Ann K. Sakai

Picture of Ann K. Sakai
Professor Emeritus, Ecology & Evolutionary Biology
School of Biological Sciences
Ph.D., University of Michigan
B.A., Oberlin College
Phone: (949) 824-6581
Fax: (949) 824-2181
University of California, Irvine
Ecology and Evolutionary Biology
321 Steinhaus Hall
Mail Code: 2525
Irvine, CA 92697
Research Interests
evolutionary ecology, plant breeding systems, conservation and restoration biology
Academic Distinctions
Distinguished Fellow of the Botanical Society of America 2019
Fellow, American Association for the Advancement of Science 2012
William Evans Fellow, University of Otago (New Zealand) 2012
Celebration of Teaching-award for Teaching Excellence, School of Biological
Sciences, 2010
Chancellor’s Award for fostering undergraduate research 2002
Senior Mellon Fellow, Smithsonian Institution 1994
Research Abstract
My research interests are in evolutionary ecology and conservation biology, with a focus on the evolution of plant breeding systems and their impact on speciation. Most flowering plant species are hermaphroditic, but evolution of dioecy (separate male and female plants) has occurred independently in many lineages. I am interested in identifying the genetic and ecological factors that may promote the evolution of dioecy. I have examined these factors in the Hawaiian flora, an isolated flora with a high incidence of endemism and dioecy. In collaboration with Stephen Weller, we have examined factors promoting the evolution of dioecy in the endemic Hawaiian genus Schiedea (Caryophyllaceae). We use a multi-disciplinary approach, with field studies of the pollination biology and ecology of populations in Hawaii, greenhouse studies of inbreeding depression and outcrossing levels, phylogenetic analyses including genomics, and studies of the genetic potential for changes in allocation patterns to male and female function through measurements of narrow sense heritabilities, genetic correlations, and artificial selection experiments. My research interests also include conservation biology and restoration biology, particularly in island settings. The native Hawaiian flora is disappearing at an alarming rate. I am interested in factors that affect the invasiveness of alien species,the invasibility of native communities, community interactions of alien and native plants and animals, and the impact of global climate change on these interactions. Working in collaboration with Hawaiian biologists, we seek to use this knowledge to better manage alien invasive species and protect the native biota.

I also directed an NSF-funded outreach program for 11 years that provides undergraduates from diverse backgrounds with travel grants and mentors so that they can attend the national meetings of several societies focused on the plant sciences. This experience provides these students the opportunity to explore their academic and research interests in the plant sciences and to broaden their career opportunities.
Awards and Honors
Botanical Society of America Impact Award 2022, for significant contribution to advancing diversity, accessibility, equity, and/or inclusion in botanical scholarship, research and education
Mazer, Susan J., A. K. Sakai, S. G. Weller, and Eugenio Larios. 2022. What determines the evolutionary trajectories of wild plant species? Approaches to the study of quantitative fitness-related traits. American Journal of Botany 109: 1673-1682.
Campbell, D.R., A.K. Sakai, S.G. Weller, T.M. Culley, A.K. Dunbar-Wallis, A.M. Andres, T.G. Wong, T. Dang, B. Au, M. Ku, A.R. Marcantonio, P.J. Ngo, A.A. Nguyen, M.H. Tran, and Q.-P. Tran. 2022. Genetic potential for changes in breeding systems: predicted and observed trait changes during artificial selection for male and female allocation in a gynodioecious species. American Journal of Botany 109: 1918-1938.
Powers, J. M., A. K. Sakai, S. G. Weller, and D. R. Campbell. 2022. Variation in floral volatiles across time, sexes, and populations of wind-pollinated Schiedea globosa (Caryophyllaceae). American Journal of Botany. DOI: 10.1002/ajb2.1820
Powers JM, Seco R, Faiola CL, Sakai AK, Weller SG, Campbell DR and Guenther A. 2020. Floral scent composition and fine-scale timing in two moth-pollinated Hawaiian Schiedea (Caryophyllaceae). Front. Plant Sci. 11:1116. doi: 10.3389/fpls.2020.01116

Henkhaus N, Bartlett M, Gang D, Grumet R, Jordon-Thaden I, Lorence A, Lyons E, Miller S, Murray S, Nelson A, Specht C, Tyler B, Wentworth T, Ackerly D, Baltensperger D, Benfey P, Birchler J, Chellamma S, Crowder R, Donoghue M, Dundore-Aria JP, Fletcher J, Fraser V, Gillespie K, Guralnick L, Haswell E, Hunter M, Kaeppler S, Kepinski S, Li F-W, Mackenzie S, McDade L, Min Y, Nemhauser J, Pearson B, Petracek P, Rogers K, Sakai A, Sickler D, Taylor C, Wayne L, Wendroth O, Zapata F, Stern D. Plant science decadal vision 2020–2030: Reimagining the potential of plants for a healthy and sustainable future. Plant Direct. 2020; 00:1–24.

