Submitted to: Molecular Biology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2002
Publication Date: 6/1/2002
Citation: Roehrdanz, R.L., Degrugillier, M.E., Black, W.C. 2002. Novel rearrangements of arthropod mitochondrial DNA detected with long-PCR: Applications to arthropod phylogeny and evolution. Molecular Biology and Evolution. 19(6):841-849. Interpretive Summary: In the past decade the special properties of animal mitochondrial DNA have been exploited to advance our knowledge of population distributions, biosystematics, and evolutionary relationships of animals from humans to lowly worms. Arthropods are an extremely morphologically diverse and species rich group of animals. Interactions between arthropods and humans are multifaceted and have been so throughout the short span of human evolution. Arthropods bite and chew on humans, and groups such as mosquitoes, ticks and lice serve as vectors for numerous serious pathogens. Phytophagous insects compete with humans for food and have been a scourge to human agriculture since the beginnings. Arthropods are also a vital component of plant sexual reproduction without which agriculture would likely not exist. Marine crustaceans are an irreplaceable link in oceanic food chains and are a major contributor both directly and indirectly to human nutrition. Major arthropod lines have long been defined (insects, crustaceans, spiders & ticks, millipedes, centipedes etc.) but the phylogenetic relationships among these groups remain open to conjecture. The arrangement of mitochondrial genes can be used to help determine these relationships. Using a long polymerase chain reaction procedure developed at this ARS facility, we have discovered several new arrangements of arthropod mitochondrial DNA that further refine our view of arthropod phylogeny and systematics. The technique employed is suitable for quickly examining a large number of taxa for gene rearrangements to determine which groups deserve more detailed study.
Technical Abstract: Rearrangements of the mitochondrial DNA gene order have been touted as a tool for defining the pattern of evolutionary divergence in arthropod taxa. We have employed a combination of highly conserved or "universal" insect-based PCR primers with long-PCR to survey fourteen non-insect arthropods for mitochondrial gene rearrangements. The size of the amplified fragments was used to order the primer containing genes. Five chelicerates exhibit amplicons that are consistent with the insect mtDNA gene order. These five species comprise two soft ticks, two prostriate hard ticks and a harvestman. Six other chelicerates, all metastriate hard ticks, have a different arrangement that has been previously detailed in a complete mtDNA sequence. Three new gene arrangements are described here. They were recovered from a terrestrial crustacean (Isopoda, sowbug) and two myriapods (Chilopoda, centipede; Diplopoda, millipede). The t-RNA(Met) gene can be found transcriptionally upstream of the 12S rRNA gene in the annelids and most molluscs. A rearrangement linking Met to ND2 has occurred in both the bivalve molluscs and previously studied arthropods, indicating that the same translocation arose more than once in evolution. We report two new positions for Met in arthropods. A crustacean isopod and a myriapod diplopod have Met positioned between the 12S and 16S rRNAs on the downstream side of 12S. A myriapod chilopod has Met located between CytB and ND4. Within the arthropods, trees that combine the positional data of t-RNA (Met) and t- RNA (Leu-UUR) require either multiple origins of specific translocations or reversions. The long-PCR approach affords an opportunity to readily screen divergent taxa for major rearrangements.