scholarly journals Fossil fern rhizomes as a model system for exploring epiphyte community structure across geologic time: evidence from Patagonia

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8244 ◽  
Author(s):  
Alexander C. Bippus ◽  
Ignacio H. Escapa ◽  
Peter Wilf ◽  
Alexandru M.F. Tomescu
Keyword(s):  
Community Structure ◽  
Fossil Record ◽  
Model System ◽  
Plant Interactions ◽  
Thin Sections ◽  
Geologic Time ◽  
Epiphyte Communities ◽  
Ancient Ecosystems ◽  
Epiphyte Community

Background In extant ecosystems, complex networks of ecological interactions between organisms can be readily studied. In contrast, understanding of such interactions in ecosystems of the geologic past is incomplete. Specifically, in past terrestrial ecosystems we know comparatively little about plant biotic interactions besides saprotrophy, herbivory, mycorrhizal associations, and oviposition. Due to taphonomic biases, epiphyte communities are particularly rare in the plant-fossil record, despite their prominence in modern ecosystems. Accordingly, little is known about how terrestrial epiphyte communities have changed across geologic time. Here, we describe a tiny in situ fossil epiphyte community that sheds light on plant-animal and plant-plant interactions more than 50 million years ago. Methods A single silicified Todea (Osmundaceae) rhizome from a new locality of the early Eocene (ca. 52 Ma) Tufolitas Laguna del Hunco (Patagonia, Argentina) was studied in serial thin sections using light microscopy. The community of organisms colonizing the tissues of the rhizome was characterized by identifying the organisms and mapping and quantifying their distribution. A 200 × 200 µm grid was superimposed onto the rhizome cross section, and the colonizers present at each node of the grid were tallied. Results Preserved in situ, this community offers a rare window onto aspects of ancient ecosystems usually lost to time and taphonomic processes. The community is surprisingly diverse and includes the first fossilized leafy liverworts in South America, also marking the only fossil record of leafy bryophyte epiphytes outside of amber deposits; as well as several types of fungal hyphae and spores; microsclerotia with possible affinities in several ascomycete families; and evidence for oribatid mites. Discussion The community associated with the Patagonian rhizome enriches our understanding of terrestrial epiphyte communities in the distant past and adds to a growing body of literature on osmundaceous rhizomes as important hosts for component communities in ancient ecosystems, just as they are today. Because osmundaceous rhizomes represent an ecological niche that has remained virtually unchanged over time and space and are abundant in the fossil record, they provide a paleoecological model system that could be used to explore epiphyte community structure through time.

scholarly journals Fossil fern rhizomes as a model system for biotic interactions across geologic time: Evidence from Patagonia

2017 ◽  
Author(s):  
Alexander C. Bippus ◽  
Ignacio H. Escapa ◽  
Peter Wilf ◽  
Alexandru M. F. Tomescu
Keyword(s):  
Fossil Record ◽  
Oribatid Mite ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Model System ◽  
Thin Sections ◽  
Geologic Time ◽  
Ancient Ecosystems ◽  
Plant Plant

Background. A wealth of data on the networks of ecological interactions present in the modern biota can be readily obtained, due to the ease of unlimited access to the living organisms that form these networks. In contrast, understanding of such interactions in ecosystems of the geologic past is incomplete. Specifically, in terrestrial ecosystems we know comparatively little about plant biotic interactions besides herbivory, oviposition, galling. Here we describe a tiny in situ fossil community which sheds light on concurrent plant-plant, plant-fungal, and plant-animal interactions. Methods. A single silicified osmundaceous rhizome from a new locality of the early Eocene (ca. 52 Ma) Tufolitas Laguna del Hunco was studied in serial thin sections using light microscopy. The community of organisms colonizing the tissues of the rhizome was characterized by identifying the organisms, as well as mapping and quantifying their distribution. For this, a 200 x 200 µm grid was superimposed onto the rhizome cross section and the colonizers present at each node of the grid were tallied. Results. Preserved in situ, this community offers a rare window onto aspects of ancient ecosystems usually lost to time and taphonomic processes. The community is surprisingly diverse and includes the first fossilized leafy liverworts in South America, also marking the only fossil record of leafy bryophyte epiphytes; several types of fungal hyphae and spores; microsclerotia with probable affinities in several ascomycete families; and oribatid mite coprolites. Discussion. The community associated with the Patagonian rhizome enriches our understanding of plant biotic interactions in the distant past and adds to a growing body of literature, which indicates that osmundaceous rhizomes were important hosts for component communities in ancient ecosystems, just as they are today. Because osmundaceous rhizomes represent an ecological niche that has remained unchanged over time and space, and are abundant in the fossil record, they provide a good paleoecological model system that could be used for exploring plant biotic interactions across geologic time.

