Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data

Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system.Instituto de Botánica "Dr. Carlos Spegazzini

Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data

Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system.Instituto de Botánica "Dr. Carlos Spegazzini

Tropical frogs as a model system to understand host-pathogen-microbiota interactions

In my thesis, I undertook a broad survey of Bd in wild amphibian populations using non-invasive molecular techniques, and using natural history traits of the host along with spatial climatic parameters. I found that Bd is geographically and taxonomically widely distributed, and its presence is best explained by environmental parameters related to temperature and precipitation. Since Bd was also detected in Lowland species of the threatened genus Atelopus, I examined whether the species tested positive for Bd harbor cutaneous symbiotic bacteria capable of inhibiting Bd growth, allowing them to survive. Atelopus aff. elegans was the only species that tested positive for Bd, and holds the skin bacteria with the strongest anti-Bd action. This suggests that bacterial communities may have resulted from natural selection represented by Bd infection. In order to evaluate whether Bd can be considered as a potential tln. eat for Atelopus species, I also assessed Bd prevalence and infection intensity by examining live animals during contemporary field surveys and archived museum specimens. My results showed a decrease in abundance of A. spurrelli suggesting that Bd may have contributed to the apparent decline. In contrast, A. aff elegans remain stable despite the presence of the pathogen fltting an enzootic pattem ofhost/pathogen dynamic. I also evaluated the impact of captivity on the beneficial skin-associated bacterial community. Currently, the only method that has been proposed as an effective way to avoid the extinction of amphibian species is the establishment of captive assurance colonies. Therefore it is imperative to understand and evaluate how captivity could affect the disease dynamics and outcomes. Interestingly, I found that frogs in captivity still harbor bacteria with anti-Bd activity suggesting that captivity programs do not necessarily change bacterial communities of the toad skin in a way that impedes Bd growth control. Lastly, using as a study model two sympatric species of Andean frogs, Dendropsophus labialis and Rheobates palmatus, I provided key information on how microbial pathogen interactions differ across life stages, and how changes in bacterial community composition may affect the response to Bd infection. This thesis highlights the importance of using holistic approaches to better understand disease outcomes in diverse frog species and environments, and informs of possible mitigation efforts that can be implemented in the near future to help control and reduce Bd outbreaksDoctor en Ciencias - BiologíaDoctorad

El sistema de comunicación en Eleutherodactylus johnstonei

ilMagíster en Ciencias BiológicasMaestrí

La belleza está en los oídos del que la oye

Experimentos de playback de sonidos e imágenes ha sido utilizados no solo para resolver preguntas sobre comunicación animal, sino también específicamente con seres humanos, en psicología, mercadeo y publicida

Conservación

Colombia, al ser un país ubicado en la región Neotropical y exhibir una variada topografía, tiene una alta diversidad de anfibios y reptiles. Uno de los ecosistemas con gran diversidad, en particular de reptiles, es el bosque seco tropical (bs-T). No obstante, debido a los efectos de actividades extractivas como la ganadería, la agricultura y el comercio ilegal, al menos 15 especies de anfibios y reptiles, que presentan parte o la totalidad de su rango de distribución en áreas de bs-T, incluido el Caribe insular, están bajo algún grado de amenaza. Por sus características biológicas (e.g. ectotermia y baja movilidad), los anfibios y reptiles son particularmente sensibles a la destrucción y degradación de su hábitat; de hecho, son considerados como buenos indicadores de los efectos de pérdida o disminución en la calidad del hábitat.  En Colombia existen actualmente  diversas estrategias para contrarrestar  dichas amenazas; por ejemplo, el establecimiento de áreas protegidas para la conservación de especies in situ, además del mantenimiento de especies en condiciones ex situ, permiten  mitigar  la pérdida acelerada de especies y poblaciones; sin embargo, aún persisten enormes vacíos en las políticas ambientales que contemplen, entre otros, mecanismos de vigilancia que permitan  generar alertas tempranas, como es el caso de aparición  de enfermedades  infecciosas.  Actualmente, las políticas se dirigen al control de actividades extractivas, las cuales, no son suficientes para mitigar la pérdida acelerada de especies

Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data

Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system

Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data

Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system

Biología de los anfibios y reptiles en el bosque seco tropical del norte de Colombia.

Los anfibios y reptiles son animales asombrosos y su biología es mucho más Fascinante y variada de lo que originalmente se consideraba. Esta afirmación se soporta fácilmente en múltiples aspectos, entre los cuales sobresale, su reproducción (Duellman & Trueb 1994; Wells 2007; Balshine 2012; Gómez-Mestre et al. 2012; Vitt & Caldwell 2014; Pough et al. 2016). En los anfibios, por ejemplo, muchas especies no dejan sus huevos en charcas y lagunas, como tradicionalmente ha creído el común de las personas, sino que las hembras los depositan en ambientes terrestres, tales como la superficie de hojas o en ambientes húmedos que se dan a nivel del suelo entre hojarasca y bajo troncos caídos, piedras o raíces de árboles (Duellman & Trueb 1994; Crump 2015). Más aún, hay especies cuya reproducción es tan especializada que los padres o madres transportan a los renacuajos en diferentes partes de su cuerpo , ya sea, por pocas horas o días, mientras los depositan en ambientes específicos, o hasta que las crías terminan su ciclo de metamorfosis y se desarrollen como un adulto, pero en miniatura  (Noble 1927; Mendelson et al. 2000; Castroviejo-Fisher et al. 2015). Con respecto a los reptiles, hay ejemplos de especies, donde, - las hembras no requieren que un gameto masculino fertilice sus óvulos para producir crías, o especies, donde el sexo de la progenie no está determinado genéticamente, sino por la temperatura ambiental, lo cual, permiten la incubación de huevos (Tinkle & Gibbons 1977; Shine 1995; Vitt & Caldwell 2014). Los factores o procesos asociados a la evolución de este último aspecto en la reproducción de reptiles, es todo un enigma para los científicos (BlacNburn 2006; Shine 2015). Estos y muchos más ejemplos, que se encuentran a lo largo de este libro, contradicen la imagen que durante décadas se tuvo de los anfibios y reptiles, incluso, por científicos y naturalistas tan prestigiosos como, Carlos Linneo, quien afirmó que estos vertebrados eran animales repulsivos, en los cuales el creador no había ejercido toda su sabiduría y poder (Halliday & Adler 1986)

Biodiversidad 2018. Reporte de estado y tendencias de la biodiversidad continental de Colombia

Las cifras y temáticas contenidos en el presente Reporte, aunque no son el panorama completo del estado del conocimiento de la biodiversidad en Colombia, son un compendio seleccionado de los temas que, desde el Instituto Humboldt, consideramos son relevantes y merecen ser discutidos por el público general. En muchos de los casos, las cifras no son esperanzadoras u son un llamado urgente a la acción. En otro casos son la evidencia de que se requieren acciones a nivel nacional, y más allá de esto, son muchas las iniciativas que están germinando desde los territorios, cada vez desde una mayor variedad de actores.Bogotá, D. C., Colombi