Sakai, A. K., S. G. Weller, W. Yang, S. Ching Harbin, T. Portner, G. Mansker, and M. Bruegmann. 2017. The intersection of basic research and conservation: a 30 year study of the Critically Endangered Schiedea adamantis (Caryophyllaceae) on Le‘ahi (Diamond Head Crater), Hawai‘i. Oryx: doi:10.1017/S0030605316001162
Weller, S. G., A. K. Sakai, D. R. Campbell, J. M. Powers, S. R. Peña, M. J. Keir, A. K. Loomis, S. M. Heintzman, and L. Weisenberger. 2017. An enigmatic Hawaiian moth is a missing link in the adaptive radiation of Schiedea. New Phytologist 213: 1533-1542

Weller, S. G., A. K. Sakai, C. A. Lucas, J. J. Weber, C. A. Domínguez, and F. E. Molina- Freaner. 2015. Genetic basis of tristyly in tetraploid Oxalis alpina (Oxalidaceae). Botanical Journal of the Linnean Society. 179: 308-318.

Redelings, B. D., S. Kumagai, A. Tatarenkov, L. Wang, A. K. Sakai, S. G. Weller, T. M. Culley, J. C. Avise, and M. K. Uyenoyama. 2015. Bayesian co-estimation of selfing rate and locus-specific mutation rates for a partially selfing population. Genetics. 201(3): 1171-1188.

Weller, S.G., A. K. Sakai, T. Gray, J. J. Weber, O. V. Tsyusko, C. A. Domínguez, J. Fornoni,and F. E. Molina-Freaner. 2015. Variation in heterostylous breeding systems in neighboring populations of Oxalis alpina (Oxalidaceae). Plant Biology. doi:10.1111/plb.12340

Weisenberger, L. A., S. G. Weller, and A. K. Sakai. 2014. Remnants of populations provide effective source material for reintroduction of an endangered Hawaiian plant, Schiedea kaalae Caryophyllaceae). American Journal of Botany 101:1954-1962.

