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Fig. 17.4 in Chapter 17: Gigantism, Dwarfism, and Cope's Rule: "Nothing in Evolution Makes Sense without a Phylogeny"

Fig. 17.4. Left, phylogeny of the Equidae, with emphasis on the North American record. Right, temporal distribution of the Equidae, with relative size indicated by skull length derived from toothlength dimensions (see appendix 17.2 and methodology discussion in text). Branches indicated by A, B, and C represent bodysize increase (giantism); D, E, F, and G represent bodysize decrease (nanism).

Fig. 17.2 in Chapter 17: Gigantism, Dwarfism, and Cope's Rule: "Nothing in Evolution Makes Sense without a Phylogeny"

Fig. 17.2. (a) The most recent phylogenetic hypothesis of varanid relationships based on mtDNA (Ast, 2001) compared to (b) a compilation of the hypotheses of bodysize evolution of varanids (taken from Pianka, 1995). The maximum total lengths for the species were retrieved from King and Green, 1999, and Mertens, 1942; these are listed in appendix 17.1. Note the following terminal clades were collapsed for the sake of brevity: Varanus salvator togianus, V. salvator bivittatus, V. indicus, and V. panoptes (horni).

Fig. 17.3 in Chapter 17: Gigantism, Dwarfism, and Cope's Rule: "Nothing in Evolution Makes Sense without a Phylogeny"

Fig. 17.3. Patterns of bodysize evolution in fossil horses from North America, based on MacFadden (1987; modified figure reproduced in MacFadden, 1992). Reproduced with permission of Cambridge University Press.

Fig. 17.1 in Chapter 17: Gigantism, Dwarfism, and Cope's Rule: "Nothing in Evolution Makes Sense without a Phylogeny"

Fig. 17.1. Threetaxon statements illustrating the four kinds of bodysize change discussed in the text.

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Fig. 17.5 in Chapter 17: Gigantism, Dwarfism, and Cope's Rule: "Nothing in Evolution Makes Sense without a Phylogeny"

Fig. 17.5. Three examples of bodysize evo

opencc-zeroJul 2019View details →

Data from: Cope's Rule in a modular organism: directional evolution without an overarching macroevolutionary trend

Cope's Rule describes increasing body size in evolutionary lineages through geological time. This pattern has been documented in unitary organisms but does it also apply to module size in colonial organisms? We address this using 1169 cheilostome bryozoans ranging through the entire 150 million years of their evolutionary history. The temporal pattern evident in cheilostomes as a whole shows no overall change in zooid (module) size. However, individual subclades show size increases: within a genus, younger species often have larger zooids than older species. Analyses of (paleo)latitudinal shifts show that this pattern cannot be explained by latitudinal effects (Bergmann's Rule) coupled with younger species occupying higher latitudes than older species (an 'out of the tropics' hypothesis). While it is plausible that size increase was linked to the advantages of large zooids in feeding, competition for trophic resources and living space, other proposed mechanisms for Cope's Rule in unitary organisms are either inapplicable to cheilostome zooid size or cannot be easily evaluated. Patterns and mechanisms in colonial organisms cannot and should not be extrapolated from the better-studied unitary organisms. And even if macroevolution simply comprises repeated rounds of microevolution, evolutionary processes occurring with lineages are not always detectable from macroevolutionary patterns.

opencc-zeroDec 2016View details →

Data from: Body size evolution in an old insect order: no evidence for Cope's Rule in spite of fitness benefits of large size

We integrate field data and phylogenetic comparative analyses to investigate causes of body size evolution and stasis in an old insect order: odonates ("dragonflies and damselflies"). Fossil evidence for "Cope's Rule" in odonates is weak or non-existent since the last major extinction event 65 million years ago, yet selection studies show consistent positive selection for increased body size among adults. In particular, we find that large males in natural populations of the banded demoiselle (Calopteryx splendens) over several generations have consistent fitness benefits both in terms of survival and mating success. Additionally, there was no evidence for stabilizing or conflicting selection between fitness components within the adult life-stage. This lack of stabilizing selection during the adult life-stage was independently supported by a literature survey on different male and female fitness components from several odonate species. We did detect several significant body size shifts among extant taxa using comparative methods and a large new molecular phylogeny for odonates . We suggest that the lack of Cope's rule in odonates results from conflicting selection between fitness advantages of large adult size and costs of long larval development. We also discuss competing explanations for body size stasis in this insect group.

