Department of Botany and Molecular Biology
1000 E. University Ave.
University of Wyoming
Laramie, WY 82071
Aven Nelson 126
(307) 766-6378 (office)
(307) 766-5098 (fax)
Molecular evolutionary ecology of plant adaptation to heterogeneous settings.
The majority of variation segregating in natural populations is quantitative, and its expression depends on genetic background, environment, and interactions with these two factors. Traditionally, the evolution of quantitative traits has been described using statistical genetic techniques. However, one of the greatest advantages of these approaches is also one of their primary limitations: it is possible to estimate genetic variation and covariation in traits without any direct knowledge of the underlying loci or molecular genetic details. In like fashion, it is possible to estimate the pattern of natural selection on quantitative traits in the absence of knowledge of loci that determine fitness.
Advances in collecting and analyzing molecular data promise to reveal the molecular genetic basis of quantitative trait variation. Identifying the molecular elements responsible for variation in quantitative traits may provide insight into basic evolutionary and genetic processes, including the minimum number and effect of genes that contribute to variation in quantitative traits, how the expression of variation at specific loci varies across environments, whether selection at specific loci differs across environments, whether pleiotropy or linkage disequilibrium underlie genetic correlations and potential evolutionary constraints, as well as the genetic basis of similarity (or dissimilarity) of trait expression among congeners.
Adaptation to heterogeneous density environments
Developmental flexibility is often viewed as an adaptive strategy that enables organisms to match their phenotype to their surroundings. In natural settings, the position of a plant within its stand can be an important determinant of fitness, because plants require sunlight to photosynthesize and acquire carbon compounds. The ability to both perceive neighbors in advance of direct shading and initiate competitive responses should provide a fitness advantage. In collaboration with Julin Maloof (UC Davis), we are examining both 1) the mechanisms underlying plant perception of and responses to the environment and 2) how variation at specific developmental loci affects fitness.
Genetic analysis of natural variation in the control of flowering timing and inflorescence architecture in Brassica rapa
Many plant species have a broad geographic range, and experience systematic changes in abiotic conditions across latitudes. In collaboration with Rob McClung (Dartmouth College) and Rick Amasino (University of WI), we are examining the genetic architecture of plant responses to variable combinations of temperature and photoperiod. In this project, we are also evaluating how circadian rhythms regulate the expression of adaptive phenotypes.
Quantitative variation in floral organ size
Although the genetic basis of qualitative differences in floral morphology (e.g., differences in shape between different taxa) has received substantial attention, very little is known about the genes that underlie quantitative variation in floral organ size (e.g., length of petals). Yet, these traits can strongly affect fitness of plants in natural populations and yield in cultivars. We have initiated genome-wide association analyses and segregation analyses to identify the loci that affect floral organ size.
Brock, M. T., P. L. Tiffin, and C. Weinig. 2007. Sequence diversity and haplotype associations with phenotypic responses to crowding: GIGANTEA affects fruit set in Arabidopsis thaliana. Molecular Ecology 16: 3050-3062
Brock, M. T., and C. Weinig. 2007. Floral plasticity to light environments and environment-specific floral-vegetative (co)variances. Evolution 61: 2913-2924
Weinig, C., J. A. Johnston, C. G. Willis, and J. N. Maloof. 2007. Antagonistic multilevel selection on size and architecture in variable density settings. Evolution 61: 58-67
Weinig, C., Z. M. German, L. M. Demink, and J. A. Johnston. 2006. Local and global costs of adaptive plasticity. American Naturalist 126: 826-836
Weinig, C. 2005. Rapid evolutionary responses to selection in heterogeneous environments among agricultural and non-agricultural weeds. International Journal of Plant Sciences 166: 641-647
Olsen, K. M., S. S. Halldorsdottir, J. R. Stinchcombe, C. Weinig, J. Schmitt, and M. D. Purugganan. 2004. Linkage disequilibrium mapping of Arabidopsis CRY2 flowering time alleles. Genetics 167: 1361-136
Weinig, C., K. Gravuer, N. C. Kane, and J. Schmitt. 2004. Testing adaptive plasticity to UV: costs and benefits of stem elongation and light-induced phenolics. Evolution 58: 2645-2655
Weinig, C., L. A. Dorn, N. C. Kane, Z. German, S. S. Halldorsdottir, M. C. Ungerer, T. F. C. Mackay, M. D. Purugganan, and J. Schmitt. 2003. Heterogeneous selection at specific loci in natural environments in Arabidopsis thaliana. Genetics 165: 321-329
Weinig, C., M. C. Ungerer, L. A. Dorn, S. S. Halldorsdottir, Y. Toyonaga, T. F. C. Mackay, M. D. Purugganan, and J. Schmitt. 2002. Novel loci control variation in reproductive timing in Arabidopsis thaliana in natural environments. Genetics 162: 1875-1884
Weinig, C. and L. F. Delph. 2001. Phenotypic plasticity early in life constrains developmental responses later. Evolution 55: 930-936