RESUMO
The responses of marine species to environmental changes and anthropogenic pressures (e.g., fishing) interact with ecological and evolutionary processes that are not well understood. Knowledge of changes in the distribution range and genetic diversity of species and their populations into the future is essential for the conservation and sustainable management of resources. Almaco jack (Seriola rivoliana) is a pelagic fish with high importance to fisheries and aquaculture in the Pacific Ocean. In this study, we assessed contemporary genomic diversity and structure in loci that are putatively under selection (outlier loci) and determined their potential functions. Using a combination of genotype-environment association, spatial distribution models, and demogenetic simulations, we modeled the effects of climate change (under three different RCP scenarios) and fishing pressure on the species' geographic distribution and genomic diversity and structure to 2050 and 2100. Our results show that most of the outlier loci identified were related to biological and metabolic processes that may be associated with temperature and salinity. The contemporary genomic structure showed three populations-two in the Eastern Pacific (Cabo San Lucas and Eastern Pacific) and one in the Central Pacific (Hawaii). Future projections suggest a loss of suitable habitat and potential range contractions for most scenarios, while fishing pressure decreased population connectivity. Our results suggest that future climate change scenarios and fishing pressure will affect the genomic structure and genotypic composition of S. rivoliana and lead to loss of genomic diversity in populations distributed in the eastern-central Pacific Ocean, which could have profound effects on fisheries that depend on this resource.
Las respuestas de las especies marinas ante los cambios ambientales y presiones antropogénicas (por ejemplo, la sobrepesca) interactúan con procesos ecológicos y evolutivos que no se comprenden bien. El conocimiento del cambio en el rango de distribución y la diversidad genética de las especies y sus poblaciones en el futuro es fundamental para la conservación y gestión sostenible de los recursos. El jurel (Seriola rivoliana) es un pez pelágico de gran importancia para la pesca y la acuicultura en el Océano Pacífico. En este estudio, evaluamos la diversidad y estructura genómica contemporánea en loci que supuestamente están bajo selección (loci atípicos) y determinamos sus funciones potenciales. Se utilizó la combinación de métodos de asociación genotipo-ambiente, modelos de distribución espacial y simulaciones demogenéticas, para modelar los efectos del cambio climático (bajo tres escenarios RCP diferentes) y presión de pesca sobre la distribución geográfica de la especie, la diversidad y estructura genómica para los años 2050 y 2100. Nuestros resultados mostraron que la mayoría de los loci atípicos están relacionados con procesos biológicos y metabólicos que pueden estar asociados con la temperatura y la salinidad. La estructura genómica contemporánea mostró tres poblaciones: dos en el Pacífico oriental (Cabo San Lucas y el Pacífico oriental) y una en el Pacífico central (Hawai). Las proyecciones futuras sugieren una pérdida de hábitat idóneo y posibles contracciones del área de distribución para la mayoría de los escenarios, mientras que la presión de la pesca redujo la conectividad de las poblaciones. Nuestros resultados sugieren que los escenarios de cambio climático y la presión pesquera afectarán la estructura genómica y la composición genotípica de S. rivoliana y conducirán a la pérdida de diversidad genómica en las poblaciones distribuidas en el Océano Pacífico centro-oriental, lo que podría tener efectos en las pesquerías que dependen de este recurso.
