Phylogeny and taxonomy of the genusIlyodonEigenmann, 1907 (Teleostei: Goodeidae), based on mitochondrial and nuclear DNA sequences

Abstract

Taxonomy of the live-bearing fish of the genus Ilyodon Eigenmann, 1907 (Goodeidae), in Mexico, is controversial, with morphology and mitochondrial genetic analyses in disagreement about the number of valid species. The present study accumulated a comprehensive DNA sequences dataset of 98 individuals of all Ilyodon species and mitochondrial and nuclear loci to reconstruct the evolutionary history of the genus. Phylogenetic inference produced five clades, one with two subclades, and one clade including three recognized species. Genetic distances in mitochondrial genes (cytb: 0.5%-2.1%; coxI: 0.5%-1.1% and d-loop: 2.3%-10.2%) were relatively high among main clades, while, as expected, nuclear genes showed low variation (0.0%-0.2%), with geographic concordance and few shared haplotypes among river basins. High genetic structure was observed among clades and within basins. Our genetic analyses, applying the priority principle, suggest the recognition only of Ilyodon whitei and Ilyodon furcidens, with I. cortesae relegated to an invalid species, the populations of which belong to I. whitei.

Speciation of silversideChirostoma attenuatum(Pisces: Atheriniformes) in Central Mexico

“…In this case, the lack of resolution and mixed haplotypes in the S7 genetic tree reflected the combined effects of low variation and incomplete lineage sorting that is consistent with the low evolutionary rate and high coalescence time for nuclear loci (Egge et al., ). These variation patterns are usually demonstrated by species complexes that have undergone relatively recent divergence (Beltrán‐López et al., ; Buj, Šanda, Marčić, Ćaleta, & Mrakovčić, ; Buj et al., ), which is consistent with the most recent common ancestor of C. a. attenuatum and C. a. zirahuen populations dated ca . 600,000 years ago (Figure ), considered a recent isolation event compared to divergence of the Patzcuaro endemic A. lacustris dated 1.9 Ma ago.…”

“…In Atherinopsidae that inhabit continental habitats, high species richness has been attributed to the frequency of allopatric speciation events resulting from emergence of vicariant barriers, limiting gene flow and promoting genetic divergence (Barbour, ; Bloom et al., ; Echelle & Echelle, ; García‐Martínez, Mejia, García ‐De León, & Barriga‐Sosa, ; Miller, Minckley & Norris, ). For fish species distributed throughout Central Mexico, allopatric events related to geological activity in the Trans‐Mexican Volcanic Belt (TMVB), together with the climate history, are regarded as the main source of diversification (Beltrán‐López et al., ; Domínguez‐Domínguez, Doadrio, & Pérez‐Ponce de León, ; Pérez‐Rodríguez, Domínguez‐Domínguez, Doadrio, Cuevas‐Gacía, & Pérez‐Ponce de León, ). Diversification of the genus Chirostoma Swainson 1839 from Central Mexico has been associated with such allopatric speciation events as well as with sympatric ecological segregation, particularly in the species inhabiting lacustrine ecosystems (Barbour, ; Barbour & Chernoff, ; Echelle & Echelle, ).…”

Distribution and current conservation status of the Mexican Goodeidae (Actinopterygii, Cyprinodontiformes)

“…Substantial morphological and genetic variation exists within and among populations of Ilyodon (Kingston 1979), and the taxonomy of the genus has long been confused. Based on recent genetic analyses (Beltrán-López et al 2017), we recognize only two species, but some ichthyologists and aquarists have recognized as many as five or six.…”

Mind the gap! The mitochondrial control region and its power as a phylogenetic marker in echinoids

“…Apart from the general advantages of mitochondrial markers in animal phylogenetic studies, namely their maternal inheritance, lack of recombination, and fast rate of evolution [ 9 , 10 ], several unique qualities make the CR a favoured marker sequence for genetic diversity analyses, in particular, its exceptionally fast evolutionary rate (even in comparison to the rest of the mitochondrial genome [ 11 , 12 ]), polymorphic nature [ 13 ] and presumed selective neutrality as a non-coding region (but see [ 14 , 15 ]). Consequently, this region has been widely used as a genetic marker in phylogenetic studies of various animals including vertebrate classes such as fish (e.g., [ 16 , 17 ]), amphibians [ 18 ], reptiles [ 19 ], birds [ 20 ] and mammals [ 21 , 22 ] as well as numerous invertebrate taxa (e.g., [ 23 – 26 ]. Nevertheless, despite being extremely useful for some species, several factors may hinder the utility of this marker in others.…”