scholarly journals Experimental taphonomy of organelles and the fossil record of early eukaryote evolution

2021 ◽  
Vol 7 (5) ◽  
pp. eabe9487
Author(s):  
Emily M. Carlisle ◽  
Melina Jobbins ◽  
Vanisa Pankhania ◽  
John A. Cunningham ◽  
Philip C. J. Donoghue
Keyword(s):  
Green Algae ◽  
Time Scale ◽  
Fossil Record ◽  
Decay Resistance ◽  
Seed Plants ◽  
Eukaryote Evolution ◽  
Experimental Taphonomy ◽  
Origin Of Eukaryotes

The timing of origin of eukaryotes and the sequence of eukaryogenesis are poorly constrained because their fossil record is difficult to interpret. Claims of fossilized organelles have been discounted on the unsubstantiated perception that they decay too quickly for fossilization. We experimentally characterized the pattern and time scale of decay of nuclei, chloroplasts, and pyrenoids in red and green algae, demonstrating that they persist for many weeks postmortem as physical substrates available for preservation, a time scale consistent with known mechanisms of fossilization. Chloroplasts exhibit greater decay resistance than nuclei; pyrenoids are unlikely to be preserved, but their presence could be inferred from spaces within fossil chloroplasts. Our results are compatible with differential organelle preservation in seed plants. Claims of fossilized organelles in Proterozoic fossils can no longer be dismissed on grounds of plausibility, prompting reinterpretation of the early eukaryotic fossil record and the prospect of a fossil record of eukaryogenesis.

scholarly journals Nucleus preservation in early Ediacaran Weng'an embryo-like fossils, experimental taphonomy of nuclei and implications for reading the eukaryote fossil record

2020 ◽  
Vol 10 (4) ◽  
pp. 20200015 ◽  
Author(s):  
Weichen Sun ◽  
Zongjun Yin ◽  
John A. Cunningham ◽  
Pengju Liu ◽  
Maoyan Zhu ◽  
...  
Keyword(s):  
Fossil Record ◽  
Chemical Characterization ◽  
Host Cells ◽  
Experimental Conditions ◽  
Microbial Biofilms ◽  
Eukaryote Evolution ◽  
The Common ◽  
Experimental Taphonomy ◽  
Physical And Chemical

The challenge of identifying fossilized organelles has long hampered attempts to interpret the fossil record of early eukaryote evolution. We explore this challenge through experimental taphonomy of nuclei in a living eukaryote and microscale physical and chemical characterization of putative nuclei in embryo-like fossils from the early Ediacaran Weng'an Biota. The fossil nuclei exhibit diverse preservational modes that differ in shape, presence or absence of an inner body and the chemistry of the associated mineralization. The nuclei are not directly fossilized; rather, they manifest as external moulds. Experimental taphonomy of epidermal cells from the common onion ( Allium cepa ) demonstrates that nuclei are more decay resistant than their host cells, generally maintaining their physical dimensions for weeks to months post-mortem, though under some experimental conditions they exhibit shrinkage and/or become shrouded in microbial biofilms. The fossil and experimental evidence may be rationalized in a single taphonomic pathway of selective mineralization of the cell cytoplasm, preserving an external mould of the nucleus that is itself resistant to both decay and mineral replication. Combined, our results provide both a secure identification of the Weng'an nuclei as well as the potential of a fossil record of organelles that might help arbitrate in long-standing debates over the relative and absolute timing of the evolutionary assembly of eukaryote-grade cells.

scholarly journals A molecular time-scale for eukaryote evolution recalibrated with the continuous microfossil record

2006 ◽  
Vol 273 (1596) ◽  
pp. 1867-1872 ◽  
Author(s):  
Cédric Berney ◽  
Jan Pawlowski
Keyword(s):  
Time Scale ◽  
Small Subunit ◽  
Molecular Dating ◽  
Time Estimates ◽  
Early Diversification ◽  
Eukaryote Evolution ◽  
Eukaryotic Origin ◽  
The Rich ◽  
Early Radiation ◽  
Relaxed Molecular Clock

Recent attempts to establish a molecular time-scale of eukaryote evolution failed to provide a congruent view on the timing of the origin and early diversification of eukaryotes. The major discrepancies in molecular time estimates are related to questions concerning the calibration of the tree. To limit these uncertainties, we used here as a source of calibration points the rich and continuous microfossil record of dinoflagellates, diatoms and coccolithophorids. We calibrated a small-subunit ribosomal RNA tree of eukaryotes with four maximum and 22 minimum time constraints. Using these multiple calibration points in a Bayesian relaxed molecular clock framework, we inferred that the early radiation of eukaryotes occurred near the Mesoproterozoic–Neoproterozoic boundary, about 1100 million years ago. Our results indicate that most Proterozoic fossils of possible eukaryotic origin cannot be confidently assigned to extant lineages and should therefore not be used as calibration points in molecular dating.

