Biology subjects

Rossoni, D. M.

Publications and source records attributed to Rossoni, D. M..

3 recordsLinked to original sources

bioRxiv2026

Conserved covariance structure underlies 60 million years of morphological diversification in primates

Evolvability, the capacity of populations to respond to selection, is shaped by the structure and amount of variation transmitted from generation to generation. Whether the heritable covariance structure itself remains stable or evolves rapidly is a central, yet unresolved, question in phenotypic evolution. Competing hypotheses suggest that trait covariation may be constrained by developmental and genetic architectures or, alternatively, reshaped by persistent directional selection. Here, we test whether covariance structure and evolvability are stable over macroevolutionary timescales by applying a comparative evolutionary quantitative genetics framework on primates. We quantified cranial variation using over ten thousand specimens representing 309 species and compared phenotypic covariance matrices for 57 genera within a Bayesian framework. Our results show that despite extensive morphological divergence, primates show remarkably conserved patterns of variation, modular organization, and capacity to respond to selection. Reconstruction of selection gradients across the primate radiation revealed that selection was highly structured, with preferential directions aligned with major axes of cranial variation. These results suggest that the stability of evolvability does not reflect evolutionary stasis, but rather emerges from the alignment between conserved developmental architecture and selection. Our findings demonstrate that covariance structure and the evolutionary potential it provides can persist over deep evolutionary timescales, providing a mechanistic framework for understanding how developmental systems shape the trajectories of major radiations.

evolutionary biology↗

bioRxiv2025

Invasion of new adaptive zones retains telltale signs of directional selection at macroevolutionary scales in mammals

Directional selection is often viewed as a transient force in macroevolution, with its signal eroded over time by stabilizing and fluctuating selection. Yet, transitions into new adaptive zones are predicted to impose strong and sustained selective pressures that may leave a detectable signature even across deep timescales. We test this prediction by comparing the rates of multivariate skull morphological evolution required to traverse the boundaries between adaptive zones against genetic drift expectations. Our dataset includes 11,793 specimens spanning 231 species from 12 mammalian clades, each containing unique ecological transitions into new adaptive zones. Using a quantitative genetics framework, we estimated the phenotypic distances between ancestral and derived adaptive zones and contrasted them with null expectations under genetic drift. While a few adaptive zone invasions (e.g., marsupials and rodents) are consistent with drift, most exhibit substantially elevated rates of evolution. These results suggest that directional selection has recurrently shaped mammalian cranial evolution during major ecological shifts. We propose that adaptive zone transitions represent evolutionary contexts in which adaptation leaves a persistent macroevolutionary signal, challenging the prevailing view that long-term patterns are dominated by static forces.

evolutionary biology↗

bioRxiv2025

Appendometer: A system for simultaneous, high-throughput morphometry of Drosophila legs and wings

O_LIThe inheritance of many different organismal features is correlated, as is their evolution, sug-gesting that we need to understand the pattern and causes of those correlations to understand evolution. Unfortunately, we generally lack the ability to rapidly and accurately measure large numbers of traits, making it difficult to describe the patterns of trait relationships or for-mulate hypothesis about the causes of their entanglement. We have previously developed a system to make high-dimensional measurements of Drosophilid fly wings in live specimens. Here, we report the extension of this approach to rapidly assess the dimensions of the distal leg segments, femur, tibia, and tarsi. Using the system, we describe the covariance of the wing and leg morphology and evaluate the relative rates of evolution of legs and wings. C_LIO_LIWe use two simple suction devices to immobilize and position legs and wings of an anaes-thetized fly for imaging, then take a single image incorporating both appendages. We em-ployed a machine learning method to measure leg segment lengths, which should be broadly applicable across diverse taxa. Experienced users can image the legs and wings of a fly every two minutes, with outlier detection and correction taking approximately 40 seconds. To demonstrate the usefulness of these methods, we measured the legs and wings of over 4,000 specimens from 43 different Drosophilid taxa. We estimated the rate of wing and leg evolu-tion using a phylogenetic mixed model. C_LIO_LIRepeatabilities of leg segments lengths averaged over 80%. The rate of evolution of wing and leg sizes are similar, but the rate of wing proportion evolution is 1.6 times as high as that of leg proportions due to strong allometric changes in wing shape. Within-species variation in leg proportions is highly correlated with the rate of leg proportion evolution, as is true for wings. Relative lengths of leg segments showed a strong pattern of negative correlations be-tween the lengths of the tarsal segments and of the femurs and tibias, while all other segment correlations were positive. This pattern was repeated in the rate estimates, suggesting that se-lection favors tradeoffs between tarsi and the remainder of the leg. C_LIO_LIOur simple system for imaging and measuring legs and wings simultaneously has high throughput and repeatability. It is readily applicable to a wide variety of winged insects and other traits, including wings, that could be imaged. Applied to Drosophila, our morphometric system enlarges the ability to study inheritance, pleiotropy, and evolution in this important model taxon. C_LI

evolutionary biology↗