RESUMO
Coastal dunes are unique habitats, threatened by human activities. In biogeographical terms, coastal dunes are habitat islands, being discrete and distinct patches of similar habitat among themselves, separated from each other by a different type of habitat. Furthermore, coastal dunes harbor endemic species, adapted to living solely in the habitats found on specific dune systems. For example, the honeypot ant Myrmecocystus baja is endemic and restricted to coastal dunes of Mexico's Baja California Pacific coast. This ecological and biogeographical scenario led to the questions whether their geographical isolation is reflected in their genetic diversity and structuring, and how their demographic history is related with the formation of the dune system habitats. To answer these questions, population genetic, isolation-with-migration, and phylogeographical analyses were carried out, based on mitochondrial and five nuclear intronic markers. Minimal gene flow was detected only between two of the dune systems sampled; otherwise, the M. baja populations were found to be isolated and genetically structured, and their divergence generally pre-dated the modern-day dune systems. It is therefore highly likely that these ants were already present in paleodunes and that each of the populations was established from founder populations as the dunes formed. These findings highlight the importance of coastal dunes for species such as the honeypot ant from Baja California, in promoting genetic differentiation.
Assuntos
Formigas , Ecossistema , Variação Genética , Animais , Formigas/genética , Formigas/classificação , México , DNA Mitocondrial/genética , Fluxo Gênico , FilogeografiaRESUMO
Gelatinous zooplankton constitutes a polyphyletic group with a convergent evolutionary history and poorly known biogeographical patterns. In the Gulf of Mexico, a region with complex geological, hydrological, and biotic histories, the study of this group has been limited to taxonomical and ecological aspects. In this study, we implemented a track analysis to identify distributional patterns of gelatinous zooplankton in the Gulf of Mexico and adjacent waters based on a dataset of 6067 occurrence records corresponding to Hydrozoa, Scyphozoa, Cubozoa, Ctenophora, Chaetognatha, Thaliacea, and Appendicularia. Information was compiled from the Global Biodiversity Facility Information (GBIF) and Ocean Biodiversity Information System (OBIS) databases and peer-reviewed literature. Individual tracks were constructed by joining the minimum distance between the occurrence localities of each taxon using a minimum spanning tree algorithm. We identified generalized tracks using parsimony analysis of endemicity with progressive character elimination (PAE-PCE). The areas where different generalized tracks overlapped were considered to represent panbiogeographical nodes. Seven generalized tracks (two with nested patterns) and six panbiogeographical nodes were recognized, mainly in neritic zones. The distributional patterns of gelatinous zooplankton allowed us to identify four biogeographic areas, supporting previously proposed biogeographic schemes. Gelatinous zooplankton in the Gulf of Mexico showed a convergent spatial distribution that can be explained by vicariant and dispersal events. The historical biogeography of the gelatinous biotas of the Gulf of Mexico has been little studied compared to ecological approaches, and the lack of integrative studies considering historical patterns is evident. This type of research is fundamental to understanding the evolutionary history of natural resources from a spatial perspective, identifying sites of biodiversity and endemism, and establishing a biogeographic baseline of the region for further studies.
Assuntos
Biodiversidade , Zooplâncton , Zooplâncton/classificação , Zooplâncton/fisiologia , Animais , Golfo do México , Evolução Biológica , FilogeografiaRESUMO
Amazonia contains the most extensive tropical forests on Earth, but Amazon carbon sinks of atmospheric CO2 are declining, as deforestation and climate-change-associated droughts1-4 threaten to push these forests past a tipping point towards collapse5-8. Forests exhibit complex drought responses, indicating both resilience (photosynthetic greening) and vulnerability (browning and tree mortality), that are difficult to explain by climate variation alone9-17. Here we combine remotely sensed photosynthetic indices with ground-measured tree demography to identify mechanisms underlying drought resilience/vulnerability in different intact forest ecotopes18,19 (defined by water-table depth, soil fertility and texture, and vegetation characteristics). In higher-fertility southern Amazonia, drought response was structured by water-table depth, with resilient greening in shallow-water-table forests (where greater water availability heightened response to excess sunlight), contrasting with vulnerability (browning and excess tree mortality) over deeper water tables. Notably, the resilience of shallow-water-table forest weakened as drought lengthened. By contrast, lower-fertility northern Amazonia, with slower-growing but hardier trees (or, alternatively, tall forests, with deep-rooted water access), supported more-drought-resilient forests independent of water-table depth. This functional biogeography of drought response provides a framework for conservation decisions and improved predictions of heterogeneous forest responses to future climate changes, warning that Amazonia's most productive forests are also at greatest risk, and that longer/more frequent droughts are undermining multiple ecohydrological strategies and capacities for Amazon forest resilience.
