There and back again: historical biogeography of neotropical magnolias based on high-throughput sequencing

TL;DR

This paper uses genetic data to trace the evolutionary history of Neotropical magnolias, showing how they migrated and diversified over millions of years.

Contribution

The study provides a detailed biogeographic history of Neotropical magnolias using high-throughput sequencing data.

Findings

The ancestors of section Talauma colonized the Neotropics 38 million years ago via long-distance dispersal from North America.

Magnolia and Macrophylla sections migrated from Asia to North America and later to the Neotropics around 11 million years ago.

Geological events like the Panama isthmus emergence influenced magnolia migration between continents.

Abstract

The Neotropics are considered one of the most biodiverse areas in the world, housing at least one third of all vascular plant species. One of the genera that has diversified in the Neotropics is Magnolia, with about 174 species of three sections (Macrophylla, Magnolia and Talauma) endemic to the Americas. In this work, we study the biogeographic history of the Neotropical Magnolia species using high-throughput sequencing data. Sequences from 39 species (38 from Magnolia and one from the sister genus Liriodendron) were assembled. The dataset contained sequences from 239 nuclear targets and complete chloroplast genomes. Phylogenomic hypotheses and the ancestral distribution range of Magnolia were reconstructed.

The results of the calibrated phylogenetic hypotheses and ancestral range construction suggest that the earliest arrival in the Neotropics were the ancestors of section Talauma (38 million years ago), which colonized the Pacific region. This early presence in South America suggests long-distance, overwater dispersal from North America, the presumed origin of the genus Magnolia. The analysis and the extant Talauma distribution indicate a south to north recolonization. The ancestors of the other two Neotropical sections, Magnolia and Macrophylla, migrated around 19 mya from Asia to North America, radiating southward to the Neotropics afterwards, around 11 mya.

Our results suggest that Neotropical magnolias originated from a North American ancestor. The current sections arrived at the region independently influenced by climatic processes such as temperature drops or the Miocene Climatic Optimum. Additionally, geological processes, such as the movement of the South and North American land masses and the emergence of the Panama isthmus, facilitated the migration between continents.

The online version contains supplementary material available at 10.1186/s12862-025-02379-7.

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