DNA sequences provide numerous, potentially independent, characters that can be used study evolutionary relationships between taxa at different taxonomic levels. rDNA sequences (mostly SSU-rDNA) are widely used to infer relationships at higher taxonomic levels whereas more rapidly evolving sequences like ITS (internal transcribed spacer) the D2-D3 expansion zone of LSU rDNA and mitochondrial genes can resolve species complexes and identify distinct populations thus providing an extremely useful tool for ecological an biogeographical research. The molecular approach also allows comparison of genetic and morphological diversity and may thus provide a handle to study functional biodiversity (adaptive radiation).
We have collaborated
with various teams to reconstruct the radiation of the phylum Nematoda,
as based on a phylogenetic analysis of 53 SSU rDNA sequences. Our database
now contains more than 100 sequences covering plant-parasitic and free-living
taxa only. We are currently focussing on the phylogenetic relations within
major pest taxa including cyst (Heteroderidae) and root-knot (Meloidogynidae)
nematodes. We expect that the molecular approach will help to unravel the
problem of huge phenotypic variation that is seen in some dominant deep
sea nematode genera. We also collaborate with other researchers of
our department in implementing sequence analysis in the study of the phylogeny,
taxonomy and biogeography of Odonata and various crustacean taxa, including
rotifers, branchiopods, copepods and Mysidacea.
For more detailed information
on sequencing we refer to Andy's