ABSTRACT
Species of Gila comprise a heterogeneous and widespread group of freshwater fishes inhabiting drainage systems of western North America. The classification of species of Gila and relatives has been complicated and sometimes compromised by differences in body shapes, sizes, habitats, variable taxonomic placement by early taxonomists, and instances of hypothesized hybridization. While most attention on Gila has focused on hybridization in USA, little is actually know about their intra and intergeneric relationships. We present a molecular phylogeny using 173 specimens for all 19 recognized species of Gila, covering their entire distributions in 31 major drainages. Using one mitochondrial and three nuclear genes, specimens of Gila were analyzed with 10 other North American genera that comprise the Revised Western Clade. All analyses identified most species of Gila in a lineage that always included the monotypic genera Moapa and Acrocheilus, and we recommend the synonymy of both genera with Gila. The composition of this Gila lineage varied depending on the genes analyzed. Within the Gila lineage, similar morphotypes (forms adapted to fast currents vs. general forms) were not resolved as closest relatives. Analyses of mitochondrial DNA resolved all species of Gila from Mexico in reciprocally monophyletic clades except G. modesta. Most species of Gila in the USA were nested in 3 major clades, potentially indicating some level of historic or contemporary interspecific hybridization. Herein, we redefine the ranges for all species of Gila in Mexico. Relevant taxonomic and conservation implications stemming from the results are discussed.
Subject(s)
Cyprinidae/genetics , Phylogeny , Animals , Cyprinidae/classification , DNA, Mitochondrial/genetics , Evolution, Molecular , Hybridization, Genetic , Mexico , Mitochondria/genetics , Sequence Analysis, DNA , Southwestern United StatesABSTRACT
In this study, phylogenetic and phylogeographic analyses of populations identified as Hypostomus strigaticeps from the upper Paraná River basin were conducted in order to test whether these different populations comprises cryptic species or structured populations and to assess their genetic variability. The sequences of the mitochondrial DNA ATP sintetase (subunits 6/8) of 27 specimens from 10 populations (one from Mogi-Guaçu River, five from Paranapanema River, three from Tietê River and one from Peixe River) were analyzed. The phylogeographic analysis showed the existence of eight haplotypes (A-H), and despite the ancestral haplotype includes only individuals from the Tietê River basin, the distribution of H. strigaticeps was not restricted to this basin. Haplotypes A, B and F were the most frequent. Haplotypes D, E, F, G, and H were present in the sub-basin of Paranapanema, two (A and B) were present in the sub-basin of the Tietê River, one (C) was exclusively distributed in the sub-basin of the Peixe River, and one (B) was also present in the sub-basin of the Grande River. The phylogenetic analysis showed that the populations of H. strigaticeps indeed form a monophyletic unit comprising two lineages: TG, with representatives from the Tietê, Mogi-Guaçu and Peixe Rivers; and PP, with specimens from the Paranapanema River. The observed degree of genetic divergence within the TG and PP lineages was 0.1% and 0.2%, respectively, whereas the genetic divergence between the two lineages themselves was approximately 1%. The results of the phylogenetic analysis do not support the hypothesis of existence of crypt species and the phylogeographic analysis confirm the presence of H. strigaticeps in other sub-basins of the upper Paraná River: Grande, Peixe, and Paranapanema sub-basins.(AU)
Neste estudo, foram conduzidas análises filogenéticas e filogeográficas de populações identificadas como Hypostomus strigaticeps na bacia do alto rio Paraná a fim de testar se essas populações compreendem espécies crípticas ou populações estruturadas e avaliar a variabilidade genética das mesmas. Foram analisadas sequências do DNA mitocondrial ATP sintetase (subunidades 6/8) de 27 espécimes de 10 populações (uma do rio Mogi-Guaçu, cinco do rio Paranapanema, três do rio Tietê e uma do rio do Peixe). A análise filogeográfica mostrou a existência de oito haplótipos (A-H), e apesar do haplótipo ancestral incluir apenas indivíduos da bacia do rio Tietê, a distribuição de H. strigaticeps não se restringe a esta bacia. Os haplótipos A, B e F foram os mais frequentes. D, E, F, G e H estão presentes na sub-bacia do rio Paranapanema, dois (A e