Este documento discute la hipótesis de los refugios pleistocénicos en América del Sur y presenta nuevos análisis para evaluarla. Los autores analizan secuencias de ADN de murciélagos sudamericanos y realizan análisis biogeográficos y de divergencia. Sus resultados muestran que los patrones de especiación y dispersión no apoyan la idea de que los refugios pleistocénicos fueron la principal causa de diversificación, y que explicaciones alternativas como tasas variables de especiación deb
Charla dictada el martes 29 de mayo del 2012 por el PhD. Jaime Chaves, a los estudiantes de la Universidad Central del Ecuador - Sede Galápagos, con el Tema: "Uso de la información genética para entender la historia evolutiva de las aves de Galápagos".
Uso de la información genética para entender la historia evolutiva de las ave...Franklin Ortega
Charla dictada el martes 29 de mayo del 2012 por el PhD. Jaime Chávez, a los estudiantes de la Universidad Central del Ecuador - Sede Galápagos, con el Tema: "Uso de la información genética para entender la historia evolutiva de las aves de Galápagos".
A decade ago, DNA barcoding was proposed as a fast, cost-efficient and simple taxonomic method based on the use of a unique, short and standardized gene region for identifying existing species and speeding the discovery of new ones. However, due to technical problems, few DNA barcoding studies in squamate reptiles have been conducted so far. In this work, using three sets of primers, we successfully DNA barcoded 380 individuals of all presently recognized species of reptiles in the Socotra Archipelago (31 species, 12 genera), classified as a UNESCO World Heritage Site. Although no barcoding gap exists in the whole dataset, the specimen identification success rate of DNA barcoding is moderate to high (68-94%) based on distance-based and tree-based techniques. The low levels of inter-specific genetic divergence observed between some species are consistent with paraphyly of Pristurus sokotranus. On the other hand, the high levels of intra-specific variability found within some species suggest cryptic diversity. Depending on the species delimitation approaches, between 4 and 37 more species than those presently recognized should be taken into account for future conservation efforts. Through this study, we conclude that DNA barcoding is very useful for specimen identification, but for species discovery and description, it will only be effective if incorporated into a more integrative taxonomic framework.
Labs without Borders: Methods for Extracting, Amplifying, and Sequencing in t...Liliana Davalos
Genomic methods have revolutionized current understanding of the evolution and ecology of bats worldwide. At the same time, air travel restrictions and concerns about emerging diseases have made transporting bat tissues an increasingly expensive and fraught pursuit. To both overcome these restrictions and build capacity in high biodiversity countries, we implemented field-based molecular protocols. First, we sequenced the prokaryotic microbiome of multiple individuals in the field using a standard centrifuge, mini-PCR and mini-gel rigs, and a MinIon sequencer. Modifications to lab protocols included: 1) centrifugation steps robust at high- or mini-centrifuge speed, 2) extending proteinase-K incubation at ambient temperature and evaluating the elimination of ethanol in clean-up during extraction, 3) using lyophilized mastermix in amplification, and 4) eluting in molecular-grade water in library prep. The lack of a high-sensitivity method for quantifying DNA, however, limited the efficiency of multiplexing and reduced the life of the cell in sequencing. Second, we generated mtDNA barcodes using a cheaper, hybrid approach of extracting and amplifying in the field, with subsequent lab-based Sanger sequencing. We added a temperature control ceramic mug and Qubit fluorometer to the kit. By modifying standard procedures, and substituting some equipment with modestly priced consumer products (e.g., the mug), our protocols make critical steps in molecular genetics field-accessible, and open possibilities for future research on genomics, transcriptomics, and disease surveillance in bats.
Charla dictada el martes 29 de mayo del 2012 por el PhD. Jaime Chaves, a los estudiantes de la Universidad Central del Ecuador - Sede Galápagos, con el Tema: "Uso de la información genética para entender la historia evolutiva de las aves de Galápagos".