Deciphering the fossil record of early bilaterian embryonic development in light of experimental taphonomy

2008 ◽  
Vol 10 (3) ◽  
pp. 339-349 ◽  
Author(s):  
Neil J. Gostling ◽  
Ceri-Wyn Thomas ◽  
Jenny M. Greenwood ◽  
Xiping Dong ◽  
Stefan Bengtson ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Fossil Record ◽  
Experimental Taphonomy

Bark Anatomy of an Early Carboniferous Tree from Australia

IAWA Journal ◽  
2013 ◽  
Vol 34 (2) ◽  
pp. 183-196 ◽  
Author(s):  
Anne-Laure Decombeix
Keyword(s):  
Fossil Record ◽  
Western Europe ◽  
Growth Habit ◽  
Early Carboniferous ◽  
Seed Plants ◽  
Secondary Phloem ◽  
Phloem Tissue ◽  
Axial Parenchyma ◽  
Sieve Cells ◽  
Bark Anatomy

Our knowledge of the evolution of secondary phloem and periderm anatomy in early lignophytes (progymnosperms and seed plants) is limited by the scarcity of well-preserved fossil bark. Here, I describe the bark of a Mississippian (Early Carboniferous) tree from Australia based on macro- and microscopic observation of two permineralized specimens. The bark tissues are up to 1.5 cm in thickness. The secondary phloem is organized in repeated, multicellular tangential layers of fibers and of thin-walled cells that correspond to axial parenchyma and sieve cells. Fibers are abundant even in the youngest, presumably functional, secondary phloem. Older phloem shows a proliferation of axial parenchyma that further separates the fiber layers. Successive periderm layers originate deep within the phloem and lead to the formation of a rhytidome-type bark, one of the oldest documented in the fossil record. These fossils add to our knowledge of the bark anatomy of Early Carboniferous trees, previously based on a few specimens from slightly younger strata of Western Europe. The complexity of the secondary phloem tissue in Devonian-Carboniferous lignophytes and possible anatomical differences related to growth habit are discussed.

scholarly journals The Heavy Links between Geological Events and Vascular Plants Evolution: A Brief Outline

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Aldo Piombino
Keyword(s):  
Fossil Record ◽  
Vascular Plants ◽  
Vascular Plant ◽  
Flowering Plants ◽  
Plant Evolution ◽  
Seed Plants ◽  
Fast Diffusion ◽  
Extinction Rate ◽  
Environmental Condition ◽  
Plant Origin

Since the rise of photosynthesis, life has influenced terrestrial atmosphere, particularly the O2 and the CO2 content (the latter being originally more than 95%), changing the chemistry of waters, atmosphere, and soils. Billions of years after, a far offspring of these first unicellular forms conquered emerging lands, not only completely changing landscape, but also modifying geological cycles of deposition and erosion, many chemical and physical characteristics of soils and fresh waters, and, more, the cycle of various elements. So, there are no doubts that vascular plants modified geology; but it is true that also geology has affected (and, more, has driven) plant evolution. New software, PyRate, has determined vascular plant origin and diversification through a Bayesian analysis of fossil record from Silurian to today, particularly observing their origination and extinction rate. A comparison between PyRate data and geological history suggests that geological events massively influenced plant evolution and that also the rise of nonflowering seed plants and the fast diffusion of flowering plants can be explained, almost partly, with the environmental condition changes induced by geological phenomena.

scholarly journals Endosymbiotic theories for eukaryote origin

2015 ◽  
Vol 370 (1678) ◽  
pp. 20140330 ◽  
Author(s):  
William F. Martin ◽  
Sriram Garg ◽  
Verena Zimorski
Keyword(s):  
Evolutionary History ◽  
Eukaryotic Cell ◽  
Facultative Anaerobe ◽  
Eukaryotic Nucleus ◽  
Evolutionary Innovation ◽  
Eukaryote Evolution ◽  
Cell Organization ◽  
Energetic Constraints ◽  
Origin Of Eukaryotes

For over 100 years, endosymbiotic theories have figured in thoughts about the differences between prokaryotic and eukaryotic cells. More than 20 different versions of endosymbiotic theory have been presented in the literature to explain the origin of eukaryotes and their mitochondria. Very few of those models account for eukaryotic anaerobes. The role of energy and the energetic constraints that prokaryotic cell organization placed on evolutionary innovation in cell history has recently come to bear on endosymbiotic theory. Only cells that possessed mitochondria had the bioenergetic means to attain eukaryotic cell complexity, which is why there are no true intermediates in the prokaryote-to-eukaryote transition. Current versions of endosymbiotic theory have it that the host was an archaeon (an archaebacterium), not a eukaryote. Hence the evolutionary history and biology of archaea increasingly comes to bear on eukaryotic origins, more than ever before. Here, we have compiled a survey of endosymbiotic theories for the origin of eukaryotes and mitochondria, and for the origin of the eukaryotic nucleus, summarizing the essentials of each and contrasting some of their predictions to the observations. A new aspect of endosymbiosis in eukaryote evolution comes into focus from these considerations: the host for the origin of plastids was a facultative anaerobe.

