Neutral evolutionary processes played a major role in the Amazonian Teleostean diversification

Author: NICOLAS LEROUX

Position: Master’s student – Laval University (Canadá)

Funding: NSERC Discovery grant, NSERC CGS M grant, Ressources Aquatique

Quebec, FRQNT, Laval University, INCT ADAPTA II grants and the André Darveau Grant.

Note[1]

 

Abstract

 

Amazonia is characterized by very heterogeneous riverscapes dominated by three drastically divergent water types: black (ion-poor and acidic), white- (nutrient-rich and turbid) and clear- (high transparency) waters. Recent phylogeographic studies have associated the ecotone formed by these environments to an ecologically driven speciation in fish species. With the objective of understanding the evolutive forces behind the Amazonian Teleostean diversification, we sampled 300 Mesonauta festivus (Figure 1) from 15 strategically positioned sites of the different water types already described for Amazonia. Our genetic dataset of 56,090 SNPs is contrasting with previous results and supports a low influence of water types on evolutionary processes. Conversely, we detected strong influences of past events of vicariance associated with the Amazon river formation and salt-water incursions since 2.5 Ma. While ecological speciation admittedly played a role in Amazonian fish’s diversification, we argue that past isolation by geological processes mainly explains the divergence in M. festivus populations. These major evolutive processes potentially played a central role in the Amazonian fish diversity genesis.

   

Figure 1. Master’s student Nicolas Leurox with a mesonauta specimen. Source: François-Etiénne Sylvain.

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[1]Reviewers: Ph.D students Jonatas da Silva Castro and Samara Santos de Souza.

Editor: Ph.D. student Renan Diego Amanajás Lima da Silva.