Conservation of genetic diversity in slippery elm (<Emphasis Type="Italic">Ulmus rubra</Emphasis>) in Wisconsin despite the devastating impact of Dutch elm disease

Forest pest epidemics are responsible for many population declines reported in forest trees. While forest tree populations tend to be genetically diverse, in principle mortality resulting from disease could diminish that genetic diversity and alter the genetic structure of the remnant populations with consequences for the ability of a species to adapt to changing environments. Slippery elm (Ulmus rubra Muhl.) is a long-lived, wind-pollinated forest tree with a native range covering essentially all of eastern North America. Dutch elm disease (DED) caused by an introduced fungal pathogen (Ophiostoma ulmi) devastated North American elm populations, including slippery elm, beginning in the 1930s. Estimates of the numbers of elms lost to DED are unknown but range into the hundreds of millions of trees given their former abundance. In this study, the genotypes of 77 herbarium specimens collected between 1890 and 2004 in Wisconsin, and of 100 slippery elm trees from five wild Wisconsin populations, were characterized using 13 microsatellite loci. Levels of genetic diversity were compared between the herbarium specimens collected pre- and post-DED spread in Wisconsin. In addition, the levels of genetic diversity and degree of genetic differentiation were quantified in the five wild populations. The allelic diversity and expected levels of heterozygosity were similar between the pre- and post-DED herbarium specimens. The five wild populations were only slightly differentiated and no genetic bottleneck was detected for any population. At least in Wisconsin, slippery elm apparently has maintained levels of genetic diversity that could facilitate adaptation to future climatic and environmental changes.     

Gonadal Dysgenesis Determinants in a Natural Population of DROSOPHILA MELANOGASTER

Three populations of Drosophila melanogaster from northern California were surveyed for the ability to produce and resist gonadal dysgenesis in the P-M system of hybrid dysgenesis. Males from all three populations produced low to moderate levels of gonadal dysgenesis in crosses to Oregon-R M females. Most females had the P cytotype, but the M cytotype occurred occasionally. The three populations could not be statistically differentiated from one another, but were easily distinguished from populations from Australia and Wisconsin on the basis of gonadal dysgenesis potential. The California populations had higher levels of M cytotype than did the Wisconsin population. Thirteen X chromosomes and 11 pairs of autosomes were extracted from one of the California populations, using a modification of the standard balancer chromosome technique to suppress hybrid dysgenesis during extraction. All lines produced strongly skewed sterility distributions in crosses to M-strain females, and mean levels of sterility were less than 50%. There was evidence of nonadditive interactions between the autosomes. Most extraction lines had the P cytotype, but M and intermediate cytotypes were observed. Some of the intermediate cytotypes were stable over time. Lines were tested at two different times after extraction. Some lines evolved higher sterility potential as they were kept in the laboratory, even in the presence of P cytotype. The results point out a number of deficiencies in current genetic and population genetic models of hybrid dysgenesis and imply that gonadal dysgenesis is unlikely to be an important evolutionary force in this population.     

Three independent genetic systems that control initiation of a fungal fruiting body

Summary The initiation of monokaryotic fruiting in the basidiomycetous fungus Schizophyllum commune has been observed to occur spontaneously, in response to biochemical substances, and following mechanical injury. The responses to these three stimuli are genetically separable and under polygenic control.Paper #2259 from the Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706Supported in part by the College of Agriculture and Life Science, University of Wisconsin and NIH Predoctoral Training Grant #GM 07133 to the Laboratory of Genetics, University of WisconsinSupported in part by the College of Agriculture and Life Sciences, University of Wisconsin and by grant PCM77-05581 from the National Science Foundation     

Late Pleistocene divergence between eastern and western populations of wood ducks (Aix sponsa) inferred by the 'isolation with migration' coalescent method

During the Late Pleistocene, glaciers sundered many species into multiple glacial refugia where populations diverged in allopatry. Although deeply divergent mitochondrial DNA (mtDNA) lineages often reflect the number of refugia occupied, it is unlikely that populations that split during the recent Wisconsin glaciations will have reached reciprocal monophyly. We examined mtDNA control region sequences from eastern and western populations of wood ducks (Aix sponsa) to determine whether their current, disjunct distribution is consistent with the occupancy of two glacial refugia. We used the 'isolation with migration' coalescent method (im) to simultaneously estimate effective population sizes, maternal gene flow, and time since divergence. We found 24 unique haplotypes, none of which were shared between the eastern and western populations, but we did not find diagnostic monophyletic lineages suggestive of long-term isolation in multiple glacial refugia. However, a high Phi ST (0.31) indicates that eastern and western populations are well differentiated in mtDNA, and results from im suggest that these populations have been diverging, without extensive gene flow, for 10,000 to 124,000 years. Results from im further suggest that these populations most likely split about 34,000 years ago, and this time of divergence is consistent with the occupancy of multiple glacial refugia during the Late Wisconsin glaciation. Eastern wood ducks are characterized by high genetic diversity, a large effective population size, and a recent population expansion, while western wood ducks have much less genetic diversity, a smaller population size, and have not undergone a recent population expansion.     

