Biology subjects

Scott, G. R.

Publications and source records attributed to Scott, G. R..

6 recordsLinked to original sources

bioRxiv2026

DeMoDa: A global open access database for comparative research in human dental morphological variation

Human dental morphology is diverse and varies both within and between populations worldwide. Common variants include different numbers of cusps and roots, as well as different configurations in the fissures, ridges, and grooves on tooth crowns. Because teeth preserve well in taphonomic contexts and retain strong genetic signatures in their morphology, researchers across disciplines use dental form for research ranging from population affinity identification in forensic cases to the reconstruction of population history in archaeological and paleontological studies, and to explore the genetic underpinnings of dental development. However, these analyses are limited, as no publicly available comprehensive database of human dental morphological variation currently exists. Data are typically shared only within professional networks, excluding scientists outside those circles. Information is dispersed across repositories and the supplementary materials that accompany peer-reviewed publications, creating a fragmented and difficult-to-navigate data landscape. Although numberous dental anthropologists devoted their careers to collecting extensive datasets from thousands of individuals worldwide, their data have not yet been published in raw form nor made compatible. Here, we introduce the Dental Morphological Database (DeMoDa), an open access repository comprising 246 dental traits for 17,308 individuals across 32 major geographic regions worldwide spanning the past several thousand years. These data are from the legacy datasets of Turner, Hanihara, Scott, and Irish. Because these researchers used different scoring systems, we developed a scoring system with two steps that enables the three most-common scoring systems to be combined. We provide two versions of the data that correspond to these two steps: one with more nuanced trait scores at the cost of a smaller sample size, and another with less nuanced trait scores but broader sample coverage. We discuss the implications of publishing these legacy data and outline our decision-making process that guided their release in accordance with both the FAIR and CARE principles of open science.

evolutionary biology↗

bioRxiv2025

Elevational variation in heart mass and suppression of hypoxia-induced right ventricle hypertrophy in Andean leaf-eared mice (Phyllotis)

In lowland mammals that ascend to high elevation, hypoxia-induced changes in the pulmonary circulation can give rise to hypoxic pulmonary hypertension (HPH) and associated right-ventricle (RV) hypertrophy. Some mammals that are native to high elevation have evolved a means of attenuating HPH, demonstrating how environmental adaptation may sometimes counteract the effects of ancestral acclimatization responses. Here, we examine elevational variation in heart mass and measures of RV hypertrophy in four closely related species of leaf-eared mice (genus Phyllotis) that are broadly co-distributed across a steep elevational gradient on the Western slope of the Andes. There was a positive relationship overall between heart mass and elevation that reflected proportional changes in both the right and left ventricles. Thus, elevation-related increases in overall heart mass were not generally attributable to RV hypertrophy, suggesting that this group of predominantly highland species have evolved a means of avoiding HPH and/or attenuating the cardiac response to HPH. To gain insight into possible transcriptional mechanisms, we examined patterns of transcriptomic variation in the right ventricles of Phyllotis vaccarum from two geographically distinct highland populations (both from elevations >5000 m) that exhibit strikingly different levels of RV hypertrophy. Suppression of RV hypertrophy is associated with differential expression of key regulatory genes involved in striated muscle, immune processes, and the inflammatory response. Analysis of co-expression modules identified a promising set of candidate genes for mediating the development of RV hypertrophy at extremely high elevations.

evolutionary biology↗

bioRxiv2024

Local adaptation, plasticity, and evolved resistance to hypoxic cold stress in high-altitude deer mice

A fundamental question in evolutionary biology concerns the relative contributions of phenotypic plasticity vs. local adaptation (genotypic specialization) in enabling wide-ranging species to inhabit diverse environmental conditions. Here we conduct a long-term hypoxia acclimation experiment to assess the relative roles of local adaptation and plasticity in enabling highland and lowland deer mice (Peromyscus maniculatus) to sustain aerobic thermogenesis at progressively increasing elevations. We assessed the relative physiological performance capacities of highland and lowland natives as they were exposed to progressive, stepwise increases in hypoxia, simulating the gradual ascent from sea level to an elevation of 6000 m. The final elevation of 6000 m far exceeds the highest attainable elevations within the species range, and therefore tests the animals ability to tolerate levels of hypoxia that surpass the prevailing conditions within their current distributional limits. Our results demonstrate that highland natives exhibit superior thermogenic capacities at the most severe levels of hypoxia, suggesting that the species broad fundamental niche and its ability to inhabit such a broad range of elevational zones is attributable to a combination of genetically based local adaptation and plasticity. Transcriptomic and physiological measurements identify evolved changes in the acclimation response to hypoxia that contribute to the enhanced thermogenic capacity of highland natives. SIGNIFICANCE STATEMENTIn species that are distributed across steep environmental gradients, the ability to inhabit a broad range of conditions may be attributable to local adaptation and/or a generalized acclimatization capacity (phenotypic plasticity). By experimentally acclimating highland and lowland deer mice (Peromyscus maniculatus) to progressively increasing levels of hypoxia during a simulated ascent to 6000 m, we assessed the relative roles of evolved and plastic changes in thermogenic capacity. At especially severe levels of hypoxia, the superior thermogenic performance of highland natives relative to lowland conspecifics suggests that the broad fundamental niche of deer mice is largely attributable to local adaptation to different elevational zones, including evolved plasticity in gene expression and respiratory traits.

