Integrating Fossil Flowers into the Angiosperm Phylogeny using a Total Evidence Approach

Abstract

Fossil flowers are essential to infer past angiosperm evolutionary processes. The assignment of fossil flowers to extant clades has traditionally relied on morphological similarity and on apomorphies shared with extant taxa. The use of explicit phylogenetic analyses to establish their affinity has so far remained limited. In this study, we built a comprehensive framework to investigate the phylogenetic placement of 24 exceptionally preserved fossil flowers. For this, we assembled a new species-level dataset of 30 floral traits for 1201 extant species that were sampled to represent the stem and crown nodes of all angiosperm families. We explored multiple analytical approaches to integrate the fossils into the phylogeny, including different phylogenetic estimation methods, topological-constrained analyses, and a total evidence approach combining molecular and morphological data of extant and fossil species. Our results were widely consistent across approaches, with minor differences in the support of fossils at different phylogenetic positions. The placement of some fossils is in agreement with previously suggested relationships, but for others, a new placement is indicated. We also identified fossils that are well constrained within particular extant families, whereas others showed high phylogenetic uncertainty. Finally, we present recommendations for future total evidence analyses, regarding the selection of fossils and appropriate methodologies, and provide some perspectives on how to integrate fossils into the investigation of divergence times and the temporal evolution of morphological traits.

New finding of Toxorhina (Ceratocheilus) limoniid fly in Eocene Baltic amber and the biogeographical context of the genus

“…The phylogenetic position of the genus Toxorhina within Limoniinae remains unclear, but it could be assumed that it separated somewhere in Late Cretaceous with diversification and spread to various habitats of nectar producing angiosperms 34,35 . Tendency to elongation of rostrum is observed in Helius since the Cretaceous with wide diversity in the Eocene 32,33 , and similar disparity pattern could be assumed for ancestors of Toxorhina. In addition, the morphological disparity of the Toxorhina is exposed also in venation patterns resulting in taxonomic separation to subgenera.…”

“…in thermophilic ants 23 or Lophopidae planthoppers [27][28][29] could be a good reference for reconstruction of biogeographic scenario of 30 , as documented by fossils from Baltic amber. The Limoniidae genera Elephantomyia Osten Sacken and Helius Lepeletier and Serville have rostrum elongate as in Toxorhina and its subgenera, in the genus Geranomyia Haliday mouth parts of are strongly elongate, but rostrum short 9,[31][32][33] . The phylogenetic position of the genus Toxorhina within Limoniinae remains unclear, but it could be assumed that it separated somewhere in Late Cretaceous with diversification and spread to various habitats of nectar producing angiosperms 34,35 .…”

Variación morfológica foliar de Brickellia sección Barroetea (A. Gray) E.E. Schill. & R. Scott y especies afines

“…La divergencia temprana del linaje C en el árbol filogenético y un cambio morfológico mayor es un patrón similar al observado en animales, donde las especies que están más relacionados a linajes de divergencia temprana muestran un cambio morfológico mayor en comparación con los de ramas más recientemente derivadas (Oyston et al 2016, López-Estrada et al 2019 En plantas se han evaluado grandes linajes con ayuda de caracteres discretos de las flores y se han obtenido resultados similares a los aquí encontrados como en animales (Chartier et al 2014, Oyston et al 2016, López-Martínez et al 2022.…”

Embracing uncertainty: The way forward in plant fossil phylogenetics

“…RoguePlots are rather simple to use, being implemented in an R package (https://github.com/seraklop/ RoguePlots/; for a short tutorial, see https://mariocoiro. blog/2020/12/02/how-to-represent-uncertainty-inphylogenies-rogueplots-to-the-rescue/), and have been successfully applied to plant analyses (Coiro et al, 2020(Coiro et al, , 2023López-Martínez et al, 2023;Pessoa et al, 2023).…”

“…Even within this renaissance, researchers interested in morphological phylogenetics applied to fossil plants have had to face more challenges than colleagues working on other fossil groups. Phylogenies including plant fossils, though able to retrieve robust relationships (Schoenenberger et al, 2020;Matsunaga et al, 2021;Tang et al, 2022;Coiro et al, 2023;López-Martínez et al, 2023), sometimes retrieve uncertain relationships with low support or lack resolution compared to molecular phylogenies. This low support is partly due to the nature of the plant fossil record itself, composed of separate organs with differing levels of available characters for phylogenetic analyses (Bateman and Hilton, 2009).…”