Assuntos
Caça , Perciformes , Animais , Mudança Climática , Oceano Pacífico , Genótipo , Genômica , Pesqueiros , EcossistemaRESUMO
A high diversity of rattlesnake species can be found in the Baja California peninsula and the island of the Gulf of California, nevertheless, their venom has been poorly evaluated. The aim of this work was to present the first characterization of endemic Crotalus mitchellii, micro endemic C. polisi and C. thalassoporus venoms. All samples provoke human plasma coagulation showing doses in the rank of 2.3-41.0 µg and also produce rapid hydrolysis of the alpha chain of bovine fibrinogen while the beta chain is attacked at larger incubation periods by C. polisi and especially by C. thalassoporus. Phospholipase activity ranging from 23.2 to 173.8 U/mg. The venoms of C. thalassoporus and C. polisi show very high hemorrhagic activity (from 0.03 to 0.31 µg). A total of 130 toxin-related proteins were identified and classified into ten families. Crotalus mitchellii venom was characterized by high abundance of crotoxin-like and other phospholipase proteins (34.5%) and serine proteinases (29.8%). Crotalus polisi showed a similar proportion of metalloproteinases (34%) and serine proteinases (22.8%) components with important contribution of C-type lectins (14.3%) and CRiSP (14.0%) proteins. Venom of C. thalassoporus is dominated by metalloproteases that amount to more than 66% of total toxin proteins. These results provide a foundation for comprehending the biological, ecological and evolutionary significance of venom composition of speckled rattlesnake from the Baja California peninsula.
Assuntos
Venenos de Crotalídeos , Crotalus , Animais , Venenos de Crotalídeos/metabolismo , Crotalus/metabolismo , Metaloproteases/metabolismo , México , Fosfolipases/metabolismo , Proteínas/metabolismo , Serina Proteases/metabolismoRESUMO
Aliger gigas is an economically important and vulnerable marine species. We present a new mitogenome of A. gigas from the Mexican Caribbean and use the eight publicly available Strombidae mitogenomes to analyze intra- and interspecific variation. We present the most complete phylogenomic understanding of Hypsogastropoda to date (17 superfamilies, 39 families, 85 genera, 109 species) to revisit the phylogenetic position of the Stromboidea and evaluate divergence times throughout the phylogeny. The A. gigas mitogenome comprises 15,460 bp including 13 PCGs, 22 tRNAs, and two rRNAs. Nucleotide diversity suggested divergence between the Mexican and Colombian lineages of A. gigas. Interspecific divergence showed high differentiation among Strombidae species and demonstrated a close relationship between A. gigas and Strombus pugilis, between Lambis lambis and Harpago chiragra, and among Tridentarius dentatus/Laevistrombus canarium/Ministrombus variabilis. At the intraspecific level, the gene showing the highest differentiation is ATP8 and the lowest is NAD4L, whereas at the interspecific level the NAD genes show the highest variation and the COX genes the lowest. Phylogenomic analyses confirm that Stromboidea belongs in the non-Latrogastropoda clade and includes Xenophoridea. The phylogenomic position of other superfamilies, including those of previously uncertain affiliation, is also discussed. Finally, our data indicated that Stromboidea diverged into two principal clades in the early Cretaceous while Strombidae diversified in the Paleocene, and lineage diversification within A. gigas took place in the Pleistocene.
Assuntos
Gastrópodes/classificação , Gastrópodes/genética , Animais , Sequência de Bases , Região do Caribe , Extratos Celulares/genética , Mitocôndrias/genética , Mitocôndrias/metabolismo , NAD/metabolismo , Filogenia , RNA Ribossômico/metabolismo , RNA de Transferência/metabolismoRESUMO
Rattlesnake's venom constitutes an important ecological trait that dynamically changes over time. Venoms of adult and juvenile rattleless rattlesnakes, Crotalus catalinensis, an endemic insular species from the Gulf of California, were compared by electrophoretic profile, fibrinogenolytic activity, and proteomic composition to assess ontogenetic variability. The SDS-PAGE profiles show important differences at 12, 22, and 45 kDa, which were prominent in adult samples and absent in juvenile samples, while bands around 20, 25, and 70 kDa are almost absent in adults. Both venoms hydrolyze Aa and Bb chains of fibrinogen generating different patterns of degradation products. This activity was partially inhibited by EDTA and PMSF and completely abolished only in the presence of both inhibitors. More than 260 proteins were identified and quantified in both venoms by proteomic analysis. Metalloproteinases (more than 60%), serine proteinases (14.5% in adult venom and 17.7% in juvenile venom), and C-type lectins (7.1 and 5.9%) represent the three most abundant toxin-related protein families. Bradykinin inhibitor peptides and L-amino acid oxidases were not detected in juvenile venom. A protein-specific comparison shows that adult and juvenile venom share about 30.5% of total toxin-related proteins, while 32% and 35% are exclusively present in adult and juvenile venoms, respectively. This work represents one of the first efforts to understand phenotypic diversity in the venom composition of insular rattlesnake species from Mexico.
