Biogeographic Origin, Taxonomic Status, and Conservation Biology of Asplenium Monanthes L
Total Page：16
File Type：pdf, Size：1020Kb
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1-1-2003 Biogeographic origin, taxonomic status, and conservation biology of Asplenium monanthes L. in the southeastern United States Allison Elizabeth Shaw Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Recommended Citation Shaw, Allison Elizabeth, "Biogeographic origin, taxonomic status, and conservation biology of Asplenium monanthes L. in the southeastern United States" (2003). Retrospective Theses and Dissertations. 20038. https://lib.dr.iastate.edu/rtd/20038 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Biogeographic origin, taxonomic status, and conservation biology of Asplenium monanthes L. in the southeastern United States by Allison Elizabeth Shaw A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Ecology and Evolutionary Biology Program of Study Committee: Donald R. Farrar (Major Professor) John D. Nason Fredric J. Janzen Iowa State University Ames, Iowa 2003 11 Graduate College Iowa State University This is to certify that the master's thesis of Allison Elizabeth Shaw has met the thesis requirements of Iowa State University Signatures have been redacted for privacy iii TABLE OF CONTENTS LIST OF FIGURES v LIST OF TABLES Vlll ACKNOWLEDGEMENTS ix ABSTRACT xi GENERAL INTRODUCTION 1 Research questions 1 Thesis organization 2 Taxonomy of Asplenium monanthes 2 Apo gamy 6 Distribution and habitat of Asplenium monanthes 12 Bioclimatic history of the southeastern U.S. 23 Climate of A. monanthes' habitat in the southeastern U.S. 24 PART I. BIOGEOGRAPIDC ORIGIN AND TAXONOMIC STATUS OF ASPLENIUM MONANTHES L. IN THE SOUTHEASTERN UNITED STATES 36 INTRODUCTION 37 Goals 37 Alternative hypotheses for Asplenium monanthes' origin in southeastern U.S. 37 Causes of biogeographic disjunctions in fems 41 Justification of methods 43 MATERIALS & METHODS 46 Taxa and populations sampled 46 Comparative spore morphology 49 Comparative gametophyte morphology and ontogeny 50 Starch gel electrophoresis 50 Analysis of isozyme data 53 RESULTS 57 Comparative spore morphology 57 Comparative gametophyte morphology and ontogeny 60 Starch gel electrophoresis 73 DISCUSSION 92 Morphological and genetic diversity and differentiation 92 Origin and taxonomic status of the SEUS populations 98 Significance 103 IV PART II. CONSERVATION BIOLOGY OF ASPLENIUM MONANTHES L. IN THE SOUTHEASTERN UNITED STATES 105 INTRODUCTION 106 Goals 106 Considerations and strategies for plant conservation 106 MATERIALS & METHODS 110 Substrate and microclimate characterization 110 Starch gel electrophoresis 115 Gametophyte cultures 115 Population demographics 117 RESULTS 121 Substrate and microclimate characterization 121 Starch gel electrophoresis 143 Gametophyte cultures 144 Population demographics 150 DISCUSSION 158 SEUS microhabitat and microclimate 158 Genetic structure in the southeastern U.S. 164 Plant growth and reproduction in the southeastern U.S. 165 SEUS population trends 172 Conservation recommendations 179 GENERAL CONCLUSION 183 REFERENCES CITED 186 v LIST OF FIGURES Figure 1: Sporophytes of A. monanthes 5 Figure 2: Alternative origins of triploid species 7 Figure 3: Sporogenesis in sexual ferns and various apogamous ferns 9 Figure 4: Approximate northern distribution of A. monanthes in the New World 18 Figure 5: Range of tropical habitats of A. monanthes 19 Figure 6: Range of habitat of A. monanthes in the southeastern U.S. 21 Figure 7: Close-up of typical location hosting A. monanthes in the southeastern U.S. 22 Figure 8: Mean daily maximum temperatures at weather stations in the western Carolinas, northeastern Alabama, and panhandle Florida 26 Figure 9: Mean daily minimum temperatures at weather stations in the western Carolinas, northeastern Alabama, and panhandle Florida 27 Figure 10: Monthly precipitation at weather stations in the western Carolinas, northeastern Alabama, and panhandle Florida 28 Figure 11: Mean monthly precipitation at weather stations in the western Carolinas, northeastern Alabama, and panhandle Florida for 1991-2001 in comparison with long-term mean 29 Figure 12: Alternative colonization scenarios to explain Asplenium monanthes' current distribution in the southeastern U.S. 39 Figure 13: Zymogram showing Asplenium monanthes samples with three different alleles at an isozyme locus 52 Figure 14: Comparison of A. monanthes spores from three of the regions studied 58 Figure 15: The three spore wall layers of A. monanthes 59 Figure 16: Ontogeny of Asplenium monanthes