Biology subjects

Warnock, R. C. M.

Publications and source records attributed to Warnock, R. C. M..

5 recordsLinked to original sources

bioRxiv2026

Phylogenetic inference from an incomplete fossil record

Fossil data is crucial to construct phylogenetic time trees, which serve as the basis to test a wide range of evolutionary hypotheses. While the fossil record is known to be incomplete, modern stratigraphy provides predictions of the structure of the fossil record as expressed by gap location and duration. Advances in phylogenetic model development allow us to propagate this information into Bayesian phylogenetic inference in the form of priors on time-variable fossil sampling. However, the impact and role of stratigraphic architectures on time tree inference has so far remained unexplored. We introduce a novel simulation framework that combines realistic stratigraphic forward models with phylogenetic simulations. Using this framework, we examine (1) how stratigraphically plausible model violations of fossil sampling due to gaps affect total-evidence inference under the fossilized birth-death model and (2) if stratigraphic knowledge on gap duration and timing improves inference when incorporated in priors on fossil sampling. We find that total-evidence analysis is robust to stratigraphically plausible distribution of gaps in disparate stratigraphic architectures, with results being instead dominated by the number of morphological characters. Surprisingly, incorporating information on prominent gaps in the stratigraphic record does not improve phylogenetic inference. Our results suggest that phylogenetic inference is robust to model violations introduced by stratigraphic gaps over short timescales, with results being dominated by a priori known data availability constraints such as morphological character matrix size. This research establishes the foundations for joint modeling of phylogenetic and stratigraphic processes and narrows the knowledge gap between paleontology, stratigraphy, and neontology.

paleontology↗

bioRxiv2025

Combining fossil taxa with and without morphological data improves dated phylogenetic analyses

The fossilized birth-death (FBD) model has become an increasingly popular method for inferring dated phylogenies. This is because it is especially useful for incorporating fossil data into such analyses, integrating fossils along with their age information directly into the tree as tips or sampled ancestors. Two approaches are common for placing fossil taxa in trees: inference based on morphological character data or using taxonomic constraints to control their topological placement. These approaches have historically been treated as alternatives, though combining the two is theoretically possible. For phylogenetic inference of entirely extinct organisms, additional related fossil taxa other than those for which morphology is available are generally overlooked. Here, we implement a combined approach on an empirical dataset for a group of trilobites. We use a morphological matrix and ages for 56 taxa and age information for another 196 taxa from the Paleobiology Database. To evaluate the effects of a combined approach, we conducted FBD dated phylogenetic analyses using a combined approach with morphology and taxonomic constraints and compared them to analyses of taxa with morphology alone. We find that a combined approach yields topologies that are more stratigraphically congruent, substantially more precise parameter estimates (e.g., divergence times), and more informative tree distributions. These findings are a consequence of the substantial increase in stratigraphic age information and a more representative sample of their temporal distributions.

evolutionary biology↗

bioRxiv2024

Assessing the Adequacy of Morphological Models used in Palaeobiology

Reconstructing the evolutionary history of different groups of organisms provides insight into how life originated and diversified on Earth. Phylogenetic trees are commonly used to estimate this evolutionary history, providing a hypothesis of the events. Within Bayesian phylogenetics a major step in estimating a tree is in choosing an appropriate model of character evolution. In the case of most extinct species, our only source of information to decipher their phylogenetic relationships is through the morphology of fossils. We therefore use a model of morphological character evolution, the most common of which being the Mk Lewis model. While it is frequently used in palaeobiology, it is not known whether the simple Mk substitution model, or any extensions to it, provide a sufficiently good description of the process of morphological evolution. To determine whether or not the Mk model is appropriate for fossil data we used posterior predictive simulations, a model adequacy approach, to estimate absolute fit of the model to morphological data sets. We first investigate the impact that different versions of the Mk model have on key parameter estimates using tetrapod data sets. We show that choice of substitution model has an impact on both topology and branch lengths, highlighting the importance of model choice. Next, we use simulations to investigate the power of posterior predictive simulations for morphology. Having validated this approach we show that current variations of the Mk model are in fact performing adequately in capturing the evolutionary dynamics that generated our data. We do not find any preference for a particular model extension across multiple data sets, indicating that there is no one size fits all when it comes to morphological data and that careful consideration should be given to choosing models of discrete character evolution. By using suitable models of character evolution, we can increase our confidence in our phylogenetic estimates, which should in turn allow us to gain more accurate insights into the evolutionary history of both extinct and extant taxa.

paleontology↗

bioRxiv2023

Challenges in estimating species age from phylogenetic trees

AimSpecies age, the elapsed time since origination, can give an insight into how species longevity might influence eco-evolutionary dynamics and has been hypothesized to influence extinction risk. Traditionally, species ages have been measured in the fossil record. However, recently, numerous studies have attempted to estimate the ages of extant species from the branch lengths of time-calibrated phylogenies. This approach poses problems because phylogenetic trees contain direct information about species identity only at the tips and not along the branches. Here, we show that incomplete taxon sampling, extinction, and different assumptions about speciation modes can significantly alter the relationship between true species age and phylogenetic branch lengths, leading to high error rates. We found that these biases can lead to erroneous interpretations of eco-evolutionary patterns derived from the comparison between phylogenetic age and other traits, such as extinction risk. InnovationFor bifurcating speciation, which is the default assumption in most analyses, we propose a probabilistic approach to improve the estimation of species ages, based on the properties of a birth-death process. We show that our model can reduce the error by one order of magnitude under cases of high extinction and high percentage of unsampled extant species. Main conclusionOur results call for caution in interpreting the relationship between phylogenetic ages and eco-evolutionary traits, as this can lead to biased and erroneous conclusions. We show that, under the assumption of bifurcate, it is possible to obtain better approximations of species age by combining information from branch lengths with the expectations of a birth-death process.

evolutionary biology↗

bioRxiv2021

Does time matter in phylogeny? A perspective from the fossil record

The role of time (i.e. taxa ages) in phylogeny has been a source of intense debate within palaeontology for decades and has not yet been resolved fully. The fossilised birth-death range process is a model that explicitly accounts for information about species through time. It presents a fresh opportunity to examine the role of stratigraphic data in phylogenetic inference of fossil taxa. Here, we apply this model in a Bayesian framework to an exemplar dataset of well-dated conodonts from the Late Devonian. We compare the results to those obtained using traditional unconstrained tree inference. We show that the combined analysis of morphology and stratigraphic data under the FBD range process reduces overall phylogenetic uncertainty, compared to unconstrained tree inference. We find that previous phylogenetic hypotheses based on parsimony and stratophenetics are closer to trees generated under the FBD range process. However, the results also highlight that irrespective of the inclusion of age data, a large amount of topological uncertainty will remain. Bayesian inference provides the most intuitive way to represent the uncertainty inherent in fossil datasets and new flexible models increase opportunities to refine hypotheses in palaeobiology.

paleontology↗