Origins and Early Evolution of Predation

2002 ◽  
Vol 8 ◽  
pp. 289-318 ◽  
Author(s):  
Stefan Bengtson
Keyword(s):  
Fossil Record ◽  
Cambrian Explosion ◽  
Major Transitions ◽  
Microbial Ecosystems ◽  
Life Itself ◽  
Evolutionary Event ◽  
History Of ◽  
Ultimate Result ◽  
Major Transitions In Evolution ◽  
Theoretical Considerations

Predation, in the broad sense of an organism killing another organism for nutritional purposes, is probably as old as life itself and has originated many times during the history of life. Although little of the beginnings is caught in the fossil record, observations in the rock record and theoretical considerations suggest that predation played a crucial role in some of the major transitions in evolution. The origin of eukaryotic cells, poorly constrained to about 2.7 Ga by geochemical evidence, was most likely the ultimate result of predation among prokaryotes. Multicellularity (or syncytiality), as a means of acquiring larger size, is visible in the fossil record soon after 2 Ga and is likely to have been mainly a response to selective pressure from predation among protists. The appearance of mobile predators on bacteria and protists may date back as far as 2 Ga or it may be not much older than the Cambrian explosion, or about 600 Ma. The combined indications from the decline of stromatolites and the diversification of acritarchs, however, suggest that such predation may have begun around 1 Ga. The Cambrian explosion, culminating around 550 Ma, represents the transition from simple, mostly microbial, ecosystems to ones with complex food webs and second- and higher-order consumers. Macrophagous predators were involved from the beginning, but it is not clear whether they originated in the plankton or in the benthos. Although predation was a decisive selective force in the Cambrian explosion, it was a shaper rather than a trigger of this evolutionary event.

scholarly journals Darwin's dilemma: the realities of the Cambrian ‘explosion’

2006 ◽  
Vol 361 (1470) ◽  
pp. 1069-1083 ◽  
Author(s):  
Simon Conway Morris
Keyword(s):  
Fossil Record ◽  
Current Work ◽  
Cambrian Explosion ◽  
Molecular Clocks ◽  
Burgess Shale ◽  
Cause And Effect ◽  
Evolutionary Event ◽  
History Of ◽  
Wrong Sort

The Cambrian ‘explosion’ is widely regarded as one of the fulcrum points in the history of life, yet its origins and causes remain deeply controversial. New data from the fossil record, especially of Burgess Shale-type Lagerstätten, indicate, however, that the assembly of bodyplans is not only largely a Cambrian phenomenon, but can already be documented in fair detail. This speaks against a much more ancient origin of the metazoans, and current work is doing much to reconcile the apparent discrepancies between the fossil record, including the Ediacaran assemblages of latest Neoproterozoic age and molecular ‘clocks’. Hypotheses to explain the Cambrian ‘explosion’ continue to be generated, but the recurrent confusion of cause and effect suggests that the wrong sort of question is being asked. Here I propose that despite its step-like function this evolutionary event is the inevitable consequence of Earth and biospheric change.

The Major Transitions in Evolution

1997 ◽  
Author(s):  
John Maynard Smith ◽  
Eors Szathmary
Keyword(s):  
Full Range ◽  
Evolution Of Cooperation ◽  
Major Transitions ◽  
Insect Societies ◽  
Wide Range ◽  
Major Transition ◽  
Life Itself ◽  
History Of ◽  
Emergence Of Cooperation ◽  
Multicellular Organisms

Over the history of life there have been several major changes in the way genetic information is organized and transmitted from one generation to the next. These transitions include the origin of life itself, the first eukaryotic cells, reproduction by sexual means, the appearance of multicellular plants and animals, the emergence of cooperation and of animal societies, and the unique language ability of humans. This ambitious book provides the first unified discussion of the full range of these transitions. The authors highlight the similarities between different transitions--between the union of replicating molecules to form chromosomes and of cells to form multicellular organisms, for example--and show how understanding one transition sheds light on others. They trace a common theme throughout the history of evolution: after a major transition some entities lose the ability to replicate independently, becoming able to reproduce only as part of a larger whole. The authors investigate this pattern and why selection between entities at a lower level does not disrupt selection at more complex levels. Their explanation encompasses a compelling theory of the evolution of cooperation at all levels of complexity. Engagingly written and filled with numerous illustrations, this book can be read with enjoyment by anyone with an undergraduate training in biology. It is ideal for advanced discussion groups on evolution and includes accessible discussions of a wide range of topics, from molecular biology and linguistics to insect societies.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

scholarly journals The origin and early radiation of terrestrial vertebrates

2001 ◽  
Vol 75 (6) ◽  
pp. 1202-1213 ◽  
Author(s):  
Robert L. Carroll
Keyword(s):  
Fossil Record ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Lower Carboniferous ◽  
Major Transitions ◽  
Terrestrial Vertebrates ◽  
History Of ◽  
Paleozoic Tetrapods ◽  
Early Radiation ◽  
Ways Of Life

The origin of tetrapods from sarcopterygian fish in the Late Devonian is one of the best known major transitions in the history of vertebrates. Unfortunately, extensive gaps in the fossil record of the Lower Carboniferous and Triassic make it very difficult to establish the nature of relationships among Paleozoic tetrapods, or their specific affinities with modern amphibians. The major lineages of Paleozoic labyrinthodonts and lepospondyls are not adequately known until after a 20–30 m.y. gap in the Early Carboniferous fossil record, by which time they were highly divergent in anatomy, ways of life, and patterns of development. An even wider temporal and morphological gap separates modern amphibians from any plausible Permo-Carboniferous ancestors. The oldest known caecilian shows numerous synapomorphies with the lepospondyl microsaur Rhynchonkos. Adult anatomy and patterns of development in frogs and salamanders support their origin from different families of dissorophoid labyrinthodonts. The ancestry of amniotes apparently lies among very early anthracosaurs.

