Arthropod phylogeny: An overview from the perspectives of morphology, molecular data and the fossil record

2010 ◽  
Vol 39 (2-3) ◽  
pp. 74-87 ◽  
Author(s):  
Gregory D. Edgecombe
Keyword(s):  
Fossil Record ◽  
Molecular Data

scholarly journals Major features of protistan evolution: controversies, problems and a few answers

2006 ◽  
Vol 29 (1) ◽  
pp. 55-80
Author(s):  
Jere H Lipps
Keyword(s):  
Fossil Record ◽  
Molecular Data ◽  
Trophic Levels ◽  
Early Earth ◽  
Huge Number ◽  
Geologic Time ◽  
Earth History ◽  
Important Development ◽  
Fossil Evidence

The major features of protist evolution are fraught with controversies, problems and few answers, especially in early Earth history. In general they are based on molecular data and fossil evidence that respectively provide a scaffold and details of eukaryotic phylogenetic and ecologic histories. 1. Their origin, inferred from molecular sequences, occurred very early (>;3Ga). They are a chimera of different symbiont-derived organelles, including possibly the nucleus. 2. The initial diversification of eukaryotes may have occurred early in geologic time. Six supergroups exist today, each with fossils known from the Proterozoic and Phanerozoic. 3. Sex, considered an important development, may have been inherited from bacteria. 4. Precambrian protists were largely pelagic cyst-bearing taxa, but benthic forms were probably quite diverse and abundant. 5. Protists gave rise to animals long before 600 Ma through the choanoflagellates, for which no fossil record exists. 6. Acritarchs and skeletonized protists radiated in the Cambrian (544-530 my). From then on, they radiated and became extinct at all the major events recorded in the metazoan fossil record. 7. Protists dominated major environments (shelves and reefs) starting with a significant radiation in the Ordovician, followed by extinctions and other radiations until most died out at the end of the Permian. 8. In the Mesozoic, new planktic protozoa and algae appeared and radiated in pelagic environments. 9. Modern protists are important at all trophic levels in the oceans and a huge number terrestrial, parasitic and symbiotic protists must have existed for much of geologic time as well. 10. The future of protists is likely in jeopardy, just like most reefal, benthic, and planktic metazoans. An urgent need to understand the role of protists in modern threatened oceans should be addressed soon.

scholarly journals Improvements in the fossil record may largely resolve current conflicts between morphological and molecular estimates of mammal phylogeny

2018 ◽  
Vol 285 (1893) ◽  
pp. 20181632 ◽  
Author(s):  
Robin M. D. Beck ◽  
Charles Baillie
Keyword(s):  
Maximum Likelihood ◽  
Fossil Record ◽  
Morphological Character ◽  
Phylogenetic Analyses ◽  
Molecular Data ◽  
Morphological Data ◽  
Ancestral State ◽  
Case Scenario ◽  
State Reconstruction ◽  
Consensus View

Phylogenies of mammals based on morphological data continue to show several major areas of conflict with the current consensus view of their relationships, which is based largely on molecular data. This raises doubts as to whether current morphological character sets are able to accurately resolve mammal relationships. We tested this under a hypothetical ‘best case scenario’ by using ancestral state reconstruction (under both maximum parsimony and maximum likelihood) to infer the morphologies of fossil ancestors for all clades present in a recent comprehensive DNA sequence-based phylogeny of mammals, and then seeing what effect the subsequent inclusion of these predicted ancestors had on unconstrained phylogenetic analyses of morphological data. We found that this resulted in topologies that are highly congruent with the current consensus phylogeny, at least when the predicted ancestors are assumed to be well preserved and densely sampled. Most strikingly, several analyses recovered the monophyly of clades that have never been found in previous morphology-only studies, such as Afrotheria and Laurasiatheria. Our results suggest that, at least in principle, improvements in the fossil record—specifically the discovery of fossil taxa that preserve the ancestral or near-ancestral morphologies of the nodes in the current consensus—may be sufficient to largely reconcile morphological and molecular estimates of mammal phylogeny, even using current morphological character sets.

Fungi from the Rhynie chert: a view from the dark side

2003 ◽  
Vol 94 (4) ◽  
pp. 457-473 ◽  
Author(s):  
T. N. Taylor ◽  
S. D. Klavins ◽  
M. Krings ◽  
E. L. Taylor ◽  
H. Kerp ◽  
...  
Keyword(s):  
Fossil Record ◽  
Molecular Data ◽  
Host Responses ◽  
Dark Side ◽  
Early Devonian ◽  
Mycorrhizal Associations ◽  
Rhynie Chert ◽  
Complex Ecosystem ◽  
Taxonomic Groups ◽  
Fungal Interactions