Chloroplast DNA phylogeography of the arctic-montane species Saxifraga hirculus (Saxifragaceae)

The genetic structure of populations of an arctic-montane herb, Saxifraga hirculus (Saxifragaceae), was analysed by means of chloroplast restriction fragment-length polymorphism. Sampled populations were distributed across Europe and North America (Alaska and Colorado). There was no evidence for geographically structured genetically divergent lineages, and although no haplotypes were shared between North America and Europe, the haplotypes from different continents were intermixed on a minimum spanning tree. European populations were much more highly differentiated and had much lower levels of haplotype diversity than their Alaskan counterparts. Centres of haplotype diversity were concentrated in those Alaskan populations located outside the limits of the last (Wisconsin) glaciation, suggesting that they may have acted as refugia during the Pleistocene. It was not possible to identify putative migration routes or corresponding refugia in the European genepool. One British population, from the Pentland Hills, was genetically very distant from all the others, for reasons that are as yet unknown.     

Patterns in the species composition of fish assemblages among Wisconsin streams

Synopsis To better understand patterns of fish assemblage composition in Wisconsin streams in relation to major environmental gradients, I carried out multivariate direct gradient analysis (canonical correspondence analysis) of two large independent datasets on fish species abundance in Wisconsin streams. Analysis of the two datasets yielded similar results, suggesting that observed patterns and relationships were real. Stream sites were distributed along fish species-environment gradients, but segregation into distinct stream temperature and geographic groups was also evident. The strongest gradient in both datasets was related to summer water temperature patterns, and encompassed a transition from small, coldwater streams dominated by salmonids, cottids, certain cyprinids, and few other species, to both small and large, warmwater streams dominated by a high diversity of different cyprinids, catostomids, ictalurids, centrarchids, and percids. A second gradient in both datasets was complex but largely geographic. Within it, sites from each of the four ecoregions that occupy Wisconsin formed fairly discrete groups. The strongest differences were between sites in the two southern Wisconsin ecoregions, the Driftless Area and the Southeastern Wisconsin Till Plains, that were dominated by certain cyprinids, ictalurids, and centrarchids, and sites in the two northern Wisconsin ecoregions, the North Central Hardwood Forests and the Northern Lakes and Forests, that were dominated by a different set of cyprinids and ictalurids, plus some petromyzontids, salmonids, catostomids, and percids. Sites from the Driftless Area that were mostly higher-gradient (steep stream slope) and had many riffle-dwelling species could also be distinguished from sites in the Southeastern Wisconsin Till Plains that were mostly lower-gradient and had many pool-dwelling species. The patterns of fish assemblage composition among sites and the associated fish species-environment relationships that were revealed by the analyses provided a framework for developing an ecologically meaningful hierarchical classification of Wisconsin stream sites based on stream thermal regime, ecoregion, stream size, and stream gradient.     

Hematozoa of wild turkeys from the midwestern United States: translocation of wild turkeys and its potential role in the introduction of Plasmodium kempi

Twenty-three of 310 blood samples taken from live-trapped eastern wild turkeys (Meleagris gallopavo silvestris) from Missouri (USA), and hunter-killed birds from Wisconsin, North Dakota and Minnesota (USA), and inoculated into domestic broad-breasted-white turkey poults were positive for two species of Plasmodium. Twenty-one of the positive samples were infected with P. (Novyella) kempi, and two samples from Wisconsin were infected with P. (Giovannolaia) lophurae. Twenty percent of 310 blood smears were positive for Haemoproteus melagridis, while only 3% were infected with Leucocytozoon smithi. A statistically higher prevalence of Plasmodium spp. from 1983 to 1984 was observed in Wisconsin, and in the samples from Minnesota when compared with both Missouri and Wisconsin. Turkeys from Wisconsin and Minnesota had both a statistically higher prevalence and mean intensity of H. meleagridis than birds from Missouri. Evidence indicates that P. kempi has been introduced into other states along with the vertebrate hosts. It is suggested that greater care should be exercised when translocated wild turkeys are introduced into areas where there are other endangered or threatened avian species.     

