Telephone: (828) 526-2602

Fax: (828) 526-2797

E-mail: wyatt@wcu.edu

Office: Highlands Biological Station

Selected References

I am a broadly trained population biologist with primary interests in the ecology and evolution of plant reproduction. My background is unusual in combining training in systematics and evolutionary biology with both population genetics and population ecology. I believe that this combination of approaches and skills makes me unusually well-qualified to study in an integrated fashion aspects of the evolution of breeding systems, pollination ecology, and biosystematics. I have worked with a diverse range of plant taxa from mosses and lichens to ferns and flowering plants.

I believe in the primacy of biological questions. I have always been willing to learn appropriate techniques when it became apparent that they could help to answer fundamental questions of interest. Thus, my research projects have ranged from those employing traditional morphology and systematics, through population ecology and genetics, to those involving biochemical and molecular methods. I am always open to innovative new tools that will enable me to answer questions more effectively or more efficiently, whether that tool involves a new laboratory technique or a new way to analyze data.

My present research is focused in two areas: reproductive ecology of milkweeds and systematics, ecology, and evolution of mosses. In Asclepias I have recently used paternity analysis to quantify male, as well as female, fitness of these hermaphroditic plants. Using isozyme markers from horizontal starch-gel electrophoresis, it has been possible to determine the parentage of fruits produced in natural populations. Contrary to predictions of sexual selection theory, the results suggest that male fitness does not increase more rapidly as a function of inflorescence size than does female fitness. These results have now been confirmed by experimental manipulation of inflorescence size in garden plots. In the future I plan to extend these studies to other species and to study in more detail the plant-pollinator interactions and pollen-pistil interactions that determine components of male and female reproductive success.

I am also deeply involved in a study of the phylogenetic relationships among species in the moss family Mniaceae. Thus far, my attention has focused on Plagiomnium section Rosulata, which consists of six haploid and one diploid species. Isozyme markers have been used to show that the diploid is an allopolyploid. This is the first discovery of this mode of speciation in any bryophyte! Moreover, the genetic evidence proves that this taxon has had multiple origins and, despite its bisexual nature, regularly outcrosses. Data for other species of Mniaceae, as well as for the unrelated families Polytrichaceae and Fissidentaceae, suggest that allopolyploidy is widespread and common in mosses, just as it is in other land plants. Furthermore, detailed studies of several species of mosses from eastern North America indicate unexpectedly high levels of genetic variation in these haploid-dominant organisms. Presently, I am extending our analyses to additional haploid-polyploid species pairs, comparing levels of genetic differentiation between intercontinentally disjunct populations, and using data from morphology, isozymes, and DNA to reconstruct phylogenies within the Mniaceae and Polytrichaceae.

I have had a continuing interest in hybridization and introgression, dating back to my dissertation research on leaf-shape variation in butterflyweed (Asclepias tuberosa). This work has been extended to recent studies documenting interspecific gene exchange between A. syriaca, A. exaltata, and other species. I have used morphological, chemical, and isozyme markers to measure levels of intergradation and to study hybridization as a process. Presently, I am planning more refined studies of pollinator behavior and pollen-pistil interactions to obtain more information about the dynamics of gene exchange in natural populations. I have also been busy growing milkweeds in the greenhouse to perform crosses, both to assess the success of interspecific pollinations and to determine the nature of self-incompatibility in these plants. I also hope to continue and extend studies of an unusually broad, asymmetrical hybrid zone in buckeyes (Aesculus), which offers an interesting contrast to the localized pattern of hybridization in milkweeds.

As is evident from inspection of my publications, my interests and those of my students have ranged widely both in taxonomic scope and in approach. All of these studies, however, center around the themes of ecology and evolution of plant reproduction and/or variation and evolution, especially in relation to hybridization and speciation. My wife, Dr. Ann Stoneburner, and I have jointly pursued research on mosses for some time now. My recent work on milkweeds with Dr. Steven B. Broyles has continued, despite his having assumed a faculty position in New York. The same is true for Dr. Claude W. dePamphilis, presently of Vanderbilt University, who has retained an interest in the buckeye populations that were part of his doctoral research. Over the years, I have been fortunate to be able to maintain grant support for these and other projects from the National Science Foundation, Whitehall Foundation, and other sources. I hope that this situation will continue, enabling even more basic research on those questions that my students and I find most interesting.

In summary, I believe that my major contributions to our knowledge of the ecology and evolution of plant reproduction are: (1) I devised new methods for crossing the incredibly complex flowers of milkweeds and was the first person to demonstrate self-compatibility in the genus. (2) I coined the term "inflorescence architecture" and opened up a new field of research into the effects of flower number and arrangement. (3) I showed that Robert E. Woodson's classic example of rapid genetic change in two hybridizing subspecies could not be due to natural selection. (4) I carried out the first paternity analysis in a natural population and called into question the major tenets of the pollen donation hypothesis. (5) I documented the first cases of hybridization in milkweeds and contrasted the patterns and processes to those occurring in other flowering plants. (6) I performed an especially rigorous examination of the evolution of self-pollination in granite outcrop sandworts and formulated the hypothesis that its genesis lies in competition for pollinators. (7) I showed that levels of genetic variation are unexpectedly high in haploid mosses. (8) I documented the first cases of allopolyploidy in mosses and showed that they can have multiple times and places of origin.