Cultivation and antibiotic activity of mycorrhizal basidiomycetes

In 17 species (35 strains) of basidiomycetes which form mycorrhizas with Scotch pine (Pinus silvestris L.) the influence of media and method of cultivation on growth and manifestation of antibiotic activity were investigated under laboratory conditions. The antibiotic activity was influenced by the composition of the nutrient media as well as by mode of cultivation, while the ability and intensity of growth depended first of all on the composition of the media.Amanita citrina, Clitopilus prunulus, Lactarius helvus, Rhizopogon roseolus, Russula fragilis, Tricholoma albobrunneum, Tricholoma imbricatum, andTricholoma saponaceum exhibited antibiotic activity. The intracellular antibiotics ofTricholoma saponaceum andRhizopogon roseolus exerted the highest activity. It has been confirmed that the antibiotic activity of the cultures corresponds in most cases to the activity of the fruit-bodies grown in nature.     

Vertical partitioning between sister species of Rhizopogon fungi on mesic and xeric sites in an interior Douglas‐fir forest

Understanding ectomycorrhizal fungal (EMF) community structure is limited by a lack of taxonomic resolution and autecological information. Rhizopogon vesiculosus and Rhizopogon vinicolor (Basidiomycota) are morphologically and genetically related species. They are dominant members of interior Douglas‐fir (Pseudotsuga menziesii var. glauca) EMF communities, but mechanisms leading to their coexistence are unknown. We investigated the microsite associations and foraging strategy of individual R. vesiculosus and R. vinicolor genets. Mycelia spatial patterns, pervasiveness and root colonization patterns of fungal genets were compared between Rhizopogon species and between xeric and mesic soil moisture regimes. Rhizopogon spp. mycelia were systematically excavated from the soil and identified using microsatellite DNA markers. Rhizopogon vesiculosus mycelia occurred at greater depth, were more spatially pervasive, and colonized more tree roots than R. vinicolor mycelia. Both species were frequently encountered in organic layers and between the interface of organic and mineral horizons. They were particularly abundant within microsites associated with soil moisture retention. The occurrence of R. vesiculosus shifted in the presence of R. vinicolor towards mineral soil horizons, where R. vinicolor was mostly absent. This suggests that competition and foraging strategy may contribute towards the vertical partitioning observed between these species. Rhizopogon vesiculosus and R. vinicolor mycelia systems occurred at greater mean depths and were more pervasive in mesic plots compared with xeric plots. The spatial continuity and number of trees colonized by genets of each species did not significantly differ between soil moisture regimes.     

Allelopathic invasive tree (<Emphasis Type="Italic">Rhamnus cathartica</Emphasis>) alters native plant communities

Many plants release allelopathic chemicals that can inhibit germination, growth, and/or survival in neighboring plants. These impacts appear magnified with the invasion of some non-native plants which may produce allelochemicals against which native fauna have not co-evolved resistance. Our objective was to examine the potential allelopathic impact of an invasive non-native shrub/tree on multiple plant species using field observation and experimental allelopathy studies. We surveyed and collected an invasive, non-native tree/shrub (Rhamnus cathartica) at Tifft Nature Preserve (a 107-ha urban natural area near Lake Erie in Buffalo, NY). We also surveyed understory plant communities in the urban forest to examine correlations between R. cathartica abundance and local plant community abundance and richness. We then used experimental mesocosms to test if patterns observed in the field could be explained by adding increased dosages of R. cathartica to soils containing five plant species, including native and non-native woody and herbaceous species. In the highly invaded urban forest, we found that herbaceous cover, shrubs and woody seedlings negatively covaried with R. cathartica basal area and seedlings density. In the mesocosm experiments, R. cathartica resulted in significant decreases in plant community species richness, abundance, and shifted biomass allocation from roots. Our results provide evidence that R. cathartica is highly allelopathic in its invaded range, that R. cathartica roots have an allelopathic effect and that some plant species appear immune. We suggest that these effects may explain the plant’s ability to form dense monocultures and resist competitors, as well as shift community composition with species-specific impacts.     