Long-distance dispersal of the gypsy moth (Lepidoptera: Lymantriidae) facilitated its initial invasion of Wisconsin

Gypsy moth (Lymantria dispar L.) spread is dominated by stratified dispersal, and, although spread rates are variable in space and time, the gypsy moth has invaded Wisconsin at a consistently higher rate than in other regions. Allee effects, which act on low-density populations ahead of the moving population that contribute to gypsy moth spread, have also been observed to be consistently weaker in Wisconsin. Because a major cause of an Allee effect in the gypsy moth is mate-finding failure at low densities, supplementing low-density populations with immigrants that arrive through dispersal may facilitate establishment and consequent spread. We used local indicator of spatial autocorrelation methods to examine space-time gypsy moth monitoring data from 1996 to 2006 and identify isolated, low-density colonies that arrived through dispersal. We measured the distance of these colonies from the moving population front to show that long-distance dispersal was markedly present in earlier years when Wisconsin was still mainly uninfested. Recently, however, immigrants arriving through long-distance dispersal may no longer be detected because instead of invading uninfested areas, they are now supplementing high-density colonies. In contrast, we observed no temporal pattern in the distance between low-density colonies and the population front in West Virginia and Virginia. We submit that long-distance dispersal, perhaps facilitated through meteorological mechanisms, played an important role in the spread dynamics of the initial Wisconsin gypsy moth invasion, but it currently plays a lesser role because the portion of Wisconsin most susceptible to long-distance immigrants from alternate sources is now heavily infested.     

Uptake of phenylacetic acid by two strains of Penicillium chrysogenum

Uptake of phenylacetic acid, the side-chain precursor of benzylpenicillin, was studied in Penicillium chrysogenum Wisconsin 54-1255 and in a strain yielding high levels of penicillin. In penicillin fermentations with the high-yielding strain, 100% recovery of phenylacetic acid in benzylpenicillin was found, whereas in the Wisconsin strain only 17% of the supplied phenylacetic acid was incorporated into benzylpenicillin while the rest was metabolized. Accumulation of total phenylacetic acid-derived carbon in the cells was nonsaturable in both strains at high external concentrations of phenylacetic acid (250-3500 microM), and in the high-yielding strain at low phenylacetic acid concentrations (2. 8-100 microM), indicating that phenylacetic acid enters the cells by simple diffusion, as concluded earlier for P. chrysogenum by other authors. However, at low external concentrations of phenylacetic acid saturable accumulation appeared in the Wisconsin strain. HPLC-analyses of cell extracts from the Wisconsin strain showed that phenylacetic acid was metabolized immediately after entry into the cells and different [14C]-labeled metabolites were detected in the cells. Up to approximately 50% of the accumulated phenylacetic acid was metabolized during the transport-assay period, the conversion having an impact on the uptake experiments. Nevertheless, accumulation of free unchanged phenylacetic acid in the cells showed saturation kinetics, suggesting the possible involvement of a high-affinity carrier in uptake of phenylacetic acid in P. chrysogenum Wisconsin 54-1255. At high concentrations of phenylacetic acid, contribution to uptake by this carrier is minor in comparison to simple diffusion and therefore, of no importance in the industrial production of penicillin.     

Response of stomatal resistance and photosynthesis to night temperature in Populus deltoides

Summary Ramets from stem cuttings of three populations of Populus deltoides Bartr. from Wisconsin, Illinois, and Louisiana representing a latitudinal gradient were grown in pots outdoors at Urbana, Illinois and brought indoors for growth chamber studies. Leaf resistance and photosynthetic response to low night temperatures of 4° and 10° C were determined relative to 20° C controls for plants measured over one growing season. Plants from Louisiana, where nights are warm, reacted to cool nights of 4° and 10° C by opening their stomata slower upon illumination the following day than those from farther north where nights are cooler. The optimum night temperature for rate of opening was lower in the Wisconsin population than in populations from farther south. The Wisconsin population showed more ideal homeostasis of photosynthesis at different temperatures than the southern population which exhibited greater plasticity. No seasonal differences in these relationships were apparent other than at the time of leaf senescence.As plants approached senescence, which occurred earliest in the Wisconsin population, leaf resistance increased and photosynthesis declined, but stomata still retained their functional ability to respond to changes in night temperature. The change in leaf resistance, noted in the Wisconsin population, was related more to closure of lower-leaf surface stomata than upper. Only the Louisiana population had significantly more stomata on the lower than upper leaf surface.     