Assuntos
Venenos de Crotalídeos , Crotalus , Proteoma/metabolismo , Animais , Humanos , Metaloproteases , México , ProteômicaRESUMO
The almaco jack, Seriola rivoliana, is a circumtropical pelagic fish of importance both in commercial fisheries and in aquaculture. To understand levels of genetic diversity within and among populations in the wild, population genetic structure and the relative magnitude of migration were assessed using mtDNA sequence data and single nucleotide polymorphisms (SNPs) from individuals sampled from locations in the Pacific and Atlantic Oceans. A total of 25 variable sites of cytochrome c oxidase subunit 1 and 3678 neutral SNPs were recovered. Three genetic groups were identified, with both marker types distributed in different oceanic regions: Pacific-1 in central Pacific, Pacific-2 in eastern Pacific and Atlantic in western Atlantic. Nonetheless, the analysis of SNP identified a fourth population in the Pacific coast of Baja California Sur, Mexico (Pacific-3), whereas that of mtDNA did not. This mito-nuclear discordance is likely explained by a recently diverged Pacific-3 population. In addition, two mtDNA haplogroups were found within the western Atlantic, likely indicating that the species came into the Atlantic from the Indian Ocean with historical gene flow from the eastern Pacific. Relative gene flow among ocean basins was low with r m < 0.2, whereas in the eastern Pacific it was asymmetric and higher from south to north (r m > 0.79). The results reflect the importance of assessing genetic structure and gene flow of natural populations for the purposes of sustainable management.
Assuntos
Conservação dos Recursos Naturais , Pesqueiros , Variação Genética , Perciformes/genética , Animais , DNA Mitocondrial/genética , Fluxo Gênico , Genética Populacional , México , Oceanos e Mares , Perciformes/classificação , Clima TropicalRESUMO
In accordance with the Red Queen hypothesis, the lower genotypic diversity in clonally reproducing species should make them easier targets for pathogen infection, especially when closely related sexually reproducing species occur in close proximity. We analyzed two populations of clonal P. formosa and their sexual parental species P. mexicana by correlating individual parasite infection with overall and immune genotype. Our study revealed lower levels of overall genotypic diversity and marginally fewer MHC class I alleles in P. formosa individuals compared to sexually reproducing P. mexicana. Parasite load, however, differed only between field sites but not between species. We hypothesize that this might be due to slightly higher genotypic diversity in P. formosa at the innate immune system (toll like receptor 8) which is likely due to the species' hybrid origin. In consequence, it appears that clonal individuals do not necessarily suffer a disadvantage compared to sexual individuals when fighting parasite infection.
Assuntos
Poecilia/fisiologia , Poecilia/parasitologia , Reprodução Assexuada/genética , Reprodução Assexuada/imunologia , Imunidade Adaptativa/genética , Alelos , Animais , Feminino , Proteínas de Peixes/genética , Proteínas de Peixes/imunologia , Genes MHC Classe I , Variação Genética , Genótipo , Especificidade de Hospedeiro/genética , Especificidade de Hospedeiro/imunologia , Imunidade Inata/genética , Masculino , México , Modelos Genéticos , Modelos Imunológicos , Carga Parasitária , Poecilia/genética , Reprodução/genética , Reprodução/imunologia , Especificidade da Espécie , Receptor 8 Toll-Like/genética , Receptor 8 Toll-Like/imunologiaRESUMO
Understanding the factors that explain the patterns of genetic structure or phylogeographic breaks at an intraspecific level is key to inferring the mechanisms of population differentiation in its early stages. These topics have been well studied in the Baja California region, with vicariance and the dispersal ability of individuals being the prevailing hypothesis for phylogeographic breaks. In this study, we evaluated the phylogeographic patterns in the desert iguana (Dipsosaurus dorsalis), a species with a recent history in the region and spatial variation in life history traits. We analyzed a total of 307 individuals collected throughout 19 localities across the Baja California Peninsula with 15 microsatellite DNA markers. Our data reveal the existence of 3 geographically discrete genetic populations with moderate gene flow and an isolation-by-distance pattern presumably produced by the occurrence of a refugium in the Cape region during the Pleistocene Last Glacial Maximum. Bayesian methods and ecological niche modeling were used to assess the relationship between population genetic structure and present and past climatic preferences of the desert iguana. We found that the present climatic heterogeneity of the Baja California Peninsula has a marked influence on the population genetic structure of the species, suggesting that there are alternative explanations besides vicariance. The information obtained in this study provides data allowing a better understanding of how historical population processes in the Baja California Peninsula can be understood from an ecological perspective.
