Body size, ecological dominance and Cope's rule

Nature ◽  
1986 ◽  
Vol 324 (6094) ◽  
pp. 248-250 ◽  
Author(s):  
James H. Brown ◽  
Brian A. Maurer
Evolution ◽  
2014 ◽  
Vol 69 (1) ◽  
pp. 201-215 ◽  
Author(s):  
Morgan Churchill ◽  
Mark T. Clementz ◽  
Naoki Kohno
Keyword(s):  

2009 ◽  
Vol 6 (2) ◽  
pp. 265-269 ◽  
Author(s):  
James C. Lamsdell ◽  
Simon J. Braddy

Gigantism is widespread among Palaeozoic arthropods, yet causal mechanisms, particularly the role of (abiotic) environmental factors versus (biotic) competition, remain unknown. The eurypterids (Arthropoda: Chelicerata) include the largest arthropods; gigantic predatory pterygotids (Eurypterina) during the Siluro-Devonian and bizarre sweep-feeding hibbertopterids (Stylonurina) from the Carboniferous to end-Permian. Analysis of family-level originations and extinctions among eurypterids and Palaeozoic vertebrates show that the diversity of Eurypterina waned during the Devonian, while the Placodermi radiated, yet Stylonurina remained relatively unaffected; adopting a sweep-feeding strategy they maintained their large body size by avoiding competition, and persisted throughout the Late Palaeozoic while the predatory nektonic Eurypterina (including the giant pterygotids) declined during the Devonian, possibly out-competed by other predators including jawed vertebrates.


Nature ◽  
1987 ◽  
Vol 328 (6126) ◽  
pp. 117-118 ◽  
Author(s):  
DAVID GRIFFITHS

Paleobiology ◽  
2008 ◽  
Vol 34 (3) ◽  
pp. 342-359 ◽  
Author(s):  
Seth Finnegan ◽  
Mary L. Droser

Major shifts in ecological dominance are one of the most conspicuous but poorly understood features of the fossil record. Here we examine one of the most prominent such shifts, the Ordovician shift from trilobite to brachiopod dominance of benthic ecosystems. Using an integrated database of high-resolution paleoecological samples and body size data, we show that while the average local richness and relative abundance of trilobites declined significantly through the Ordovician, the estimated standing biomass of trilobites, and by implication the amount of energy that they used, remained relatively invariant. This is attributable to an increase in the average body size of trilobite species in our data set, and especially to the widespread occurrence of the exceptionally large Middle-Late Ordovician trilobite genus Isotelus. Brachiopods increase in both mean body size and relative abundance throughout the Ordovician, so that estimates of brachiopod biomass and energetic use increase substantially between the Early and Late Ordovician. Although the data set includes a range of depositional environments, similar trends are observed in both shallow subtidal and deep subtidal settings. These results suggest that diversification of the Paleozoic Fauna did not come at the energetic expense of the Cambrian Fauna. The declining relative abundance of trilobites may reflect a combination of numerical dilution and the necessary energetic trade-offs between body size and abundance.


2014 ◽  
Vol 281 (1783) ◽  
pp. 20133122 ◽  
Author(s):  
Jonathan L. Payne ◽  
Noel A. Heim ◽  
Matthew L. Knope ◽  
Craig R. McClain

Brachiopods and bivalves feed in similar ways and have occupied the same environments through geological time, but brachiopods were far more diverse and abundant in the Palaeozoic whereas bivalves dominate the post-Palaeozoic, suggesting a transition in ecological dominance 250 Ma. However, diversity and abundance data alone may not adequately describe key changes in ecosystem function, such as metabolic activity. Here, we use newly compiled body size data for 6066 genera of bivalves and brachiopods to calculate metabolic rates and revisit this question from the perspective of energy use, finding that bivalves already accounted for a larger share of metabolic activity in Palaeozoic oceans. We also find that the metabolic activity of bivalves has increased by more than two orders of magnitude over this interval, whereas brachiopod metabolic activity has declined by more than 50%. Consequently, the increase in bivalve energy metabolism must have occurred via the acquisition of new food resources rather than through the displacement of brachiopods. The canonical view of a mid-Phanerozoic transition from brachiopod to bivalve dominance results from a focus on taxonomic diversity and numerical abundance as measures of ecological importance. From a metabolic perspective, the oceans have always belonged to the clams.


2019 ◽  
Author(s):  
Indrė Žliobaitė ◽  
Mikael Fortelius

AbstractThe Red Queen’s hypothesis portrays evolution as a never-ending competition for expansive energy, where one species’ gain is another species’ loss. The Red Queen is neutral with respect to body size, implying that neither small nor large species have a universal competitive advantage. The maximum population growth in ecology; however, clearly depends on body size – the smaller the species, the shorter the generation length, and the faster it can expand. Here we ask whether, and if so how, the Red Queen’s hypothesis can accommodate a spectrum of body sizes. We theoretically analyse scaling of expansive energy with body mass and demonstrate that in the Red Queen’s zero-sum game for resources, neither small nor large species have a universal evolutionary advantage. We argue that smaller species have an evolutionary advantage only when resources in the environment are not fully occupied, such as after mass extinctions or following key innovations allowing expansion into freed up or previously unoccupied resource space. Under such circumstances, we claim, generation length is the main limiting factor for population growth. When competition for resources is weak, smaller species can indeed expand faster, but to sustain this growth they also need more resources. In the Red Queen’s realm, where resources are fully occupied and the only way for expansion is to outcompete other species, acquisition of expansive energy becomes the limiting factor and small species lose their physiological advantage. A gradual transition from unlimited resources to a zero-sum game offers a direct mechanistic explanation for observed body mass trends in the fossil record, known as Cope’s Rule. When the system is far from the limit of resources and competition is not maximally intense, small species take up ecological space faster. When the system approaches the limits of its carrying capacity and competition tightens, small species lose their evolutionary advantage and we observe a wider range of successful body masses, and, as a result, an increase in the average body mass within lineages.


2016 ◽  
Author(s):  
Richard C. Tillquist ◽  
Lauren G. Shoemaker ◽  
Kevin Bracy Knight ◽  
Aaron Clauset

Body size is a key physiological, ecological, and evolutionary characteristic of species. Within most major clades, body size distributions follow a right-skewed pattern where most species are relatively small while a few are orders of magnitude larger than the median size. Using a novel database of 742 extant and extinct primate species’ sizes over the past 66 million years, we find that primates exhibit the opposite pattern: a left-skewed distribution. We investigate the long-term evolution of this distribution, first showing that the initial size radiation is consistent with plesiadapiformes (an extinct group with an uncertain ancestral relationship to primates) being ancestral to modern primates. We calculate the strength of Cope’s Rule, showing an initial tendency for descendants to increase in size relative to ancestors until the trend reverses 40 million years ago. We explore when the primate size distribution becomes left-skewed and study correlations between body size patterns and climactic trends, showing that across Old and New World radiations the body size distribution initially exhibits a right-skewed pattern. Left-skewness emerged early in Old World primates in a manner consistent with a previously unidentified possible maximum body size, which may be mechanistically related to primates’ encephalization and complex social groups.


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