Meeting Abstract
Diploid and polyploid populations of Lumbriculus were genetically compared through sequence analysis of mitochondrial 16S rRNA and cytochrome oxidase subunit 1 genes and the nuclear ITS and 18S rRNA genes. These genes are useful markers in the determination of phylogenetic relationships between organisms with differences in sequences being correlated with evolutionary divergence and speciation events. The populations examined were those, mostly from North American sources and natural habitats, that we have previously characterized using flow cytometry for DNA content and protein profiles, with results indicating that the diploid and polyploid populations should be classified as distinct species. DNA was isolated from the specimens of Lumbriculus and the marker genes were amplified using the polymerase chain reaction. PCR products were sequenced and then analyzed using genomics databases. Phylogenetic trees were constructed and showed that polyploid and diploid populations segregated into separate lineages. This genetic data was consistent with our biochemical data, further supporting the taxonomic separation of populations of Lumbriculus into at least two distinct species. Resolution of the taxonomy is important, as ploidy levels could impact interpretation of the results of physiological, transcriptomics, toxicological, ecobiology, and other studies being done using different populations from the Lumbriculus complex.