Assuntos
Clima Desértico , Genética Populacional , Iguanas/genética , Animais , Teorema de Bayes , Ecossistema , Fluxo Gênico , México , Repetições de Microssatélites , Modelos Genéticos , Filogenia , Filogeografia , Análise de Sequência de DNARESUMO
Population-level morphometrc variation of the Mountain Mullet (Agonostomus monticola) was assessed in 419 adult specimens from 25 sample sites (river basins) across its Middle American distribution (Pacific and Atlantic-Caribbean drainages). This analysis was based on 36 standardized linear measurements and 19 landmarks on geometric morphometrics approach. Discriminant function analysis (DFA) revealed 19 linear morphological characters with significant variation among groups. Geometrically, the most notable changes were associated to the curvature of the frontal region of the head, the anterior and posterior insertion of the first dorsal and anal fins. The resulting grouping based on the DFA and geometric morphometrics techniques (Pacific-A, Pacific-B and NE México-Caribbean) were similar to those previously recovered by genetic techniques, where the Pacific-B (Ayuquila river basin) was the most different group. Our results provide morphological evidence for considering Agonostomus monticola as a complex of evolutionary entities, represented by two forms in the Pacific Ocean and another in the Atlantic Ocean.(AU)
La variación morfométrica de poblaciones de la lisa de montaña Agonostomus monticola fue evaluada en 419 especímenes adultos recolectados en 25 sitios (cuencas) a través de su distribución mesoamericana (Pacífico, Atlántico y cuencas del Caribe). El análisis fue basado en 36 medidas lineales estandarizadas y 19 puntos de referencia basados en morfometría geométrica. El análisis de función discriminante (AFD) reveló 19 caracteres morfométricos con variación significativa entre grupos. Geométricamente, los cambios más notables estuvieron asociados con la curvatura de la región frontal de la cabeza y la inserción anterior y posterior de la primera aleta dorsal y de la aleta anal. Los agrupamientos resultantes del AFD y del análisis de morfometría geométrica (Pacífico-A, Pacífico-B y NE México-Caribe) fueron similares con los previamente definidos mediante técnicas genéticas. El grupo Pacífico-B (cuenca de Ayuquila) fue el más disímil. Nuestros resultados proveen evidencia morfológica para considerar a Agonostomus monticola como un complejo de entidades evolutivas, representadas por dos formas en la cuenca del océano Pacífico y una forma en la cuenca del océano Atlántico.(AU)
Assuntos
Animais , Smegmamorpha/anatomia & histologia , Demografia/tendênciasRESUMO
Population-level morphometric variation of the Mountain Mullet (Agonostomus monticola) was assessed in 419 adult specimens from 25 sample sites (river basins) across its Middle American distribution (Pacific and Atlantic-Caribbean drainages). This analysis was based on 36 standardized linear measurements and 19 landmarks on geometric morphometrics approach. Discriminant function analysis (DFA) revealed 19 linear morphological characters with significant variation among groups. Geometrically, the most notable changes were associated to the curvature of the frontal region of the head, the anterior and posterior insertion of the first dorsal and anal fins. The resulting grouping based on the DFA and geometric morphometrics techniques (Pacific-A, Pacific-B and NE México-Caribbean) were similar to those previously recovered by genetic techniques, where the Pacific-B (Ayuquila river basin) was the most different group. Our results provide morphological evidence for considering Agonostomus monticola as a complex of evolutionary entities, represented by two forms in the Pacific Ocean and another in the Atlantic Ocean.(AU)
