RESUMO
Transposable elements (TEs) are important components of eukaryotic genomes and compose around 30% of the genome of Rhinella marina, an invasive toad species. Considering the possible role of TEs in the adaptation of populations, we have analyzed the expression of TEs in publicly available spleen tissue transcriptomic data generated for this species after immune and stress challenge. By analyzing the transcriptome assembly, we detected a high number of TE segments. Moreover, some distinct TE families were differentially expressed in some conditions. Our result shows that several TEs are capable of being transcribed in R. marina and they could help to generate a rapid response of specimens to the environment. Also, we can suggest that these TEs could be activated in the germinative cells as well producing variability to be selected and shaped by the evolutionary processes behind the success of this invasive species. Thus, the TEs are important targets for investigation in the context of R. marina adaptation.
Assuntos
Bufo marinus/genética , Bufo marinus/imunologia , Elementos de DNA Transponíveis/genética , Elementos de DNA Transponíveis/imunologia , Estresse Fisiológico/genética , Estresse Fisiológico/imunologia , Animais , Feminino , MasculinoRESUMO
The high levels of Neotropical biodiversity are commonly associated with the intense Neogene-Quaternary geological events and climate dynamics. Here, we investigate the evolutionary history of two species of Neotropical closely related amphibians (R. horribilis and R. marina). We combine published data with new mitochondrial DNA sequences and multiple nuclear markers, including 12 microsatellites. The phylogenetic analyses showed support for grouping the samples in two main clades; R. horribilis (Central America and Mexico) and R. marina (South America east of the Andes). However, the phylogenetic inferences also show an evident mito-nuclear discordance. We use Approximate Bayesian Computation (ABC) to test the role of different events in the diversification between the two groups recovered. We found that both species were affected primarily by a recent Pleistocene divergence, which was similar to the divergence estimate revealed by the Isolation-with-Migration model, under persistent bidirectional gene flow through time. We provide the first evidence that R. horribilis is differentiated from the South American R. marina at the nuclear level supporting the taxonomic status of R. horribilis, which has been controversial for more than a century.
Assuntos
Bufo marinus/classificação , Animais , Teorema de Bayes , Evolução Biológica , Bufo marinus/genética , América Central , Citocromos b/química , Citocromos b/classificação , Citocromos b/genética , DNA Mitocondrial/genética , Fluxo Gênico , Variação Genética , Repetições de Microssatélites/genética , Filogenia , Filogeografia , Proteínas Ribossômicas/química , Proteínas Ribossômicas/classificação , Proteínas Ribossômicas/genética , América do SulRESUMO
Contamination with pesticide residues affects the environmental health of agroecosystems, especially the amphibian fauna that lives in these environments. The objective of the present study was to determine pesticides concentrations in sediments of agroecosystems and to evaluate genetic damage in Rhinella marina populations living in these zones. A total of 91 individuals were collected, 51 in the group exposed in different areas of the middle region of the Sinú River (Irrigation District of Mocari 16, Irrigation District of Aguas Negras 21, Irrigation District of Cerete 14) and 40 in a control group; at the same time, 36 subsamples of sediments were taken at each sampled station to determine pesticides organochlorine by means of chromatography coupled with ISQ Thermo Scientific mass spectrometer. The micronucleus test was applied in erythrocytes of the individuals collected. Results showed the presence of persistent organochlorine pesticides (POPs) in the sediment samples (p,p'-DDT, p,p'-DDE, and p,p'-DDD) of agricultural soils. Two individuals were registered with abnormalities in their limbs at the Mocari station, representing 12.5% of the morphological malformations to this sector. Micronucleus analysis revealed statistically significant genetic damage in exposed individuals (Mocari 9.87 ± 5.1, Cerete 7.7 ± 1.7, Aguas Negras 5.6 ± 3.6) with respect to the control group (2.4 ± 1.9) (p < 0.05). Spearman correlation analysis revealed a positive association between genetic damage and POP concentrations (p < 0.05). In addition, cellular alterations such as nuclear buds, and pyknosis (cell death), were statistically significant in the exposed group compared to the control group (p < 0.05). This study suggests that there is evidence for morphological and genotoxic effects in R. marina populations inhabiting areas influenced by agriculture, possibly associated with the presence of p,p'-DDT, p,p'-DDD, and p,p'-DDE.
Assuntos
Agricultura/métodos , Bufo marinus/genética , Monitoramento Ambiental/métodos , Resíduos de Praguicidas/análise , Rios/química , Poluentes do Solo/análise , Animais , Bufo marinus/anormalidades , Bufo marinus/sangue , Colômbia , Ecossistema , Humanos , Micronúcleos com Defeito Cromossômico/efeitos dos fármacos , Micronúcleos com Defeito Cromossômico/estatística & dados numéricos , Resíduos de Praguicidas/toxicidade , Estações do Ano , Solo/química , Poluentes do Solo/toxicidadeRESUMO
The Amazonian coast has several unique geological characteristics resulting from the interaction between drainage pattern of the Amazon River and the Atlantic Ocean. It is one of the most extensive and sedimentologically dynamic regions of the world, with a large number of continental islands mostly formed less than 10,000 years ago. The natural distribution of the cane toad (Rhinella marina), one of the world's most successful invasive species, in this complex Amazonian system provides an intriguing model for the investigation of the effects of isolation or the combined effects of isolation and habitat dynamic changes on patterns of genetic variability and population differentiation. We used nine fast-evolving microsatellite loci to contrast patterns of genetic variability in six coastal (three mainlands and three islands) populations of the cane toad near the mouth of the Amazon River. Results from Bayesian multilocus clustering approach and Discriminant Analyses of Principal Component were congruent in showing that each island population was genetically differentiated from the mainland populations. All FST values obtained from all pairwise comparisons were significant, ranging from 0.048 to 0.186. Estimates of both recent and historical gene flow were not significantly different from zero across all population pairs, except the two mainland populations inhabiting continuous habitats. Patterns of population differentiation, with a high level of population substructure and absence/restricted gene flow, suggested that island populations of R. marina are likely isolated since the Holocene sea-level rise. However, considering the similar levels of genetic variability found in both island and mainland populations, it is reliable to assume that they were also isolated for longer periods. Given the genetic uniqueness of each cane toad population, together with the high natural vulnerability of the coastal regions and intense human pressures, we suggest that these populations should be treated as discrete units for conservation management purposes.