Biology subjects

Palacios, C.

Publications and source records attributed to Palacios, C..

6 recordsLinked to original sources

bioRxiv2025

Seasonal neurogenomic changes provide genetic links between male song and testosterone-mediated neurogenesis in a wild songbird

Seasonal changes in testosterone mediate the transition from reduced singing in the non-breeding season to high song rates in the early breeding season in male temperate songbirds, a process accompanied by marked neurogenesis in song control regions of the brain. However, the resulting genetic changes and their association with the subsequent behavioral, neuroanatomical and reproductive changes remain poorly understood. Here, we compared gene expression in HVC, a major song control nucleus, between the non-breeding and breeding season in male northern house wrens (Troglodytes aedon) and we examined associations with HVC volume, plasma testosterone concentrations, and testes size. Differential gene expression analysis identified three genes (CLIP4, FAM169A, and TTR) consistently linked to seasonal transitions from non-breeding to three breeding stages (pre-laying, egg-laying and incubation). Notably, TTR, which transports thyroid hormone (TH), was highly expressed in the nonbreeding season, consistent with a possible role of TH in regulating seasonal shifts in song output and structure. We also identified seasonal changes in networks of genes related to neural connectivity, cellular restructuring, and cell migration. Weighted gene co-expression network analysis (WGCNA) revealed gene clusters specifically correlated with testosterone and HVC volume. Testosterone-associated genes included genes involved in neural circuit remodeling, chromatin organization, and cytoskeletal dynamics, consistent with testosterone-mediated regulation of these neuroanatomical changes. Genes linked to seasonal increases in HVC volume were involved in neuronal restructuring and neuron migration, implicating these genes in seasonal neurogenesis. Together, our findings link novel gene expression patterns to hormone regulation and neurogenesis underlying seasonal transitions in birdsong.

genomics↗

bioRxiv2024

Genomic insights into the successful invasion of the avian vampire fly (Philornis downsi) in the Galapagos Islands

Invasive species disrupt island ecosystems, posing significant threats to native species. The avian vampire fly (Philornis downsi), introduced into the Galapagos Islands, has become a major threat to endemic birds including Darwins finches, yet the genetic mechanisms of its invasion remain unclear. This study used whole-genome sequencing of P. downsi populations from Galapagos and its native range in mainland Ecuador, revealing reduced genetic diversity in Galapagos, indicative of a recent bottleneck. We found evidence of ongoing gene flow among island populations and identified regions under positive selection near genes related to neural signaling, muscle development, and metabolic processes, which may have contributed to the flys invasion success in Galapagos. These findings highlight the importance of genomic research for mitigating the impact of P. downsi on Galapagos biodiversity.

evolutionary biology↗

bioRxiv2023

Unraveling cryptic diversity: Genomic approaches to study the taxonomy and evolution of Woolly-necked storks using museum specimens

The availability of large-scale genomics data for current research in evolutionary biology has enabled a comprehensive examination of the intricate interplay between diverse evolutionary processes associated with speciation. Despite these advancements, the genomic basis of taxonomic classification remains challenging in many species, one such example being the Woolly-necked storks (Ciconia sps.). The Woolly-necked storks are distributed in Asia and Africa with a taxonomic classification (C. episcopus and C. microcelis) that has been a matter of contention and ambiguity. Asian and African Woollynecks were just recently recognized as different species based on their morphological differences, however genetic/genomic studies on Woolly-necked storks are lacking. In this study, we have used [~]70-year-old museum samples to explore the taxonomy and evolution of the Woolly-necked storks. We used a whole-genome sequencing strategy and generated 13.5 million single nucleotide polymorphisms (SNPs) that were polymorphic among populations of Asian and African Woollynecks. Our study has revealed that Asian and African Woollyneck are genetically distinct, consistent with the current taxonomic classification based on morphological features. However, we also found a high genetic divergence between the Asian subspecies C. e. neglecta and C. e. episcopus suggesting this classification harbors cryptic diversity that requires a detailed examination to explore processes of ongoing speciation. Because taxonomic classification directly impacts conservation efforts, and there is evidence of declining populations of Asian Woollynecks in Southeast Asia, our results suggest populations-scale studies are urgent to determine the genetic, ecological, and phylogenetic diversity of these birds. Moreover, our study also provides historical genomic resources to examine genomic signatures of local adaptation associated with the distribution, ecology, and evolution of African and Asian Woollynecks.