La variación morfométrica de poblaciones de la lisa de montaña Agonostomus monticola fue evaluada en 419 especímenes adultos recolectados en 25 sitios (cuencas) a través de su distribución mesoamericana (Pacífico, Atlántico y cuencas del Caribe). El análisis fue basado en 36 medidas lineales estandarizadas y 19 puntos de referencia basados en morfometría geométrica. El análisis de función discriminante (AFD) reveló 19 caracteres morfométricos con variación significativa entre grupos. Geométricamente, los cambios más notables estuvieron asociados con la curvatura de la región frontal de la cabeza y la inserción anterior y posterior de la primera aleta dorsal y de la aleta anal. Los agrupamientos resultantes del AFD y del análisis de morfometría geométrica (Pacífico-A, Pacífico-B y NE México-Caribe) fueron similares con los previamente definidos mediante técnicas genéticas. El grupo Pacífico-B (cuenca de Ayuquila) fue el más disímil. Nuestros resultados proveen evidencia morfológica para considerar a Agonostomus monticola como un complejo de entidades evolutivas, representadas por dos formas en la cuenca del océano Pacífico y una forma en la cuenca del océano Atlántico.(AU)
Assuntos
Animais , Demografia/tendências , Smegmamorpha/anatomia & histologiaRESUMO
Studies of phylogeographic patterns provide insight into the processes driving lineage divergence in a particular region. To identify the processes that caused phylogeographic breaks, it is necessary to use historical information and a set of appropriate molecular data to explain current patterns. To understand the influence of geological or ecological processes on the phylogeography of the only species of hummingbird endemic to the Baja California Peninsula, Hylocharis xantusii, mitochondrial DNA sequences of three concatenated genes (Cyt-b, COI and ND2; 2297bp in total) in 100 individuals were analyzed. The spatial analyses of genetic variation showed phylogeographic structure consisting of a north, central and south regions. According to estimated divergence times, two vicariant events are supported, permanent separation of the peninsula and formation of the Gulf of California at 5mya and temporary isolation of the southern region at the Isthmus of La Paz at 3mya. The temporal frame of genetic differentiation of intraspecific haplotypes indicates that 90% of haplotypes diverged within the last 500,000years, with a population expansion 80,000years ago. Only four haplotypes diverged â¼2.2 my and occurred in the south (Hxan_36, 38 and 45), and north (Hxan_45 and 56) regions; only haplotype 45 is shared between south and north populations. These regions also have the most recent haplotypes from 12,500 to 16,200years ago, and together with high levels of genetic diversity, we suggest two refuge areas, the Northern and Southern regions. Our results indicate that the phylogeographic pattern first results from vicariance processes, then is followed by historical and recent climate fluctuations that influenced conditions on the peninsula, and it is also related to oases distribution. This study presents the first investigation of phylogeography of the peninsular' endemic Xantus' hummingbird.
Assuntos
Aves/classificação , Variação Genética , Animais , Aves/genética , Citocromos b/química , Citocromos b/genética , Citocromos b/metabolismo , DNA Mitocondrial/química , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Haplótipos , História Antiga , México , NADH Desidrogenase/química , NADH Desidrogenase/genética , NADH Desidrogenase/metabolismo , Filogenia , Filogeografia/históriaRESUMO
The Isla Guadalupe white shark mitochondrial structure is similar to the one previously reported for a white shark individual from Taiwan with a total length of 16,745 and 16,742 bp respectively; the base composition of the genomes was as follow A (30.60%), T (28.67%), C (26.86%) and G (13.87%), contains 13 protein-coding genes and 24 tRNA genes and the non-coding control region. The tRNA genes range from 70-72 bp. Gene order is the same as in other vertebrates and teleosts.