Assuntos
Resistência à Seca , Secas , Florestas , Água Subterrânea , Fotossíntese , Solo , Luz Solar , Árvores , Brasil , Sequestro de Carbono , Secas/estatística & dados numéricos , Água Subterrânea/análise , Solo/química , Árvores/classificação , Árvores/metabolismo , Árvores/fisiologia , Clima Tropical , Resistência à Seca/fisiologia , Filogeografia , Conservação dos Recursos NaturaisRESUMO
Plastomes are used in phylogenetic reconstructions because of their relatively conserved nature. Nonetheless, some limitations arise, particularly at lower taxonomic levels due to reduced interspecific polymorphisms and frequent hybridization events that result in unsolved phylogenies including polytomies and reticulate evolutionary patterns. Next-generation sequencing technologies allow access to genomic data and strongly supported phylogenies, yet biased topologies may be obtained due to insufficient taxon sampling. We analyze the hypothesis that intraspecific plastome diversity reflects biogeographic history and hybridization cycles among taxa. We generated 12 new plastome sequences covering distinct latitudinal locations of all species of subgenus Nothofagus from North Patagonia. Chloroplast genomes were assembled, annotated, and searched for simple sequence repeats (SSRs). Phylogenetic reconstructions included species and sampled locations. The six Nothofagus species analyzed were of similar size and structure; only Nothofagus obliqua of subgenus Lophozonia, used as an outgroup, presented slight differences in size. We detected a variable number of SSRs in distinct species and locations. Phylogenetic analyses of plastomes confirmed that subgenus Nothofagus organizes into two monophyletic clades each consisting of individuals of different species. We detected a geographic structure within subgenus Nothofagus and found evidence of local chloroplast sharing due to past hybridization, followed by adaptive introgression and ecological divergence. These contributions enrich the comprehension of transversal evolutionary mechanisms such as chloroplast capture and its implications for phylogenetic and phylogenomic analyses.
Assuntos
Filogenia , Filogeografia , Repetições de Microssatélites , Genoma de Cloroplastos , Variação Genética , Hibridização Genética , ArgentinaRESUMO
While genetic variation in any species is potentially shaped by a range of processes, phylogeography and landscape genetics are largely concerned with inferring how environmental conditions and landscape features impact neutral intraspecific diversity. However, even as both disciplines have come to utilize SNP data over the last decades, analytical approaches have remained for the most part focused on either broad-scale inferences of historical processes (phylogeography) or on more localized inferences about environmental and/or landscape features (landscape genetics). Here we demonstrate that an artificial intelligence model-based analytical framework can consider both deeper historical factors and landscape-level processes in an integrated analysis. We implement this framework using data collected from two Brazilian anurans, the Brazilian sibilator frog (Leptodactylus troglodytes) and granular toad (Rhinella granulosa). Our results indicate that historical demographic processes shape most the genetic variation in the sibulator frog, while landscape processes primarily influence variation in the granular toad. The machine learning framework used here allows both historical and landscape processes to be considered equally, rather than requiring researchers to make an a priori decision about which factors are important.