gametophytes 62 Figure 17: Various thalloid growth forms observed in A. monanthes gametophytes 63 Figure 18: Filamentous gametophytes and eventual thallus initiation 64 Vl Figure 19: Development of multiple sporophytes from a single gametophyte 65 Figure 20: Sporophyte initiation 67 Figure 21: Toothed ridges 68 Figure 22: Variations in sporophytes' first fiddleheads 69 Figure 23: Comparison of select gametophytes from the four regions studied 70 Figure 24: Branching of developing fiddlehead 71 Figure 25: Similar filamentous development in gametophytes of A. resiliens, A. heteroresiliens, and A. monanthes 72 Figure 26: Assignment of each allele or phenotypic pattern of A. monanthes to regions to show patterns of similarity among regions 73 Figure 27: Principle Coordinates Analysis of populations based on allele frequencies. Outgroups included. 81 Figure 28: Principle Coordinates Analysis of populations based on allele frequencies. Outgroups excluded. 82 Figure 29: Neighbor Joining tree of populations based on allele frequencies, utilizing Nei's genetic distance 84 Figure 30: Principle Coordinates Analysis of genotypes based on presence/absence of alleles. Outgroups included. 85 Figure 31: Principle Coordinates Analysis of genotypes based on presence/absence of alleles. Outgroups excluded. 89 Figure 32: Neighbor Joining tree of genotypes based on presence/absence of alleles, utilizing Dice's dissimilarity coefficient. Outgroups included. Distances not to scale. 90 Figure 33: Neighbor Joining tree of genotypes based on presence/absence of alleles, utilizing Dice's dissimilarity coefficient. Outgroups not included. Distances to scale. 91 Figure 34: Generalized diagram of an A. monanthes site in the Carolinas showing locations where microclimate data was recorded 112 Figure 35: Yearly maximum and minimum temperatures at various locations within A. monanthes sites and at corresponding weather stations 128 vii Figure 36: Air temperatures at various locations within A. monanthes populations and corresponding weather stations 131 Figure 37: Substrate temperature at various locations within A. monanthes populations 132 Figure 38: Relative humidity at various locations within A. monanthes populations 133 Figure 39: Substrate moisture at various locations within A. monanthes populations 135 Figure 40: Visible light at various locations within A. monanthes populations 138 Figure 41: Photosynthetically active light in various locations within A. monanthes populations 139 Figure 42: Comparison of papillate to hairless Asplenium gametophytes 146 Figure 43: Young gametophytes of Asplenium platyneuron, A. trichomanes, A. resiliens, A. heteroresiliens, and A. monanthes 147 Figure 44: Mature cordate gametophytes of Asplenium platyneuron, A. trichomanes, A. resiliens, A. heteroresiliens, and A. monanthes 149 Figure 45: Population size over time at well-documented A. monanthes populations 154 viii LIST OF TABLES Table 1: SEUS populations of A. monanthes 14 Table 2: Populations of Asplenium monanthes and related species sampled genetically 47 Table 3: Genetic diversity in Asplenium monanthes in comparison with similar plants 75 Table 4: Genetic differentiation in A. monanthes in comparison with similar plants 76 Table 5: Literature review of genetic diversity and differentiation in apogamous plants 78 Table 6: Literature review of genetic differentiation and diversity in fems 79 Table 7: Alphabetical key to genotype codes used in Principle Coordinates Analysis plots and Neighbor Joining trees 86 Table 8: Multilocus isozyme genotypes encountered in each population 87 Table 9 Derivation of fecundity estimates 119 Table 10: Bryophytes at various locations within SEUS A. monanthes populations 122 Table 11: Identification of rocks hosting A. monanthes plants at each population 125 Table 12: Mineral composition of rocks hosting A. monanthes listed in Table 11 126 Table 13: Soil and bryophyte mat characteristics of select A. monanthes sites 127 Table 14: Rock permeability at various A. monanthes populations in comparison with highly permeable sandstone 136 Table 15: Light intensity at various locations within A. monanthes populations 140 Table 16: r2 values for regressions between population success (measured as number of total plants and number of fertile plants) and various microclimate variables 142 Table 17: Census of SEUS populations 151 Table 18: Average SEUS mature population vector, generalized transition matrix, and resulting demographic projection into the future 153 Table 19: Size of fertile plants and their populations 155 IX ACKNOWLEDGEMENTS I am deeply indebted