that shape sequence divergence.…”

Three deeply divided lineages of the freshwater mussel genus Anodonta in western North America

“…A sample of mantle or foot tissue (approximately 2 mm 3 ) from each field-collected specimen was dissected, and genomic DNA extracted using a salt chloroform protocol (Mullenbach et al 1989) or Qiagen DNeasy Ò Tissue kit. An approximately 650 bp region of the mitochondrial F-lineage cytochrome c oxidase subunit I (COI) gene was amplified using the primers LCO1490 and HCO2198 (Folmer et al 1994;King et al 1999). We designed two internal primers LCO1550 (5 0 -ATTCGAGCT GAGTTGGGTCAA) and HCO2100 (5 0 -GTAATAGCACC AGCTAAAACT) and used them in various combinations with LCO1490 and HCO2198 to generate bidirectional sequences of this region (GenBank accessions EU327350-EU327357).…”