Browsing by Author "Valencia Reyes, Luis Renato"
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Amazon diversification and cross- Andean dispersal of the widespread Neotropical tree species Jacaranda copaia (Bignoniaceae).(2012) Valencia Reyes, Luis Renato; Scotti-Saintagne, CarolineAim: The phylogeographical history of Neotropical species can be difficult to reconstruct because of superimposed Neogene and Quaternary histories, and because of taxonomic uncertainty. We analysed range-wide genetic diversity in a widespread pioneer tree species, Jacaranda copaia (Aubl.) D. Don, to characterize phylogeographical structure, date the evolutionary relationships among lineages, and evaluate the role of dispersal and vicariance in establishing the present geographical range. Location: Guiana Shield; central, southern and western Amazon Basin; Chocó region; Central America. Methods: We analysed nine nuclear simple sequence repeat loci (nuSSR), eight chloroplast SSRs (cpSSR), and two cpDNA intergenic sequences in 341 adult trees. Genetic differentiation at nuSSRs was inferred using Bayesian clustering. Dating of chloroplast lineage divergence was obtained using a range of published mutation rates and Bayesian coalescence analyses. Population divergence dating was performed using an isolation-with-migration model for eight loci (one cp sequence and seven nuSSRs). Results: Nuclear SSR variation identified three geographically overlapping clusters (nu-1, nu-2, nu-3). Twelve cpDNA haplotypes were clustered into two haplogroups (cp-1, cp-2) with the central Amazon harbouring the highest diversity. Molecular dating analysis suggests that cpDNA haplotype diversification started around the end of the Pliocene (2.61 Ma on average), whereas population divergence was more recent and occurred during the mid-Quaternary (point estimates between 357 and 436 ka). Main conclusions: The genetic variation of J. copaia in the Neotropics was shaped mainly by Pleistocene events. Chloroplast diversity did not display the expected cis/trans Andean disjunction, indicating recent dispersal. Nuclear variation revealed that separate regions share a recent history, with a centre of diversity in the central Amazon Basin. The geographical pattern of diversity is congruent with the distribution of the two subspecies, J. copaia copaia and J. copaia spectabilis, and evidence of nuSSR admixture between the two taxa supports their classification as subspecies.Item Open Access Ant mutualism increases long-term growth and survival of a common amazonian tree(2016-08-30) Valencia Reyes, Luis Renato; Báez, Selene; Valencia Reyes, Luis RenatoHow ecological context shapes mutualistic relationships remains poorly understood. We combined long-term tree census data with ant censuses in a permanent 25-ha Amazonian forest dynamics plot to evaluate the effect of the mutualistic ant Myrmelachista schumanni (Formicinae) on the growth and survival of the common Amazonian tree Duroia hirsuta (Rubiaceae), considering its interactions with tree growth, population structure, and habitat. We found that the mutualist ant more than doubled tree relative growth rates and increased odds of survival. However, host tree size and density of conspecific neighbors modified the effect of the ant. Smaller trees hosting the mutualist ant consistently grew faster when surrounded by higher densities of conspecifics, suggesting that the benefit to the tree outweighs any negative effects of high conspecific densities. Moreover, our findings suggest that the benefit afforded by the ant diminishes with plant age and also depends on the density of conspecific neighbors. We provide the first long-term large-scale evidence of how mutualism affects the population biology of an Amazonian tree species.Item Open Access Brownea jaramilloi (Leguminosae: Caesalpinioideae), a new, over-looked species endemic to the Ecuadorian Amazon.(2013) Valencia Reyes, Luis Renato; Pérez, Alvaro J.Brownea jaramilloi, a new species, endemic to the northeastern Ecuadorian Amazon, is described and illustrated, and its placement in the genus discussed. It is unique in the genus Brownea in being characterised by yellow flowers. In a 25-ha plot in Yasuni National Park, this new species averaged 20 individuals (with dbh ≥ 1 cm) per hectare.Item Metadata only Cambios en la funcionalidad de un bosque amazónicoPérez Castañeda, Álvaro Javier; Valencia Reyes, Luis RenatoEl presente estudio investiga cambios poblacionales y estructurales de la funcionalidad y la estructura del bosque en una parcela amazónica de 25-ha, luego de 20 años. Específicamente, se analizó si las especies de baja densidad de madera (secundarias y pioneras) han incrementado su importancia como se sugiere en estudios previos. También se investigó si hay especies que están volviéndose abundantes en ambientes menos húmedos o en los más húmedos y si estos cambios son constantes a través del