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The Andes as a semi-permeable geographical barrier: genetic connectivity between structured populations in a colorful and widespread spider
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  • Fabian Camilo Salgado-Roa,
  • Carolina Pardo-Diaz,
  • Nicol Rueda-M,
  • Diego Cisneros-Heredia,
  • Eloisa Lasso,
  • Camilo Salazar
Fabian Camilo Salgado-Roa
Universidad del Rosario

Corresponding Author:fcsalgador@gmail.com

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Carolina Pardo-Diaz
Universidad del Rosario
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Nicol Rueda-M
Universidad del Rosario
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Diego Cisneros-Heredia
Universidad San Francisco de Quito - Campus Cumbaya
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Eloisa Lasso
Universidad de los Andes Facultad de Ciencias
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Camilo Salazar
Universidad del Rosario
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Abstract

Geographic barriers, such as mountain ranges, impede genetic exchange among populations, promoting diversification and speciation. The effectiveness of these barriers in limiting gene flow varies between lineages due to each species’ unique dispersal modes and capacities. Our understanding of how the Andes orogeny contributes to species diversification comes from well-studied vertebrates and a few insects, neglecting organisms unable to fly or walk long distances. Additionally, although the Andean altitude is usually assumed to be the driver of diversification, it is not often formally tested. This limits our understanding of how landscape changes, particularly altitude, influence population structure. Some arachnids, such as the colorful spider Gasteracantha cancriformis have been hypothesized to disperse long distances via ballooning (i.e., using their silk to interact with the wind). Still, we do not know how the environment and geography shape its genetic diversity. To address this question, we sampled thousands of loci across the distribution of this spider and implemented population genetics, phylogenetic, and landscape genetic analyses. We identified two genetically distinct groups structured by the Central Andes and a third less structured group in the northern Andes that shares ancestry with the previous two. This structure is largely explained by the elevation along the Andes, which decreases in some regions, facilitating cross-Andean dispersal and gene flow. Our findings support that elevation in the Andes plays a major role in structuring populations in South America, but the strength of this barrier can be defeated by organisms with long-distance dispersal modes together with altitudinal depressions
Submitted to Molecular Ecology
05 Feb 2024Reviewer(s) Assigned
22 Feb 2024Review(s) Completed, Editorial Evaluation Pending
04 Apr 2024Review(s) Completed, Editorial Evaluation Pending
09 Apr 2024Editorial Decision: Accept