ABSTRACTThe exquisite preservation of organisms in the Early Devonian Rhynie chert ecosystem has permitted the documentation of the morphology and life history biology of fungi belonging to several major taxonomic groups (e.g., Chytridiomycota, Ascomycota, Glomeromycota). The Rhynie chert also provides the first unequivocal evidence in the fossil record of fungal interactions that can in turn be compared with those in modern ecosystems. These interactions in the Rhynie chert involve both green algae and macroplants, with examples of saprophytism, parasitism, and mutualism, including the earliest mycorrhizal associations and lichen symbiosis known to date in the fossil record. Especially significant are several types of specific host responses to fungal infection that indicate that these plants had already evolved methods of defence similar and perhaps analogous to those of extant plants. This suggests that mechanisms underlying the establishment and sustenance of associations of fungi with land plants were well in place prior to the Early Devonian. In addition, a more complete understanding of the microbial organisms involved in this complex ecosystem can also provide calibration points for phylogenies based on molecular data analysis. The richness of the microbial community in the Rhynie chert holds tremendous potential for documenting additional fungal groups, which permits speculation about further interactions with abiotic and biotic components of the environment.

scholarly journals Rapid morphological evolution in placental mammals post-dates the origin of the crown group

2019 ◽  
Vol 286 (1898) ◽  
pp. 20182418 ◽  
Author(s):  
Thomas J. D. Halliday ◽  
Mario dos Reis ◽  
Asif U. Tamuri ◽  
Henry Ferguson-Gow ◽  
Ziheng Yang ◽  
...  
Keyword(s):  
Fossil Record ◽  
Morphological Evolution ◽  
Relative Rate ◽  
Molecular Data ◽  
Placental Mammal ◽  
Dental Morphology ◽  
Crown Group ◽  
Rates Of Evolution ◽  
Early Paleocene ◽  
Molecular Evolutionary Rates

Resolving the timing and pattern of early placental mammal evolution has been confounded by conflict among divergence date estimates from interpretation of the fossil record and from molecular-clock dating studies. Despite both fossil occurrences and molecular sequences favouring a Cretaceous origin for Placentalia, no unambiguous Cretaceous placental mammal has been discovered. Investigating the differing patterns of evolution in morphological and molecular data reveals a possible explanation for this conflict. Here, we quantified the relationship between morphological and molecular rates of evolution. We show that, independent of divergence dates, morphological rates of evolution were slow relative to molecular evolution during the initial divergence of Placentalia, but substantially increased during the origination of the extant orders. The rapid radiation of placentals into a highly morphologically disparate Cenozoic fauna is thus not associated with the origin of Placentalia, but post-dates superordinal origins. These findings predict that early members of major placental groups may not be easily distinguishable from one another or from stem eutherians on the basis of skeleto-dental morphology. This result supports a Late Cretaceous origin of crown placentals with an ordinal-level adaptive radiation in the early Paleocene, with the high relative rate permitting rapid anatomical change without requiring unreasonably fast molecular evolutionary rates. The lack of definitive Cretaceous placental mammals may be a result of morphological similarity among stem and early crown eutherians, providing an avenue for reconciling the fossil record with molecular divergence estimates for Placentalia.

scholarly journals The Continuing Debate on Deep Molluscan Phylogeny: Evidence for Serialia (Mollusca, Monoplacophora + Polyplacophora)

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
I. Stöger ◽  
J. D. Sigwart ◽  
Y. Kano ◽  
T. Knebelsberger ◽  
B. A. Marshall ◽  
...  
Keyword(s):  
Molecular Clock ◽  
Fossil Record ◽  
Molecular Data ◽  
Approximately Unbiased ◽  
Data Set ◽  
Late Cambrian ◽  
Molluscan Shell ◽  
Rapid Divergence ◽  
Multiple Species

Molluscs are a diverse animal phylum with a formidable fossil record. Although there is little doubt about the monophyly of the eight extant classes, relationships between these groups are controversial. We analysed a comprehensive multilocus molecular data set for molluscs, the first to include multiple species from all classes, including five monoplacophorans in both extant families. Our analyses of five markers resolve two major clades: the first includes gastropods and bivalves sister to Serialia (monoplacophorans and chitons), and the second comprises scaphopods sister to aplacophorans and cephalopods. Traditional groupings such as Testaria, Aculifera, and Conchifera are rejected by our data with significant Approximately Unbiased (AU) test values. A new molecular clock indicates that molluscs had a terminal Precambrian origin with rapid divergence of all eight extant classes in the Cambrian. The recovery of Serialia as a derived, Late Cambrian clade is potentially in line with the stratigraphic chronology of morphologically heterogeneous early mollusc fossils. Serialia is in conflict with traditional molluscan classifications and recent phylogenomic data. Yet our hypothesis, as others from molecular data, implies frequent molluscan shell and body transformations by heterochronic shifts in development and multiple convergent adaptations, leading to the variable shells and body plans in extant lineages.

scholarly journals The inseparability of sampling and time and its influence on attempts to unify the molecular and fossil records

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 561-574 ◽  
Author(s):  
Melanie J. Hopkins ◽  
David W. Bapst ◽  
Carl Simpson ◽  
Rachel C. M. Warnock
Keyword(s):  
Mathematical Models ◽  
Fossil Record ◽  
Evolutionary History ◽  
Molecular Data ◽  
The Other ◽  
Deep Time ◽  
Approaches To Studying ◽  
Data Source ◽  
Fossil Records ◽  
Estimate Uncertainty

AbstractThe two major approaches to studying macroevolution in deep time are the fossil record and reconstructed relationships among extant taxa from molecular data. Results based on one approach sometimes conflict with those based on the other, with inconsistencies often attributed to inherent flaws of one (or the other) data source. Any contradiction between the molecular and fossil records represents a failure of our ability to understand the imperfections of our data, as both are limited reflections of the same evolutionary history. We therefore need to develop conceptual and mathematical models that jointly explain our observations in both records. Fortunately, the different limitations of each record provide an opportunity to test or calibrate the other, and new methodological developments leverage both records simultaneously. However, we must reckon with the distinct relationships between sampling and time in the fossil record and molecular phylogenies. These differences impact our recognition of baselines and the analytical incorporation of age estimate uncertainty.