tiempo. Se espera que los años 2005 y 2010, cuyas precipitaciones estuvieron por debajo de la media, se perciban variaciones funcionales y estructurales del bosque. Los resultados muestran que la estructura y composición está cambiando más de lo que se esperaría por azar. Las especies con menor densidad específica de la madera y de mayor tamaño (diámetro) están volviéndose más importantes que las tolerantes a la sombra, de crecimiento lento. Todo parece indicar que las especies secundarias han sido más exitosas en este período, en concordancia con las predicciones realizadas por otros estudios. Sin embargo, podría ser que los cambios climáticos y en las características funcionales del bosque correspondan a ciclos que de manera natural ocurren en el planeta. Todavía es prematuro saber si la tendencia encontrada permanecerá constante y si afectará de manera significativa a la composición del bosque en el futuro inmediato.Item Metadata only Canopy structure and forest understory conditions in a wet Amazonian forest-No change over the last 20 years(2020) Valencia Reyes, Luis Renato; Valencia Reyes, Luis RenatoClimate change is altering forest dynamics in the tropics, with large potential impacts on forest structure and understory conditions. However, we found that canopy height distribution and openness remained stable over two decades in the western Amazon, and that gap creation rates would need to increase 300% before affecting equilibrium.Item Metadata only Climate sensitive size-dependent survival in tropical trees(2018-08-13) Valencia Reyes, Luis Renato; Valencia Reyes, Luis RenatoSurvival rates of large trees determine forest biomass dynamics. Survival rates of small trees have been linked to mechanisms that maintain biodiversity across tropical forests. How species survival rates change with size offers insight into the links between biodiversity and ecosystem function across tropical forests. We tested patterns of size-dependent tree survival across the tropics using data from 1,781 species and over 2 million individuals to assess whether tropical forests can be characterized by size-dependent life-history survival strategies. We found that species were classifiable into four ‘survival modes’ that explain life-history variation that shapes carbon cycling and the relative abundance within forests. Frequently collected functional traits, such as wood density, leaf mass per area and seed mass, were not generally predictive of the survival modes of species. Mean annual temperature and cumulative water deficit predicted the proportion of biomass of survival modes, indicating important links between evolutionary strategies, climate and carbon cycling. The application of survival modes in demographic simulations predicted biomass change across forest sites. Our results reveal globally identifiable size-dependent survival strategies that differ across diverse systems in a consistent way. The abundance of survival modes and interaction with climate ultimately determine forest structure, carbon storage in biomass and future forest trajectories.Item Open Access A Common but Overlooked New Species in the Hyper-Diverse Genus Inga Mill. from the Northwestern Amazon(2019) Hernández Rentería, Consuelo Bethsabé; Valencia Reyes, Luis Renato; Hernández Rentería, Consuelo Bethsabé y Valencia Reyes, Luis RenatoInga kursarii is a new species collected in the terra firme forests of the northwestern Amazon, one of the regions with the highest tree species diversity in the world. According to morphological and phylogenetic analyses, the new species is morphologically similar and sister to Inga gracilifolia Ducke, but it can be distinguished by having 5–6 pairs of caducous leaflets, elliptical leaflets with acute apex and slightly asymmetrical base, spiked inflorescence, subsessile flowers, calyx tube with 4 lobes, tufts of hairs at the apex of calyx lobes, corolla tube with non reflexed lobes, shorter staminal tubes, and capitate stigma. In addition, analyses of the chemical defensive profile (chemocoding) show that both taxa are chemically different, with I. kursarii having a chemistry based on gallocatechin/epigallocatechin gallates, and I. gracilifolia producing a series of dihydroflavonols. Finally, we present a table with a comparison of diagnostic characters that allows separation of the two species.Item Open Access The Contribution of Rare species to Community Phylogenetic Diversity across a Global Network of Forest Plots.