scholarly journals Fossil fern rhizomes as a model system for biotic interactions across geologic time: Evidence from Patagonia

2017 ◽  
Author(s):  
Alexander C. Bippus ◽  
Ignacio H. Escapa ◽  
Peter Wilf ◽  
Alexandru M. F. Tomescu
Keyword(s):  
Fossil Record ◽  
Oribatid Mite ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Model System ◽  
Thin Sections ◽  
Geologic Time ◽  
Ancient Ecosystems ◽  
Plant Plant

Background. A wealth of data on the networks of ecological interactions present in the modern biota can be readily obtained, due to the ease of unlimited access to the living organisms that form these networks. In contrast, understanding of such interactions in ecosystems of the geologic past is incomplete. Specifically, in terrestrial ecosystems we know comparatively little about plant biotic interactions besides herbivory, oviposition, galling. Here we describe a tiny in situ fossil community which sheds light on concurrent plant-plant, plant-fungal, and plant-animal interactions. Methods. A single silicified osmundaceous rhizome from a new locality of the early Eocene (ca. 52 Ma) Tufolitas Laguna del Hunco was studied in serial thin sections using light microscopy. The community of organisms colonizing the tissues of the rhizome was characterized by identifying the organisms, as well as mapping and quantifying their distribution. For this, a 200 x 200 µm grid was superimposed onto the rhizome cross section and the colonizers present at each node of the grid were tallied. Results. Preserved in situ, this community offers a rare window onto aspects of ancient ecosystems usually lost to time and taphonomic processes. The community is surprisingly diverse and includes the first fossilized leafy liverworts in South America, also marking the only fossil record of leafy bryophyte epiphytes; several types of fungal hyphae and spores; microsclerotia with probable affinities in several ascomycete families; and oribatid mite coprolites. Discussion. The community associated with the Patagonian rhizome enriches our understanding of plant biotic interactions in the distant past and adds to a growing body of literature, which indicates that osmundaceous rhizomes were important hosts for component communities in ancient ecosystems, just as they are today. Because osmundaceous rhizomes represent an ecological niche that has remained unchanged over time and space, and are abundant in the fossil record, they provide a good paleoecological model system that could be used for exploring plant biotic interactions across geologic time.

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

scholarly journals Usefulness of the immunogold technique in quantitation of a soluble protein in ultra-thin sections.

1987 ◽  
Vol 35 (4) ◽  
pp. 405-410 ◽  
Author(s):  
G Posthuma ◽  
J W Slot ◽  
H J Geuze
Keyword(s):  
Model System ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Embedded Model ◽  
Intracellular Compartments ◽  
Embedded Blocks ◽  
Gelatin Concentration ◽  
Lowicryl K4m

We used a model system to study whether measurements of absolute local antigen concentrations at the electron microscopic level are feasible by counting immunogold labeling density in ultra-thin sections. The model system consisted of a matrix of a variable concentration of gelatin, which was mixed with given concentrations of rat pancreas amylase and fixed according to various fixation protocols. With a relatively mild fixation, there was no clear proportionality between anti-amylase gold labeling and amylase concentration in ultra-thin cryosections. This was presumably due to uncontrolled loss of amylase from the sections. After stronger fixation with 2% glutaraldehyde for 4 hr, labeling density reflected the amylase concentration very well. We observed that matrix (gelatin) density influenced labeling density. A low gelatin concentration of 5% allowed penetration of immunoreagents into the cryosection, resulting in a high and variable labeling density. In gelatin concentrations of 10% and 20%, labeling density was lower but proportional to amylase concentration. To establish an equal (minimal) penetration of immunoreagents, we embedded model blocks with different matrix densities in polyacrylamide (PAA). In ultra-thin cryosections of these PAA-embedded blocks, anti-amylase labeling was proportional to amylase concentration even at a low (5%) gelatin concentration. Anti-amylase labeling in ultra-thin sections from Lowicryl K4M low temperature-embedded blocks was higher than in PAA sections, but the results were less consistent and depended to some extent on matrix density. These results, together with the earlier observation that acrylamide completely penetrates intracellular compartments (Slot JW, Geuze HJ: Biol Cell 44:325, 1982), demonstrate that it is possible to measure true intracellular concentrations of soluble proteins in situ using ultra-thin cryosections of PAA-embedded tissue.

