Biology subjects

Marroig, G.

Publications and source records attributed to Marroig, G..

5 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↗

bioRxiv2021

Morphological integration during postnatal ontogeny: implications for evolutionary biology

How covariance patterns of phenotypes change during development is fundamental for a broader understanding of evolution. There is compelling evidence that mammalian skull covariance patterns change during ontogeny. However, it is unclear to what extent variation in covariance patterns during ontogeny can impact the response to selection. To tackle this question we explored: i) the extent to which covariance patterns change during postnatal ontogeny; ii) in which ontogenetic stages covariance patterns differ the most, and iii) the extent to which the phenotypic covariance pattern at different ontogenetic stages can be explained by the same processes determining additive genetic covariance. We sampled postnatal ontogenetic series for both marsupials, and placentals. Within each ontogenetic series, we compared covariance matrices (P-matrices) at different ontogenetic stages. Furthermore, we compared these P-matrices to two target matrices [adult P-matrix and an additive genetic covariance matrix (G-matrix)]. Our results show that for all ontogenetic series, covariance patterns from weaning onward are conserved and probably shaped by the same processes determining the G-matrix. We conclude that irrespective of eventual differences in how selection operates during most of postnatal ontogeny, the net response to such pressures will probably not be affected by ontogenetic differences in the covariance pattern.

developmental biology↗

bioRxiv2021

The preeminent role of directional selection in generating extreme morphological change in Glyptodonts (Cingulata; Xenarthra)

The prevalence of stasis on macroevolution has been classically taken as evidence of the strong role of stabilizing selection in constraining morphological evolution. Rates of evolution calculated over longer time scales tend to fall below the expected under genetic drift, suggesting that the signal for directional selection is erased at longer time scales. Here we investigated the rates of morphological evolution of the skull in a fossil lineage that underwent extreme morphological modification, the glyptodonts. Contrary to what was expected, we show here that directional selection was the main process during the evolution of glyptodonts. Furthermore, the reconstruction of selection patterns shows that traits selected to generate a glyptodont morphology are markedly different from those operating on extant armadillos. Changes in both direction and magnitude of selection are probably tied to glyptodonts invasion of a specialist-herbivore adaptive zone. These results suggest that directional selection might have played a more important role in the evolution of extreme morphologies than previously imagined.

evolutionary biology↗

bioRxiv2016

A Phylogenetic Analysis of Shape Covariance Structure in the Anthropoid Skull

Phenotypic traits evolve in a coordinated manner due to developmental and functional interactions, mediated by the dynamics of natural selection; the dependence between traits arising from these three factors is captured by genetic (G) and phenotypic (P) covariance matrices. Mammalian skull development produces an intricate pattern of tissue organization and mutual signaling that integrates this structure, although the set of functions it performs is quite disparate. Therefore, the interplay between these interactions, and their relationships with the adaptive landscape may thus influence divergence in covariance structure among sister lineages. Here, we evaluate the stability of phenotypic covariance structure in skull size and shape along the diversification of Anthropoid Primates under a explicit phylogenetic framework. We estimate diversity in covariance structure, testing hypotheses concerning the phylogenetic distribution of P-matrix variation and pinpoint which traits are associated with this variation. We find that most changes occurred in the basal split between Platyrrhini and Catarrhini, and that these changes occurred within both Orbital and Basicranial trait sets, while Oral, Nasal and Vault trait sets present stable associations along the Anthropoid phylogeny. Therefore, changes in P-matrix structure among Anthropoids are restricted to trait sets whose functional significance is associated with the accommodation of the two precursor tissues that compose the skull, while the stability in the remaining regions hints at the stability of the underlying functional relationships imposed by the adaptive landscape.

evolutionary biology↗