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The major goal of our research is to understand why sexual recombination is necessary for the evolutionary success of multicellular life– why sex is nearly universal among multicellular eukaryotes and why the vast majority of species that abandon sexual reproduction are rapidly driven to extinction. Despite more than 150 years of attention, these questions remain one of the central mysteries of biology, with broad implications in genetics, ecology, and evolution. Combining aspects of molecular genetics, population genetics, evolutionary genomics, and phylogenetics, our research explores these questions by examining the consequences of long-term asexuality on genome structure and on host immune systems, and by studying the ecological and evolutionary dynamics of sex loss and preservation in facultatively sexual cryptic species.
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Read about our research in Nature.
David Mark Welch's CV >>
Recent publications from the Mark Welch lab:
Mark Welch, D.B.,
C. Ricci
and M. Meselson, 2009.
Bdelloid rotifers: progress in understanding the success of an evolutionary scandal.
pp 259-279 In: I. Schön, K. Martens, and P. van Dijk (eds.)
Lost Sex: The Evolutionary Biology of Parthenogenesis,
Springer, 615 p.
Witek, A.,
H. Herlyn,
I. Ebersberger,
D. B Mark Welch,
and T. Hankeln, 2009.
Support for the monophyletic origin of Gnathifera from phylogenomics. Mol. Phylogenet. Evol. 53: 1037-1041.
doi:10.1016/j.ympev.2009.07.031
Snell, T.W., Shearer T.L., Smith H.A., Kubanek J., Gribble, K.E., and Mark Welch D.B. 2009.
Genetic determinants of mate recognition in Brachionus manjavacas (Rotifera). BMC Biology 7:60.
Lasek-Nesselquist, E.,
D. B. Mark Welch,
R.C.A. Thompson, R.F. Steuart, and
M.L. Sogin.
2008.
Genetic exchange within and between assemblages of Giardia intestinalis
J. Eukar. Microbiol. 56: 504-518.
doi: 10.1111/j.1550-7408.2009.00443.x
Gribble, K.E., D.M. Anderson, D.W. Coats. 2009.
Sexual and Asexual Processes in Protoperidinium steidingerae Balech (Dinophyceae), with Observations on Life-History Stages of Protoperidinium depressum (Bailey) Balech (Dinophyceae). Journal of Eukaryotic Microbiology 56(1): 88-103.
Huber, J. A., H. G. Morrison, S. M. Huse,
P. R. Neal, M. L. Sogin, and D. B. Mark Welch. 2009.
Effect of PCR amplicon size on assessments of clone library microbial diversity and community structure. Environmental Microbiology 11:1292-1302.
S.M. Huse, L. Dethlefsen, J.A. Huber, D. Mark Welch, D.A. Relman, M.L. Sogin.
2008 Exploring Microbial Diversity and Taxonomy Using SSU rRNA Hypervariable
Tag Sequencing. PLoS Genetics 4(11): e1000255 doi:10.1371/journal.pgen.1000255
Lasek-Nesselquist, E., A. Bogomolni, R. Gast,
D. Mark Welch, J.C. Ellis,
M.L. Sogin, and M. Moore. 2008. Molecular characterization of Giardia intestinalis in marine animals: variation and zoonotic potential. Diseases of Aquatic Organisms 81: 39-51.
Suga, K.,
D. B. Mark Welch,
Y. Tanaka, Y. Sakakura,
and A. Hagiwara, 2008.
Two circular chromosomes of unequal copy number make up the mitochondrial genome of the rotifer Brachionus plicatilis.
Molecular Biology and Evolution
2008 25: 1129-1137.
Mark Welch D.B, , J.L. Mark Welch, J.L., and M. Melselson. (2008)
Evidence for degenerate tetraploidy in bdelloid rotifers. Proc Nat Acad Sci USA 105: 5145-5149.
Meselson, M.
and
D.B. Mark Welch. 2007. Stable heterozygosity?
Science 318: 202-203.
Huber, J.A.,
D.B. Mark Welch,
H.G. Morrison,
S.M. Huse,
P.R. Neal,
D.A. Butterfield, and
M.L. Sogin. 2007.
Microbial population structures in the deep marine biosphere.
Science
318: 97-100.
Gribble, K.E., G. Nolan, and D.M. Anderson. 2007. Biodiversity, biogeography and
potential trophic impact of Protoperidinium spp. (Dinophyceae) of the southwestern
coast of Ireland. Journal of Plankton Research 29 (11): 931-947.
Gribble, K.E., and D.M. Anderson. 2007.
High intragenomic variability in LSU rDNA genes in the heterotrophic dinoflagellates Protoperidinium, Diplopsalis, and Preperidinium (Dinophyceae).
Phycologia 46 (3): 315-324.
Suga, K., D.B. Mark Welch, Y. Tanaka, Y. Sakakura, and A. Hagiwara. 2007. Analysis of expressed sequence tags of the cyclically parthenogenetic rotifer
Brachionus plicatilis.
PLoS ONE
2(8): e671.
Huse, S.M., J.A. Huber, H.G. Morrison, M.L. Sogin, and D.B. Mark Welch. 2007. Accuracy and quality of massively parallel pyrosequencing.
Genome Biology
8: R143.
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