The Putative Jurassic Angiosperm Wood Suevioxylon Zonatum Revisited

IAWA Journal ◽  
2007 ◽  
Vol 28 (1) ◽  
pp. 95-100 ◽  
Author(s):  
Marc Philippe ◽  
Dmitri Gromyko
Keyword(s):  
Light Microscopy ◽  
Fossil Record ◽  
Molecular Data ◽  
Type Material ◽  
Thin Sections ◽  
Material Specimen ◽  
Group A ◽  
Phylogeny And Evolution

As the phylogeny and evolution of angiosperms is being completely rewritten by molecular data, there is renewed interest in the earliest fossil record of the group. A putative Jurassic Angiosperm wood, Suevioxylon zonatum Kräusel is revisited. We reinvestigated the type material (specimen and five thin sections) with light microscopy and SEM. This reappraisal indicates that Suevioxylon zonatum is actually a poorly preserved softwood and not an angiosperm.

scholarly journals Eocene Loranthaceae pollen pushes back divergence ages for major splits in the family

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3373 ◽  
Author(s):  
Friðgeir Grímsson ◽  
Paschalia Kapli ◽  
Christa-Charlotte Hofmann ◽  
Reinhard Zetter ◽  
Guido W. Grimm
Keyword(s):  
Fossil Record ◽  
Middle Miocene ◽  
Molecular Data ◽  
Late Eocene ◽  
Molecular Dating ◽  
The Family ◽  
Minimum Age ◽  
Age Constraints ◽  
Scanning Electron ◽  
Lineage Diversification

BackgroundWe revisit the palaeopalynological record of Loranthaceae, using pollen ornamentation to discriminate lineages and to test molecular dating estimates for the diversification of major lineages.MethodsFossil Loranthaceae pollen from the Eocene and Oligocene are analysed and documented using scanning-electron microscopy. These fossils were associated with molecular-defined clades and used as minimum age constraints for Bayesian node dating using different topological scenarios.ResultsThe fossil Loranthaceae pollen document the presence of at least one extant root-parasitic lineage (Nuytsieae) and two currently aerial parasitic lineages (Psittacanthinae and Loranthinae) by the end of the Eocene in the Northern Hemisphere. Phases of increased lineage diversification (late Eocene, middle Miocene) coincide with global warm phases.DiscussionWith the generation of molecular data becoming easier and less expensive every day, neontological research should re-focus on conserved morphologies that can be traced through the fossil record. The pollen, representing the male gametophytic generation of plants and often a taxonomic indicator, can be such a tracer. Analogously, palaeontological research should put more effort into diagnosing Cenozoic fossils with the aim of including them into modern systematic frameworks.

Review: Freshwater and Soil Foraminifera – A Story of Long-Forgotten Relatives

2021 ◽  
Vol 51 (4) ◽  
pp. 318-331
Author(s):  
Maria Holzmann ◽  
Andrew J. Gooday ◽  
Ferry Siemensma ◽  
Jan Pawlowski
Keyword(s):  
Fossil Record ◽  
Phylogenetic Analyses ◽  
Molecular Data ◽  
Complex Environments ◽  
Molecular Phylogenetic ◽  
Terrestrial Habitats ◽  
Genomic Studies ◽  
Morphological And Molecular Data ◽  
Fresh Impetus ◽  
The 19Th Century

ABSTRACT Foraminifera are a primarily marine taxon widespread in all oceanic habitats, from shallow, brackish-water settings to deep-seafloor and pelagic realms. Their diversity is remarkable with several thousand species described and a fossil record tracing back to the Cambrian. While foraminifera represent one of the best-studied groups of marine meiofauna, much less is known about their non-marine relatives. The first freshwater foraminifera were described in the 19th century by European and North American protozoologists, but interest in them lapsed during much of the 20th century and was not rekindled until the advent of molecular systematics provided a fresh impetus to their study. Several new species, genera, and families have been described recently based on morphological and molecular data derived from cultured specimens. In parallel, environmental genomic studies revealed that foraminifera are highly diverse and ubiquitous in freshwater and soil environments. Molecular phylogenetic analyses places non-marine foraminifera in a few clades among the large array of single-chambered (monothalamous) lineages, suggesting that several independent colonization events of freshwater and terrestrial habitats occurred. Non-marine foraminifera are turning from obscure curiosities to being recognized as an important part of soil and freshwater microbial communities, a major component of these complex environments.

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