Diversity partitioning of a Late Ordovician marine biotic invasion: controls on diversity in regional ecosystems

Paleobiology ◽  
2007 ◽  
Vol 33 (2) ◽  
pp. 295-309 ◽  
Author(s):  
Mark E. Patzkowsky ◽  
Steven M. Holland
Keyword(s):  
Fossil Record ◽  
Resource Limitation ◽  
Late Ordovician ◽  
Ecosystem Change ◽  
Diversity Partitioning ◽  
Marine Communities ◽  
Geologic Time ◽  
Long Time ◽  
Ancient Ecosystems ◽  
Biotic Invasion

Biotic invasions are a common feature of the fossil record, yet remarkably little is known about them, given their enormous potential to reveal the processes that regulate local and regional diversity over long time scales. We used additive diversity partitioning to examine how diversity structure changed as a result of a marine biotic invasion in tropical, shallow and deep subtidal environments spanning approximately 4 Myr in the Late Ordovician. The biotic invasion increased richness in the regional ecosystem by nearly 40%. Within-habitat turnover diversity accounts for most of the increase in richness, with between-habitat turnover diversity contributing a lesser amount. Increases in these components of diversity were accommodated by increased packing of species along a depth gradient and increased habitat heterogeneity. Diversity metrics that incorporate taxon abundance (Shannon information, Simpson's D) show similar patterns and reveal that many invading taxa were locally abundant and widespread in their occurrence. Extinction of incumbent taxa did not foster the invasion; rather the invasion appears to be linked to a regional or global warming event. Taken together, these observations indicate that these Late Ordovician marine communities were open to invasion and not saturated with species. Moreover, the increase in species diversity caused by the invasion was not ephemeral; instead it lasted for at least 1 Myr. Similar studies of other biotic invasions in the fossil record are necessary to determine (1) the factors, such as extinction of incumbents or resource limitation, that may facilitate or inhibit invasion in ancient ecosystems; (2) how local and regional ecosystems respond to invasion; and (3) the extent to which biotic invasions play a substantial role in ecosystem change through geologic time.

A TEM study of the microstructure of avian eggshells

1992 ◽  
Vol 50 (2) ◽  
pp. 1102-1103
Author(s):  
S. Q. Xiao ◽  
S. Baden ◽  
A. H. Heuer
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Nucleation And Growth ◽  
Growth Mechanisms ◽  
Shell Surface ◽  
Thin Sections ◽  
Polycrystalline Metals ◽  
Transmission Electron ◽  
Nucleation And Growth Mechanisms

The avian eggshell is one of the most rapidly mineralizing biological systems known. In situ, 5g of calcium carbonate are crystallized in less than 20 hrs to fabricate the shell. Although there have been much work about the formation of eggshells, controversy about the nucleation and growth mechanisms of the calcite crystals, and their texture in the eggshell, still remain unclear. In this report the microstructure and microchemistry of avian eggshells have been analyzed using transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS).Fresh white and dry brown eggshells were broken and fixed in Karnosky's fixative (kaltitanden) for 2 hrs, then rinsed in distilled H2O. Small speckles of the eggshells were embedded in Spurr medium and thin sections were made ultramicrotome.The crystalline part of eggshells are composed of many small plate-like calcite grains, whose plate normals are approximately parallel to the shell surface. The sizes of the grains are about 0.3×0.3×1 μm3 (Fig.l). These grains are not as closely packed as man-made polycrystalline metals and ceramics, and small gaps between adjacent grains are visible indicating the absence of conventional grain boundaries.

scholarly journals Metagenome-assembled genomes infer potential microbial metabolism in alkaline sulphidic tailings

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Wenjun Li ◽  
Xiaofang Li
Keyword(s):  
Community Structure ◽  
Mine Tailings ◽  
Fluorescent In Situ Hybridization ◽  
High Throughput Sequencing ◽  
Microbial Consortia ◽  
Metabolic Reconstruction ◽  
Metal Release ◽  
Community Members ◽  
Oxidative Stresses

Abstract Background Mine tailings are hostile environment. It has been well documented that several microbes can inhabit such environment, and metagenomic reconstruction has successfully pinpointed their activities and community structure in acidic tailings environments. We still know little about the microbial metabolic capacities of alkaline sulphidic environment where microbial processes are critically important for the revegetation. Microbial communities therein may not only provide soil functions, but also ameliorate the environment stresses for plants’ survival. Results In this study, we detected a considerable amount of viable bacterial and archaeal cells using fluorescent in situ hybridization in alkaline sulphidic tailings from Mt Isa, Queensland. By taking advantage of high-throughput sequencing and up-to-date metagenomic binning technology, we reconstructed the microbial community structure and potential coupled iron and nitrogen metabolism pathways in the tailings. Assembly of 10 metagenome-assembled genomes (MAGs), with 5 nearly complete, was achieved. From this, detailed insights into the community metabolic capabilities was derived. Dominant microbial species were seen to possess powerful resistance systems for osmotic, metal and oxidative stresses. Additionally, these community members had metabolic capabilities for sulphide oxidation, for causing increased salinity and metal release, and for leading to N depletion. Conclusions Here our results show that a considerable amount of microbial cells inhabit the mine tailings, who possess a variety of genes for stress response. Metabolic reconstruction infers that the microbial consortia may actively accelerate the sulphide weathering and N depletion therein.

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