Genotypic differences in phosphorus use physiology in producers (<Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>) and consumers (<Emphasis Type="Italic">Daphnia pulex</Emphasis>) interact to alter primary and secondary production

By considering the relative abundance of elements in trophic interactions, ecological stoichiometry makes predictions about key ecological processes such as biomass production and consumer-driven nutrient recycling. Theoretical and empirical work has focused on interspecific variation in elemental composition, and stoichiometric imbalances between resources and consumers in determining productivity, particularly at the base of foodwebs. Recent work has found considerable intraspecific variation in elemental composition. We know little about the ecological relevance of such variation, and whether predictions of stoichiometric theory hold at the intraspecific level. Here, we used two genotypes of a primary producer Chlamydomonas reinhardtii, and two genotypes of a primary consumer Daphnia pulex, which are already known to vary considerably in their phosphorus (P) use physiology, under conditions of P abundance and limitation, to explore whether such intraspecific differences alter primary as well as secondary production. Specifically, we tested whether there are intraspecific differences in the carbon: phosphorus (C:P) stoichiometry of Chlamydomonas genotypes, whether such differences affect growth and abundance of the two Daphnia genotypes, and whether the two Daphnia genotypes had distinct effects on primary production and growth of the two Chlamydomonas genotypes. We found significant differences in C:P stoichiometry between the two Chlamydomonas genotypes in both P supply conditions. Such intraspecific differences altered the growth of Daphnia genotypes, and affected the outcome of genotypic competition. Finally, Daphnia genotype affected primary production, and interacted with P supply to distinctly affect the growth of the two Chlamydomonas genotypes. Together, our results highlight the potential ecological relevance of intraspecific differences in nutrient use physiology and elemental composition, and the utility of ecological stoichiometry in understanding such consequences.     

Seaweed of the littoral zone at Cove Island in Long Island Sound: annual variation and impact of environmental factors

A site in the western part of Long Island Sound was monitored from January 2000 to May 2002. The littoral was divided into five different zones from the supra-littoral fringe (A) to the infra-littoral fringe (E). The midshore was dominated by Fucus vesiculosus L. and the sublittoral fringe by Chondrus crispus Stackh. There was a significant change in community structure over the years and the predominant change occurred between 2001 and 2002. The alternation in community structure was caused by an increase in abundance of species like Porphyra suborbiculata Kjellm., Porphyra leucosticta Type A and C (Neefus et al. 2000), Ceramium virgatum Roth, and Codium fragile subsp. tomentosoides (van Goor)Silva and a decrease in abundance in Fucus vesiculosus, Blidingia minima (Nägeli ex Kütz.) Kylin and Ulva lactuca L. The changes in community structure coincided with the change in environmental conditions. Air temperature as well as surface seawater temperature (depth <2 m) were the most important factors of those analyzed. Temperature seems to be the bottom-up force regulating the community structure.     

Soil spore banks of ectomycorrhizal fungi in endangered Japanese Douglas-fir forests

Interactions between trees and ectomycorrhizal fungi are critical to the growth and survival of both partners. However, ectomycorrhizal symbiosis has barely been explored in endangered trees, and no information is available regarding soil spore banks of ectomycorrhizal fungi from forests of threatened trees. Here, we evaluated soil spore banks of ectomycorrhizal fungi from endangered Japanese Douglas-fir (Pseudotsuga japonica) forests using bioassay approaches with congeneric P. menziesii and Pinus densiflora seedlings in combination with molecular identification techniques. Rhizopogon togasawariana was predominant in soil propagule banks and was found in all remaining P. japonica forests when assayed with P. menziesii, while no colonization of this fungus was observed on Pinus seedlings. Given the observed specificity of R. togasawariana for P. menziesii and its phylogenetic position within the Pseudotsuga-specific Rhizopogon lineage, its geographical distribution is likely restricted to the remaining Japanese Douglas-fir forests, indicating a high extinction risk for this fungus as well as its endangered host. Spore banks of R. togasawariana remained highly infective after preservation for 1 year or heat treatment at 70 °C, suggesting an ecological strategy of establishing ectomycorrhizal associations on regenerating Japanese Douglas-fir seedlings after disturbance, as observed in other Rhizopogon–Pinaceae combinations. Therefore, the regeneration of Japanese Douglas-fir seedlings may depend largely on the soil spore banks dominated by R. togasawariana, which has co-evolved with the Japanese Douglas-fir for over 30 million years. More attention must be paid to underground ectomycorrhizal fungi for the conservation of endangered tree species, especially in the era of human-induced mass extinction.     