(2012) Valencia Reyes, Luis Renato; Xiangcheng, Mi.Niche differentiation has been proposed as an explanation for rarity in species assemblages. To test this hypothesis requires quantifying the ecological similarity of species. This similarity can potentially be estimated by using phylogenetic relatedness. In this study, we predicted that if niche differentiation does explain the cooccurrence of rare and common species, then rare species should contribute greatly to the overall community phylogenetic diversity (PD), abundance will have phylogenetic signal, and common and rare species will be phylogenetically dissimilar. We tested these predictions by developing a novel method that integrates species rank abundance distributions with phylogenetic trees and trend analyses, to examine the relative contribution of individual species to the overall community PD. We then supplement this approach with analyses of phylogenetic signal in abundances and measures of phylogenetic similarity within and between rare and common species groups. We applied this analytical approach to 15 long-term temperate and tropical forest dynamics plots from around the world. We show that the niche differentiation hypothesis is supported in six of the nine gap-dominated forests but is rejected in the six disturbance-dominated and three gap-dominated forests. We also show that the three metrics utilized in this study each provide unique but corroborating information regarding the phylogenetic distribution of rarity in communities.Item Metadata only Crecimiento de Cedrela odorata L. (cedro) y su relación con el clima, la concentración de CO2 y el hábitat en un bosque de la Amazonía ecuatorianaValencia Reyes, Luis RenatoCedrela odorata (cedro) forma anillos de crecimiento anual en bosques amazónicos con cierta estacionalidad. Sin embargo, en bosques amazónicos no estacionales, esta condición es desconocida. En este estudio, realizado en el bosque amazónico no estacional del Parque Nacional Yasuní, se investigó si los anillos del cedro son anuales, cuál es la relación de su formación con el clima y si el crecimiento fue mayor en algún hábitat en particular (colina, valle o pantano). Adicionalmente, se exploró el crecimiento histórico y reciente (en dos intervalos de tiempo entre 2013 y 2015) en una muestra de 110 árboles con diámetros entre 1 cm y más de 100 cm. Esta muestra incluye 44 árboles de los que se obtuvieron muestras de barrena para el estudio de los anillos. Los resultados demostraron que 1) los anillos de cedro son anuales y en consecuencia fue posible determinar que los 44 árboles estudiados tuvieron entre 14 y 146 años; 2) el crecimiento de estos cedros estuvo ligado a pequeñas variaciones de precipitación, temperatura y concentración de CO2, y 3) que no existen diferencias significativas en el crecimiento de cedro entre valle, pantano y colina. Sin embargo, el crecimiento fue mayor en árboles que estuvieron en claros de bosque o cerca de estos.Item Open Access Crecimiento y dendrocronología de Cedrela Odorata en un bosque de la Amazonía ecuatoriana(PUCE - Quito, 2015) Nacimba Chicaiza, Mayra Alexandra; Valencia Reyes, Luis RenatoEl estudio de anillos de crecimiento en bosques no estacionales de la Amazonía es todavía incipiente. Se conoce que la mayoría de árboles no forman anillos de crecimiento anual en estos bosques. En cedro (Cedrela odorata, Meliaceae), sin embargo, se ha reportado la formación de anillos anuales en un bosque ligeramente estacional de la Amazonía boliviana. Mediante este método, el presente estudio explora si es posible establecer la edad y la dinámica de crecimiento del cedro en el bosque no estacional del Parque Nacional Yasuní. Para esto se obtuvieron muestras de barreno de 44 árboles y se tomaron mediciones diamétricas de 110 individuos entre 2013 y 2015. La correlación entre anillos de crecimiento y precipitación fue positiva y significativa en 28 de los 44 árboles estudiados. Se determinó que el cedro en el área de estudio sí forma anillos de crecimiento anual y que el período hidrológico va de julio a junio. En promedio el crecimiento histórico del cedro (1865–2012) fue de 6,27 mm al año, mientras que la tasa medida entre 2013 y 2015 fue de apenas 4,7 mm. El tamaño de los anillos de un mismo año varió ampliamente entre los individuos estudiados, de tal manera que árboles de edad similar tuvieron diámetros muy distintos. Por ejemplo, los árboles de 600 mm de diámetro tuvieron edades comprendidas entre 48 y más de 140 años. Las tasas de crecimiento más altas se encontraron en individuos con diámetros entre 400 y 800 mm. Los resultados evidencian que el ciclo de corte de 20 años para árboles con diámetro ≥600 mm, sugerido para el cedro en la normativa ecuatoriana, no parece sostenible. Algunos árboles pueden tardar más de 100 años en alcanzar el diámetro mínimo de corte. El presente estudio muestra que el uso de anillos de crecimiento es un método ingenioso para conocer la dinámica de las especies en épocas pasadas y entender el crecimiento de los árboles en el bosque no estacional de la Amazonía ecuatoriana.Item Open Access Cryptic species and phylogeographical structure in the tree Cedrela odorata L. throughout the Neotropics.