Biogeographic Patterns in Northern Hemisphere Flora

The flora of the Northern Hemisphere displays a rich tapestry of distribution patterns shaped by deep-time geological events, climatic shifts and evolutionary processes. Major disjunctions between eastern Asia, North America and Europe reflect a history of migration across ancient corridors such as the Bering land bridge, followed by vicariance driven by mountain uplift, sea-level change and glacial cycles. Phylogeographic studies integrating genomic data with fossil records have clarified the timing of lineage divergences, revealing Eocene origins for many temperate clades and a pulse of diversification through the Miocene and Pliocene. Key processes include repeated cycles of range expansion and contraction, long-distance dispersal events that established amphitropical and amphi-Pacific links, and the fragmentation of once-continuous boreotropical forests. Understanding these patterns is critical for predicting responses to ongoing climate change, guiding conservation strategies for endemic taxa and informing restoration of temperate forest ecosystems.

Research from Nature Portfolio

Recent studies have combined high-resolution phylogenomic analyses with abundant fossil data to reconstruct the biogeographic history of temperate trees. In one case, integration of a robust genomic phylogeny for a widespread forest genus with fossil calibrations revealed an origin in western North America during the Eocene. Subsequent intercontinental dispersal and vicariance events were shown to coincide with major climatic transitions, demonstrating that shifts between warm and cool regimes facilitated both expansion across continents and the isolation of regional lineages. This work highlights the importance of combining molecular and palaeobotanical evidence to infer reliable ancestral areas and to disentangle the relative roles of dispersal versus vicariance in shaping modern distributions.

Biogeographic Patterns in Northern Hemisphere Flora publication trend

The graph below shows the total number of articles in biogeographic patterns in northern hemisphere flora across all publications each year (not limited to Nature Index journals).

Technical terms

Vicariance: The splitting of a species’ range into discrete areas by geological or climatic barriers, leading to lineage divergence.

Phylogeography: The study of the geographic distribution of genetic lineages to infer historical population movements and diversification.

Disjunct distribution: A pattern in which closely related taxa occur in widely separated regions with no continuous range between them.

Ancestral area reconstruction: A method that infers the most likely geographic origin of a lineage based on phylogenetic and biogeographic data.

Bering land bridge: A former terrestrial connection between Asia and North America that enabled intercontinental migration of plants and animals during the Cenozoic.

References

1. Historical climate change and vicariance events contributed to the intercontinental disjunct distribution pattern of ash species (Fraxinus, Oleaceae). Communications Biology (2024).
2. Phylogenetic relationships and biogeography of Asia Callicarpa (Lamiaceae), with consideration of a long-distance dispersal across the Pacific Ocean —insights into divergence modes of pantropical flora. Frontiers in Plant Science (2023).
3. Asymmetric biotic interchange across the Bering land bridge between Eurasia and North America. National Science Review (2019).
4. A reappraisal of the phylogeny and historical biogeography of Sparganium (Typhaceae) using complete chloroplast genomes. BMC Plant Biology (2022).