Describing patterns of connectivity among organs is essential for identifying anatomical homologies among taxa. It is also critical for revealing morphogenetic processes and the associated constraints that control the morphological diversification of clades. This is particularly relevant for studies of organisms with skeletons made of discrete elements such as arthropods, vertebrates, and echinoderms. Nonetheless, relatively few studies devoted to morphological disparity have considered connectivity patterns as a level of morphological organization or developed comparative frameworks with proper tools. Here, we analyze connectivity patterns among apical plates in Atelostomata, the most diversified clade among irregular echinoids. The clade comprises approximately 1600 fossil and Recent species (e.g., 25% of post-Paleozoic species of echinoids) and shows high levels of morphological disparity. Plate connectivity patterns were analyzed using tools and statistics of graph theory. To describe and explore the diversity of connectivity patterns among plates, we symbolized each pattern as a graph in which plates are coded as nodes that are connected pairwise by edges. We then generated a comparative framework as a morphospace of connections, in which the disparity of plate patterns observed in nature was mapped and analyzed. Main results show that apical plate patterns are both highly disparate between and within atelostomate groups and limited in number; overall, they also constitute small, compact, and simple structures compared to possible random patterns. Main traits of the evolution of apical plate patterns reveal the existence of strong morphogenetic constraints that are phylogenetically determined. In contrast, evolutionary radiations within atelostomates were accompanied by a clear increase in disparity, suggesting a release of some constraints at the origin of clades.

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We have devised a simple model for assessing the role of development in shaping the evolution of morphological disparity. Disparity of a clade at any given time is expressed in terms of the developmental dynamics that lead to the variety of adult morphotypes observed. We use assumed phenotypic manifestations of developmental processes, as they could be detected from allometric characterizations, to distinguish a few, nonexclusive types of evolutionary changes in ontogeny. On the basis of this formalization, we describe the diversification of hypothetical clades, using the standard curve of adult morphological disparity, the curve of juvenile disparity, and the curve of allometric disparity, the latter quantifying the diversification of clades in allometric space. Contrasts of these curves reflect the underlying developmental scheme that drives temporal changes in disparity. We then vary the parameters of the model to assess the expected signature of each metric under specific conditions: changes in the relative frequencies of the types of evolutionary developmental changes, changes in the transition magnitude attached to each of them, and effects of temporal variation in average adult size on disparity curves and patterns of morphospace occupation. Results emphasize the potential contribution of these proxies for developmental dynamics—juvenile morphological disparity, allometric disparity, and average adult size—in enriching the interpretation of standard disparity curves and the description of clade histories, with possible process-oriented inferences.

Here, we advance novel uses of allometric spaces—multidimensional spaces specifically defined by allometric coefficients—with the goal of investigating the focal role of development in shaping the evolution of morphological disparity. From their examination, operational measures of allometric disparity can be derived, complementing standard signals of morphological disparity through an intuitive and process-oriented refinement of established analytical protocols used in disparity studies. Allometric spaces thereby become a promising context to reveal different patterns of evolutionary developmental changes and to assess their relative prevalence and importance. Such spaces offer a novel domain of investigation of phenotypic variation and should help in detecting large-scale trends, thus placing various macroevolutionary phenomena in an explicitly developmental context. Ammonoidea (Cephalopoda) at the Lower-Middle Jurassic transition were chosen as a case study to illustrate this methodological approach. We constructed two phenotypic spaces: a static, adult one (adult morphospace) and a dynamic, developmental one (allometric space). Comparative disparity analyses show a strikingly stable occupation in both spaces, despite extensive change in taxonomic composition. In contrast, disparity analyses of subclades reveal clearly distinct morphological and allometric disparity dynamics. Allometric approaches allow developmental insights into morphological diversification otherwise intractable from the analysis of adult morphospace alone.

For decades, theoretical morphological studies of different groups of organisms have been successfully pursued in biological, paleontological, and computational contexts, often with distinct modeling approaches and research questions. A regular influx of new perspectives and varied expertise has contributed to the emergence of a veritable multidisciplinary outlook for theoretical morphology. The broadening of this discipline is reflected in a substantial increase in the number of models, leading to a bewildering diversity that has yet to be scrutinized. In this work, we tackle this issue in a synthetic fashion, with a quantitative meta-analysis that allows an objective comparison of theoretical morphological models treated as entities. By analogy with empirical morphospace analyses of actual organisms, we performed a multivariate ordination of a representative sample of models, producing a metaspace of models in which patterns of similarity and difference are visualized. A phenetic tree was used to characterize the relationships between models. Four major groups have been identified, and their disparity analyzed. We suggest this typology as a useful starting point to identify a core set of fundamental principles and protocols for better interpretation of the plethora of current models and for more efficient construction of models in the future. This in turn can help in diversifying the scope of macroevolutionary, developmental, and bioenvironmental questions in theoretical morphology.