Uso de la información genética para entender la historia evolutiva de las ave...Franklin Ortega
Charla dictada el martes 29 de mayo del 2012 por el PhD. Jaime Chávez, a los estudiantes de la Universidad Central del Ecuador - Sede Galápagos, con el Tema: "Uso de la información genética para entender la historia evolutiva de las aves de Galápagos".
A decade ago, DNA barcoding was proposed as a fast, cost-efficient and simple taxonomic method based on the use of a unique, short and standardized gene region for identifying existing species and speeding the discovery of new ones. However, due to technical problems, few DNA barcoding studies in squamate reptiles have been conducted so far. In this work, using three sets of primers, we successfully DNA barcoded 380 individuals of all presently recognized species of reptiles in the Socotra Archipelago (31 species, 12 genera), classified as a UNESCO World Heritage Site. Although no barcoding gap exists in the whole dataset, the specimen identification success rate of DNA barcoding is moderate to high (68-94%) based on distance-based and tree-based techniques. The low levels of inter-specific genetic divergence observed between some species are consistent with paraphyly of Pristurus sokotranus. On the other hand, the high levels of intra-specific variability found within some species suggest cryptic diversity. Depending on the species delimitation approaches, between 4 and 37 more species than those presently recognized should be taken into account for future conservation efforts. Through this study, we conclude that DNA barcoding is very useful for specimen identification, but for species discovery and description, it will only be effective if incorporated into a more integrative taxonomic framework.
Labs without Borders: Methods for Extracting, Amplifying, and Sequencing in t...Liliana Davalos
Genomic methods have revolutionized current understanding of the evolution and ecology of bats worldwide. At the same time, air travel restrictions and concerns about emerging diseases have made transporting bat tissues an increasingly expensive and fraught pursuit. To both overcome these restrictions and build capacity in high biodiversity countries, we implemented field-based molecular protocols. First, we sequenced the prokaryotic microbiome of multiple individuals in the field using a standard centrifuge, mini-PCR and mini-gel rigs, and a MinIon sequencer. Modifications to lab protocols included: 1) centrifugation steps robust at high- or mini-centrifuge speed, 2) extending proteinase-K incubation at ambient temperature and evaluating the elimination of ethanol in clean-up during extraction, 3) using lyophilized mastermix in amplification, and 4) eluting in molecular-grade water in library prep. The lack of a high-sensitivity method for quantifying DNA, however, limited the efficiency of multiplexing and reduced the life of the cell in sequencing. Second, we generated mtDNA barcodes using a cheaper, hybrid approach of extracting and amplifying in the field, with subsequent lab-based Sanger sequencing. We added a temperature control ceramic mug and Qubit fluorometer to the kit. By modifying standard procedures, and substituting some equipment with modestly priced consumer products (e.g., the mug), our protocols make critical steps in molecular genetics field-accessible, and open possibilities for future research on genomics, transcriptomics, and disease surveillance in bats.
Past, present, and future of deforestation in the northwestern AmazonLiliana Davalos
With the largest extent of tropical forest in the world, the dynamics of forest loss and fragmentation in Brazil have been the focus of attention for over 50 years. Global shifts in trade to the Pacific and growing infrastructure, however, threaten the western end of the forests in the Andean region, including the Amazon. Research combining spatial and socioeconomic analyses, as well as exploring the 20th-century history of the region, reveals three surprising findings. First, wedges of deforestation are strongly associated with directed colonization projects more than 40 years old. Second, although pastures are the end state of much formerly forested land, demand for beef is a poor predictor of this process and urbanization following infrastructure upgrade is a better correlate. Finally, coca cultivation, widely believed to be a motor of forest loss, contributes little to the process both directly and indirectly. Instead, the clearing of these forests corresponds to the transformation of nominally state-owned forests into private properties, and occurs in tandem with local urbanization and despite overall rural depopulation.
Extinction, Extinction: How it Was and How to Stop it From the Miocene to TodayLiliana Davalos
The central question of our time is whether we can manage global ecosystems to support us today and into the future. While many current challenges, such as massive carbon dioxide emissions or nitrogen fixation, are unprecedented, others have in fact been unfolding for thousands of years. Here I show the results of studies combining the fossil record with DNA analyses and advanced statistical techniques to discover the footprint of human activities deep into the past. Using the islands of the Caribbean as a microcosm offers crucial lessons for the future: the signature of human landscape transformation on biodiversity is extinction, and it would take nature millions of years to restore what was lost over only a few hundred years.
