One of the strengths of our lab is that we have a thorough understanding of the systematics of both the host and parasite groups we work on. Over the years, members of the lab have published many papers on the systematics of birds and lice. Our publications include work on taxonomy, phylogenetic reconstruction, and comparisons of host and parasite phylogenies to assess the extent of host-parasite cospeciation in particular groups.
To understand the evolution of parasite diversity and the ecological factors influencing host-specificity we must first understand what parasites exist, where they occur, and which hosts they infest. Research in our lab includes faunal surveys of parasites that infest birds around the world (and occasionally other terrestrial vertebrates and their parasites). Major projects in the past have focused on China, the Galapagos, New Guinea, the Philippines, Sweden, and other countries (see map), as well as projects within the United States. Currently, projects in our lab are focused on Argentina, the Bahamas, the Galapagos, and China.
This approach frequently leads to the discovery and description of new genera and species, phylogenetic and co-phylogenetic studies of parasites and their hosts, as well as a greater understanding of the relationship between habitat change and parasite diversity, and host-parasite coextinction.
Lice are wingless, obligate ectoparasites of birds and mammals. Since they pass their entire life cycle on the body of the host, lice are unusually tractable organisms for research in population biology. Their close association with the host has resulted in pronounced host specificity and cospeciation in some groups. Indeed, lice are one of the most common model systems used in the development of analytical methods for assessing patterns and rates of cospeciation. Their tractability in ecological time, combined with a history of cospeciation, also makes them one of the best groups for research on ecological factors governing the process of speciation, in general.
Unfortunately, the role of lice as models for broad-based research continues to be hampered by the miserable state of louse systematics. The host specificity of many genera has been exaggerated by the circular reasoning common among earlier taxonomists, who often described new species on the basis of host associations, rather than on the basis of the lice themselves. We use morphological and molecular approaches to provide species descriptions and revisionary taxonomy for feather lice. With sound alpha taxonomy and robust phylogenies, we compare the louse phylogeny to existing host trees to investigate the relative importance of co-speciation, host-switching, and host biogeography in the evolution of feather lice.
Map showing field-work locations of the Clayton-Bush lab. It is estimated that there are at least 5 million species on Earth. Of these, only 1.5 million are known to science. A majority of the unknown animal species, however, are small organisms like free-living insects and parasites that live on or in other organisms. One main goal of faunal surveys is to document the presence of species before it is too late. Indeed, research in our lab indicates that parasites are even more susceptible to habitat loss than their hosts, meaning that "too late" may come especially soon for parasites. (see paper - here.)
Please note that the PDFs are for personal use only, definitive versions are available from the publishers.
Gustafsson, D. R., S. E. Bush, and R. L. Palma. 2019. The genera and species of the Brueelia-complex (Phthiraptera: Philopteridae) described by Mey (2017). Zootaxa 4615:252-284. PDF
Gustafsson, D. R., E. DiBlasi, U. Olsson, T. Najer, O. Sychra and S. E. Bush. 2018. Checklist and key to the lice (Insecta: Phthiraptera) of Sweden. Entomologisk Tidskrift139: 205-394. PDF.
Gustafsson, D. R., D. H. Clayton, and S. E. Bush. 2018. Twelve new species of Priceiella Gustafsson & Bush, 2017 (Phthiraptera: Ischnocera: Philopteridae) from Old World babblers, with a key and comprehensive host-parasite checklist. Zootaxa 4382 (3): 401–449. PDF.
Boyd, B. M., J. A. Allen, N. Nguyen, A. D. Sweet, T. Warnow, M. Shapiro, S. M. Villa, S. E. Bush, D. H. Clayton, K. P. Johnson. 2017. Phylogenomics using target restricted assembly resolves intra-generic relationships of parasitic lice (Phthiraptera: Columbicola). Systematic Biology 66:896-911. PDF.
Gustafsson, D. R., and S. E. Bush. 2017. Zootaxa. Morphological revision of the hyperdiverse Brueelia-complex (Insecta: Phthiraptera: Ischnocera: Philopteridae) with new taxa, checklists and generic key. Zootaxa 4313: 1-443. PDF.
Bush, S. E., J. D. Weckstein, D. R. Gustafsson, J. Allen, E. DiBlasi, S. M. Shreve, R. Boldt, H. R. Skeen, and K. P. Johnson. 2016. Unlocking the black box of feather louse diversity: a molecular phylogeny of the hyper-diverse genus Brueelia. Molecular Phylogenetics and Evolution 94: 737-751. PDF.
S. E. Bush, M. Reed & S. Maher. 2013. Impact of forest size on parasite biodiversity: implications for conservation of hosts and parasites. Biodiversity and Conservation 22: 1391-1404. PDF.
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Koop, J. A. H. and D. H. Clayton. 2013. Evaluation of two methods for quantifying passeriform lice. Journal of Field Ornithology 84: 210-215. PDF.
Villa, S. M., Le Bohec, C., Koop, J. A. H., Proctor, H. D., and D. H. Clayton. 2013. Diversity of feather mites (Acari: Astigmata) on Darwin's Finches. Journal of Parasitology 99: 756-762. PDF.