Form and function: structural analysis in evolutionary morphology

Abstract

A theoretical approach to the analysis of historical factors (Raup 1972) in evolutionary morphology is presented which addresses transformational hypotheses about structural systems. This (structural) approach to testing historical hypotheses about phylogenetic constraints on form and function and structural and functional versatility involves (1) the reconstruction of nested sets of structural features in monophyletic taxa, (2) the use of general or emergent organizational properties of structural and functional systems (as opposed to uniquely derived morphological features), and (3) the comparative examination of the consequences for structural and functional diversity of these general features in related monophyletic taxa.Three examples of emergent organizational properties are considered: structural complexity, repetition of parts, and the decoupling of primitively constrained systems. Two classes of hypotheses about the evolution of design are proposed. Transformational hypotheses concern historical pathways of change in form as a consequence of general organizational features which are primitive for a lineage. Relational hypotheses involve correlations between structure-function networks primitive for a clade and morphological diversity both between and within terminal taxa. To the extent that transformational and relational hypotheses about form are corroborated, they provide evidence of underlying regularity in the transformation of organic design that may be a consequence of the hierarchical organization of structural and functional patterns in organisms.

To feed or to breed: morphological constraints of mouthbrooding in coral reef cardinalfishes

“…Functional coupling is widespread in natural systems and is often viewed as a major constraint on evolutionary diversification [3,15,18], yet there have been few attempts to explore the implications of performing multiple functions within a single anatomical structure (see Wainwright & Turingan [21] and Konow & Sandford [22] for exceptions). Using paternal mouthbrooding cardinalfishes as a model system, we found strong interrelationships between feeding and reproduction, supporting the view that functional coupling may constrain organismal design.…”

“…Functional decoupling-the duplication and redundancy of individual design elements-has contributed to increased diversity in many groups through the release of functional constraints [1,3,16]. Perhaps the best-documented example of functional decoupling is the development of a pharyngeal jaw apparatus in several fish families [2,17,18].…”

On Vastness and Variability: Cultural Transmission, Historicity, and the Paleoindian Record in Eastern South America

“…There is an intense debate in biology regarding the role that each of these factors plays in the evolutionary trajectories of organisms (Conway Morris 2003, Gould and Lewontin 1979, Mayr 1983, Lauder 1981, 1982, and we can ask the same question regarding the evolutionary paths taken by different cultures. Therefore, we can suppose that the diversity of the ESAP record could be due to selection, drift, or history.…”

The Origin of Morphological Characters and the Biological Basis of Homology

“…This fact can be used to test a transformational hypothesis by the comparative method (Lauder, 1981); if the fin hooks are epigenetic traps, the fins of Acanthemblemaria and Xenomeda must be primitive, rather than derived. Thus, the fin hooks of Blenniids represent a simple system in which the evolution of a small ontogenetic network can be studied by experimental and comparative methods.…”