My research interests center around natural variation, both genetic and phenotypic, and its significance in population and species divergence. In particular, I am interested in how processes at the genetic level contribute to phenotypes important for speciation.
While pursuing a B.A. in Integrative Biology at the University of California, Berkeley, I tested the validity of subspecies for a highly morphologically variable species, the long-nosed snake (Rhinocheilus lecontei), using thin-plate spline morphometrics and multivariate analysis of linear morphometrics and color pattern (Manier, 2004).
My Ph.D. dissertation at Oregon State University examined patterns of population genetic structure at microsatellite loci for three species (two garter snakes and a toad) coexisting on a common landscape and engaging in predator-prey and competitive interactions. Bi-directional estimates of migration rate (migration to and from) identified source-sink population dynamics for both garter snake species (Manier and Arnold, 2005) and a more stable population structure for the toad (Manier and Arnold, 2006). Ecological correlates of population genetic parameters were identified and compared for all three species (Manier and Arnold, 2006). I also estimated selection on quantitative traits (scale counts and coloration) across ecotypes for one of the garter snakes (Thamnophis elegans) using Fst-Qst analysis and correlational selection analysis (Manier et al. 2007).
My current research as an NIH NRSA Postdoctoral Fellow in the Palumbi lab seeks to understand how variation in sperm morphology is controlled through regulatory changes in gene expression or structural variation in protein-coding regions. Rapid evolution of spermatozoal traits has been associated with natural and sexual selection in diverse taxa and may play a significant role in the reproductive isolation of free-spawning organisms. I am using competitive hybridizations of testis cDNA from sea urchin males with different sperm morphologies against high-density oligonucleotide arrays that exploit the recently sequenced sea urchin genome.
I am also interested in the functional significance of variation in sperm morphology within and between populations of the green sea urchin, Strongylocentrotus droebachiensis. An ongoing project investigates how sperm morphology affects fertilization success, in particular through interactions with the gamete recognition protein, bindin. Estimating the shape of the fitness function of sperm morphology against fertilization success will allow me develop a theoretical model to define conditions under which multiple phenotypic optima are maintained within a population. Such a model will elucidate the conditions responsible for promoting the high levels of phenotypic variation I have observed within and among natural populations of the green sea urchin and other species.
Manier MK. 2004. Geographic variation in the long-nosed snake (Rhinocheilus lecontei): beyond the subspecies debate. Biological Journal of the Linnean Society 83(1): 65-85. [PDF]
Manier MK and SJ Arnold. 2005. Population genetic analysis identifies source-sink dynamics for two sympatric garter snake species (Thamnophis elegans and T. sirtalis). Molecular Ecology 14(13): 3965-3976 [PDF][Supplementary Tables]
Manier MK and SJ Arnold. 2006. Ecological correlates of population genetic structure: a comparative approach using a vertebrate metacommunity. Proceedings of the Royal Society, London B 273(1604): 3001-3009. [PDF]
Manier MK, CM Seylor and SJ Arnold. 2007. Adaptive divergence between ecotypes of the terrestrial garter snake, Thamnophis elegans, assessed with Fst-Qst comparisons. Journal of Evolutionary Biology 20(5): 1705-1719. [PDF] Supplements [A1][A2]
Howard D, SR Palumbi, L Birge and MK Manier. in press. Sperm and speciation. In Sperm Evolution (TR Birkhead, DJ Hosken and S Pitnick, eds). Elsevier.
Manier, MK and SR Palumbi. in review. Intraspecific divergence in sperm morphology of the green sea urchin, Strongylocentrotus droebachiensis: implications for selection in broadcast spawners. BMC Evolutionary Biology.
Manier MK and SR Palumbi. in prep. Evolution in small packages: variation in sperm morphology. Trends in Ecology and Evolution.
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