The Amazon river is a suture zone for a polyphyletic group of co-mimetic heliconiine butterflies

Author(s)

Rosser, Neil ^{[1, 2]} ; Shirai, Leila T. ^{[3, 4]} ; Dasmahapatra, Kanchon K. ^[2] ; Mallet, James ^[1] ; Freitas, Andre V. L. ^{[3, 4]}

Affiliation

^[1] Harvard Univ, Dept Organism & Evolutionary Biol, Cambridge, MA 02138 - USA

^[2] Univ York, Dept Biol, Wentworth Way, Heslington - England

^[3] Univ Estadual Campinas, Inst Biol, Dept Biol Anim, Campinas, SP - Brazil

^[4] Univ Estadual Campinas, Inst Biol, Museu Zool, Campinas, SP - Brazil

• Document type: Journal article
• Source: ECOGRAPHY; v. 44, n. 2 NOV 2020.
• Web of Science Citations: 1

Abstract

The Amazon basin contains few obvious geographic barriers, yet it is the most biodiverse region on Earth. One hypothesis to explain its diversity is that the very large rivers promote allopatric divergence. Consistent with this, maps of heliconiine butterflies made from museum specimens show high subspecies richness close to the Amazon river, suggesting that it may produce or maintain intra-specific phenotypic variability. However, museum data are subject to strong spatial biases (the `Wallacean shortfall' of distribution data), raising the possibility that this pattern is a sampling artefact. To test this, we systematically collected along a similar to 900 km north-south transect running through central Amazonia. We found a significant association between phenotypic diversity and major rivers, with distance from the Amazon river explaining 61% of the variance in the mean polymorphism of 25 species. This association is partly because many species exhibit different phenotypes on either side of the river. Nonetheless, we also find sites with high polymorphism close to the river, indicating continual cross-river dispersal. Our results strongly suggest the presence of a suture zone (a region where multiple species have hybrid zones) near the city of Manaus. However, the effect of the river on spatial patterns of intra-specific phenotypic diversity depends on a species' mimetic phenotype. Rather than being absolute barriers, our results support the idea that rivers can act as partial barriers that trap moving hybrid zones, resulting in a suture zone. As such, the wide Amazonian rivers help generate and maintain colour pattern diversity, but to date there is no evidence that they lead to speciation in our study group. (AU)

• FAPESP's process: 11/50225-3 - Natural history, phylogeny and conservation of Neotropical Lepidoptera
• Grantee: André Victor Lucci Freitas
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants
• FAPESP's process: 12/50260-6 - Structure and evolution of the Amazonian biota and its environment: an integrative approach
• Grantee: Lúcia Garcez Lohmann
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 14/23504-7 - The contribution of the developmental hierarchy on morphological diversification
• Grantee: Leila Teruko Shirai
• Support Opportunities: Scholarships in Brazil - Post-Doctoral