Susie M. Dunham

Patterns of vegetative growth and gene flow in Rhizopogon vinicolor and R. vesiculosus (Boletales, Basidiomycota)

We have collected sporocarps and tuberculate ectomycorrhizae of both Rhizopogon vinicolor and Rhizopogon vesiculosus from three 50 × 100 m plots located at Marys Peak in the Oregon Coast Range (USA); linear map distances between plots ranged from c. 1 km to c. 5.5 km. Six and seven previously developed microsatellite markers were used to map the approximate size and distribution of R. vinicolor and R. vesiculosus genets, respectively. Genetic structure within plots was analysed using spatial autocorrelation analyses. No significant clustering of similar genotypes was detected in either species when redundant samples from the same genets were culled from the data sets. In contrast, strong clustering was detected in R. vesiculosus when all samples were analysed, but not in R. vinicolor. These results demonstrate that isolation by distance does not occur in either species at the intraplot sampling scale and that clonal propagation (vegetative growth) is significantly more prevalent in R. vesiculosus than in R. vinicolor. Significant genetic differentiation was detected between some of the plots and appeared greater in the more clonal species R. vesiculosus with ΦST values ranging from 0.010 to 0.078*** than in R. vinicolor with ΦST values ranging from −0.002 to 0.022** (*P < 0.05, **P < 0.01, ***P < 0.001). When tested against the null hypothesis of no relationship between individuals, parentage analysis detected seven likely parent/offspring pairs in R. vinicolor and four in R. vesiculosus (α = 0.001). Of these 11 possible parent/offspring pairs, only two R. vinicolor pairs were still supported as parent/offspring when tested against the alternative hypothesis of being full siblings (α = 0.05). In the latter two cases, parent and offspring were located at approximately 45 m and 28 m from each other. Challenges to parentage analysis in ectomycorrhizal fungi are discussed.

Molecular analysis of bacterial communities associated with the roots of Douglas fir (Pseudotsuga menziesii) colonized by different ectomycorrhizal fungi

We studied the effect of ectomycorrhizal fungi on bacterial communities colonizing roots of Douglas fir (Pseudotsuga menziesii). Mycorrhizal tips were cleaned of soil and separated based on gross morphological characteristics. Sequencing of the internal transcribed spacers of the nuclear rRNA gene cluster indicated that the majority of the tips were colonized by fungi in the Russulaceae, with the genera Russula and Lactarius comprising 70% of the tips. Because coamplification of organellar 16S rRNA genes can interfere with bacterial community analysis of root tips, we developed and tested a new primer pair that permits amplification of bacterial 16S rRNA genes but discriminates more effectively against organellar sequences than commonly used bacterial primer sets. We then used terminal restriction fragment length polymorphism (T-RFLP) and sequence analysis of the 16S rRNA gene to examine differences in bacterial communities associated with the mycorrhizal tips. Cluster analysis of T-RFLP profiles indicated that there were different bacterial communities among the root tips; however, the communities did not seem to be affected by the taxonomic identity of the ectomycorrhizal fungi. Terminal restriction fragment profiling and sequencing of cloned partial 16S rRNA genes indicated that most bacteria on the ectomycorrhizal tips were related to the Alphaproteobacteria and the Bacteroidetes group.

Analysis of nrDNA sequences and microsatellite allele frequencies reveals a cryptic chanterelle species Cantharellus cascadensis sp. nov. from the American Pacific Northwest