B) estão presentes na sub-bacia do rio Tietê, um (C) está exclusivamente distribuído na sub-bacia do rio do Peixe, e um (B) também está presente na sub-bacia do rio Grande. A análise filogenética mostrou que as populações de H. strigaticeps realmente formam uma unidade monofilética que compreende duas linhagens: TG, com representantes do rio Tietê, rio Mogi-Guaçu e rio do Peixe, e PP, com espécimes do rio Paranapanema. O grau de divergência genética observada nas linhagens de TG e PP foram de 0,1% e 0,2%, respectivamente, enquanto que a divergência genética entre as duas linhagens foi de aproximadamente 1%. Os resultados da análise filogenética não suportam a hipótese da existência de espécies crípticas e a análise filogeográfica confirma a presença de H. strigaticeps em outras sub-bacias do alto rio Paraná: sub-bacias do rio Grande, rio do Peixe e rio Paranapanema.(AU)
Subject(s)
Animals , Characiformes/anatomy & histology , Animal Fins/anatomy & histology , Animal Distribution/physiology , Rivers , Species SpecificityABSTRACT
In this study, phylogenetic and phylogeographic analyses of populations identified as Hypostomus strigaticeps from the upper Paraná River basin were conducted in order to test whether these different populations comprises cryptic species or structured populations and to assess their genetic variability. The sequences of the mitochondrial DNA ATP sintetase (subunits 6/8) of 27 specimens from 10 populations (one from Mogi-Guaçu River, five from Paranapanema River, three from Tietê River and one from Peixe River) were analyzed. The phylogeographic analysis showed the existence of eight haplotypes (A-H), and despite the ancestral haplotype includes only individuals from the Tietê River basin, the distribution of H. strigaticeps was not restricted to this basin. Haplotypes A, B and F were the most frequent. Haplotypes D, E, F, G, and H were present in the sub-basin of Paranapanema, two (A and B) were present in the sub-basin of the Tietê River, one (C) was exclusively distributed in the sub-basin of the Peixe River, and one (B) was also present in the sub-basin of the Grande River. The phylogenetic analysis showed that the populations of H. strigaticeps indeed form a monophyletic unit comprising two lineages: TG, with representatives from the Tietê, Mogi-Guaçu and Peixe Rivers; and PP, with specimens from the Paranapanema River. The observed degree of genetic divergence within the TG and PP lineages was 0.1% and 0.2%, respectively, whereas the genetic divergence between the two lineages themselves was approximately 1%. The results of the phylogenetic analysis do not support the hypothesis of existence of crypt species and the phylogeographic analysis confirm the presence of H. strigaticeps in other sub-basins of the upper Paraná River: Grande, Peixe, and Paranapanema sub-basins.
Neste estudo, foram conduzidas análises filogenéticas e filogeográficas de populações identificadas como Hypostomus strigaticeps na bacia do alto rio Paraná a fim de testar se essas populações compreendem espécies crípticas ou populações estruturadas e avaliar a variabilidade genética das mesmas. Foram analisadas sequências do DNA mitocondrial ATP sintetase (subunidades 6/8) de 27 espécimes de 10 populações (uma do rio Mogi-Guaçu, cinco do rio Paranapanema, três do rio Tietê e uma do rio do Peixe). A análise filogeográfica mostrou a existência de oito haplótipos (A-H), e apesar do haplótipo ancestral incluir apenas indivíduos da bacia do rio Tietê, a distribuição de H. strigaticeps não se restringe a esta bacia. Os haplótipos A, B e F foram os mais frequentes. D, E, F, G e H estão presentes na sub-bacia do rio Paranapanema, dois (A e B) estão presentes na sub-bacia do rio Tietê, um (C) está exclusivamente distribuído na sub-bacia do rio do Peixe, e um (B) também está presente na sub-bacia do rio Grande. A análise filogenética mostrou que as populações de H. strigaticeps realmente formam uma unidade monofilética que compreende duas linhagens: TG, com representantes do rio Tietê, rio Mogi-Guaçu e rio do Peixe, e PP, com espécimes do rio Paranapanema. O grau de divergência genética observada nas linhagens de TG e PP foram de 0,1% e 0,2%, respectivamente, enquanto que a divergência genética entre as duas linhagens foi de aproximadamente 1%. Os resultados da análise filogenética não suportam a hipótese da existência de espécies crípticas e a análise filogeográfica confirma a presença de H. strigaticeps em outras sub-bacias do alto rio Paraná: sub-bacias do rio Grande, rio do Peixe e rio Paranapanema.
