Welcome to the Bradshaw-Holzapfel Lab

William E. Bradshaw, Professor Ph.D., University of Michigan bradshaw@darkwing.uoregon.edu	Christina M. Holzapfel, Research Associate Ph.D., University of Michigan holz@darkwing.uoregon.edu
Center For Ecology and Evolutionary Biology  5289 University of Oregon  Eugene, Oregon 97403-5289   People in the Lab Full Publication List	Laboratory: 305 Pacific Hall Phone: (541) 346-4542 Fax: (541) 346-2364 "An Evolving Partnership" - CAS Cascade Spring 2002

"In Mosquito, a small tale of climate change" - Boston Globe, Spring 2007 [video]

"DNA Files - The heat is on: evolution in action" [mp3]

Synopsis of research

Our research involves evolutionary genetics, seasonal development, photoperiodism and population biology. Our major interest lies in the pursuit of the general question of "how has the genetic differentiation of populations actually taken place in nature?" We have chosen to study insects as our primary research organism because they are ideal for answering basic questions in evolutionary biology and, at the same time, are of medical and economic importance. Because of tractability in sampling and manipulation of natural populations, we have concentrated on insects developing in restricted or container habitats such as pitcher-plant leaves and tree holes. We are seeking to answer basic questions about genetics and evolution in several areas:
• 1. What are the major adaptations that permit dispersal in the temperate zone and what is the genetic basis for the evolution of these adaptations? The study of adaptation often has meant a post-hoc rationalization for the "adaptive significance" of particular structures or physiological processes. We are able to rear the mosquito, Wyeomyia smithii, entirely in its natural habitat, the pitcher-plant, Sarracenia purpurea, in elaborate controlled-environment rooms that can be programmed for any climate between Florida and Newfoundland. We are then able to assess the actual contribution to fitness of a putative adaptation among populations, selected lines, or genetic manipulations in a seasonal context. These rooms also allow us effectively to perform reciprocal transplants between wide geographic areas without confounding photoperiod and latitude of origin.
• 2. The ability to cue seasonal development by assessing and responding to daylength (photoperiodism) is widespread among temperate plants and animals. Photoperiodism represents the most fundamental adaptation to seasonal environments over geographic gradients in climate. The mean daylength used to switch from active development to dormancy in Wyeomyia smithii has evolved over 10 phenotypic standard deviations from Florida to Canada and has a heritability ranging from 25-70% within populations. We are therefore able to work with large evolved differences between natural populations and high genetic variation within populations.
• 2a. We are using Wyeomyia smithii to resolve the relative importance of seasonal and climatic adaptation through photoperiodic response as opposed to adaptive modification of thermal tolerances. When confronted with global climate change, for example, organisms need not confront new sources of thermal stress head-on; rather they may evade it by the adaptive modification of the timing of important seasonal events in their life history (Bradshaw and Holzapfel 2001, Bradshaw et al. 2004).
• 2b. We are using Wyeomyia smithii to ask whether the loci contributing to genetic variability within populations are the same as those that contribute to genetic variability between populations. To answer these questions, we are using QTL mapping to determine the congruence of QTLs for thermal tolerance and for photoperiodic response within and between populations from Florida to Newfoundland.
• 2c. We are also using Wyeomyia smithii to ask whether circadian rhythmicity is a component of photoperiodic response, is a modifier of photoperiodic response, or represents a distinct physiological process. To answer these questions, we are investigating how variation of circadian rhythm genes at the molecular level covary with quantitative variation in photoperiodic response within and between populations. We are also using microarray technology to discover genes that control photoperiodism specifically.
• 3. What is the relationship between founder events in the establishment of populations and genetic variability within the descendent population? Do multiple founder events release additive from epistatic effects and, consequently, affect phenotypic as well as genetic differentiation of populations. Does the reduction in heterozygosity following founder events result in susceptibility to inbreeding depression? To answer these questions, we are looking at the degree to which outcrossing increases fitness in both optimal and stressful environments among populations from along a geographic gradient of sequential founder events.

