43 research outputs found
The Fastest Flights in Nature: High-Speed Spore Discharge Mechanisms among Fungi
Get PDFBACKGROUND: A variety of spore discharge processes have evolved among the fungi. Those with the longest ranges are powered by hydrostatic pressure and include "squirt guns" that are most common in the Ascomycota and Zygomycota. In these fungi, fluid-filled stalks that support single spores or spore-filled sporangia, or cells called asci that contain multiple spores, are pressurized by osmosis. Because spores are discharged at such high speeds, most of the information on launch processes from previous studies has been inferred from mathematical models and is subject to a number of errors. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we have used ultra-high-speed video cameras running at maximum frame rates of 250,000 fps to analyze the entire launch process in four species of fungi that grow on the dung of herbivores. For the first time we have direct measurements of launch speeds and empirical estimates of acceleration in these fungi. Launch speeds ranged from 2 to 25 m s(-1) and corresponding accelerations of 20,000 to 180,000 g propelled spores over distances of up to 2.5 meters. In addition, quantitative spectroscopic methods were used to identify the organic and inorganic osmolytes responsible for generating the turgor pressures that drive spore discharge. CONCLUSIONS/SIGNIFICANCE: The new video data allowed us to test different models for the effect of viscous drag and identify errors in the previous approaches to modeling spore motion. The spectroscopic data show that high speed spore discharge mechanisms in fungi are powered by the same levels of turgor pressure that are characteristic of fungal hyphae and do not require any special mechanisms of osmolyte accumulation
Native Tallgrass Prairie Remnants as "Living Museums": Landscape Context, Metacommunity Dynamics, and Private Management Practices of Native Prairie Hay Meadows
No full textIn fragmented tallgrass prairie remnants within eastern Kansas, smaller patch area, greater isolation, and poorer matrix quality are predicted to result in (1) decreased species richness, (2) decreased site `quality,' and (3) decreased presence of specialist species. Within five counties, 301 native tallgrass remnants were surveyed. Total site area, as well as habitat heterogeneity, contributed to richness and quality, but isolation and matrix quality did not. In fact, isolation and matrix quality appeared to contribute to decreasing richness and quality. These results can be explained by regional environmental variation and historic non-random process of human landscape changes at the time of settlement. This suggests that the hypothesis that dispersal plays a role in the community assembly of tallgrass prairie remnants is probably false. Although species-rich communities may persist for decades and possibly centuries after fragmentation, in the long term the effects of random local extinction have been underestimated for native tallgrass prairie communities
Data from: Processes of community assembly in an environmentally heterogeneous, high biodiversity region
No full textDespite decades of study, the relative importance of niche-based versus neutral processes in community assembly remains largely ambiguous. Recent work suggests niche-based processes are more easily detectable at coarser spatial scales, while neutrality dominates at finer scales. Analyses of functional traits with multi-year multi-site biodiversity inventories may provide deeper insights into assembly processes and the effects of spatial scale. We examined associations between community composition, species functional traits, and environmental conditions for plant communities in the Kouga-Baviaanskloof region, an area within South Africa's Cape Floristic Region (CFR) containing high α and β diversity. This region contains strong climatic gradients and topographic heterogeneity, and is comprised of distinct vegetation classes with varying fire histories, making it an ideal location to assess the role of niche-based environmental filtering on community composition by examining how traits vary with environment. We combined functional trait measurements for over 300 species with observations from vegetation surveys carried out in 1991/1992 and repeated in 2011/2012. We applied redundancy analysis, quantile regression, and null model tests to examine trends in species turnover and functional traits along environmental gradients in space and through time. Functional trait values were weakly associated with most spatial environmental gradients and only showed trends with respect to vegetation class and time since fire. However, survey plots showed greater compositional and functional stability through time than expected based on null models. Taken together, we found clear evidence for functional distinctions between vegetation classes, suggesting strong environmental filtering at this scale, most likely driven by fire dynamics. In contrast, there was little evidence of filtering effects along environmental gradients within vegetation classes, suggesting that assembly processes are largely neutral at this scale, likely the result of very high functional redundancy among species in the regional species pool
Baviaanskloof percent cover, trait, and environment dataset
No full textA dataset combining trait measurements for species observed in releve plots in the Baviaankloof region of South Africa. Environmental conditions at those plots also included
Processes of plant community assembly in the environmentally heterogeneous, high biodiversity Baviaanskloof Mega-reserve
No full text<p>A talk about community assembly in the Baviaanskloof region of South Africa given at the symposium Plant Diversity in the GCFR: From Genomes to Biomes</p
