{
  "id": 2256150,
  "title": "Phylogenetic reconstruction of trait summary statistics and disparity dynamics",
  "url": "https://urgent.news/2026/08/20/phylogenetic-reconstruction-of-trait-summary-statistics-and-disparity",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-20T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.16.745082v1?rss=1"
  },
  "original_language": "en",
  "account": "In the field of phylogenetics, the study of trait summaries and disparity dynamics is crucial. Typically, trait measurements are gathered for living and fossil species, but the focus is on understanding how these traits evolve over time, not just their current state. By applying Brownian evolution theory, researchers can determine the conditional distributions of these traits at both extant and fossil points. This enables the reconstruction of trajectories for both summary statistics and quantification of their uncertainties. Among these summaries, variance stands out as a key indicator of past phenotypic disparity. To measure disparity, the probability that a randomly chosen value from the conditional variance distribution exceeds a randomly chosen value from the standard Brownian distribution is calculated. This disparity level offers a universal, dimensionless measure that can be compared across different periods, groups, phylogenetic trees, and datasets. When applied to cetacean body length data, the disparity trajectories vary significantly among major subclades, suggesting that most of the overall disparity in the group is due to differences among these subclades. An analysis of body mass in living and fossil mammals shows low disparity throughout much of the Mesozoic era, followed by a significant increase starting around the K-Pg boundary. These findings align with earlier analyses of similar datasets, while offering a direct reconstruction of how trait distributions change over time. The methodology is available in the R package PastMoments.",
  "summary": "Summary statistics are essential tools for understanding the overall behaviour of a collection of measurements. In a phylogenetic context, however, trait measurements are generally observed only for extant taxa and, when available, fossil taxa, while the questions of interest concern the evolution of the trait through time rather than only its static properties among the observed taxa. To…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}