(2013) Valencia Reyes, Luis Renato; Stephen, CaversAim: The origins of much Neotropical biodiversity remain a topic of debate, with both palaeogeographical and more recent climatic drivers playing a role in diversification both among and within species. Here we use a combination of molecular data to assess genetic variation within and among species in the Neotropical tree genus Cedrela, with a focus on Cedrela odorata, to test hypotheses on the drivers of diversification, to place known ecotypic variation in context and to detect intraspecific phylogeographical structure. Location: Central and South America, Cuba, Cayman Islands, Trinidad and Guadeloupe. Methods: Samples were collected from the field, existing collections and herbaria from across the geographical range, including a total of 528 individuals from 72 sites. A phylogenetic framework was constructed using internal transcribed spacer (ITS) sequence data (intergenic spacers plus flanking 18S and 26S regions), and genetic structure was analysed using a combination of chloroplast DNA sequences (trnC–ycf6, trnH–psbA) and chloroplast and nuclear microsatellite (single sequence repeat, SSR) loci. Phylogenetic reconstruction was undertaken using a combination of Bayesian and parsimony-based approaches; divergence times were estimated for major nodes. Geographical structure in chloroplast SSR data was analysed using SAMOVA, while that in nuclear SSR data was assessed using a combination of Bayesian clustering and principal coordinates analysis. Results: ITS sequence data supported phylogenetic distinctiveness of four morphologically cryptic species within C. odorata. Chloroplast sequence and microsatellite data showed geographical structuring both among and within species, suggesting the influence of climatic and geographical drivers. Intraspecific genetic divergence was also present in nuclear microsatellite data, suggesting contemporary gene flow limitation across sea and mountain barriers. Main conclusions: The data support diversification of the genus Cedrela in South America with subsequent recolonization into Central America prior to the formation of the Isthmus of Panama. At least four morphologically cryptic taxa were evident within C. odorata and within-species phylogeographical divergence across the Andes and within Central America was present, the latter suggestive of Pleistocene climatic influence. Previously recognized ecotypes in Central America should be elevated to species level. The new molecular data support the recent reclassification and will support the monitoring of exploitation in the genus.Item Metadata only CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change(2014-09) Valencia Reyes, Luis Renato; Valencia Reyes, Luis RenatoGlobal change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25 ha), all stems ≥1 cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25°S–61°N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 °C), changes in precipitation (up to ±30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8 g N m−2 yr−1 and 3.1 g S m−2 yr−1), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5 km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.Item Open Access Demographic consequences of chromatic leaf defence in tropical tree communities - do red young leaves increase growth and survival?(2013) Valencia Reyes, Luis Renato; Queenborough, Simón, A.Background: Many tropical forest tree species delay greening their leaves until full expansion. This strategy is thought to provide newly flushing leaves with protection against damage by herbivores by keeping young leaves devoid of nutritive value. Because young leaves suffer the greatest predation from invertebrate herbivores, delayed greening could prevent costly tissue loss. Many species that delay greening also produce anthocyanin pigments in their new leaves, giving them a reddish tint. These anthocyanins may be fungicidal, protect leaves against UV damage or make leaves cryptic to herbivores blind to the red part of the spectrum. Methods: A comprehensive survey was undertaken of seedlings, saplings and mature trees in two diverse tropical forests: a rain forest in western Amazonia (Yasuní National Park, Ecuador) and a deciduous forest in Central America (Barro Colorado Island, Panamá). A test was made of whether individuals and species with delayed greening or red-coloured young leaves showed lower mortality or higher relative growth rates than species that did not. Key results: At both Yasuní and Barro Colorado Island, species with delayed greening or red young leaves comprised significant proportions of the seedling and tree communities. At both sites, significantly lower mortality was found in seedlings and trees with delayed greening and red-coloured young leaves. While there was little effect of leaf colour on the production of new leaves of seedlings, diameter relative growth rates of small trees were lower in species with delayed greening and red-coloured young leaves than in species with regular green leaves, and this effect remained when the trade-off