We maintain an active laboratory of post-docs, graduate, and undergraduate researchers that is equipped with several controlled-environment rooms, more than ten incubators, and eighty photoperiod chambers. We encourage students to ask questions and to combine experimental and theoretical approaches in both the lab and in the field. Our research has been supported by the National Science Foundation, the National Geographic Society, the John S. Guggenheim Foundation, and the Fulbright Commission. We are particularly interested in working with doctoral and post-doctoral researchers on the molecular and quantitative genetic aspects of evolution in the context of seasonal and climatic adaptation.

 Selected topical publications from our lab

Emerson, K.J., Bradshaw, W.E., and Holzapfel, C.M. 2008. Concordance of the circadian clock with the environment is necessary to maximize fitness in natural popualtions. Evolution 62(4):979 - 983. [pdf]

Bradshaw, W.E., and Holzapfel, C.M. 2008. Evolution of animal photoperiodism. Annual Reviews of Ecology, Evolution and Systematics 38:1 - 35. [pdf]

Bradshaw, W.E., and Holzapfel, C.M. 2008. Genetic response to rapid climate change: it's seasonal timing that matters. Molecular Ecology 17(1):157 - 166. [doi - open access from Blackwell-Synergy]

Mathias, D.M., Jacky, L., Bradshaw, W.E., and Holzapfel, C.M. 2007. Quantitative trait loci associated with photoperiodic response and stage of diapause in the pitcher-plant mosquito, Wyeomyia smithii. Genetics 176:391 - 402. [pdf]

Bradshaw, W.E. and Holzapfel, C.M. 2006. Climate change - Evolutionary response to rapid climate change. Science 312 (5779): 1477 - 1478. [pdf]

Bradshaw, W.E., Holzapfel, C.M., and Mathias, D. 2006. Circadian rhythmicity and photoperioidism in the pitcher-plant mosquito: Can the seasonal timer evolve independently of hte circadian clock? The American Naturalist 167(4): 601 - 605. [pdf]

Mathias, D.A., Jacky, L., Bradshaw, W.E., and Holzapfel, C.M. 2005. Geographic and developmental variation in expression of the circadian rhythm gene, timeless, in the pitcher-plant mosquito, Wyeomyia smithii. Journal of Insect Physiology 51:661 - 667. [pdf]

Bradshaw, W.E., Haggerty B.P., and Holzapfel, C.M. 2005. Epistasis underlying a fitness trait within a natural population of the pitcher-plant mosquito, Wyeomyia smithii. Genetics 169:485-488. [pdf]

Bradshaw, W.E., Zani, P.A., and Holzapfel, C.M 2004. Adaptation to temperate climates. Evolution 58(8):1748 - 1762. [pdf]

Bradshaw, W.E., Quebodeaux, M.C., and Holzapfel, C.M. 2003. Circadian rhythmicity and photoperiodism in the pitcher-plant mosquito: Adaptive rsponse to the photic environment or correlated response to climatic adaptation? The American Naturalist 161:735-748. [pdf]

Bradshaw, W. E., and Holzapfel, C. M. 2001. Genetic shift in photoperiodic response correlated with global warming. Proc. Nat. Acad Sci. USA. 98:14509-14511. [pdf]

Bradshaw, W. E., and Holzapfel, C. M. 2001. Phenotypic evolution and the genetic architecture underlying photoperiodic time measurement. J. Insect. Physiol. 47:809-820. [pdf]

Bradshaw, W. E., and Holzapfel, C. M. 2000. The evolution of genetic architectures and the divergence of natural populations. Pp. 245-263 in J. Wolf, E. D. Brodie, and M. Wade, eds. Epistasis and the Evolutionary Process. Oxford University Press. [pdf]

Armbruster, P. A., Bradshaw, W. E., and Holzapfel, C. M. 1998. Effects of postglacial range expansion on allozyme and quantitative genetic variation in the pitcher-plant mosquito, Wyeomyia smithii. Evolution 52:1697-1704. [pdf]

Lair, K. P., Bradshaw, W. E., and Holzapfel, C. M. 1997. Evolutionary divergence of the genetic architecture underlying photoperiodism in the pitcher-plant mosquito, Wyeomyia smithii. Genetics 147:1873-1883. [pdf]

Complete list of publications of the Bradshaw-Holzapfel lab