Tissue Culture of Cassava on Chemically Defined Media

Defined media that promote the initiation and undifferentiated growth of callus derived from stem explants of four cultivars of cassava, Manihot esculenta Crantz, are described. Growth rates and yields of cassava callus after 4 weeks of culture are shown to be comparable to those of callus of Nicotiana tabacum L. cv. Wisconsin No. 38. Nitrogen sources of ammonium nitrate or of ammonium chloride plus succinate supported growth of all four cultivars. Sucrose was superior to glucose as a carbon source. The cassava cultivars differed in their response to increasing concentrations of sucrose between 0.5% (w/v) and 3%, two of them increasing in dry matter with increasing sucrose concentrations of up to 3%. When cultured in the light on defined media that contained higher ratios of cytokinin to auxin, callus of the latter two cultivars turned green. Roots but not shoots differentiated from the callus of all cultivars. The influence of hormone concentrations, sucrose level, and nitrogen source on greening and root formation is summarized.     

Effect of the fumigant dazomet on the development of mycorrhizae and growth of nursery stock

Summary The harmful effect of the fumigant Dazomet (DMTT, Mylone 50 D) on the development of mycorrhiza-forming fungi and accompanying growth of nursery stock is usually due to an inadequate pre-seeding detoxification period and/or a prolonged occurrence during this period of temperatures below 10°C. The eradication of the symbionts is occasionally caused by the lateral movement of water causing local high concentrations of the toxic chemical. A low supply of soil organic matter greatly aggravates the vulnerability of the mycorrhiza-formers to damages by the eradicant. During the past many years, a critical demycorrhization of stock in Wisconsin nurseries was observed predominantly in soils with organic matter content of less than 1.5% in the 15-cm surface layer.Research supported by the College of Agricultural and Life Sciences, Univ. of Wisconsin, Madison, and the Wisconsin in Department of Natural Resources.     

Survival of Adult Martens in Northern Wisconsin

Abstract: Low adult marten (Martes americana) survival may be one factor limiting their population growth >30 yr after their reintroduction in Wisconsin, USA. We estimated annual adult marten survival at 0.81 in northern Wisconsin, with lower survival during winter (0.87) than summer-fall (1.00). Fisher (Martes pennanti) and raptor kills were infrequent, and each reduced marten adult annual survival <10%. Annual adult survival was similar to or higher than survival in other areas, suggesting that it was not unusually low and therefore did not limit recovery of marten populations in northern Wisconsin. We captured few juvenile martens, suggesting low reproduction or reduced juvenile survival.     

Monokaryotic fruiting in Schizophyllum commune: Genetic control of the response to mechanical injury

Summary Monokaryotic fruiting is used as a tool to study mushroom development and differentiation in Schizophyllum commune. This paper reports data which further elucidate the genetic control of the monokaryotic fruiting response to mechanical injury. Models relating the various genes implicated in monokaryotic fruiting body production are proposed and evaluated on their ability to explain the observed data. A minimum estimate is made of the number of genes involved in the initiation of monokaryotic fruiting in response to mechanical injury.Paper # 2260 from the Laboratory of Genetics, University of Wisconsin, Madison. Wisconsin 53706, USASupported in part by the College of Agriculture and Life Sciences, University of Wisconsin and by NIH Predoctoral Training Grant # GM 07133 to the Laboratory of Genetics, University of Wisconsin     

Hybridization among divergent stocks of largemouth bass (Micropterus salmoides) results in altered cardiovascular performance: the influence of genetic and geographic distance

Animal populations exhibit wide ranges of divergence associated with both geographic and genetic distances. Here, we examined the role of crossing distance on the cardiovascular response to exhaustive exercise among differentiated stocks of largemouth bass Micropterus salmoides at 10 degrees C and 20 degrees C. Stocks of 2+ fish were produced using adults from three regions in the midwestern United States (southeastern Wisconsin, northwestern Wisconsin, and west central Minnesota) and were crossed with fish from central Illinois. Doppler flow probes were used to quantify cardiac output, heart rate, and stroke volume. Cardiac variables (both resting and maximal) were consistently lowest in pure Illinois fish relative to the F(1) interstock hybrids. Additionally, when exposed to exercise, cardiac variables for F(1) interstock hybrids required approximately 40% longer to return to resting levels compared with the pure Illinois stock. However, the time required to exhaust fish was similar across stocks. Interestingly, all of the stocks (including the interstock hybrids and pure Illinois) maintained cardiac scope. In general, the patterns observed in cardiovascular performance were consistent for both water temperatures. Multiple regression analysis was used to determine which of the divergence metrics contributed to variation in cardiovascular performance in interstock hybrids. Mitochondrial DNA data (genetic distance) were infrequently identified as a significant source of variation in cardiovascular performance. However, genetic distance data for the neutral allozyme markers revealed that these stocks have experienced significant divergence. Latitude (geographic distance) accounted for between 31% and 45% of variation observed in the recovery parameters. This study suggests that the magnitude of stock divergence is an important determinant in the degree to which cardiovascular performance of bass is altered from interstock hybridization and associated breakdown of coadapted gene complexes. Furthermore, these data suggest that translocating bass among even geographically discrete regions or among stocks with reasonable genetic similarity can result in substantial performance alterations at the F(1) generation.     