evolutionary biology↗

bioRxiv2020

Iota carrageenan and xylitol inhibit SARS-CoV-2 in Vero cell culture

COVID-19 (coronavirus disease 2019) is a pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome-coronavirus 2) infection affecting millions of persons around the world. There is an urgent unmet need to provide an easy-to-produce, affordable medicine to prevent transmission and provide early treatment for this disease. The nasal cavity and the rhinopharynx are the sites of initial replication of SARS-CoV-2. Therefore, a nasal spray may be a suitable dosage form for this purpose. The main objective of our study was to test the antiviral action of three candidate nasal spray formulations against SARS-CoV-2. We have found that iota-carrageenan in concentrations as low as 6 {micro}g/ mL inhibits SARS-CoV-2 infection in Vero cell cultures. The concentrations found to be active in vitro against SARS-CoV-2 may be easily achieved by the application of nasal sprays already marketed in several countries. Xylitol at a concentration of 5 % m/V has proved to be viricidal on its own and the association with iota-carrageenan may be beneficial, as well.

pharmacology and toxicology↗

bioRxiv2020

Complete mitochondrial genomes do not distinguish phenotypically distinct lineages of Andean Coeligena hummingbirds

Lack of divergence in mitochondrial DNA between species with clear phenotypic differences may be the result of low resolution of markers, incomplete lineage sorting, introgression, or the interplay of various evolutionary mechanisms acting on different traits and genomic regions through time. Previous work revealed that the Andean hummingbirds Coeligena bonapartei and C. helianthea lack genetic divergence in the mitochondrial ND2 gene, which shows variation discordant with coloration phenotype but consistent with geography. We sequenced and analyzed complete mitochondrial genomes for C. b. bonapartei, C. b. consita, C. h. helianthea and C. h. tamai to assess whether patterns revealed by ND2 analyses hold when considering the entire mitogenome, and to shed light into the evolutionary history of these hummingbirds. We found very low genetic differentiation in mitogenomes among the four lineages of Coeligena, confirming patterns based on ND2 data. Estimates of genetic differentiation, phylogenies and haplotype network analyses of complete mitogenomes did not separate phenotypically distinct taxa, but were consistent with a previously described pattern of northern vs. southern divergence along the Cordillera Oriental of Colombia. Mitogenomes of C. b. bonapartei and C. h. helianthea are indistinguishable, suggesting incomplete lineage sorting or strong introgression. Mitogenomes of C. b. consita and C. h. tamai are slightly differentiated, but they are more similar to each other than either is to that of its respective nominate subspecies, a result also suggestive of mtDNA introgression despite distinct phenotypic differences. Our results indicate that various evolutionary mechanisms playing out over a complex biogeographic scenario in the Colombian Andes drove divergence in phenotypes and mitochondrial genomes of Coeligena hummingbirds, and lead to alternative hypotheses to be tested with whole-genome analyses.

evolutionary biology↗

bioRxiv2018

Shallow evolutionary divergence between two Andean hummingbirds: Speciation with gene flow?

Ecological speciation can proceed despite genetic interchange when selection counteracts homogeneizing effects of migration. We tested predictions of this divergence-with-gene-flow model in Coeligena helianthea and C. bonapartei, two parapatric Andean hummigbirds with marked plumage divergence. We sequenced neutral markers (mtDNA and nuclear ultra conserved elements) to examine genetic structure and gene flow, and a candidate gene (MC1R) to assess its role underlying divergence in coloration. We also tested the prediction of Glogers rule that darker forms occur in more humid environments, and compared ecomorphological variables to assess adaptive mechanisms potentially promoting divergence. Genetic differentiation between species was very low and coalescent estimates of migration were consistent with divergence with gene flow. MC1R variation was unrelated to phenotypic differences. Species did not differ in macroclimatic niches but were distinct in ecomorphology. Although we reject adaptation to variation in humidity as the cause of divergence, we hypothesize that speciation likely occurred in the face of gene flow, driven by other ecological pressures or by sexual selection. Marked phenotypic divergence with no neutral genetic differentiation is remarkable for Neotropical birds, and makes C. helianthea and C. bonapartei an appropriate system in which to search for the genetic basis of species differences employing genomics.

evolutionary biology↗