Weller, S. G., A. K. Sakai, T. M. Culley, L. Duong, and R. E. Danielson. 2014. Segregation of male sterility alleles across a species boundary. Journal of Evolutionary Biology 27: 429-436.
Sakai, A. K., S. G. Weller, D. R. Campbell, T. M. Culley, A. K. Dunbar-Wallis, and A. M. Andres. 2013. Measure for measure: comparing morphological and biomass traits for sex allocation in two gynodioecious species. American J. Botany. 100(6): 1071-1082.
Weller, S. G., K. Suding, and A. K. Sakai. 2013. Botany and a changing world: introduction to the special issue on global biological change. American J. Botany. 100(7):1229-1233.
Weber, J. J., S. G. Weller, A. K. Sakai, L.-Q. Nguyen, and D. Khuu. 2013. Breeding system evolution in Oxalis alpina: asymmetrical expression of tristylous incompatibility. International J. Plant Sciences. 174:179-188.
Weber, J. J., S. G. Weller, A. K. Sakai, O. V. Tsyusko, T. C. Glenn, C. A. Dominguez, F. E. Molina-Freaner, J. Fornoni, M. Tran, N. Nguyen, K. Nguyen, L-K Tran, G. Joice, and E. Harding. 2013. The role of inbreeding depression and mating system in the evolution of heterostyly. Evolution 67: 2309-2322.
Weber, J. J., S.G. Weller, A.K. Sakai, A. Nguyen, N.D. Tai, C.A. Dominguez, and F.E. Molina-Freaner. 2012. Purging of inbreeding depression within a population of Oxalis alpina (Oxalidaceae). American J. Botany 99:923-932.
Jürgens, A., M. Bischoff, A.K. Sakai, S.G. Weller. 2012. Floral scent of four Hawaiian Schiedea species (Caryophyllaceae). Biochemical Systematics and Ecology. 45: 194-197.
Vary, LB, DL Gillen, M Randrianjanahary, PP Lowry II, AK. Sakai, and SG. Weller. 2011. Dioecy, monoecy, and their ecological correlates in the littoral forest of Madagascar. Biotropica. 43: 582-590.
Kutaka, JJ, SG Weller, CA Dominguez, AK Sakai, FE Molina-Freaner, P Sosenski, and J Fornoni. 2011. Female and male mediation of incompatibility modifications during the tristyly-distyly transition in Oxalis alpina. International J. Plant Sciences. 172:644-654.
Vary LB, Sakai AK, Weller SG. 2011. Morphological and functional sex expression in the Malagasy endemic Tina striata (Sapindaceae). American J. Botany 98(6):1040-8.
Wallace LE, Culley TM, Weller SG, Sakai AK, Kuenzi A, Roy T, Wagner WL, Nepokroeff M. 2011. Asymmetrical gene flow in a hybrid zone of Hawaiian Schiedea (Caryophyllaceae) species with contrasting mating systems. PLoS One 6(9):e24845
Campbell DR, Weller SG, Sakai AK, Culley TM, Dang PN, Dunbar-Wallis AK. 2011. Genetic variation and covariation in floral allocation of two species of Schiedea with contrasting levels of sexual dimorphism. Evolution 65(3):757-70.
Willyard A, Wallace LE, Wagner WL, Weller SG, Sakai AK, Nepokroeff M. 2011. Estimating the species tree for Hawaiian Schiedea (Caryophyllaceae) from multiple loci in the presence of reticulate evolution. Mol Phylogenet Evol.
Weller, SG., RJ Cabin, DH Lorence, S Perlman, K Wood, T Flynn, and AK Sakai. 2011. Alien plant invasions, introduced ungulates, and alternative states in a mesic forest in Hawaii. Restoration Ecology 19: 671-680.
Caujapé-Castells, J., K. Beaver, D. J. Crawford, F. B. Vincent Florens, I. Gómes, R. Jardim, W. Lobin, M. Moura, A. Sakai, A. Santos-Guerra, A. Tye, C. Kueffer. 2010. Conservation of oceanic island floras: present and future global challenges. Perspectives in Plant Ecology, Evolution and Systematics 12:107-129.
Wallace, L. E., S. G. Weller, W. L. Wagner, A. K. Sakai, and M. Nepokroeff. 2009. Phylogeographic patterns and demographic history of Schiedea globosa (Caryophyllaceae) on the Hawaiian Islands. American Journal of Botany 96: 958-967.
Culley, T. M., S. G. Weller, A. K. Sakai, and K. Putnam. 2008. Characterization of microsatellite loci in the Hawaiian endemic shrub, Schiedea adamantis (Caryophyllaceae) and amplification in related species and genera. Molecular Ecology Resources (formerly Molecular Ecology Notes). 8: 1081-1084.
Sakai, A. K., S. G. Weller , T. M. Culley, D. R. Campbell, A. K. Dunbar-Wallis, and A. Andres. 2008. Sexual dimorphism and the genetic potential for evolution of sex allocation in the gynodioecious plant, Schiedea salicaria. Journal of Evolutionary Biology 21:18-29.
Poulin, J., A. K. Sakai, S. G. Weller, and T. Nguyen. 2007. Phenotypic plasticity, precipitation, and invasiveness in the fire-promoting grass, Pennisetum setaceum (Poaceae). American Journal of Botany. 94:533-541.