Twenty million years of extinction and survival in the Caribbean (v.2)Liliana Davalos
Whether equilibrium dynamics between extinction and processes generating new species governs biodiversity, or instead stochastic changes shape diversity over time is one of the central questions in evolutionary biology. But tests of equilibrium dynamics since MacArthur and Wilson formulated their model have primarily involved colonization and extinction, neglecting speciation. Analyses using recently developed algorithms fitted to branching times for both extant and extinct bats from the Greater Antilles reveal a 20-40-million year equilibrium between high extinction rates offset by both colonization and speciation. Since at least 13 species have gone extinct over the last 20,000 years, however, this fauna is no longer in equilibrium. It would take millions of years for dynamics were to restore the lost diversity to their equilibrium preceding the Holocene. There is a longstanding debate on whether this pulse of mammalian extinction, which extended to all of North America, is linked to human colonization, or instead corresponds to the loss of island area and climate change at the end of the last glaciation. On the islands, however, humans only arrived a few thousand years ago, providing an opportunity to test these hypotheses. Bayesian models of the difference between faunal last appearance and human first appearance, together with the largest database of archaeological and paleontological radiocarbon dates reveal the majority of extinction events occurred after human arrival. While some large bodied species were lost soon after human colonization and may have been hunted, others may have been vulnerable to pre-Columbian agriculture, and many more to predators introduced during European colonization. The demise of the Caribbean mammal fauna as a result of increasing human transformation of local ecosystems provides lessons for our own time and the extinction events today and into the future.
¿De dónde viene y para dónde va la deforestación en Colombia?Liliana Davalos
Talk given at ICESI university in Cali, Colombia on 17 July. En las últimas décadas la deforestación en Colombia a menudo se explica como una consecuencia, directa o indirecta, de los cultivos ilícitos. Sin embargo, la influencia de los cultivos ilícitos y especialmente de los sembrados de coca sobre la deforestación requiere un contexto con otras actividades agrícolas, además de comparaciones entre los tres países productores: Colombia, Perú y Bolivia. Esta presentación examina los resultados de múltiples estudios sobre deforestación para evaluar el impacto de los ilícitos sobre la deforestación utilizando modelos cuantitativos. Aunque los cultivos de coca son responsables de una fracción importante de la deforestación directa, esta es mínima comparada con otras actividades, especialmente la praderización de todas las regiones forestales del país. Al mismo tiempo, la coca actúa como punta de lanza de la frontera agrícola en la Amazonía y puede tener consecuencias nefastas para la flora y fauna endémica de bosques andinos y del Chocó biogeográfico. Ya que el PIB de ganadería se desplomó al dispararse la pérdida de bosque, tampoco es el mercado del ganado el responsable de la deforestación, por lo menos en el departamento del Guaviare. Por tanto la praderización en Guaviare y probablemente en otras regiones está más ligada a la urbanización y desarrollo de mercados locales de tierras que a la ganadería. La principal conclusión de este análisis es que la causa última de buena parte de la deforestación es la conversión de la reserva forestal a propiedades privadas en zonas de rápido desarrollo. Paradójicamente, la coca es ancilar a este motor de deforestación.
1891 - Primera discusión semicientífica sobre Una Nave Espacial Propulsada po...Champs Elysee Roldan
La primera discusión semicientífica sobre una nave espacial propulsada por cohetes la realizó el alemán Hans Ganswindt, quien abordó los problemas de la propulsión no mediante la fuerza reactiva de los gases expulsados sino mediante la eyección de cartuchos de acero que contenían dinamita. Supuso que la explosión de una carga transferiría energía cinética a la pared de la nave espacial y la impulsaría en la dirección deseada. Supuso que múltiples explosiones proporcionarían suficiente velocidad para alcanzar la órbita y la velocidad de escape.