SUMMARY Two major research themes in Evolutionary Developmental Biology and in Paleobiology, respectively, have each become central for the analysis and interpretation of morphological changes in evolution: the study of ontogeny/phylogeny connections, mainly within the widespread and controversial framework of heterochrony; and the study of morphological disparity, the morphological signal of biodiversity, describing secular changes in morphospace occupation during the history of any given clade. Although enriching in their respective fields, these two themes have remained rather isolated to date, despite the potential value of integrating them as some recent studies begin to suggest. Here, we explore the recent notion of developmental morphospace—morphospace carrying ontogenetic information—as a potential tool for bridging the gap between disparity dynamics and developmental dynamics. We elaborate this approach with a case study of Early Jurassic ammonite family Hildoceratidae (Mollusca, Cephalopoda). Morphometric analyses of the shell shape of 20 species spanning the morphological spectrum of the family are used to quantify and contrast juvenile and adult disparity levels. Adult disparity is significantly greater than juvenile disparity at the family level; yet, some subclades also display different patterns. In addition, comparisons of ontogenetic trajectories underline the prevalence of heterochrony‐based evolutionary modifications within subfamilies (via ontogenetic scaling); they also point to the probable existence of pervasive developmental constraints structuring inhomogeneous morphospace occupation.

The analysis of morphological disparity and of morphospace occupation through the macroevolutionary history of clades is now a major research program in paleobiology, and increasingly so in organismal and comparative biology. Most studies have focused on the relationship between taxonomic diversity and morphological disparity, and on ecological or developmental controls. However, the geographic context of diversification has remained understudied. Here we address geography quantitatively. Diversity, disparity, and paleogeographic dispersion are used to describe the evolutionary history of an extinct echinoderm clade, the class Stylophora (cornutes, mitrates), from the Middle Cambrian to the Middle Devonian (about 128 Myr subdivided into 12 stratigraphic intervals). Taxonomic diversity is estimated from a representative sample including 73.3% of described species and 92.4% of described genera. Stylophoran morphology is quantified on the basis of seven morphometric parameters derived from image analysis of homologous skeletal regions. Three separate principal coordinates analyses (PCO) are performed for thecal outlines, plates from the lower thecal surface, and plates from the upper thecal surface, respectively. PCO scores from these three separate analyses are then used as variables for a single, global, meta-PCO. For each time interval, disparity is calculated as the sum of variance in the multidimensional morphospace defined by the meta-PCO axes. For each time interval, a semiquantitative index of paleogeographic dispersion is calculated, reflecting both global (continental) and local (regional) aspects of dispersion.Morphospace occupation of cornutes and mitrates is partly overlapping, suggesting some morphologic convergences between the two main stylophoran clades, probably correlated to similar modes of life (e.g., symmetrical cornutes and primitive mitrocystitids). Hierarchical clustering allowed the identification of three main morphological sets (subdivided into 11 subsets) within the global stylophoran morphospace. These morphological sets are used to analyze the spatiotemporal variations of disparity. The initial radiation of stylophorans is characterized by a low diversity and a rapid increase in disparity (Middle Cambrian-Tremadocian). The subsequent diversification involved filling and little expansion of morphospace (Arenig-Middle Ordovician). Finally, both stylophoran diversity and disparity decreased relatively steadily from the Late Ordovician to the Middle Devonian, with the exception of a second (lower) peak in the Early Devonian. Such a pattern is comparable to that of other Paleozoic marine invertebrates such as blastozoans and orthid brachiopods. During the Lower to Middle Ordovician, the most dramatic diversification of stylophorans took place with a paleogeographic dispersion essentially limited to the periphery of Gondwana. In the Late Ordovician, stylophorans steadily extended toward lower paleolatitudes, and new environmental conditions, where some of them radiated, and finally survived the end-Ordovician mass extinction (e.g., anomalocystitids). This pattern of paleobiogeographic dispersion is comparable to that of other examples of Paleozoic groups of marine invertebrates, such as bivalve mollusks.