In the Pacific Northwest, yellow chanterelles have long been referred to as Cantharellus cibarius, synonymous with the European yellow chanterelle. Broad scale genetic surveys of North American chanterelles with C. cibarius-like morphology have demonstrated that the nrDNA internal transcribed spacer exhibits length variability, suggesting that this common morphology masks a species complex. Recently researchers have used morphological and genetic data to identify the yellow chanterelle most frequently harvested from American Pacific Northwest forests as C. formosus, a species once thought to be rare in the region. We present three genetic data sets and one morphological data set that characterize a previously undescribed, species of yellow chanterelle from the central Cascade Mountains of Oregon. Phylogenetic analyses of the nrDNA large subunit and ITS regions show that C. cascadensis sp. nov., along with two other yellow chanterelle taxa (C. cibarius var. roseocanus and European C. cibarius), are more closely related to white chanterelles (C. subalbidus) than they are to C. formosus. Data from five microsatellite loci provide evidence that C. formosus, C. subalbidus, and C. cascadensis sp. nov. do not interbreed when they co-occur spatially and temporally in Douglas fir-western hemlock forests. This demonstrates that these three sympatric chanterelles are biological species with boundaries congruent with those delineated by nrDNA phylogenetic clades. Morphological data indicate that the colour of the pileus and shape of the stipe can be used to separate fresh collections of the two yellow species now known to co-occur in Douglas fir-western hemlock forests in Oregon.

Species richness and community composition of mat-forming ectomycorrhizal fungi in old- and second-growth Douglas-fir forests of the HJ Andrews Experimental Forest, Oregon, USA

We investigated the species identity of mat-forming ectomycorrhizal (EM) fungi associated with old- and second-growth Douglas-fir stands. Using molecular analyses of rhizomorphs and EM root tips, we characterized 28 unique internal transcribed spacer sequences and considered them proxies for mat-forming EM species. In both stand age classes, one Athelioid species in the genus Piloderma dominated our sample of the mat-forming fungal community. In second-growth stands, the second most frequently encountered mat-forming EM species belonged to the genus Hysterangium. In old-growth stands, several Ramaria species were associated with a frequently encountered mat morphology but no species dominated the community. After using rarefaction analysis to standardize sampling effort, the total species richness did not differ statistically between old- and second-growth habitats. Both an abundance of infrequently encountered species and incomplete sampling of the mat-forming EM community may have limited our ability to detect potential differences in species richness. Several frequently encountered Piloderma species appear to have broad (holarctic) distributions and diverse host associations and their potential importance in forest ecosystems warrants further study.

A Review of Urban Water Body Challenges and Approaches: (1) Rehabilitation and Remediation

AbstractWe review how urbanization alters aquatic ecosystems, as well as actions that managers can take to remediate urban waters. Urbanization affects streams by fundamentally altering longitudinal and lateral processes that in turn alter hydrology, habitat, and water chemistry; these effects create physical and chemical stressors that in turn affect the biota. Urban streams often suffer from multiple stressor effects that have collectively been termed an “urban stream syndrome,” in which no single factor dominates degraded conditions. Resource managers have multiple ways of combating the urban stream syndrome. These approaches range from whole-watershed protection to reach-scale habitat rehabilitation, but the prescription must be matched to the scale of the factors that are causing the problem, and results will likely not be immediate because of lengthy recovery times. Although pristine or reference conditions are far from attainable, urban stream rehabilitation is a worthy goal because appropriate act...

Spatial analysis of within-population microsatellite variability reveals restricted gene flow in the Pacific golden chanterelle (Cantharellus formosus)

We examined the within-population genetic structure of the Pacific golden chanterelle (Cantharellus formosus) in a 50 y old forest stand dominated by Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga heterophylla) with spatial autocorrelation analysis. We tested the null hypothesis that multilocus genotypes possessed by chanterelle genets were randomly distributed within the study area. Fruit bodies from 203 C. formosus genets were collected from a 50 ha study plot. One hundred six unique multilocus genotypes were identified after scoring these collections at five microsatellite loci. Statistically significant positive spatial autocorrelation was detected indicating the presence of fine-scale genetic structure within the area. Repeated autocorrelation analyses with varied minimum distance classes (50–500 m) detected positive spatial genetic structure up to 400 m. Therefore nonrandom evolutionary processes (e.g., isolation by distance) can cause fine-scale genetic structure in C. formosus. The implications of this research for future broad-scale population studies of this species are that population samples should be separated by at least 400 m to be considered statistically independent. Sampling designs that account for fine-scale genetic structure will better characterize heterogeneity distributed across the landscape by avoiding the effects of pseudo replication.

