The Vegetation of the Paleozoic Plateau, Northeastern Iowa

The present vegetation of the Paleozoic Plateau region of Iowa is a fragmented representation of the original complex of oak-hickory forest mixed with more mesophytic forest, open oak savanna and hill prairie. Because of the topographic variation and the relatively cool, moist environment of the region, the forests are the best developed of those in Iowa, and show the greatest variation, including two types of alluvial forests (Salix thickets and alluvial hardwood forest), and several kinds of upland forests (Tilia, Acer, Quercus borealis, Q, alba and Pinus forests). These types represent points along a more-or-less continuous topographic gradient. Many of the native oak savannas have been eliminated, but oak-juniper glades may be found on cliff faces and steep ridges. The remaining hill prairies are rich in species characteristic of the dry prairies farther to the west. Cold, north-facing slopes ( algific slopes ) are the setting for a unique community containing a large number of rare and disjunct species. Outcrops of sandstones and limestone have characteristic microcommunities, often distinguished by their bryophyte or pteridophyte flora. There is a dearth of quantitative vegetation data from the region, and there are numerous research questions about the communities and their plant species that need answers. Preservation and conservation of plant communities and plant species are extremely important and should be addressed by a landscape approach to inventory and management

Population genetics of hydrophilous angiosperms

Comparisons between genetic variation and life history and ecological characteristics have been produced for over 400 plant species since the advent of starch gel electrophoresis. Knowledge of how aquatic life histories relate to population genetic structure is lacking, however. Four hydrophilous species - Zostera marina L., Vallisneria americana Michx., Ceratophyllum demersum L., and Ceratophyllum echinatum Gray - have been studied using allozyme estimates of variation within and among populations. At the species level, the percent of polymorphic loci is equal to, or higher than, the average reported for all plant species. At the population level, however, hydrophilous taxa have lower percent of polymorphic loci, fewer alleles per locus, and lower levels of heterozygosity than non-hydrophiles. Except for Z. marina, hydrophilous species show much greater partitioning of variation among populations than non-hydrophiles, particularly when compared with anemophilous species. Explanations for these patterns include limited sexuality (Ceratophyllum), extensive clonal spread (all four species), and the greater isolation of freshwater populations (lakes as islands) relative to most terrestrial species and to coastal species such as Z. marina

Population genetics of the invasive shrub multiflora rose (Rosa multiflora Thunb.) in northeastern Ohio

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Ectomycorrhizal fungal diversity interacts with soil nutrients to predict plant growth despite weak plant-soil feedbacks

Background and aims: Plant-soil feedbacks are the result of multiple abiotic and biotic mechanisms. However, few studies have addressed how feedbacks vary based on abiotic context or attempted to identify microbiota responsible for feedbacks. We investigated whether plant-soil feedbacks of an ectomycorrhizal tree (Quercus macrocarpa) varied based on soil nutrient status and whether fungal community composition and diversity could explain feedback patterns. Methods: We inoculatedQ. macrocarpaseedlings with field-sampled soils taken from five soil origins - including heterospecific and conspecific trees and an old field - which were profiled using fungal DNA metabarcoding. Results: There was a positive home vs. away plant-soil feedback, though feedbacks with individual hosts were not significant regardless of fertilization. Still, hosts harbored distinctive fungal communities that were predictive of plant growth. There was a growth promotive effect of ectomycorrhizal OTU diversity that was weakened with fertilization, suggesting context-dependent relationships between plant growth and a guild of fungal mutualists. Conclusions: Our results demonstrate that the host-specific accumulation of functionally important soil microbes is not always sufficient to drive species level plant-soil feedbacks. Our data provide support for a role of ECM fungal diversity in mediating plant growth responses, though it is unclear whether this effect was direct or indirect

Electrophoretic Evidence for Tetrasomic Inheritance in the Dioecious Tree Maclura pomifera (Raf.) Schneid