Assuntos
Genoma Mitocondrial , Análise de Sequência de DNA/métodos , Tubarões/genética , Animais , Composição de Bases , Ordem dos Genes , Tamanho do Genoma , México , Mitocôndrias/genéticaRESUMO
The mitogenome of the tenguayaca, Petenia splendida (GenBank accession number KJ914664) has a total length of 16,518 bp, and the arrangement consist of 15 protein-coding genes, 2 ribosomal RNA (rRNA) genes and 22 transfer RNA (tRNA) genes. Gene order was equal to the mitogenomes of other new world cichlids.
Assuntos
Ciclídeos/genética , Genoma Mitocondrial , Mitocôndrias/genética , Animais , Composição de Bases , Ordem dos Genes , Tamanho do Genoma , FilogeniaRESUMO
The bull shark mitochondrial structure is similar to that of other elasmobranchs; it has a total length of 16,100 bp, the base composition of the genomes was as follows: A (31.35%), T (31.35%), C (24.38%) and G (12.90%). It contains 13 protein-coding genes and 23 tRNA genes. The tRNA genes range from 70-72 bp. Gene order is the same as in other vertebrates and teleosts.
Assuntos
DNA Mitocondrial/genética , Tubarões/genética , Animais , Composição de Bases/genética , Ordem dos Genes , Fases de Leitura Aberta/genética , Filogenia , Análise de Sequência de DNARESUMO
The mitogenome of the endemic coral Porites panamensis (Genbank accession number KJ546638) has a total length of 18,628 bp, and the arrangement consist of 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes and 2 transfer RNA (tRNA) genes. Gene order was equal to other scleractinian coral mitogenomes.
Assuntos
Antozoários/genética , DNA Mitocondrial/genética , Genoma Mitocondrial , Animais , Sequência de Bases , Ordem dos Genes , Oceano Pacífico , FilogeniaRESUMO
Pocillopora corals are the main reef builders in the eastern tropical Pacific. The validity of Pocillopora morphospecies remains under debate because of disagreements between morphological and genetic data. To evaluate the temporal stability of morphospecies in situ, we monitored the shapes of individual colonies in three communities in the southern Gulf of California for 44 months. Twenty-three percent of tagged colonies of Pocillopora damicornis changed to Pocillopora inflata morphology during this time. This switch in identity coincided with a shift to a higher frequency of storms and lower water turbidity (i.e., lower chlorophyll a levels). Seven months after the switch, P. inflata colonies were recovering their original P. damicornis morphology. All colonies of both morphospecies shared a common mitochondrial identity, but most P. damicornis colonies undergoing change were at a site with low-flow conditions. This is the first in situ study to document switching between described morphospecies, and it elucidates the influence of temporal shifts in environmental conditions on morphologically plastic responses.
Assuntos
Antozoários/anatomia & histologia , Antozoários/classificação , Adaptação Fisiológica , Animais , Clorofila , Clorofila A , Meio Ambiente , Oceanos e Mares , Fenótipo , Água do Mar/química , Especificidade da Espécie , Tempo (Meteorologia)RESUMO
Pocillopora corals, the dominant reef-builders in the Eastern Tropical Pacific, exhibit a high level of phenotypic plasticity, making the interpretation of morphological variation and the identification of species challenging. To test the hypothesis that different coral morphospecies represent phenotypes that develop in different flow conditions, we compared branch characters in three Pocillopora morphospecies (P. damicornis, P. verrucosa, and P. meandrina) from two communities in the Gulf of California exposed to contrasting flow conditions. Morphological variation and branch modularity (i.e., the tendency of different sets of branch traits to vary in a coordinated way) were assessed in colonies classified as Pocillopora type 1 according to two mitochondrial regions. Our results can be summarized as follows. (1) Pocillopora type 1 morphospecies corresponded to a pattern of morphological variation in the Gulf of California. Overall, P. damicornis had the thinnest branches and its colonies the highest branch density, followed by P. verrucosa, and then by P. meandrina, which had the thickest branches and its colonies the lowest branch density. (2) The differentiation among morphospecies was promoted by different levels of modularity of traits. P. verrucosa had the highest coordination of traits, followed by P. damicornis, and P. meandrina. (3) The variation and modularity of branch traits were related to water flow condition. Morphology under the high-flow condition was more similar among morphospecies than under the low-flow condition and seemed to be related to mechanisms for coping with these conditions. Our results provide the first evidence that in scleractinian corals different levels of modularity can be promoted by different environmental conditions.
