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Phylogenetic perspectives on biome shifts in Leucocoryne (Alliaceae) in relation to climatic niche evolution in western South America

Authors

  • Paola Jara-Arancio,

    Corresponding author
    1. Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Santiago, Chile
    2. Departamento de Ciencias Biológicas y Departamento de Ecología y Biodiversidad, Universidad Andrés Bello, Santiago, Chile
    • Correspondence: Paola Jara-Arancio, Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 CP 7800024, Ñuñoa, Santiago, Chile.

      E-mail: pjarancio@gmail.com

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  • Mary T. K. Arroyo,

    1. Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Santiago, Chile
    2. Departamento de Ciencias Ecológicas, Universidad de Chile, Ñuñoa, Santiago, Chile
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  • Pablo C. Guerrero,

    1. Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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  • Luis F. Hinojosa,

    1. Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Santiago, Chile
    2. Departamento de Ciencias Ecológicas, Universidad de Chile, Ñuñoa, Santiago, Chile
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  • Gina Arancio,

    1. Instituto de Ecología y Biodiversidad (IEB), Facultad de Ciencias, Universidad de Chile, Santiago, Chile
    2. Departamento de Biología, Facultad de Ciencias, Universidad de La Serena, La Serena, Chile
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  • Marco A. Méndez

    1. Departamento de Ciencias Ecológicas, Universidad de Chile, Ñuñoa, Santiago, Chile
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Abstract

Aim

Shifts between the western South American sclerophyll and winter-rainfall desert biomes and their relationship to climatic niche evolution and aridity development were investigated in the South American endemic geophytic Leucocoryne (Alliaceae) clade.

Location

Western South America.

Methods

We constructed a molecular phylogeny (internal transcribed spacer, ITS), estimated lineage divergence times, and identified ancestral biomes and biome shifts. The multivariate climatic niche of present-day species was described using occurrence data and bioclimatic variables. Climatic niche similarity was evaluated using Mahalanobis and Fisher distances. Brownian motion (BM) and Ornstein–Uhlenbeck (OU) models of evolution were used to characterize temperature and precipitation niche evolution. Ancestral temperature and precipitation were estimated using the phylogenetic generalized least-squares method.

Results

Leucocoryne exhibits a low level of phylogenetic biome conservatism. The clade arose in the early Miocene in an ancestral sclerophyll biome and subsequently moved northwards into the arid winter-rainfall biome on two separate occasions, during the late Miocene and Pliocene, respectively, with very recent diversification of species in the winter-rainfall desert. Overall, the multivariate climatic niche showed significant differentiation, and phylogenetic and climatic niche distances were correlated. Temperature and precipitation niche evolution within lineages followed a pattern that is consistent with stabilizing selection (OU model).

Main conclusions

The low level of phylogenetic biome conservatism found in Leucocoryne is associated with considerable expansion of the precipitation and temperature niche axes. Unidirectional biome shifts from a wetter biome characterized by higher species richness and more continuous vegetation cover, into a drier biome with lower species richness and much sparser vegetation cover, suggest that the availability of and lower biotic resistance within open habitats facilitated biome shifts in Leucocoryne. Incursion into the arid winter-rainfall desert and diversification there may have been facilitated by the conservative geophytic life-form of Leucocoryne, the generally cool coastal conditions, and the wet/dry climatic cycles occurring since the late Miocene.

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