Forest Type Influences Population Densities of Nocturnal Lemurs in Manompana,Northeastern Madagascar

Forest loss, fragmentation, and anthropization threaten the survival of forest species all over the world. Shifting agriculture is one of these threatening processes in Madagascar. However, when its cycle is halted and the land is left to regenerate, the resulting growth of secondary forest may provide a viable habitat for folivorous and omnivorous lemur species. We aimed to identify the response of nocturnal lemurs to different successional stages of regenerating secondary, degraded mature, and mature forest across a mosaic-type landscape. We surveyed four nocturnal lemur species (Avahi laniger, Microcebus cf. simmonsi, Allocebus trichotis, and Daubentonia madagascariensis) in four forest types of varying habitat disturbance in northeastern Madagascar. We estimated densities in mature and regenerating secondary forest for the eastern woolly lemur (Avahi laniger) and mouse lemur (Microcebus cf. simmonsi), two sympatric species with folivorous and omnivorous diets respectively. We did not estimate densities of Allocebus trichotis and Daubentonia madagascariensis owing to small sample size; however, we observed both species exclusively in mature forest. We found higher population densities of A. laniger and M. cf. simmonsi in secondary than in mature forest, showing the potential of regenerating secondary forest for lemur conservation. Several environmental factors influenced the detectability of the two lemur species. While observer and habitat type influenced detection of the eastern woolly lemur, canopy height and vine density influenced detection of mouse lemurs. Understanding how different species with different diets interact with anthropogenically impacted habitat will aid future management decisions for the conservation of primate species.     

Regulation of population numbers in the <Emphasis Type="Italic">Rana arvalis</Emphasis> frog according to the results of long-term observations on the same population

An analysis of the results of long-term stationary studies (1987–1996) on a Rana arvalis population showed that the mean body length and reproductive parameters of females increased with age. Significant interannual changes in body length and egg size (but not in fecundity and reproductive effort) were also accounted for by conditions of the warm season preceding the breeding season. The dependence of egg diameter and reproductive effort on the female body length weakened with age, and only the relationship between body length and fecundity was characterized by positive allometry. The survival rate of mature females depended on the premetamorphic survival rate and, therefore, was higher in earlier generations, in which the aquatic phase proceeded under more favorable conditions. The rate of reproduction (R ₀) decreased and, therefore, further population growth slowed down only after the initial abundance of the generation had reached a relatively high level. An increase in the initial abundance of the generation exerts a strong influence on R ₀ via a decrease in the survival of premetamorphic animals and, to a lesser extent, via a decrease in the body length and fecundity of tree-and four-year-old females. Changes in the annual abundance of breeding females in R. arvalis were more abrupt and less prolonged than those in the sympatric R. temporaria population. The holding capacity of the environment for the aquatic phase of the R. arvalis life cycle was higher than that for R. temporaria. Therefore, the population abundance of R. arvalis, compared to R. temporaria, was not subject to stringent negative feedback regulation dependent on the initial number of animals.     

Influence of abiotic factors on the structure of the population of the brown alga <Emphasis Type="Italic">Fucus vesiculosus</Emphasis> in East Murman (Barents Sea)

The peculiarities of the structure of the population of the brown alga Fucus vesiculosus in East Murman at different combinations of abiotic factors were studied. Salinity below 10‰ and high surf activity reduced the average life span of the plants (to 1 year) and caused a significant predominance of female specimens (60–90% of the fertile specimens). The proportion of female specimens increased with age. The greatest average age (3 branchings) and the highest survival of F. vesiculosus occurred in the wave-protected parts of bays. The distribution of F. vesiculosus was related to water movement intensity, salinity, and substrate type. The size-weight characteristics of F. vesiculosus thalli were decreased during maximum salinity fluctuations. The optimal conditions for this species were those existing on a weakly protected shore with short-term fluctuations of salinity (24–25‰).     

