Environmental Drivers of Diversification and Hybridization in Neotropical Butterflies

Nicol Rueda-M,Fabian C Salgado-Roa,Carlos H Gantiva-Q,Camilo Salazar,Carolina Pardo-Díaz

doi:10.3389/fevo.2021.750703

Abstract

Studying how the environment shapes current biodiversity patterns in species rich regions is a fundamental issue in biogeography, ecology, and conservation. However, in the Neotropics, the study of the forces driving species distribution and richness, is mostly based on vertebrates and plants. In this study, we used 54,392 georeferenced records for 46 species and 1,012 georeferenced records for 38 interspecific hybrids of the Neotropical Heliconius butterflies to investigate the role of the environment in shaping their distribution and richness, as well as their geographic patterns of phylogenetic diversity and phylogenetic endemism. We also evaluated whether niche similarity promotes hybridization in Heliconius. We found that these insects display five general distribution patterns mostly explained by precipitation and isothermality, and to a lesser extent, by altitude. Interestingly, altitude plays a major role as a predictor of species richness and phylogenetic diversity, while precipitation explains patterns of phylogenetic endemism. We did not find evidence supporting the role of the environment in facilitating hybridization because hybridizing species do not necessarily share the same climatic niche despite some of them having largely overlapping geographic distributions. Overall, we confirmed that, as in other organisms, high annual temperature, a constant supply of water, and spatio-topographic complexity are the main predictors of diversity in Heliconius. However, future studies at large scale need to investigate the effect of microclimate variables and ecological interactions.

Highlights

Understanding how the environment shapes species distribution and affects patterns of biological diversity is still a challenging task, especially in species rich regions, such as the Neotropics (Hawkins et al, 2003; Gotelli et al, 2009; Brown et al, 2020)
Heliconius is widely represented in databases, such as global biodiversity information Facility (GBIF), we did not include such records to ensure the use of data that have been curated by specialists both in terms of georeference and taxonomy, or that have images of each specimen that would allow us to confirm the taxonomy
We found that Heliconius butterflies display five general distribution patterns, namely: (i) wide distribution, (ii) transAndes, (iii) biogeographic Choco + Costa Rica, (iv) cisAndes + Pacific of Ecuador, and (v) highland Andes

Summary

Introduction

Understanding how the environment shapes species distribution and affects patterns of biological diversity is still a challenging task, especially in species rich regions, such as the Neotropics (Hawkins et al, 2003; Gotelli et al, 2009; Brown et al, 2020). Within the Neotropics, the Amazon and the foothills of Environmental Drivers of Diversification and Hybridization the North-eastern Andes are examples of regions that combine these conditions, and they exhibit high levels of species richness and phylogenetic diversity in monkeys, snakes, birds, amphibians, palms, and vascular plants (Kreft and Jetz, 2007; Fenker et al, 2014; Vallejos-Garrido et al, 2017; Velazco et al, 2021) Regions such as the Biogeographic Choco, Costa Rica, and the Amazon show high levels of phylogenetic endemism (e.g., Rosauer and Jetz, 2014; López-Aguirre et al, 2019; Varzinczak et al, 2020). Climaticbased selection likely plays a role in maintaining mosaic hybrid zones in Quercus oaks, where climatic heterogeneity favors the co-occurrence of parental species and their hybrids (Swenson et al, 2008; Ortego et al, 2014)

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