Biology subjects

Hubbe, A.

Publications and source records attributed to Hubbe, A..

4 recordsLinked to original sources

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↗

bioRxiv2024

Late Quaternary millennial-scale stability of the feeding strategy of the gray brocket deer in Southeastern Brazil.

There is only limited evidence (contemporary or archaeological/paleontological) regarding the feeding ecology of the gray brocket deer (Subulo gouazoubira) in Brazil's Cerrado biome. Using stable carbon ({delta}13C) and oxygen ({delta}18O) isotope analyses of dental enamel from individuals recovered from Cuvieri Cave, Minas Gerais, we explore dietary and environmental changes between the Late Pleistocene and Holocene epochs for S. gouazoubira living in this biome. {delta}13C data suggest no significant shift in feeding strategy between the Late Pleistocene and Holocene, with both sets of individuals displaying carbon isotope values consistent with browsing in open environments rather than closed canopy forests. A shift in {delta}18O values, on the other hand, indicates climatic changes in the area of Cuvieri Cave from the late Pleistocene to Holocene epoch. This study highlights the stability in the feeding behavior of the gray brocket deer despite biotic and abiotic changes between the epochs.

paleontology↗

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↗