opencc-zeroDec 2014View details →

Data from: Cope's rule and the universal scaling law of ornament complexity

Luxuriant, bushy antlers, bizarre crests, and huge, twisting horns and tusks are conventionally understood as products of sexual selection. This view stems from both direct observation and from the empirical finding that the size of these structures grows faster than body size (i.e., ornament size shows positive allometry). We contend that the familiar evolutionary increase in the complexity of ornaments over time in many animal clades is decoupled from ornament size evolution. Increased body size comes with extended growth. Since growth scales to the quarter power of body size, we predicted that ornament complexity should scale according to the quarter power law as well, irrespective of the role of sexual selection in the evolution and function of the ornament. To test this hypothesis, we selected three clades (ammonites, deer, and ceratopsian dinosaurs) whose species bore ornaments that differ in terms of the importance of sexual selection to their evolution. We found that the exponent of the regression of ornament complexity to body size is the same for the three groups and is statistically indistinguishable from 0.25. We suggest that the evolution of ornament complexity is a by-product of Cope's rule. We argue that although sexual selection may control size in most ornaments, it does not influence their shape.

publicMar 2015View details →

Data from: Cope’s rule and the universal scaling law of ornament complexity

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publicJul 2017View details →

Data from: Body size evolution in an old insect order: no evidence for Cope’s Rule in spite of fitness benefits of large size

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publicOct 2011View details →

Data from: Ecological specialization in fossil mammals explains Cope's rule

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publicJul 2019View details →

Data from: Cope’s Rule in a modular organism: directional evolution without an overarching macroevolutionary trend

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opencc-zeroDec 2015View details →

Data from: Ornament complexity is correlated with sexual selection: (a comment on Raia et al., "Cope's rule and the universal scaling law of ornament complexity")

Raia et al. propose that the evolution of the shape and complexity of animal ornaments (e.g., deer antlers) can be explained by interspecific variation in body size and is not influenced by sexual selection. They claim to show that ornament complexity is related to body size by an 0.25-power law and argue that this finding precludes a role for sexual selection in the evolution of ornament complexity. However, their study does not test alternative hypotheses and mismeasures antler shape allometry by omitting much of the published data. We show that an index of sexual selection (sexual size dimorphism) is positively correlated with size-corrected antler complexity and that the allometric slope of complexity is substantially greater than 0.25, contra Raia et al. We conclude that sexual selection and physical constraints both affect the evolution of antler shape.

opencc-zeroDec 2016View details →

Data from: Cope's rule and the adaptive landscape of dinosaur body size evolution

The largest known dinosaurs weighed at least 20 million times as much as the smallest, indicating exceptional phenotypic divergence. Previous studies have focused on extreme giant sizes, tests of Cope's rule, and miniaturization on the line leading to birds. We use non-uniform macroevolutionary models based on Ornstein–Uhlenbeck and trend processes to unify these observations, asking: what patterns of evolutionary rates, directionality and constraint explain the diversification of dinosaur body mass? We find that dinosaur evolution is constrained by attraction to discrete body size optima that undergo rare, but abrupt, evolutionary shifts. This model explains both the rarity of multi-lineage directional trends, and the occurrence of abrupt directional excursions during the origins of groups such as tiny pygostylian birds and giant sauropods. Most expansion of trait space results from rare, constraint-breaking innovations in just a small number of lineages. These lineages shifted rapidly into novel regions of trait space, occasionally to small sizes, but most often to large or giant sizes. As with Cenozoic mammals, intermediate body sizes were typically attained only transiently by lineages on a trajectory from small to large size. This demonstrates that bimodality in the macroevolutionary adaptive landscape for land vertebrates has existed for more than 200 million years.

publicAug 2018View details →

Data from: Cope’s rule and the adaptive landscape of dinosaur body size evolution

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publicApr 2016View details →

Data from: Ornament complexity is correlated with sexual selection: (a comment on Raia et al., "Cope's rule and the universal scaling law of ornament complexity")

Open the record for dataset details and reuse information.