Subject(s)
Animals , Characiformes/anatomy & histology , Animal Distribution/physiology , Animal Fins/anatomy & histology , Rivers , Species SpecificityABSTRACT
Accurate delimitation of species is a critical first step in protecting biodiversity. Detection of distinct species is especially important for groups of organisms that inhabit sensitive environments subject to recent degradation, such as creeks, springs, and rivers in arid or semi-desert regions. The genus Dionda currently includes six recognized and described species of minnows that live in clear springs and spring-fed creeks of Texas, New Mexico (USA), and northern Mexico, but the boundaries, delimitation, and characterization of species in this genus have not been examined rigorously. The habitats of some of the species in this genus are rapidly deteriorating, and many local populations of Dionda have been extirpated. Considering the increasing concerns over degradation of their habitat, and pending a more detailed morphological revision of the genus, we undertook a molecular survey based on four DNA regions to examine variation over the range of the genus, test species boundaries, and infer phylogenetic relationships within Dionda. Based on analyses of two mitochondrial (cytb and D-loop) and two nuclear (Rag1 and S7) DNA regions from specimens collected throughout the range of Dionda, we identified 12 distinct species in the genus. Formerly synonymized names are available for two of these species, and four other species remain undescribed. We also redefine the known range of six species. The limited distribution of several of the species, coupled with widespread habitat degradation, suggests that many of the species in this genus should be targets for conservation and recovery efforts.
Subject(s)
Cyprinidae/genetics , Genes, Mitochondrial , Genes, RAG-1 , Genetic Variation , Phylogeny , Animals , Bayes Theorem , Cyprinidae/classification , Likelihood Functions , Markov Chains , Mexico , Molecular Sequence Data , Sequence Analysis, DNA , United StatesABSTRACT
We constructed phylogenetic hypotheses for Mesoamerican Rhamdia, the only genus of primary freshwater fish represented by sympatric species across Central America. Phylogenetic relationships were inferred from analysis of 1990 base pairs (bp) of mitochondrial DNA (mtDNA), represented by the complete nucleotide sequences of the cytochrome b (cyt b) and the ATP synthase 8 and 6 (ATPase 8/6) genes. We sequenced 120 individuals from 53 drainages to provide a comprehensive geographic picture of Central American Rhamdia systematics and phylogeography. Phylogeographic analysis distinguished multiple Rhamdia mtDNA lineages, and the geographic congruence across evolutionarily independent Rhamdia clades indicated that vicariance has played a strong role in the Mesoamerican diversification of this genus. Phylogenetic analyses of species-level relationships provide strong support for the monophyly of a trans-Andean clade of three evolutionarily equivalent Rhamdia taxa: R. guatemalensis, R. laticauda, and R. cinerascens. Application of fish-based mitochondrial DNA clocks ticking at 1.3-1.5% sequence divergence per million years (Ma), suggests that the split between cis- and trans-Andean Rhamdia extends back about 8 Ma, and the three distinct trans-Andean Rhamdia clades split about 6 Ma ago. Thus the mtDNA divergence observed between cis- and trans-Andean Rhamdia species is too low to support an ancient colonization of Central America in the Late Cretaceous or Paleocene as had been hypothesized in one colonization model for Mesoamerican fishes. Rather the mtDNA data indicate that Rhamdia most likely colonized Central America in the late Miocene or Pliocene, promoting a strong role for the Isthmus of Panamá in the Mesoamerican expansion of this genus. Basal polytomies suggest that both the R. laticauda and R. guatemalensis clades spread rapidly across the Central American landscape, but differences in the average mtDNA genetic distances among clades comprising the two species, indicate that the R. laticauda spread and diversified across Mesoamerica about 1 million years before R. guatemalensis.