Trace fossils of Cambrian aglaspidid arthropods

A new trace fossil, Raaschichnus gundersoni , from the Upper Cambrian St. Lawrence Formation of Wisconsin, was produced by an aglaspidid arthropod. The rusophyciform trace, which occurs singly and in series, is distinctive in showing marks left by the tail-spine. Other trace fossils previously considered to have been made by aglaspidids were probably excavated by animals lacking a tail-spine and with appendage morphologies very different from the aglaspidids of Wisconsin.     

Determination of major ginsenosides in Panax quinquefolius (American ginseng) using high-performance liquid chromatography

In order to determine the active ingredients in root extracts of Panax quinquefolius (American ginseng), a gradient HPLC method involving UV photodiode array detection was applied to separate and quantify simultaneously the ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf and Rg1. All ginseng saponins were baseline-resolved under the selected conditions, and the detection limits were 1.0 microg/mL or less. The method has been applied to analyse ginsenosides extracted from American ginseng cultivated in both Wisconsin and Illinois. Ginsenosides Re and Rb1 were the two main ginseng saponins in the root. The amounts of Re in 5- and 7-year Illinois-cultivated samples were greater than those found in ginseng cultivated for 3 or 4 years in Wisconsin, whereas the levels of Rb1 were greater in the younger Wisconsin samples.     

Effect of the differentiated or dedifferentiated state of tobacco pith tissue on its behaviour after inoculation with Agrobacterium rhizogenes

The ability of Nicotiana tabacum (cv. Wisconsin 38) pith tissue to give rise to transformed roots after inoculation with Agrobacterium rhizogenes (agropine type strain 1855) has been examined in relation to its state of differentiation. In young plants, all the stem tissues are able to initiate transformed roots while pith of adult plants does not react. Mature pith, composed mostly of polyploid and non-dividing cells, is able to recover susceptibility when placed in vitro on a medium containing auxin and kinetin. The optimal production of transformed roots is obtained after 6–10 days, when proliferating cells redifferentiated cambial-like layers and tracheids. The relationships between the inability of fully differentiated pith to give rise to roots and the underlying cell states are discussed.     

Corky Root of Lettuce Caused by Strains of a Gram-Negative Bacterium from Muck Soils of Florida, New York, and Wisconsin

Slow-growing bacteria similar to the bacterium causing lettuce corky root (CR) in California (strain CA1) were isolated from muck soils of Florida, New York, and Wisconsin, using lettuce seedlings as bait. All strains were tested for reaction with polyclonal antibodies produced against strain CA1 and for pathogenicity on CR-susceptible (Salinas) and CR-resistant (Green Lake) lettuce cultivars in a greenhouse. Five strains from Florida, three from New York, and three from Wisconsin induced severe CR symptoms on Salinas and mild symptoms on Green Lake. All strains were gram-negative, aerobic, oxidase positive, and catalase positive and reduced nitrate to ammonia. Whole-cell fatty acid compositions were similar for all strains and resembled that of Pseudomonas paucimobilis. Since this fatty acid pattern is unique, it is suggested that CR of lettuce is caused by strains of the same bacterium in Florida, New York, Wisconsin, and California.     

Serologic evidence of arboviral infections in white-tailed deer from central Wisconsin

A survey conducted during 1979-1980 on white-tailed deer (Odocoileus virginianus) in central Wisconsin revealed serological evidence of infection by selected arboviruses. Among sera from 41 deer, antibody was detected for Jamestown Canyon virus (56%) and Bunyamwera group virus (80%), demonstrating their continuing endemic activity. Antibody for La Crosse virus, not found previously in sera from deer in central Wisconsin, also was detected (5%) in this study.