Assuntos
Anuros , Inteligência Artificial , Variação Genética , Filogeografia , Animais , Anuros/genética , Anuros/classificação , Brasil , Genética Populacional , Modelos Genéticos , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Understanding the phylogeographic history of a group and identifying the factors contributing to speciation is an important challenge in evolutionary biology. The Goodeinae are a group of live-bearing fishes endemic to Mexico. Here, we develop genomic resources for species within the Goodeinae and use phylogenomic approaches to characterise their evolutionary history. We sequenced, assembled and annotated the genomes of four Goodeinae species, including Ataeniobius toweri, the only matrotrophic live-bearing fish without a trophotaenia in the group. We estimated timings of species divergence and examined the extent and timing of introgression between the species to assess if this may have occurred during an early radiation, or in more recent episodes of secondary contact. We used branch-site models to detect genome-wide positive selection across Goodeinae, and we specifically asked whether this differs in A. toweri, where loss of placental viviparity has recently occurred. We found evidence of gene flow between geographically isolated species, suggesting vicariant speciation was supplemented by limited post-speciation gene flow, and gene flow may explain previous uncertainties about Goodeid phylogeny. Genes under positive selection in the group are likely to be associated with the switch to live-bearing. Overall, our studies suggest that both volcanism-driven vicariance and changes in reproductive mode influenced radiation in the Goodeinae.
Assuntos
Fluxo Gênico , Especiação Genética , Filogenia , Animais , México , Seleção Genética , Filogeografia , Ciprinodontiformes/genética , Genoma/genéticaRESUMO
The South American Dry Diagonal, also called the Diagonal of Open Formations, is a large region of seasonally dry vegetation extending from northeastern Brazil to northern Argentina, comprising the Caatinga, Cerrado, and Chaco subregions. A growing body of phylogeography literature has determined that a complex history of climatic changes coupled with more ancient geological events has produced a diverse and endemic-rich Dry Diagonal biota. However, the exact drivers are still under investigation, and their relative strengths and effects are controversial. Pleistocene climatic fluctuations structured lineages via vegetation shifts, refugium formation, and corridors between the Amazon and Atlantic forests. In some taxa, older geological events, such as the reconfiguration of the São Francisco River, uplift of the Central Brazilian Plateau, or the Miocene inundation of the Chaco by marine incursions, were more important. Here, we review the Dry Diagonal phylogeography literature, discussing each hypothesized driver of diversification and assessing degree of support. Few studies statistically test these hypotheses, with most support drawn from associating encountered phylogeographic patterns such as population structure with the timing of ancient geoclimatic events. Across statistical studies, most hypotheses are well supported, with the exception of the Pleistocene Arc Hypothesis. However, taxonomic and regional biases persist, such as a proportional overabundance of herpetofauna studies, and the under-representation of Chaco studies. Overall, both Pleistocene climate change and Neogene geological events shaped the evolution of the Dry Diagonal biota, though the precise effects are regionally and taxonomically varied. We encourage further use of model-based analyses to test evolutionary scenarios, as well as interdisciplinary collaborations to progress the field beyond its current focus on the traditional set of geoclimatic hypotheses.
Assuntos
Filogeografia , Mudança Climática , América do Sul , Biodiversidade , Clima TropicalRESUMO
Our study identified strains of the A/H5N1 virus in analyzed samples of subsistence poultry, wild birds, and mammals, belonging to clade 2.3.4.4b, genotype B3.2, with very high genetic similarity to strains from Chile, Uruguay, and Argentina. This suggests a migratory route for wild birds across the Pacific, explaining the phylogenetic relatedness. The Brazilian samples displayed similarity to strains that had already been previously detected in South America. Phylogeographic analysis suggests transmission of US viruses from Europe and Asia, co-circulating with other lineages in the American continent. As mutations can influence virulence and host specificity, genomic surveillance is essential to detect those changes, especially in critical regions, such as hot spots in the HA, NA, and PB2 sequences. Mutations in the PB2 gene (D701N and Q591K) associated with adaptation and transmission in mammals were detected suggesting a potential zoonotic risk. Nonetheless, resistance to neuraminidase inhibitors (NAIs) was not identified, however, continued surveillance is crucial to detect potential resistance. Our study also mapped the spread of the virus in the Southern hemisphere, identifying possible entry routes and highlighting the importance of surveillance to prevent outbreaks and protect both human and animal populations.