Two orthologs of late blight resistance gene <Emphasis Type="Italic">R1</Emphasis> in wild and cultivated potato

The R1 gene for resistance to oomycete Phytophthora infestans (Mont.) de Bary, the causal agent of late blight disease of potato (Solanum tuberosum L.), was initially identified in S. demissum and potato varieties bred by introgressing the S. demissum germplasm. Later a sequence characterized amplified region (SCAR) marker R1-1205 of this gene was also found in S. stoloniferum and S. polytrichon. Here we describe the full-length R1 sequence cloned from S. stoloniferum. This sequence is translatable, and this evidence of structural gene integrity is reinforced by functional characterization of the S. stoloniferum R1 gene in an effectoromics experiment. When screened across a series of S. demissum and S. stoloniferum accessions, the R1 sequences differed by several single nucleotide polymorphisms and an indel; this indel served the basis for constructing SCAR markers R1-517 and R1-513 that reliably discerned two R1 orthologs. The demissum-specific marker R1-517 was found in all S. demissum accessions under study; it was also present in many demissum-derived potato varieties and hybrids. The stoloniferum-specific marker R1-513 was found in 27% of S. stoloniferum and S. polytrichon accessions; however, we failed to discern this marker in the genotypes of cultivated potato listing S. stoloniferum in their pedigrees. Most probably, such absence of R1-513 is best explained by an opportunistic breeding history of stoloniferum-derived founder lines, which were employed first and foremost in breeding for resistance to potato virus Y: eventually, these founder lines are devoid of the R1 gene.     

Two new species of Alcantarea (Bromeliaceae,Tillandsioideae) from Brazil

Alcantarea turgida andA. tortuosa are described and illustrated as new species from southeastern Brazil. The relationships ofA. turgida withA. extensa and withA. vinicolor and ofA. tortuosa withA. farneyi and withA. benzingii are discussed.     

Testing for the induction of anti-herbivory defences in four Portuguese macroalgae by direct and water-borne cues of grazing amphipods

Herbivory is a key factor in regulating plant biomass, thereby driving ecosystem performance. Algae have developed multiple adaptations to cope with grazers, including morphological and chemical defences. In a series of experiments we investigated whether several species of macroalgae possess anti-herbivore defences and whether these could be regulated to demand, i.e. grazing events. The potential of direct grazing on defence induction was assessed for two brown (Dictyopteris membranacea, Fucus vesiculosus) and two red seaweeds (Gelidium sesquipedale, Sphaerococcus coronopifolius) from São Rafael and Ria Formosa, Portugal. Bioassays conducted with live algal pieces and agar-based food containing lipophilic algal extracts were used to detect changes in palatability after exposure to amphipod attacks (=treatment phase). Fucus vesiculosus was the only species significantly reducing palatability in response to direct amphipod-attacks. This pattern was observed in live F. vesiculosus pieces and agar-based food containing a lipophilic extract, suggesting that lipophilic compounds produced during the treatment phase were responsible for the repulsion of grazers. Water-borne cues of grazed F. vesiculosus as well as non-grazing amphipods also reduced palatability of neighbouring conspecifics. However, this effect was only observed in live tissues of F. vesiculosus. This study is the first to show that amphipods, like isopods, are capable to induce anti-herbivory defences in F. vesiculosus and that a seasonally variable effectiveness of chemical defences might serve as a dynamic control in alga–herbivore interactions.     

Study of biological communities subject to imperfect detection: bias and precision of community <Emphasis Type="Italic">N</Emphasis>-mixture abundance models in small-sample situations

Community N-mixture abundance models for replicated counts provide a powerful and novel framework for drawing inferences related to species abundance within communities subject to imperfect detection. To assess the performance of these models, and to compare them to related community occupancy models in situations with marginal information, we used simulation to examine the effects of mean abundance \((\bar{\lambda }\): 0.1, 0.5, 1, 5), detection probability \((\bar{p}\): 0.1, 0.2, 0.5), and number of sampling sites (n _site : 10, 20, 40) and visits (n _visit : 2, 3, 4) on the bias and precision of species-level parameters (mean abundance and covariate effect) and a community-level parameter (species richness). Bias and imprecision of estimates decreased when any of the four variables \((\bar{\lambda }\), \(\bar{p}\), n _site , n _visit ) increased. Detection probability \(\bar{p}\) was most important for the estimates of mean abundance, while \(\bar{\lambda }\) was most influential for covariate effect and species richness estimates. For all parameters, increasing n _site was more beneficial than increasing n _visit . Minimal conditions for obtaining adequate performance of community abundance models were n _site  ≥ 20, \(\bar{p}\) ≥ 0.2, and \(\bar{\lambda }\) ≥ 0.5. At lower abundance, the performance of community abundance and community occupancy models as species richness estimators were comparable. We then used additive partitioning analysis to reveal that raw species counts can overestimate β diversity both of species richness and the Shannon index, while community abundance models yielded better estimates. Community N-mixture abundance models thus have great potential for use with community ecology or conservation applications provided that replicated counts are available.     

