Beyond the Highlands: Climate Drives Evolutionary Connections Between Ancient Neotropical Mountains and Lowland Biomes

bioRxiv (Cold Spring Harbor Laboratory)

Abstract

Abstract Aim The assembly of montane plant communities through time is underlain by historical and abiotic factors. However, the extent of evolutionary connectivity between ancient highland ecosystems and surrounding lowlands remains unclear. Here, we investigate the evolutionary connections between the campos rupestres , a hyperdiverse and fragmented montane vegetation complex in eastern South America, and lowland biomes surrounding it: savannas, rainforests, and seasonally dry tropical forests. Location Eastern South America. Time period Cenozoic. Major taxa studied Flowering plants. Methods Using phylogenetic beta diversity analyses for 13 angiosperm clades, we assess the degree of lineage dissimilarity between campos rupestres subregions and adjacent biomes. We also apply generalized dissimilarity modeling to determine the role of climate, soil, and geographic distance in shaping spatial patterns of phylogenetic composition. Results Our results reveal high lineage permeability between campos rupestres and surrounding biomes, with lineage sharing largely reflecting biome adjacency. This pattern is mainly driven by shared climatic conditions, which are the strongest predictors of phylogenetic dissimilarity. Main conclusions We highlight the importance of lineage exchange between lowland and montane environments for the assembly of highland floras. By showing that lineage movements across biome boundaries have been common over time and spatial scales, our study challenges the idea that ancient Neotropical mountains are isolated sky-islands. Instead, we emphasize the dynamic nature of montane plant diversity and the pivotal role of climate in shaping evolutionary connections between highlands and lowlands.

Authors 4

1. Yago Barros‐Souza corresponding Aachen Naturalis Biodiversity Center

   Naturalis Biodiversity Center · Universidade Federal de São Carlos · Universidade de São Paulo

   Affiliation as printed

   Departamento de Botânica, Universidade Federal de São Carlos, Brazil

   Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil

   Naturalis Biodiversity Center, Leiden, The Netherlands

2. Monique Maianne

   Universidade Federal de São Carlos · Universidade de São Paulo

   Affiliation as printed

   Departamento de Botânica, Universidade Federal de São Carlos, Brazil

   Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil

3. Rafael Fernandes Barduzzi

   Universidade Federal de São Carlos · Universidade de São Paulo

   Affiliation as printed

   Departamento de Botânica, Universidade Federal de São Carlos, Brazil

   Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brazil

4. L. P. BORGES

   Universidade Federal de São Carlos

   Affiliation as printed

   Departamento de Botânica, Universidade Federal de São Carlos, Brazil