The Temporal and Environmental Context of Early Animal Evolution: Considering All the Ingredients of an ‘Explosion’

Sperling, Erik A.

doi:10.1130/abs/2018am-317367

Cited by 5 publications

(7 citation statements)

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“…This observation in the White Sea area is consistent with a recent spatial analyses of~570 Ma old Ediacaran ecosystems on the Avalon Peninsula, overlapping with the White Sea area taxonomically, that showed that competition for resources was not the driving factor for local Ediacaran communities 44 . Unlike previously predicted 17,19,20 , bacteria-dominated ecosystems in Ediacaran marine basins were generally not a cause of the unusual appearance and ecology of the Ediacara biota. Rather, the ecological and evolutionary bridge leading from a mid-Proterozoic bacteria-dominated world to the appearance of Phanerozoic animal-dominated ecosystems was paved with algae-rich environments akin to those preferred by modern eumetazoan animals.…”

Section: Resultscontrasting

confidence: 73%

“…Based on the H/S data from global Ediacaran sediments, the Ediacara biota might have either inhabited newly established algae-rich environments 15,16 or, conversely, thrived in nutrientdepleted ecosystems dominated by bacterial primary productivity akin to the Tonian or Mesoproterozoic 17,20 . If latter hypothesis is correct, then the diet and ecology of organisms of the Ediacara biota must have been very distinct from most Phanerozoic animals 17,19,20 , and it would invalidate the premise that the emergence of abundant algal food sources was crucial for the ecological success of eumetazoan animals. Biomarker data from sediments directly associated with Ediacara biota fossils can shed light on this dispute.…”

Section: Resultsmentioning

confidence: 99%

“…Recent studies have reported biomarkers from Ediacaran sediments of the East European Platform (EEP) with H/S ratios that are high relative to typical Phanerozoic marine conditions 17,18 . Consequently, it has been suggested that Ediacaran macroorganisms preferentially inhabited oligotrophic environments and used bacteria as their main energy source, as either food or symbionts 17,[19][20][21] . It is notable, however, that none of the biomarker data came from localities that preserve Ediacaran macrofossils (Fig.…”

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confidence: 99%

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Food sources for the Ediacara biota communities

et al. 2020

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The Ediacara biota represents the first complex macroscopic organisms in the geological record, foreshadowing the radiation of eumetazoan animals in the Cambrian explosion. However, little is known about the contingencies that lead to their emergence, including the possible roles of nutrient availability and the quality of food sources. Here we present information on primary producers in the Ediacaran based on biomarker molecules that were extracted from sediments hosting Ediacaran macrofossils. High relative abundances of algal steranes over bacterial hopanes suggest that the Ediacara biota inhabited nutrient replete environments with an abundance of algal food sources comparable to Phanerozoic ecosystems. Thus, organisms of the Ediacara biota inhabited nutrient-rich environments akin to those that later fuelled the Cambrian explosion.

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Section: Resultscontrasting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Food sources for the Ediacara biota communities

et al. 2020

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“…Aspects of this event are discussed in a continuing stream of papers but a few points are relevant for this discussion. Molecular clock estimates indicate lags of tens to hundreds of millions of years between the origin of many of the metazoan clades and their appearance in the fossil record (Erwin et al ., 2011; dos Reis et al ., 2015; Sperling & Stockey, 2018). Many of the critical developmental novelties for the origin and early diversification of Metazoa arose in close sister groups or at the base of the clade (Tweedt & Erwin, 2015; Sebe‐Pedros et al ., 2016, 2018; Grau‐Bove et al ., 2017).…”

Section: Applicationsmentioning

confidence: 99%

A conceptual framework of evolutionary novelty and innovation

Erwin

2020

Biological Reviews

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Since 1990 the recognition of deep homologies among metazoan developmental processes and the spread of more mechanistic approaches to developmental biology have led to a resurgence of interest in evolutionary novelty and innovation. Other evolutionary biologists have proposed central roles for behaviour and phenotypic plasticity in generating the conditions for the construction of novel morphologies, or invoked the accessibility of new regions of vast sequence spaces. These approaches contrast with more traditional emphasis on the exploitation of ecological opportunities as the primary source of novelty. This definitional cornucopia reflects differing stress placed on three attributes of novelties: their radical nature, the generation of new taxa, and ecological and evolutionary impact. Such different emphasis has led to conflating four distinct issues: the origin of novel attributes (genes, developmental processes, phenotypic characters), new functions, higher clades and the ecological impact of new structures and functions. Here I distinguish novelty (the origin of new characters, deep character transformations, or new combinations) from innovation, the ecological and evolutionary success of clades. Evidence from the fossil record of macroevolutionary lags between the origin of a novelty and its ecological success demonstrates that novelty may be decoupled from innovation, and only definitions of novelty based on radicality (rather than generativity or consequentiality) can be assessed without reference to the subsequent history of the clade to which a novelty belongs. These considerations suggest a conceptual framework for novelty and innovation, involving: (i) generation of the potential for novelty; (ii) the formation of novel attributes; (iii) refinement of novelties through adaptation; (iv) exploitation of novelties by a clade, which may coincide with a new round of ecological or environmental potentiation; followed by (v) the establishment of innovations through ecological processes. This framework recognizes that there is little empirical support for either the dominance of ecological opportunity, nor abrupt discontinuities (often caricatured as ‘hopeful monsters’). This general framework may be extended to aspects of cultural and social innovation.

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“…The fossil record of complex, macroscopic community-forming organisms, including animals, begins with the Ediacara Biota (570–539 Ma). Molecular clock estimates suggest that major metazoan phyla and their constituent clades evolved prior to this period [ 1 – 4 ]; however, phylogenetic affinities for most of the Ediacara Biota remain enigmatic [ 5 ]. Potential explanations for this phylogenetic uncertainty include the simplicity of early animal forms, preservational biases, and lags between character acquisition and ecological success (e.g.…”

Section: Introductionmentioning

confidence: 99%

Developmental processes in Ediacara macrofossils

2021

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The Ediacara Biota preserves the oldest fossil evidence of abundant, complex metazoans. Despite their significance, assigning individual taxa to specific phylogenetic groups has proved problematic. To better understand these forms, we identify developmentally controlled characters in representative taxa from the Ediacaran White Sea assemblage and compare them with the regulatory tools underlying similar traits in modern organisms. This analysis demonstrates that the genetic pathways for multicellularity, axial polarity, musculature, and a nervous system were likely present in some of these early animals. Equally meaningful is the absence of evidence for major differentiation of macroscopic body units, including distinct organs, localized sensory machinery or appendages. Together these traits help to better constrain the phylogenetic position of several key Ediacara taxa and inform our views of early metazoan evolution. An apparent lack of heads with concentrated sensory machinery or ventral nerve cords in such taxa supports the hypothesis that these evolved independently in disparate bilaterian clades.

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The Temporal and Environmental Context of Early Animal Evolution: Considering All the Ingredients of an ‘Explosion’

Cited by 5 publications

References 0 publications

Food sources for the Ediacara biota communities

Food sources for the Ediacara biota communities

A conceptual framework of evolutionary novelty and innovation

Developmental processes in Ediacara macrofossils

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