Theoretical diversity of the marine biosphere

Paleobiology ◽  
2010 ◽  
Vol 36 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Michał Kowalewski ◽  
Seth Finnegan
Keyword(s):  
Empirical Data ◽  
Fossil Record ◽  
Empirical Studies ◽  
Geological History ◽  
Empirical Knowledge ◽  
Primary Target ◽  
History Of ◽  
Global Biodiversity ◽  
Theoretical Considerations ◽  
Marine Biosphere

In considering the history of biodiversity paleontologists have focused on exploratory investigations of empirical data derived from the fossil record. Starting with the pioneering work of Philips (1860), and continuing at an increasing pace through today, this inductive approach has dominated diversity research. In contrast, deductive theoretical considerations that focus on the expected history of biodiversity, and develop independently of empirical knowledge, have remained under-explored. Appreciating the need for a nomothetic paleobiology (Gould 1980), we here reconsider the history of biodiversity, using deductive models constrained by a few, self-evident parameters. This analysis centers on the marine fossil record, the primary target of most previous empirical studies on the geological history of global biodiversity (e.g., Valentine 1969; Raup 1972, 1976; Sepkoski et al. 1981; Alroy et al. 2008).

Ontogeny in the fossil record: diversification of body plans and the evolution of “aberrant” symmetry in Paleozoic echinoderms

Paleobiology ◽  
2007 ◽  
Vol 33 (1) ◽  
pp. 149-163 ◽  
Author(s):  
Colin D. Sumrall ◽  
Gregory A. Wray
Keyword(s):  
Great Reduction ◽  
Fossil Record ◽  
Evolutionary History ◽  
Total Loss ◽  
Cambrian Explosion ◽  
Growth Stages ◽  
Ecological Constraints ◽  
Fivefold Symmetry ◽  
Primary Body ◽  
History Of

Echinoderms have long been characterized by the presence of ambulacra that exhibit pentaradiate symmetry and define five primary body axes. In reality, truly pentaradial ambulacral symmetry is a condition derived only once in the evolutionary history of echinoderms and is restricted to eleutherozoans, the clade that contains most living echinoderm species. In contrast, early echinoderms have a bilaterally symmetrical 2-1-2 arrangement, with three ambulacra radiating from the mouth. Branching of the two side ambulacra during ontogeny produces the five adult rays. During the Cambrian Explosion and Ordovician Radiation, some 30 clades of echinoderms evolved, many of which have aberrant ambulacral systems with one to four rays. Unfortunately, no underlying model has emerged that explains ambulacral homologies among disparate forms. Here we show that most Paleozoic echinoderms are characterized by uniquely identifiable ambulacra that develop in three distinct postlarval stages. Nearly all “aberrant” echinoderm morphologies can be explained by the paedomorphic ambulacra reduction (PAR) model through the loss of some combination of these growth stages during ontogeny. Superficially similar patterns of ambulacral reduction in distantly related clades have resulted from the parallel loss of homologous ambulacra during ontogeny. Pseudo-fivefold symmetry seen in Blastoidea and the true fivefold symmetry seen in Eleutherozoa result from great reduction and total loss, respectively, of the 2–1–2 symmetry early in ontogeny. These ambulacral variations suggest that both developmental and ecological constraints affect the evolution of novel echinoderm body plans.

scholarly journals Enduring evolutionary embellishment of cloudinids in the Cambrian

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Tae-Yoon S. Park ◽  
Jikhan Jung ◽  
Mirinae Lee ◽  
Sangmin Lee ◽  
Yong Yi Zhen ◽  
...  
Keyword(s):  
Asexual Reproduction ◽  
Fossil Record ◽  
Evolutionary History ◽  
Structural Complexity ◽  
Cambrian Explosion ◽  
Animal Group ◽  
Reproduction Mode ◽  
First Case ◽  
History Of ◽  
Mode Tracking

The Ediacaran–Cambrian transition and the following Cambrian Explosion are among the most fundamental events in the evolutionary history of animals. Understanding these events is enhanced when phylogenetic linkages can be established among animal fossils across this interval and their trait evolution monitored. Doing this is challenging because the fossil record of animal lineages that span this transition is sparse, preserved morphologies generally simple and lifestyles in the Ediacaran and Cambrian commonly quite different. Here, we identify derived characters linking some members of an enigmatic animal group, the cloudinids, which first appeared in the Late Ediacaran, to animals with cnidarian affinity from the Cambrian Series 2 and the Miaolingian. Accordingly, we present the first case of an animal lineage represented in the Ediacaran that endured and diversified successfully throughout the Cambrian Explosion by embellishing its overall robustness and structural complexity. Among other features, dichotomous branching, present in some early cloudinids, compares closely with a cnidarian asexual reproduction mode. Tracking this morphological change from Late Ediacaran to the Miaolingian provides a unique glimpse into how a primeval animal group responded during the Cambrian Explosion.

