photo by J. Hughes
photo by R. Bonal
photo by R. Bonal
photo by J. Hughes
photo by J. Hughes
photo by R. Bonal
The hemipteroid assemblage of insects (aphids, lice, thrips, and their relatives) is of considerable importance as it contains a number of medical, horticultural and agricultural pests. Although recent molecular studies have changed our understanding of hemipteroid phylogenetic relationships, particularly with regard to the evolution of parasitism in the group, it has become clear that there remains considerable uncertainty about evolutionary relationships within this group. Deep-level phylogenies of numerous insect groups have proved resistant to traditional PCR approaches of building matrices of a few mitochondrial and nuclear markers. Phylogenies inferred from a few genes may suffer from stochastic errors. Phylogenomic approaches that employ whole genomes greatly increase the number of genes, but can suffer from problems of uncertain homology among genes due to gene duplication, and systematic errors due to limited taxonomic sampling. Large-scale EST projects offer an intermediate strategy where large numbers of gene sequences are generated from a larger number of taxa than is feasible for genomic approaches. While this goes some way towards addressing the taxonomic sampling problem, the problem of gene paralogy remains.
This project will use EST sequencing in conjunction with gene tree methods to determine phylogenetic relationships in a clade of economically important yet neglected insects. The results will be invaluable in placing the results of larger-scale genomic studies, which are inevitably more limited in taxonomic scope, in their evolutionary context. Abstract from BBSRC grant proposal
In 1948, a species of Gadfly Petrels (Pterodroma) was found on Round Island, near Mauritius. These species had not been described before despite a number of expeditions to the island and more surprisingly, the genetic divergence from populations within the island show high genetic divergence suggesting that the species is not a recent colonizer. We are sequencing lice collected from Round Island and from other Gadfly Petrels and relatives to determine the most likely origin of the Round Island Gafly Petrels using cospeciation analyses.
Mammals have 3 uncoupling proteins and these genes are thought to play a role in thermoregulation. In these genes, there is little evidence for positive selection following the duplication events. The genes are higly conserved but expressed in different tissues. Birds have lost independently two of these genes and the remaining gene (UCP3) is mainly expressed in skeletal tissue. We intend to determine whether UCP3 in birds has evolved with the particular life history of the birds (e.g., cold-acclimated versus tropical) using sequence data.
Insect-host interactions provide a rich system for evolutionary studies. Most interestingly the tempo and mode of evolution of taxa with little or no fossil record can be determined if co-speciation between the host and the parasite is present.
Many factors determine whether an insect species can utilize a wide variety of hosts or specializes on one or a few and this is often related to the diversity of insects parasitising a host. For example, body size and geographical range of seabirds could correlate with louse diversity. For insect-plant interactions a number of examples show that the relatedness of the host plants and in particular their secondary compounds play a determining factor in the evolution and diversity of the insects attacking them.
Although a number of examples demonstrate that chemical plant defenses drive diversification of insects, very few examples present plant mechanical defenses as a driving force for the evolution of morphological differentiation in insects. The morphological adaptations that have evolved in the genus Curculio to circumvent the plant defenses present a very interesting case study.
To facilitate my research and that of others studying ESTs, I am currently developing genomic tools to add to an existing EST pipeline. This software will provide a rapid overview of ESTs in a phylogenetic context and will include statistics for each phylogeny including the level of duplication of the gene or gene family. This tool will be made universally accessable and could be useful for evolutionary and comparative insect genomics. I am also writting small perl scripts to facilitate the use of phylogenetic software. more
Insects have evolved a broad range of enzymes that have enabled them to adapt to a range of food sources. Although most of the time, these adaptations are damaging to humans, livestock or crops, occasionally some enzymes may provide some benefits to humans or our industries. One particular example is the evolution of keratin (e.g. hair, feathers) digesting enzymes that are believed to be present in the guts of cadaver beetles and cloths moths. The discovery of these enzymes could provide a more environmentally friendly means of removing hair from leather. Subtracted cDNA libraries of Trogid beetles and cloths moths have been built and sequenced and are currently been analysed with a range of tools to identify a keratinase-like gene.