Spatial distribution patterns and formation of global spermatophytes.

Abstract

The evolution of spermatophytes (seed plants) is relatively well known in their evolutionary relationships over temporal changes, but their spatial evolution is another critical yet often neglected lens, especially using a taxon-based approach. Here, by integrating geographic distributions and origin locations across 429 spermatophyte families worldwide with unsupervised machine learning approaches, we constructed a Spermatophyte Spatial Evolutionary System that classifies global spermatophytes into 18 distribution types and six distribution supertypes within three primary floristic elements: cosmopolitan, tropical, and temperate. We found that the three elements all primarily originated from Gondwana, with the cosmopolitan element being the youngest and the temperate element being the oldest in terms of origin. They primarily formed during the Tertiary, particularly between the Eocene and Miocene, driven mainly by climate, long-distance dispersal, and tectonic movement, while each exhibited distinct migration routes and formation models. Our results provide novel insights into the spatial evolution of global spermatophytes and highlight that similar distribution patterns of spermatophytes were driven by their comparable formation processes and mechanisms at the levels of floristic element, distribution supertype, and type.