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Colbourne, J.

Publications and source records attributed to Colbourne, J..

2 recordsLinked to original sources

A phylogeny aware analysis of gene function for the biodiversity genomics era

In the biodiversity genomics era, vast gene catalogs have rapidly accumulated, but how gene functions map onto major evolutionary transitions remains vague. We integrated phylogenomics with functional annotations to trace the emergence of [~]4.5 million genes and their associated functions in 508 representative species across the tree of life. Using this top-down, function-centric approach, we mapped the evolutionary history of well-annotated biological functions, revealing key insights and widespread parallelism. For instance, the largest bursts of gene and function gains aligned with key evolutionary transitions, including the origins of eukaryotes, animals, land plants, and vertebrates. Independent transitions to multicellularity and terrestrial life showed convergent enrichment of semantically similar functions (involving entirely different gene families), and the presence of orthologous genes often belonging to ancient gene families. For example, terrestrialization nodes in slime molds, plants, and animals coincided with gains in stress-tolerance and developmental genes, whereas multicellularity in animals, fungi, plants, and slime molds consistently involved expansions in cell-adhesion and communication functions. Thus, our framework enables scalable interpretation of new genomes in an evolutionary context and offers a roadmap for exploring the genomic basis of biodiversity.

evolutionary biology↗

How smart was T. rex? Testing claims of exceptional cognition in dinosaurs and the application of neuron count estimates in palaeontological research

Recent years have seen increasing scientific interest in whether neuron counts can act as correlates of diverse biological phenomena. Lately, Herculano-Houzel (2023) argued that fossil endocasts and comparative neurological data from extant sauropsids allow to reconstruct telencephalic neuron counts in Mesozoic dinosaurs and pterosaurs, which might act as proxies for behaviors and life history traits in these animals. According to this analysis, large theropods such as Tyrannosaurus rex were long-lived, exceptionally intelligent animals equipped with "macaque- or baboon-like cognition" whereas sauropods as well as most ornithischian dinosaurs would have displayed significantly smaller brains and an ectothermic physiology. Besides challenging established views on Mesozoic dinosaur biology, these claims raise questions on whether neuron count estimates could benefit research on fossil animals in general. Here, we address these findings by revisiting Herculano-Houzels (2023) work, identifying several crucial shortcomings regarding analysis and interpretation. We present revised estimates of encephalization and telencephalic neuron counts in dinosaurs, which we derive from phylogenetically informed modeling and an amended dataset of endocranial measurements. For large-bodied theropods in particular, we recover significantly lower neuron counts than previously proposed. Furthermore, we review the suitability of neurological variables such as neuron numbers and relative brain size to predict cognitive complexity, metabolic rate and life history traits in dinosaurs, coming to the conclusion that they are flawed proxies of these biological phenomena. Instead of relying on such neurological estimates when reconstructing Mesozoic dinosaur biology, we argue that integrative studies are needed to approach this complex subject.

zoology↗