evolutionary biology↗

bioRxiv2022

Gene regulatory changes underlie developmental plasticity in respiration and aerobic performance in highland deer mice

Phenotypic plasticity can play an important role in the ability of animals to tolerate environmental stress, but the nature and magnitude of plastic responses are often specific to the developmental timing of exposure. Here, we examine changes in gene expression in the diaphragm of highland deer mice (Peromyscus maniculatus) in response to hypoxia exposure at different stages of development. In highland deer mice, developmental plasticity in diaphragm function may mediate changes in several respiratory traits that influence aerobic metabolism and performance under hypoxia. We generated RNAseq data from diaphragm tissue of adult deer mice exposed to 1) life-long hypoxia (before conception to adulthood), 2) post-natal hypoxia (birth to adulthood), 3) adult hypoxia (6-8 weeks only during adulthood), or 4) normoxia. We found five suites of co-regulated genes that are differentially expressed in response to hypoxia, but the patterns of differential expression depend on the developmental timing of exposure. We also identified four transcriptional modules that are associated with important respiratory traits. Many of the genes in these transcriptional modules bear signatures of altitude-related selection, providing an indirect line of evidence that observed changes in gene expression may be adaptive in hypoxic environments. Our results demonstrate the importance of developmental stage in determining the phenotypic response to environmental stressors.

molecular biology↗

bioRxiv2021

Genetic variation in haemoglobin regulates breathing in high-altitude deer mice

Physiological systems often have emergent properties but the effects of genetic variation on physiology are often unknown, which presents a major challenge to understanding the mechanisms of phenotypic evolution. We investigated the in vivo effects on respiratory physiology of genetic variants in haemoglobin (Hb) that contribute to hypoxia adaptation in high-altitude deer mice (Peromyscus maniculatus). We created F2 inter-population hybrids of highland and lowland deer mice to test the phenotypic effects of - and {beta}-globin variants on a mixed genetic background. High-altitude genotypes were associated with breathing phenotypes that enhance O2 uptake in hypoxia, including a deeper more effective breathing pattern and an augmented hypoxic ventilatory response. These effects could not be explained by erythrocyte Hb-O2 affinity or globin gene expression in the brainstem. Therefore, adaptive variation in haemoglobin can have unexpected effects on physiology that are distinct from the canonical function of this protein in circulatory O2 transport.

evolutionary biology↗

bioRxiv2020

The adaptive benefit of increases in hemoglobin-O2 affinity is contingent on tissue O2 diffusing capacity in high-altitude deer mice

BackgroundComplex organismal traits are often the result of multiple interacting genes and sub-organismal phenotypes, but how these interactions shape the evolutionary trajectories of adaptive traits is poorly understood. We examined how functional interactions between cardiorespiratory traits contribute to adaptive increases in the capacity for aerobic thermogenesis (maximal O2 consumption, V{square}O2max, during acute cold exposure) in high-altitude deer mice (Peromyscus maniculatus). We crossed highland and lowland deer mice to produce F2 inter-population hybrids, which expressed genetically based variation in hemoglobin (Hb) O2 affinity on a mixed genetic background. We then combined physiological experiments and mathematical modeling of the O2 transport pathway to examine links between cardiorespiratory traits and V{square}O2max. ResultsPhysiological experiments revealed that increases in Hb-O2 affinity of red blood cells improved blood oxygenation in hypoxia, but were not associated with an enhancement in V{square}O2max. Sensitivity analyses performed using mathematical modeling showed that the influence of Hb-O2 affinity on V{square}O2max in hypoxia was contingent on the capacity for O2 diffusion in active tissues. ConclusionsThese results suggest that increases in Hb-O2 affinity would only have adaptive value in hypoxic conditions if concurrent with or preceded by increases in tissue O2 diffusing capacity. In high-altitude deer mice, the adaptive benefit of increasing Hb-O2 affinity is contingent on the capacity to extract O2 from the blood, which helps resolve controversies about the general role of hemoglobin function in hypoxia tolerance.

physiology↗