El 27 de mayo de 1891, pronunció un discurso público en la Filarmónica de Berlín, en el que introdujo su concepto de un vehículo galáctico(Weltenfahrzeug).
Ganswindt también exploró el uso de una estación espacial giratoria para contrarrestar la ingravidez y crear gravedad artificial.
Algebra trigonometria y geometri analitica 3ra Edicio Dennis G. Zill.pdf
Una estaca al corazon de los refugios pleistocenicos
1. Una estaca al corazón de los refugios
pleistocénicos
Liliana M. Dávalos
Ecology and Evolution, SUNY at Stony Brook
Danny Rojas
Department of Biology and Centre for Environmental and Marine Studies, University of
Aveiro
Omar Warsi
Uppsala Biomediciniskt Centrum
Universidad Nacional Mayor de San Marcos
Lima, mayo 28, 2015
2. Dos clases de preguntas
Bio-
diversidad
Diversificación,
especiación
reducen
Pérdida de
hábitat
aumentan
5. Hipótesis amazónica
In the great Amazonian
plains many species … are
found up to the river banks
on one side but do not
cross to the other… The
range of the birds … is also
limited by the rivers … ; so
that in these cases we are
able to define the limits of
distribution with an unusual
degree of accuracy, and
there is little doubt the
same barriers, also limit a
large number of other
species. Wallace&1876&The$Geographical$
Distribution$of$Animals
11. Problemas con este
análisis
• Hipótesis alternas?
• Tiempo de divergencia
!= causa de
divergence
• Patrón ambiental?
• Patrón geográfico?
• Modo especiación?
Rull&2014&J.$Biogeogr.
13. Si los refugios han
sido importantes
• Aislamiento =
especiación
• Localización =
bosques húmedos
• Divergencia =
corresponden en el
tiempo al pleistoceno
Foto&de&Beth&Clare
14. Métodos
• Secuencias de:
• 6 genes
autosómicos
• 1 en cromosoma X
• 3 en genoma
mitocondrial
• Calibraciones en 8
nodos
• Con base en fósiles
• Análisis de
biogeografía
Velazco&et&al.&2013&Amer.$Mus.$Novitates
15. Ubicación de los
fósiles
• Utilizando un método
de andamios
estadísticos
• Palynephyllum está
en Lonchophyllinae
• Notonycteris es
hermano de
Vampyrum
Davalos&et&al.&2014&Syst.$Biol.
16. 40°S
20°S
0°
20°N
100°W 80°W 60°W 40°W
0
10
20
30
40
50
60
70
80
Análisis
biogeográficos
• Distribuciones de la
UICN
• Modelos optimizados con
maxima verisimilitud que
permiten:
• Vicarianza
• Dispersión
• Especiación simpátrica
• Especiación parapátrica
• Efecto fundador
Rojas&et&al.&Accepted&Syst.$Biol.
18. Simulaciones
• Utilizando modelos de
nacimiento-muerte
(BD)
• Este es un modelo
nulo
• Carece de influencia
externa
• ¿Es posible utilizar
divergencias para
evaluar los refugios?
24. Las divergencias no
prueban nada!!!
• El modelo nulo
siempre produce más
divergencias en el
cuaternario
• Tendrá que haber una
tasa más alta de
especiación en el
cuaternario
X
GarzónLOrduña&et&al.&2014&J.$Biogeogr
25. Cómo se ve exceso en cuaternario
Moyle&et&al.&2009&PNAS
31. Tratar bien a los
murciélagos
• El maltrato se have obvio
en el resultado
• Bajo rendimiento de ADN
• Por dejar morir en la
trampa
• Digestion enzimática de
ARN
• Por dejar morir en la
trampa
• Por sacrificar sin
anestesia
32. Trabajo de campo =
muchos resultados
• Tratar bien a cada
individuo
• Imperativo ético y
práctico
33. 1 individuo = muchos
resultados
• Tratar bien a cada
individuo
• La mayoría se liberan
• Los especímenes se
aprovechan al
máximo
• Disecciones de
campo permiten
estudiar muchos
sistemas de un sólo
individuo