Weller, S. G., A. K. Sakai, T. M. Culley, D. R. Campbell, P. Ngo, and A. K. Dunbar-Wallis. 2007. Sexually dimorphic inflorescence traits in a wind-pollinated species: heritabilities and genetic correlations in Schiedea adamantis (Caryophyllaceae). American Journal of Botany 94:1716-1725.
Weller, S. G., A. K. Sakai, D. R. Campbell, T. M. Culley, and A. Dunbar-Wallis. 2006. Predicting the pathway to wind pollination: heritabilities and genetic correlations of inflorescence traits associated with wind pollination in Schiedea salicaria (Caryophyllaceae). Journal of Evolutionary Biology 19: 331-342.
Sakai, A. K., S. G. Weller, W. L. Wagner, M. Nepokroeff, and T. M. Culley. 2006. Adaptive radiation and evolution of breeding systems in Schiedea (Caryophyllaceae), an endemic Hawaiian genus. Annals of the Missouri Botanical Garden. 93: 49-63.
Culley, T. M., A. K. Dunbar-Wallis, A. K. Sakai, S. G. Weller, and D. R. Campbell. 2006. Genetic variation of ecophysiological traits in two gynodioecious species of Schiedea (Caryophyllaceae). New Phytologist. 169: 589-601.
Golonka, A. M. , A. K. Sakai, and S. G. Weller. 2005. Wind pollination, sexual dimorphism, and changes in floral traits of Schiedea (Caryophyllaceae). American Journal of Botany 92:1492-1502.
Weller, S. G., A. K. Sakai, D. A. Thai, J. Tom, and A. E. Rankin. 2005. Inbreeding depression and heterosis in populations of Schiedea viscosa, a highly selfing species. Journal of Evolutionary Biology 18:1434-1444.
Culley, T. M., A. K. Dunbar-Wallis, A. K. Sakai, S. G. Weller, and D. R. Campbell. 2005. Genetic variation in ecophysiological traits and the evolution of gynodioecy in Schiedea (Caryophyllaceae). New Phytologist 169: 589-601.
Poulin J., S. G. Weller, A. K. Sakai. 2005. Genetic diversity does not affect the invasiveness of fountain grass (Pennisetum setaceum) in Arizona, California and Hawaii. Diversity and Distributions 11: 241-247.
Weller, S. G., and A. K. Sakai. 2005. Selfing and resource allocation in Schiedea salicaria (Caryophyllaceae), a gynodioecious species. Journal of Evolutionary Biology 18:301-308.
Wagner, W. L., S. G. Weller, and A. K. Sakai. 2005. Monograph of Schiedea (Caryophyllaceae subfam. Alsinoideae). Systematic Botany Monographs 72: 1-169.
Weller, S. G., A. K. Sakai, D. R. Campbell, T. M. Culley, and A. Dunbar-Wallis. 2005. Predicting the pathway to wind pollination: heritabilities and genetic correlations of inflorescence traits associated with wind pollination in Schiedea salicaria (Caryophyllaceae). Journal of Evolutionary Biology. 19: 331-342.
Rankin, A. E., S. G. Weller, and A. K. Sakai. 2002. Mating system instability in Schiedea menziesii (Caryophyllaceae). Evolution 56: 1574-1585.
Sakai, A. K., W. L. Wagner, and L. Mehrhoff. 2002. Patterns of endangerment in the Hawaiian flora. Systematic Biology 51: 276-302.
Sakai, A. K., F. W. Allendorf, J. S. Holt, D. M. Lodge, J. Molofsky, K. A. With, S. Baughman, R. J. Cabin, J. E. Cohen, N. C. Ellstrand, D. E. McCauley, P. O'Neil, I. M. Parker, J. N. Thompson, and S. G. Weller. 2001. The Population Biology of Invasive Species. Annual Review of Ecology and Systematics 32: 305-332.
Culley TM, Weller SG, Sakai AK, Rankin AE. 1999. Inbreeding depression and selfing rates in a self-compatible, hermaphroditic species, Schiedea membranacea (Caryophyllaceae). Am J Bot. 86(7):980-7.
Weller, S. G., A. K. Sakai, A. E. Rankin, A. Golonka, B. Kutcher, and K. E. Ashby. 1998. Dioecy and the evolution of wind pollination in Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae) in the Hawaiian Islands. American Journal of Botany 85:1377-1388.
Sakai, A. K., S. G. Weller, M.-L. Chen, S.-Y. Chou, and C. Tasanont. 1997. Evolution of gynodioecy and maintenance of females: the role of inbreeding depression, outcrossing rates, and resource allocation in Schiedea adamantis (Caryophyllaceae). Evolution 51:724-736.
Sakai, A. K. and M. J. Lane. 1996. National Science Foundation funding patterns of women and minorities in biology. BioScience 46: 621-625.
Goldberg, D. and A. K. Sakai. 1993. Career options for dual-career couples: results of an ESA survey on soft money research positions and shared positions. Bulletin of the Ecological Society of America. 74:146-152.
Professional Societies
American Association for the Advancement of Science
American Society of Plant Taxonomists
Botanical Society of America
Ecological Society of America
National Center for Science Education
Society for the Study of Evolution
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