Biology subjects

Hlusko, L.

Publications and source records attributed to Hlusko, L..

3 recordsLinked to original sources

bioRxiv2025

Long-fuse evolution of carnivoran skeletal phenomes through the Cenozoic

Climatic change is hypothesized to promote phenotypic diversification. While neontological analyses are often used to test this hypothesis, extant data only captures time-averaged signals of surviving lineages. More nuanced tests require paired and longitudinal climatic and organismal data. Here, we developed the most comprehensive phenomic dataset to-date of pan-carnivorans to test hypotheses that Cenozoic climatic change influenced the evolution of the cranial, appendicular, and axial skeleton. We found support for the hypothesis that a hierarchical progression of ecological diversification across the Cenozoic significantly influenced the establishment of modern carnivorans. Specifically, extinctions during the Eocene-Oligocene Transition released crown carnivorans from a constrained adaptive zone to interfamilial skeletal diversification. Intrafamilial skeletal diversification did not occur for another 20 million years until after the Mid-Miocene Climate Transition. Our work demonstrates the essential role of macroevolutionary data from the fossil record for revealing how major global climatic events steered the evolutionary trajectories of modern skeletal phenomes.

evolutionary biology↗

bioRxiv2024

The carnivoran adaptive landscape reveals trade-offs among functional traits in the skull, appendicular, and axial skeleton

Analyses of form-function relationships are widely used to understand links between morphology, ecology, and adaptation across macroevolutionary scales. However, few have investigated functional trade-offs and covariance within and between the skull, limbs, and vertebral column simultaneously. In this study, we investigated the adaptive landscape of skeletal form and function in carnivorans to test how functional trade-offs between these skeletal regions contribute to ecological adaptations and the topology of the landscape. We found that morphological proxies of function derived from carnivoran skeletal regions exhibit trade-offs and covariation across their performance surfaces, particularly in the appendicular and axial skeletons. These functional trade-offs and covariation correspond as adaptations to different adaptive landscapes when optimized by various factors including phylogeny, dietary ecology, and, in particular, locomotor mode. Lastly, we found that the topologies of the optimized adaptive landscapes and underlying performance surfaces are largely characterized as a single gradual gradient rather than as rugged, multipeak landscapes with distinct zones. Our results suggest that carnivorans may already occupy a broad adaptive zone as part of a larger mammalian adaptive landscape that masks the form and function relationships of skeletal traits.

evolutionary biology↗

bioRxiv2021

Differential taphonomic effects of petroleum seeps and karstic sinkholes on ancient dire wolf teeth: Hydrocarbon impregnation preserves fossils for chemical and histological analysis

Histological analysis of teeth can yield information on an organisms growth and development, facilitating investigations of diet, health, environment, and long-term responses to selective pressures. In the Americas, an extraordinary abundance of Late Pleistocene fossils including teeth has been preserved in petroleum seeps, constituting a major source of information about biotic changes and adaptations at the end of the last glacial period. However, the usefulness of these fossils for histological studies is unclear, due to the unknown taphonomic effects of long-term deposition in petroleum. Here, we compare histological and chemical analyses on dire wolf (Canis dirus) teeth obtained from two different environments, i.e. a petroleum seep (Rancho La Brea tar pits, California) and a carstic sinkhole (Cutler Hammock sinkhole, Florida). Optical and scanning electron microscopy (SEM) together with X-ray diffraction (XRD) analysis revealed excellent preservation of dental microstructure in the seep sample, and the petroleum-induced discoloration was found not to interfere with the histological and chemical examination. By comparison, teeth from the sinkhole sample showed severe degradation and contamination of the dentine by exogenous substances. These results indicate that petroleum seep assemblages are useful, or even ideal, environments for preserving the integrity of fossil material for chemical and histological analysis.

paleontology↗