1Interdisziplinäres Zentrum für Bioinformatik, Univers ität Leipzig 2Graduiertenkolleg Wissensrepräsentation, Universitä t Leipzig 3Lehrstuhl für Bioinformatik, Institut für Informatik, Universität Leipzig Kreuzstrasse 7b, D-04103 Leipzig, Germany 4 Centre National de la Recherche Scientifique, UMR 5561 Biog ́ eosciences, Université de Bourgogne, Dijon 21000, France 5 Institut für Theoretische Chemie und Molekulare Struktur biologie, Universität Wien Währingerstrasse 17, A-1090 Wien, Austria xtof@tbi.univie.ac.at

The large quantity and ready availability of developmental-genetic data. coupled with increased rigor and detail in the characterization of morphological phenotypes. has made the genotype-phenotype map of whole organisms a central challenge in evolutionary developmental biology. This in turn necessitates more general modeling strategies that can efficiently represent different types of biological knowledge and can be systematically applied across levels of organization. spatiotemporal scales. and taxonomic groups. Graph-based models appear useful in this context but have been remarkably underutilized in biology. Simulation of ontogenetic and evolutionary change by means of graph-rewriting algorithms has been explored as a means of providing a coordinate-free approach to form transformation in time and space. A finite set of rules describing generic graph transformations is used to encode knowledge about morphogenetic steps. Their application to skeletal growth in sea urchins effectively models ontogenesis in terms of topology rather than specific geometry. suggesting a promising approach to general modeling of developmental evolution.

The quantification of disparity is an important aspect of recent macroevolutionary studies, and it is usually motivated by theoretical considerations about the pace of innovation and the filling of morphospace. In practice, varying protocols of data collection and analysis have rendered comparisons among studies difficult. The basic question remains, How sensitive is any given disparity signal to different aspects of sampling and data analysis? Here we explore this issue in the context of the radiation of the echinoid order Spatangoida during the Cretaceous. We compare patterns at the genus and species levels, with time subdivision into subepochs and into stages, and with morphological sampling based on landmarks, traditional morphometrics, and discrete characters. In terms of temporal scale, similarity of disparity pattern accrues despite a change in temporal resolution, and a general deceleration in morphological diversification is apparent. Different morphometric methods also produce similar signals. Both the landmark analysis and the discrete character analysis suggest relatively high early disparity, whereas the analysis based on traditional morphometrics records a much lower value. This difference appears to reflect primarily the measurement of different aspects of overall morphology. Disparity patterns are similar at both the genus and species levels. Moreover, inclusion or exclusion of the sister order Holasteroida and the stem group Disasteroida in the sampled morphospace did not affect proportional changes in spatangoid disparity. Similar results were found for spatangoid subclades vis-a-vis spatangoids as a whole. The relative robustness of these patterns implies that the choice of temporal scale, morphometric scheme, and taxonomic level may not affect broad trends in disparity and the representation of large-scale morphospace structure.

Abstract Phenotypic integration is a central aspect of macroevolution. It is also an important concept in macroevolutionary theory. A number of empirical research questions and theoretical debates concerning evolution at and above the species level revolve around the issue of differential phenotypic integration through time. However, macroevolutionary studies in general and evolutionary paleobiology in particular have often conceptualized and documented phenotypic integration in ways that are not always comparable with standard, quantitative-genetic microevolutionary accounts. Thus, subjects such as evolutionary radiations, constraints, morphospace structure and occupation, disparity, allometry, heterochrony and heterotopy, the origin and proliferation of novelties, and clade dynamics, to name but a few, have been interpreted in terms of phenotypic integration (e.g., Valentine and Campbell 1975; Alberch et al. 1979; Maynard Smith et al. 1985; Gould 1989a, 1989b; Jablonski and Bottjer 1990; Erwin 1993; Zelditch and Fink 1996; Foote 1997; McGhee 1999), but with methodological protocols and theoretical motivations often distinct from those of microevolutionary research.