Assuntos
Adaptação Fisiológica , Antozoários/anatomia & histologia , Recifes de Corais , Meio Ambiente , Fenótipo , Movimentos da Água , Animais , Oceanos e Mares , Clima TropicalRESUMO
PREMISE OF THE STUDY: Microsatellite primers were developed for the cardon, a giant columnar cactus (Pachycereus pringlei) of the Sonoran Desert, to investigate intraspecific genetic patterns of diversity and population structure. ⢠METHODS AND RESULTS: Using 454 GS-FLX technology and bioinformatics tools, microsatellite primers were successfully identified on 282 reads, including di-, tri-, tetra-, penta-, and hexanucleotides. A set of 10 primers were characterized on 80 individuals collected in two areas of the Baja California peninsula, Mexico. All 10 loci were polymorphic, with a mean of 6.3 alleles per locus and overall levels of observed and expected heterozygosities ranging from 0.41 to 0.59 and from 0.40 to 0.57, respectively. Alleles per individual plant ranged from one to four, suggesting a polyploidal genome. ⢠CONCLUSIONS: These loci should be useful for future investigations of population structure, genetic diversity, and gene flow in the cardon cactus.
RESUMO
The loss of traits is a commonly observed evolutionary pattern in cave organisms, but due to extensive morphological convergence, inferring relationships between cave and surface populations can be difficult. For instance, Astyanax mexicanus (the blind Mexican cavefish) is thought to have repeatedly lost its eyes following colonization of cave environments, but the number of evolutionarily independent invasions of this species into caves remains unclear. Because of these repeated losses, it has become a model organism for studying the genetic basis of phenotypic trait loss. Here we reconstruct a high-resolution phylogeography for A. mexicanus inferred from both mitochondrial DNA and several thousand single nucleotide polymorphisms. We provide novel insight into the origin of cave populations from the Sabinos and Río Subterráneo caves and present evidence that the Sabinos cave population is part of a unique cave lineage unrelated to other A. mexicanus cave populations. Our results indicate A. mexicanus cave populations have at least four independent origins.
Assuntos
Evolução Biológica , Cavernas , Characidae/classificação , Filogenia , Animais , Teorema de Bayes , Characidae/genética , DNA Mitocondrial/genética , Funções Verossimilhança , México , Modelos Genéticos , Filogeografia , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNARESUMO
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.
Assuntos
Cyprinidae/genética , Filogenia , Animais , Cyprinidae/classificação , DNA Mitocondrial/genética , Evolução Molecular , Hibridização Genética , México , Mitocôndrias/genética , Análise de Sequência de DNA , Sudoeste dos Estados UnidosRESUMO
The valley of Cuatro Ciénegas, an aquatic oasis located in the Mexican Chihuahuan Desert, exhibits the highest level of endemism in North America and is a Mexican National Protected Area. However, little is known about the evolutionary distinctiveness of several vertebrate species present in the Cuatro Ciénegas valley. We conducted a phylogeographic study using mitochondrial haplotypes from the centrarchid fish Lepomis megalotis to determine if the populations found within the valley were evolutionarily distinct from populations outside the valley. We also examined if there was evidence of unique haplotypes of this sunfish within the valley. Genetic divergence of L. megalotis suggests populations within the valley are evolutionarily unique when compared to L. megalotis outside the valley. Significant mitochondrial sequence divergence was also discovered between L. megalotis populations on either side of the Sierra de San Marcos that bisects the valley. Our results reinforce previous studies that suggest the organisms occupying aquatic habitats not only within Cuatro Ciénegas but also in each of the two lobes of the valley generally deserve independent consideration during management decisions.