Yeast communities of <Emphasis Type="Italic">Formica aquilonia</Emphasis> colonies

Yeast abundance and species diversity in the colonies of Formica aquilonia ants in birch–pine grass forest near Novosibirsk, Russia, were studied. The average yeast number in the anthill material was 10³–10⁴ CFU/g, reaching 10⁵ CFU/g in the hatching chambers. Typical litter species (Trichosporon moniliiforme and Cystofilobasidium capitatum) were predominant in soil and litter around the anthills. Apart from these species, ascomycete species of the family Debaryomycetaceae, Debaryomyces hansenii, and Schwanniomyces vanrijiae were predominant in the anthill material. Yeast population of the ant’ bodies consisted exclusively of the members of the last two species. Thus, highly specific yeast communities formed in the colonies of Formica aquilonia ants differ from the communities of surrounding soil. These differences are caused by environment-forming activity of the ants.     

The <Emphasis Type="Italic">Adh</Emphasis> locus and adaptation of <Emphasis Type="Italic">cn</Emphasis> and <Emphasis Type="Italic">vg</Emphasis> mutants in experimental populations of <Emphasis Type="Italic">Drosophila melanogaster MEIG</Emphasis>

A complex study on the adaptation of cn and vn mutants and the allozymes of alcoholdehydrogenase (ADH) was carried out in initially pure lines, and their panmixia populations during exchange of the mutant genotype with that of wild-type flies (C-S) and D) through saturating crossings. The relative adaptation of the genotypes was estimated by their effect on reproductive efficiency in the experimentally obtained population. Fecundity, lifespan, and the resistance of the studied genotypes to hyperthermia were investigated individually. It was shown that the high level of adaptation of the cn mutants and the low level of adaptation of the vg mutants was correlated with the presence of different ADH allozymes. In the studied population, the F-allozyme of ADH accompanied the vg mutation, while the S-allozyme of the enzyme was detected in cn mutants. Saturating crossings of C-S(Adh ^S)×vg(Adh ^F) and D(Adh ^F) × cn(Adh ^S), along with the parallel determination of the allele composition of the Adh locus, demonstrated that the complete substitution of the F-allozyme of ADH in the vg mutants by the S-allozyme in D flies, as well as the substitution of the S-allozyme of ADH in the cn mutants by the F-allozyme in D flies was realized only after the 15th–20th backcrosses. These results favor the coadaptation of cn and vg marker genes with alleles of the Adh locus and indicate the important role of the latter in the adaptation of genotypes. In the studied population, selection acted primarily against the vg mutants, which were inferior to the cn mutants, and heterozygote genotypes in indices of the main adaptation components.     

Arbutoid mycorrhizas of the genus <Emphasis Type="Italic">Cortinarius</Emphasis> from Costa Rica

Arbutoid mycorrhizas of Comarostaphylis arbutoides (Arbutoidea, Ericaceae) from neotropical montane forests are rarely described. To date, only mycorrhizal associations with the fungal species Leccinum monticola, Leotia lubrica and Sebacina sp. are known from literature. The genus Cortinarius is one of the most species-rich ectomycorrhizal taxa with over 2000 assumed species. In this study, two sites in the Cordillera de Talamanca of Costa Rica were sampled, where Com. arbutoides is endemic and grows together with Quercus costaricensis. Using a combined method of rDNA sequence analysis and morphotyping, 33 sampled mycorrhizal systems of Cortinarius were assigned to the subgenera Dermocybe, Phlegmacium and Telamonia. Specific plant primers were used to identify the host plant. Here, we present the phylogenetic data of all found Cortinarii and describe four of the arbutoid mycorrhizal systems morphologically and anatomically.