Background
The Spanish toothcarp (Aphanius iberus Valenciennes, 1846) is a small fish endemic to the eastern coastline of the Iberian Peninsula and is currently listed as “Endangered” (category IUCN: EN). It mainly inhabits brackish waters which can exhibit large fluctuations in temperature and salinity throughout the year. The genetics of A. iberus are not well-known since most studies have only evaluated the genetic structure of the species under a conservation framework in order to identify its potential conservation units. Different phylogenetic relationships of Aphanius have been published based on some particular genes. In the present study, the entire mitochondrial genome of A. iberus was obtained for the first time in the context of an A. iberus reference genome and a hypothesis regarding its phylogenetic position was considered.
Methods and results
The mitogenome (a circular doble-stranded DNA sequence of 16,708 bp) was reconstructed and aligned against 83 Cyprinodontiformes and two outgroup taxa to identify the phylogenetic position of A. iberus. PartitionFinder was first used to test for the best evolutionary model and the phylogenetic analyses were performed using two methods: Maximun-Likelihood Approximation (IQ-Tree) and Bayesian inference (MrBayes). Our results show that A. iberus forms a sister group with Orestias ascotanensis, a cyprinodontiform species native to South America.
Conclusions
The results were congruent with the traditional morphometric reconstructed trees and with a geological vicariant hypothesis involving Cyprinodontiformes where Aphaniidae is shown as a monophyletic family separated from the family Cyprinodontidae. The information gathered from this study is not only valuable for improving our understanding of the evolutionary history of A. iberus, but for future genomic studies involving the species.
The Spanish toothcarp (Aphanius iberusValenciennes, 1846) is a small fish species endemic to the eastern coastline of the Iberian Peninsula. Along its area of distribution, it mainly inhabits brackish waters which can exhibit large fluctuations in temperature and salinity throughout the year. Aphanius iberus belongs to the family Aphaniidae within the order Cyprinodontiformes and is currently listed as “Endangered” (category IUCN: EN), facing a very high risk of extinction in the wild. The genetics of A. iberus are not well-known since most studies have only evaluated the genetic structure of the species under a conservation framework in order to identify its potential conservation units. In the present study, the entire mitochondrial genome of A. iberus was obtained for the first time in the context of an A. iberus reference genome. The mitogenome was reconstructed and aligned against 83 cyprinodontiformes and two outgroup taxa to create the phylogenetic reconstruction of A. iberus. PartitionFinder was first used to test for the best evolutionary model for both coding and non-coding genes and the phylogenetic analysis was performed using two methods: Maximun-Likelihood approximation (IQ-Tree) and Bayesian inference (MrBayes). Our results show that A. iberus forms a sister group with Orestias ascotanensis, a cyprinodontiform species native to South America. We believe the information gained from this study is valuable for improving our understanding of the historical evolution of A. iberus and that it can be useful for future genomic studies.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
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