Although polyploidy is recognized as an important feature of chromosomal evolution, natural autopolyploids rarely occur compared to allopolyploids. Enzymes coded by four electrophoretic loci ( Lap, Pgm-1, Pgi-2, and Tpi-2 ) in adults and full-sib progenty indicate tetrasomic inheritance in the dioecious tree Macura pomifera , strongly suggesting that this species is an autopolyploid. This study is the first to document tetrasomic inheritance in a dioecious tree. Five of 19 segregation arrays deviated significantly from expected tetrasomic ratios, whereas 11 of 19 deviated significantly from digenic disomic expectations. We observed 22 double-reduction genotypes, which provides a likely source of devistion from expected tetrasomic frequencies. We suggets that unusual patterns of sexual expression in this species are related to autopolypliody through production of unbalanced sex chromosome ratios

Comparative genetic structure of two co-occurring tree species, Maclura pomifera (Moraceae) and Gleditsia triacanthos (Leguminosae)

Maclura pomifera, an autotetraploid, and Gleditsia triacanthos, a diploid, are ecologically similar dioecious tree species that often co-occur in early successional habitats throughout the mid-western United States. We studied levels of genetic diversity and patterns of genetic structure for four polymorphic enzyme loci of M. pomifera and 16 polymorphic enzyme loci of G. triacanthos from a single population in eastern Kansas. Levels of expected heterozygosity were high for both species, averaging 0.725 for M. pomifera and 0.366 for G. triacanthos. Although genotypes for nearly all G. triacanthos loci were in Hardy-Weinberg frequencies, three of four M. pomifera loci deviated from equilibrium expectations. Two aspects of genetic structure were explored. First, the extent of clonal growth was estimated by comparing genotypes of stems within 50 G. triacanthos and 32 M. pomifera clumps. The great majority of clumps contained more than one genotype, and in many clumps, all stems were genetically unique. Secondly, as revealed by spatial autocorrelation analyses, genetic substructure was very local for both species, with significant positive autocorrelation occurring only within clumps of individuals or among near neighbours. We argue that this pattern of spatial structure for both species results from extremely local seed dispersal and establishment of individuals from the same multiseeded fruit

Evidence for multiple paternity in two species of Orconectes crayfish

Multiple mating is expected to be common in organisms that produce large clutches as a mechanism by which sexual reproduction can enrich genetic variation. For freshwater crayfish, observation of multiple mating suggests the potential for high rates of multiple paternity, but genetic confirmation is largely lacking from natural populations. We studied paternity within wild-caught broods of two crayfish species in the genus Orconectes (Sanborn\u27s crayfish ( Orconectes sanbornii (Faxon, 1884)) and the Allegheny crayfish ( Orconectes obscurus (Hagen, 1870))). Although females have been observed mating with multiple males, this is the first genetic confirmation of multiple paternity in broods of these two species. Berried females were collected in the field and maintained in aquaria until their eggs hatched. We amplified and genotyped extracted DNA from maternal and hatchling tissue for several microsatellite loci. For both species, paternity reconstruction (GERUD 2.0) yielded 2-3 sires per brood and no single paternity clutches. We discuss these results from natural populations in light of the body of work on reproductive ecology of decapod crustaceans and in the context of changes in life history following the transition from marine to freshwater habitats

Hybridization between an invasive and a native species of the crayfish genus Orconectes in north-central Ohio

Hybridization between native and invasive species is an important but little-studied factor in crayfish invasions, with few documented natural cases. Here, we report genetic evidence of hybridization between invasive O. rusticus (Girard, 1852) and native O. sanbornii (Girard, 1852) in the Huron River in north-central Ohio based on a combination of molecular markers: nuclear DNA, mitochondrial DNA, and allozymes. Although we found no fixed differences between the species at nuclear DNA loci, fixed differences in mtDNA and allozyme loci confirmed the presence of individuals of hybrid ancestry. We also found preliminary evidence of possible mitochondrial recombination and biparental inheritance (though the existence of rare haplotypes cannot be excluded at the present time). We examined morphological features of both species in sympatry and allopatry and confirmed species-diagnostic morphological features including gonopod traits and shape of the annulus ventralis. This study is the second to detect hybridization between O. rusticus and a congener, which suggests that this may be an important mechanism of invasion by O. rusticus when closely related species are present. Further study of this system, including more extensive sampling and additional molecular markers, is necessary to understand the extent and implications of hybridization for the native species