Assuntos
Surtos de Doenças , Virus da Influenza A Subtipo H5N1 , Influenza Aviária , Filogenia , Filogeografia , Animais , Brasil/epidemiologia , Influenza Aviária/virologia , Influenza Aviária/epidemiologia , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/classificação , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Aves/virologia , Mamíferos/virologia , Aves Domésticas/virologia , Humanos , Genótipo , Neuraminidase/genética , Proteínas Virais/genética , Mutação , Animais Selvagens/virologiaRESUMO
The carabid beetle Cnemalobus Guérin-Ménéville, 1838 inhabits high- and lowland grasslands of southern South America. The highest diversity is found in the Patagonian Steppe, where distribution patterns are associated with latitude and elevation. Northern Patagonia, a large volcanic region with a complex geoclimatic history, exhibits elevated grades of endemism. However, a great deal remains unknown regarding diversification and biogeographical patterns for most of the endemic groups. We describe new Cnemalobus species restricted to isolated volcanoes from these extra-Andean mountain systems. We assess the phylogenetic relationships by updating the phylogeny of the genus and conduct a Bayesian binary Markov chain-Monte Carlo (MCMC) analysis on the resulting phylogenetic tree to discuss the biogeographical distribution patterns. We also provide a taxonomic key to all currently known species of Cnemalobus from the Patagonian Steppe. Our phylogenetic analysis supports the monophyly of the new species Cnemalobus tromen sp. nov., Cnemalobus silviae sp. nov., Cnemalobus aucamahuida sp. nov. and Cnemalobus domuyo sp. nov. grouped with C. diamante and C. nevado , referred to as the 'Extra-Andean' mountain lineage. Biogeographical analysis recognises vicariant events as the most plausible explanation for the allopatric distributions of the new species. We hypothesise that these vicariant events could be related to climatic barriers that likely promoted speciation processes by generating geographical isolation in ancestral populations. Our findings contribute significantly to the biogeographical understanding of the Patagonian volcanic region, prompting new inquiries to unravel the speciation processes of the endemic biota in extra-Andean mountain systems. ZooBank: urn:lsid:zoobank.org:pub:6A7585E8-5006-45BC-A1A3-F874F18A6049.
Assuntos
Besouros , Filogenia , Animais , Besouros/genética , Besouros/classificação , Especificidade da Espécie , Filogeografia , Distribuição Animal , Argentina , Teorema de Bayes , Feminino , MasculinoRESUMO
Phylogenetic analyses of mitochondrial and nuclear data of 31 specimens of Cyphocharax from trans-Andean rivers support the presence of one lineage of Cyphocharax aspilos in Lago Maracaibo and three cryptic lineages of Cyphocharax magdalenae: (1) Cauca-Magdalena and Ranchería, (2) León and Atrato, and (3) Chucunaque-Tuira, Santa María, and Chiriquí basins of Central America. Results suggest that the Serranía del Perijá facilitated Late Miocene cladogenetic events, whereas post-Isthmian C. magdalenae expansion was enabled by gene flow across the lower Magdalena valley and Central American lowlands. Time-calibrated phylogenetics indicate that the C. magdalenae colonized lower Central America in the Pliocene (3.7 MYA; Ma), the divergence Atrato-Magdalena occurred in Late Pliocene (3.0 Ma) and the split Ranchería-Magdalena during the Middle Pleistocene (1.3 Ma). Updated geographic distribution data support the hypothesis that the Cordillera de Talamanca functions as a barrier to northward expansion of C. magdalenae in Central America.