The genetic control paradigm in biology: What we say, and what we are entitled to mean.

We comment on the article by Keith Baverstock (2021) and provide critiques of the concepts of genetic control, genetic blueprint and genetic program.

The development of shape. Modular control of growth in the lepidopteran forewing.

The mechanisms by which tissues and organs achieve their final size and shape during development are largely unknown. Although we have learned much about the mechanisms that control growth, little is known about how those play out to achieve a structure's specific final size and shape. The wings of insects are attractive systems for the study of the control of morphogenesis, because they are perfectly flat and two-dimensional, composed of two closely appressed cellular monolayers in which morphogenetic processes can be easily visualized.

A developmental perspective of homology and evolutionary novelty.

The development and evolution of multicellular body plans is complex. Many distinct organs and body parts must be reproduced at each generation, and those that are traceable over long time scales are considered homologous. Among the most pressing and least understood phenomena in evolutionary biology is the mode by which new homologs, or "novelties" are introduced to the body plan and whether the developmental changes associated with such evolution deserve special treatment.

Competitive and Coordinative Interactions between Body Parts Produce Adaptive Developmental Outcomes.

Large-scale patterns of correlated growth in development are partially driven by competition for metabolic and informational resources. It is argued that competition between organs for limited resources is an important mesoscale morphogenetic mechanism that produces fitness-enhancing correlated growth. At the genetic level, the growth of individual characters appears independent, or "modular," because patterns of expression and transcription are often highly localized, mutations have trait-specific effects, and gene complexes can be co-opted as a unit to produce novel traits.

Allometry, Scaling, and Ontogeny of Form-An Introduction to the Symposium.

Until recently, the study of allometry has been mostly descriptive, and consisted of a diversity of methods for fitting regressions to bivariate or multivariate morphometric data. During the past decade, researchers have been developing methods to extract biological information from allometric data that could be used to deduce the underlying mechanisms that gave rise to the allometry. In addition, an increasing effort has gone into understanding the kinetics of growth and the regulatory mechanisms that control growth of the body and its component parts.

Morphological Murals: The Scaling and Allometry of Butterfly Wing Patterns.

The color patterns of butterflies moths are exceptionally diverse, but are very stable within a species, so that most species can be identified on the basis of their color pattern alone. The color pattern is established in the wing imaginal disc during a prolonged period of growth and differentiation, beginning during the last larval instar and ending during the first few days of the pupal stage. During this period, a variety of diffusion and reaction-diffusion signaling mechanisms determine the positions and sizes of the various elements that make up the overall color pattern.

Exploring the Role of Insulin Signaling in Relative Growth: A Case Study on Wing-Body Scaling in Lepidoptera.

Adult forms emerge from the relative growth of the body and its parts. Each appendage and organ has a unique pattern of growth that influences the size and shape it attains. This produces adult size relationships referred to as static allometries, which have received a great amount of attention in evolutionary and developmental biology.

Wing morphogenesis in Lepidoptera.

The wings of Lepidoptera develop from imaginal disks that are made up of a simple two-layered epithelium whose structure is always congruent with the final adult wing. It is therefore possible to map every point on the imaginal disk to a location on the adult wing throughout the period of growth and morphogenesis. The wings of different species of Lepidoptera differ greatly in both size and shape, yet it is possible to fate-map homologous locations on the developing wing disks and explicitly monitor the growth, size, and shape of the wing, or any of its regions, throughout the entire ontogeny of the wing.

The distinct roles of insulin signaling in polyphenic development.

Many insects have the ability to develop alternative morphologies in response to specific environmental signals such as photoperiod, temperature, nutrition and crowding. These signals are integrated by the brain and result in alternative patterns of secretion of developmental hormones like ecdysone, juvenile hormone and insulin-like growth factors, which, in turn, direct alternative developmental trajectories. Insulin signaling appears to be particularly important when the polyphenism involves differences in the sizes of the body, appendages and other structures, such as wings, mandibles and horns.

Unmodern Synthesis: Developmental Hierarchies and the Origin of Phenotypes.

The question of whether the modern evolutionary synthesis requires an extension has recently become a topic of discussion, and a source of controversy. We suggest that this debate is, for the most part, not about the modern synthesis at all. Rather, it is about the extent to which genetic mechanisms can be regarded as the primary determinants of phenotypic characters.

The Origin of Novelty Through the Evolution of Scaling Relationships.

Morphological novelty is often thought of as the evolution of an entirely new body plan or the addition of new structures to existing body plans. However, novel morphologies may also arise through modification of organ systems within an existing body plan. The evolution of novel scaling relationships between body size and organ size constitutes such a novel morphological feature.