A New, Commercially Valuable Chanterelle Species, Cantharellus californicus sp. nov., Associated with Live Oak in California, USA

A New, Commercially Valuable Chanterelle Species, Cantharellus californicus sp. nov., Associated with Live Oak in California, USA. The prominent golden chanterelle of California’s oak woodlands is characterized as a new species, Cantharellus californicus sp. nov., using molecular and morphological data. Our observations indicate that it is the largest Cantharellus species in the world, with individual sporocraps commonly weighing 1/2 kilogram (kg) (or 1 pound) or more when mature. Other Cantharellus species in California are compared and evaluated, including their known ectomycorrhizal hosts. The California oak chanterelle is an economically valuable species, and some observations on its commercial harvest are presented.

DNA studies in the Galerina marginata complex

The distinctiveness of the European Galerina marginata and the American G. autumnalis is tested with analyses of DNA sequences from the internal transcribed spacer (ITS-2) of the nuclear ribosomal repeat and RFLP analysis of the entire ITS region. European and North American material from six taxa described in Galerina subgenus Naucoriopsis are included along with out-group material of six taxa representing two other subgenera of Galerina. The results do not indicate any genetic difference between species by Smith & Singer (1964) referred to the two ‘stirpes’ Marginata and Autumnalis of Naucoriopsis , i.e. G. autumnalis, G. marginata, G. oregonensis, G. pseudomycenopsis, G. unicolor , and G. venenata and all except G. pseudomycenopsis are considered later synonyms of G. marginata. Galerina badipes (syn. G. cedretorum var. bispora of ‘stirps’ Cedretorum is well supported as a distinct species. Subgenus Naucoriopsis appears as a distinct infrageneric unit well separated from the infrageneric units represented by the out-group species.

Within-population genetic structure differs between two sympatric sister-species of ectomycorrhizal fungi, Rhizopogon vinicolor and R. vesiculosus

Using spatial autocorrelation analysis, we examined the within-population genetic structure of Rhizopogon vinicolor and R. vesiculosus, two hypogeous ectomycorrhizal (EM) species that are sympatric sister taxa known to differ in their clonal structure. We collected 121 sporocarps and 482 tuberculate EM of both species from a 20 ha forest stand dominated by Douglas-fir (Pseudotsuga menziesii). Field collections were identified to species with restriction fragment length polymorphism analysis of the nuclear ribosomal internal transcribed spacer. Five and six microsatellite markers were used to characterize the genetic diversity of EM and sporocarp samples from R. vesiculosus and R. vinicolor respectively. After correcting for genet structure, spatial autocorrelation analyses of the EM samples were used to test the null hypothesis that multilocus genotypes characterized from each species were randomly distributed within the study area. We detected positive and statistically significant fine-scale genetic structure up to 120 m within the R. vesiculosus sample. In contrast, no spatial genetic structure was evident for R. vinicolor, indicating that the genotypes characterized for this species were randomly distributed throughout the study area. Differences in statistical power or the nuclear count of basidiospores are unlikely agents of the genetic patterns observed. Our results suggest that differences in reproductive output or competitive ability may act individually or in combination to create clusters of similar genotypes for R. vesiculosus throughout the study area.

A Review of Urban Water Body Challenges and Approaches: (2) Mitigating Effects of Future Urbanization

AbstractPreviously we examined how degraded urban streams can be rehabilitated, with emphasis on identifying solutions that match the scale of the problems (Hughes et al. 2014). Our findings showed that rehabilitation techniques are challenging but that some environmental benefits can nearly always be obtained regardless of existing conditions. Although rehabilitation is useful in many present-day situations, biologists need to consider the future and think about ways of preventing or reducing future environmental damage. We need to reduce future damage because urban areas are likely to expand greatly over the next century; if historical patterns continue, the number and length of streams experiencing urban stream syndrome will increase, with resulting high repair costs. However, there are several ways of avoiding or mitigating damage that are not only cost effective but provide benefits to humans and urban ecosystems.