scholarly journals The evolution of diversity in ancient ecosystems: a review

1998 ◽  
Vol 353 (1366) ◽  
pp. 327-345 ◽  
Author(s):  
S. Conway Morris
Keyword(s):  
Fossil Record ◽  
Molecular Data ◽  
Cambrian Explosion ◽  
Mass Extinctions ◽  
Geological Time ◽  
Biological Communities ◽  
History Of ◽  
Lag Times ◽  
Extinction Events ◽  
Ancient Ecosystems

On a perfect planet, such as might be acceptable to a physicist, one might predict that from its origin the diversity of life would grow exponentially until the carrying capacity, however defined, was reached. The fossil record of the Earth, however, tells a very different story. One of the most striking aspects of this record is the apparent evolutionary longueur, marked by the Precambrian record of prokaryotes and primitive eukaryotes, although our estimates of microbial diversity may be seriously incomplete. Subsequently there were various dramatic increases in diversity, including the Cambrian ‘explosion’ and the radiation of Palaeozoic–style faunas in the Ordovician. The causes of these events are far from resolved. It has also long been appreciated that the history of diversity has been punctuated by important extinctions. The subtleties and nuances of extinction as well as the survival of particular clades have to date, however, received rather too little attention, and there is still a tendency towards blanket assertions rather than a dissection of these extraordinary events. In addition, some but perhaps not all mass extinctions are characterized by long lag–times of recovery, which may reflect the slowing waning of extrinsic forcing factors or alternatively the incoherence associated with biological reassembly of stable ecosystems. The intervening periods between the identified mass extinctions may be less stable and benign than popularly thought, and in particular the frequency of extraterrestrial impacts leads to predictions of recurrent disturbance on timescales significantly shorter than the intervals separating the largest extinction events. Even at times of quietude it is far from clear whether biological communities enjoy stability and interlocked stasis or are dynamically reconstituted at regular intervals. Finally, can we yet rely on the present depictions of the rise and falls in the levels of ancient diversity? Existing data is almost entirely based on Linnean taxa, and the application of phylogenetic systematics to this problem is still in its infancy. Not only that, but even more intriguingly the pronounced divergence in estimates of origination times of groups as diverse as angiosperms, diatoms and mammals in terms of the fossil record as against molecular data point to the possibilities of protracted intervals of geological time with a cryptic diversity. If this is correct, and there are alternative explanations, then some of the mystery of adaptive radiations may be dispelled, in as much as the assembly of key features in the stem groups could be placed in a gradualistic framework of local adaptive response punctuated by intervals of opportunity.

The age of symbolic economic policies?

2015 ◽  
Vol 37 (2) ◽  
pp. 245-265
Author(s):  
Peter Galbács
Keyword(s):  
Economic Policy ◽  
Theoretical Framework ◽  
Policy Tools ◽  
Economic Policies ◽  
Mainstream Economics ◽  
History Of ◽  
Theoretical Considerations ◽  
Macroeconomic Environment

This paper offers a few remarks on the so-called heterodoxy commentaries of recent times (e.g. Bod 2013, Csaba 2011). In accordance with the growing popularity of unusual economic policy actions, a set of “tools” is emerging that aims to exert its effects breaking with instrumental actions. Outlining a special framework of the history of mainstream economics, it will be argued that economic policy only gradually has become capable of applying this system. In our view, both the emergence of symbolic economic policies mentioned above and the rise of heterodoxy are on the same level, since certain governments can only operate through giving signals. Although it is not the time to formulate ultimate and eternal generalised statements, it may perhaps be stated that symbolic economic policies can make some room for manoeuvring available as a last resort. In other words, the possibility of a certain kind of economic policy “tools” can be derived from theoretical considerations, and this set has become highlighted recently by some constraining changes in the macroeconomic environment. Our theoretical framework will be filled sporadically with some episodes from the last few years of the economic policy of Hungary.

Missing Links in the History of Life

2002 ◽  
Vol 11 ◽  
pp. 97-118
Author(s):  
Charles R. Marshall
Keyword(s):  
Evolutionary Theory ◽  
Fossil Record ◽  
Theory Of Evolution ◽  
History Of ◽  
Living Species

Ever since Darwin proposed his theory of evolution (or more correctly, theories; see Mayr, 1991) it has been assumed that intermediates now extinct once existed between living species. For some, the hunt for these so-called missing links in the fossil record became an obsession, a search for evidence thought needed to establish the veracity of evolutionary theory. Few modern paleontologists, however, search explicitly for ancestors in the fossil record because we now know that fossils can be used to chart the order of evolution regardless of whether they are directly ancestral either to extinct organisms or to those living today.

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