Carboniferous macrofloral biostratigraphy – an overview

2020 ◽  
pp. SP512-2020-97
Author(s):  
Stanislav Opluštil ◽  
Christopher J. Cleal ◽  
Jun Wang ◽  
Mingli Wan
Keyword(s):  
High Latitude ◽  
Fossil Record ◽  
Seed Plants ◽  
Terrestrial Vegetation ◽  
Low Resolution ◽  
Middle Latitudes ◽  
Global Cooling ◽  
The Tropics ◽  
Northern And Southern Hemispheres

AbstractIn the Carboniferous, terrestrial vegetation became widespread, diverse and abundant. The resulting fossil record has proved to be an effective biostratigraphic tool for intra- and interbasinal correlations. Besides palaeogeographic configurations, Carboniferous plant biostratigraphy is affected by a transition from greenhouse conditions during most of the Mississippian to an icehouse climate in the Pennsylvanian. The greenhouse Mississippian climate resulted in weak provincialism, with a cosmopolitan flora ranging from the tropics to middle latitudes. The global cooling around the Mississippian - Pennsylvanian boundary enhanced development of a latitudinal climatic zonation and related floral provincialism. These changes are expressed in the recognition of distinct realms or kingdoms, where the tropical Amerosinian Realm (or Euramerican and Cathaysian realms) is surrounded by the Angaran and Gondwanan realms occupying middle to high latitude of the northern and southern hemispheres, respectively. Floristic endemism in the Pennsylvanian precludes development of a global macrofloral biostratigraphy. Instead, each realm or area has its own biostratigraphic scheme. Poorer and less diverse floras of the Gondwanan and Angaran realms resulted in the establishment of relatively low-resolution macrofloral biostratigraphic schemes. Higher resolution macrofloral zonations exist only in the tropical Amerosinian Realm due to diverse and abundant floras dominated by free-sporing and early seed plants occupying extensive wetlands.

scholarly journals Insights into eukaryogenesis from the fossil record

2020 ◽  
Vol 10 (4) ◽  
pp. 20190105 ◽  
Author(s):  
Susannah M. Porter
Keyword(s):  
Fossil Record ◽  
Cyst Formation ◽  
Eukaryotic Cell ◽  
Current Evidence ◽  
Aerobic Respiration ◽  
Sterol Synthesis ◽  
Crown Group ◽  
Proxy Records ◽  
Eukaryote Evolution ◽  
Early Neoproterozoic

Eukaryogenesis—the process by which the eukaryotic cell emerged—has long puzzled scientists. It has been assumed that the fossil record has little to say about this process, in part because important characters such as the nucleus and mitochondria are rarely preserved, and in part because the prevailing model of early eukaryotes implies that eukaryogenesis occurred before the appearance of the first eukaryotes recognized in the fossil record. Here, I propose a different scenario for early eukaryote evolution than is widely assumed. Rather than crown group eukaryotes originating in the late Paleoproterozoic and remaining ecologically minor components for more than half a billion years in a prokaryote-dominated world, I argue for a late Mesoproterozoic origin of the eukaryotic crown group, implying that eukaryogenesis can be studied using the fossil record. I review the proxy records of four crown group characters: the capacity to form cysts as evidenced by the presence of excystment structures; a complex cytoskeleton as evidenced by spines or pylomes; sterol synthesis as evidenced by steranes; and aerobic respiration—and therefore mitochondria—as evidenced by eukaryotes living in oxic environments, and argue that it might be possible to use these proxy records to infer the order in which these characters evolved. The records indicate that both cyst formation and a complex cytoskeleton appeared by late Paleoproterozoic time, and sterol synthesis appeared in the late Mesoproterozioc or early Neoproterozoic. The origin of aerobic respiration cannot as easily be pinned down, but current evidence permits the possibility that it evolved sometime in the Mesoproterozoic.

scholarly journals Diversity and Frequency of The Kind of Lichen in Gumitir Mountain area of Jember Regency

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Siti Murdiyah ◽  
Pujiastuti Pujiastuti ◽  
Rino Tri Prasetyo
Keyword(s):  
Sea Level ◽  
Green Algae ◽  
Data Retrieval ◽  
Research Data ◽  
Seed Plants ◽  
Exploratory Research ◽  
Mountain Area ◽  
Blue Green Algae ◽  
The Earth

The area of Indonesia is 1.3% of the Earth, but it has the highest level of biodiversity. Biodiversity in the environment needs to be explored. The mountain area is one of the most suitable environments for exploring biodiversity, such as the Gumitir Mountain. Gumitir Mountain has altitude around 620 meters above sea level. Gumitir Mountain has high biodiversity. Mosses (Bryophyta), ferns (Pteridophyta), till seed plants (Spermatophyta), and including Lichen was found in this area. Lichen is a mutualism symbiotic organism between fungi and green algae or blue-green algae that lives on the surface of the tree or another substrate with a variety of shapes and colours. This study aims to determine the diversity of kinds and frequencies of each kind of lichen found in the Gumitir Mountain area of Jember Regency. This research classified into exploratory research. Data retrieval is using the cruised method. Lichens are found in 20 species with Phlyctis arena (Ach.) Flot. as kind of lichen that is abundant in Gumitir Mountain Area.

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