3 INTRODUCTION 4 NATURE OF THE INSECT FOSSIL RECORD 5 INSECT DIVERSITY AND DISPARITY THROUGH TIME 6 Taxonomic Diversity 8 Total diversity 8 Origination 11 Extinction 12 Ecomorphologic Disparity 13 Mouthpart Classes 13 Functional Feeding Groups 13 Dietary Guilds 14 Taxonomic Diversity and Ecomorphologic Disparity Contrasted 15 IMPORTANT PHASES IN THE HISTORY OF INSECT DIVERSITY 16 Insects in the Earliest Terrestrial Communities 17 Expansion of Diversity during the Late Paleozoic 17 The Great Permian Extinction 20 Mesozoic Rebound and Subsequent Ecological Expansion 21 Angiosperms and the Evolution of Modern Associations 23 CONCLUSION 25 ACKNOWLEDGMENTS 25 Labandeira & Eble / Insect Diversity & Disparity 3 REFERENCES CITED 26 TABLE 43 FIGURE CAPTIONS 46 FIGURES 48 Labandeira & Eble / Insect Diversity & Disparity 4 ABSTRACT The fossil record of insects documents a high proportion of modern higher-level taxa (67% for families), although this capture rate drops off considerably for lower-level taxa. This record is Lagerstatten-driven, and is deployed by complementary, parallel bodyand trace-fossil components that reveal a wealth of taxonomic and ecological detail. A family-level analysis of this record shows that past insect diversity is governed by low origination and extinction rates, both decreasing toward the Recent. This feature, in addition to prolonged taxal durations, has conferred on insects significant immunity from extinction. Nevertheless, the most profound event in insect history, the end-Permian extinction, decimated the Paleozoic Insect Fauna but allowed survival of lineages that gave rise to the Modern Insect Fauna of the Mesozoic and Cenozoic. Past insect ecomorphologic disparity can be documented as feeding attributes from the traceand body-fossil records. Three such attributes are assessed in the insect fossil record: mouthpart class, functional feeding group, and dietary guild, which collectively are divided into 74 distinctive categories. A plot of durations of these categories disclose a distinct trend of ecomorphologic disparity peaking considerably earlier than taxonomic diversity, indicating that taxonomic diversification eventually partitioned earlier-created, major ecological roles. Entry into each of these categories has occurred iteratively and convergently between and within the Paleozoic and Modern Insect Faunas. Insect history is divided into five phases. Initially there was (1) colonization of land in the earliest terrestrial ecosystems, followed by (2) taxic radiation and ecological penetration of plant tissues by numerous clades during the Late Carboniferous and Permian, a process that was curtailed by (3) the terminal Permian extinction. The (4) subsequent emergence of the Modern Insect Fauna in the Triassic and its rebound during the mid-Mesozoic was driven by ecological expansion into freshwater ecosystems, emergence of the parasitoid guild, and recolonization of new seed-plant lineages by phytophagous holometabolans. This process continued as (5)The fossil record of insects documents a high proportion of modern higher-level taxa (67% for families), although this capture rate drops off considerably for lower-level taxa. This record is Lagerstatten-driven, and is deployed by complementary, parallel bodyand trace-fossil components that reveal a wealth of taxonomic and ecological detail. A family-level analysis of this record shows that past insect diversity is governed by low origination and extinction rates, both decreasing toward the Recent. This feature, in addition to prolonged taxal durations, has conferred on insects significant immunity from extinction. Nevertheless, the most profound event in insect history, the end-Permian extinction, decimated the Paleozoic Insect Fauna but allowed survival of lineages that gave rise to the Modern Insect Fauna of the Mesozoic and Cenozoic. Past insect ecomorphologic disparity can be documented as feeding attributes from the traceand body-fossil records. Three such attributes are assessed in the insect fossil record: mouthpart class, functional feeding group, and dietary guild, which collectively are divided into 74 distinctive categories. A plot of durations of these categories disclose a distinct trend of ecomorphologic disparity peaking considerably earlier than taxonomic diversity, indicating that taxonomic diversification eventually partitioned earlier-created, major ecological roles. Entry into each of these categories has occurred iteratively and convergently between and within the Paleozoic and Modern Insect Faunas. Insect history is divided into five phases. Initially there was (1) colonization of land in the earliest terrestrial ecosystems, followed by (2) taxic radiation and ecological penetration of plant tissues by numerous clades during the Late Carboniferous and Permian, a process that was curtailed by (3) the terminal Permian extinction. The (4) subsequent emergence of the Modern Insect Fauna in the Triassic and its rebound during the mid-Mesozoic was driven by ecological expansion into freshwater ecosystems, emergence of the parasitoid guild, and recolonization of new seed-plant lineages by phytophagous holometabolans. This process continued as (5) Labandeira & Eble / Insect Diversity & Disparity 5 modern associations were established as Cretaceous angiosperms became dominant and midCenozoic temperate grasslands expanded. These data indicate that insect success is attributable to intricate, multiplicative, and probably extinction-buffered associations with other organisms, especially vascular plants.

Previous articleNext article No AccessNew Biological BooksEvolutionary Systems: Biological and Epistemological Perspectives on Selection and Self-Organization. Gertrudis Van de Vijver , Stanley N. Salthe , Manuela Delpos Gunther J. EbleGunther J. Eble Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 76, Number 3Sep., 2001 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/394025 Views: 2Total views on this site Copyright 2001 The University of ChicagoPDF download Crossref reports no articles citing this article.

ComplexityVolume 6, Issue 6 p. 24-27 The evolution of complexity Gunther J. Eble, Gunther J. Eble eble@santafe.edu. Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501 Centre National de la Recherche Scientifique, UMR 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, FranceSearch for more papers by this author Gunther J. Eble, Gunther J. Eble eble@santafe.edu. Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501 Centre National de la Recherche Scientifique, UMR 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, 21000 Dijon, FranceSearch for more papers by this author First published: 25 October 2001 https://doi.org/10.1002/cplx.10001Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume6, Issue6July/August 2001Pages 24-27 RelatedInformation