between mortality and growth was accounted for. Conclusions Herbivores exert strong selection pressure on seedlings for the expression of defence traits. A delayed greening or red-coloured young leaf strategy in seedlings appears to be associated with higher survival for a given growth rate, and may thus influence the species composition of later life stages.Item Open Access Demography of Oenocarpus bataua and implications for sustainable harvest of its fruit in western Amazon(2016-03-19) Valencia Reyes, Luis Renato; Cevallos Garzón, Daniela Victoria; Valencia Reyes, Luis RenatoOenocarpus bataua is the seventh most abundant tree in the Amazon and one of the most used palms in the region. The main resource obtained from the species is the fruits that are harvested from wild populations for human consumption. Across its distribution area adults are most frequently felled to obtain the racemes, which may affect the palm’s populations. In this paper we studied the demography of two populations of Oenocarpus bataua to assess the harvest potential of its fruits and the density variation in different habitats in the western Amazon to estimate fruit yields in different forest types. Non-inundated lands held the greatest densities with an average of 11 adults ha−1 (0–132 adults ha−1). The population finite growth rate (λ) in Amacayacu, Colombia, was 0.9103 because of slow growth and low survival of stemless individuals and low recruitment. On the contrary, in Yasuní, Ecuador, we found a growing population with λ = 1.0368. According to our simulations, adult felling reduced transient population growth (λt) in both populations, especially when harvest was frequent even at low intensities. In Amacayacu a simulated harvest of 60 % year−1 of the fruits by climbing did not modify λt substantially, while in Yasuní, a regime of 80 % of annual harvest did not diminish λt below one and the initial number of adults. The results help to understand the demography of useful palms and to address sustainable management. For instance high yields can be obtained by shifting to non-destructive harvest techniques that can meet the increasing demand and maintain the populations.Item Metadata only Dinámica forestal en un bosque amazónico de YasuníValencia Reyes, Luis RenatoEn una hectárea de bosque Amazónico en Yasuní se encuentran en promedio 670 especies de árboles y arbustos (dap ≥1 cm), de las que apenas 10% de especies tienen más de 20 individuos, mientras 25% de las especies tienen apenas un individuo por hectárea. Para estudiar la dinámica poblacional y los cambios en la funcionalidad de estos bosques es, por tanto, necesario parcelas de gran tamaño. En este estudio se investigaron los cambios poblacionales y funcionales en una parcela de 25 hectáreas en el Parque Nacional Yasuní. Estudios previos sugieren que el cambio climático está afectando la composición de especies y la estructura de los bosques amazónicos. Por ejemplo, se piensa que las especies de bosques secundarios podrían volverse más importantes con el calentamiento climático global. Igualmente se ha anticipado que los bosques experimentarán sequías más intensas y frecuentes. Si esto está ocurriendo en Yasuní, se esperaría detectar ciertos cambios consistentes con estas predicciones. Así, las especies menos tolerantes a la sequía deberían volverse más comunes en ambientes que tienden a mantenerse más húmedos, como los valles atravesados por pequeños riachuelos y menos comunes en ambientes menos húmedos como las partes altas de las colinas. En este estudio se probaron estas hipótesis la parcela de estudio que ha sido censada en cuatro ocasiones, entre 1995 y 2017, lo que permite ver los cambios del bosque en tres intervalos de tiempo de 5, 6 y 9 años (~22 años). A través del tiempo la proporción de especies con cambios poblacionales significativos creció de 26.2% a 42.1% a través del tiempo, siendo 10% mayor en las colinas que en los valles. Muy pocas especies tuvieron cambios poblacionales direccionales, ya sea aumentando o disminuyendo su población a lo largo en todos los intervalos de tiempo (4.8% en la colina y 1.7% en el valle). Cambios constantes y direccionales en los dos hábitats al mismo tiempo fue muy bajo (<1%).Item Metadata only Dinamismo y cambios direccionales en un bosque del Parque nacional YasuníHernández Rentería, Consuelo Bethsabé; Pérez Castañeda, Álvaro Javier; Valencia Reyes, Luis RenatoLa Escuela Superior Politécnica del Litoral, impulsando la sociedad del conocimiento, mediante la Facultad de Ciencias de la Vida encargada de organizar las cuadragésimas XL Jornadas Nacionales de Biología, evento promocionado por la Sociedad Ecuatoriana de Biología y que se constituye como el más importante espacio para la difusión de la investigación e innovación en el área de las Ciencias de la Vida; a realizarse desde el 16 al 18 de noviembre de 2016 en el Campus Prosperina de la ESPOL, en el Auditorio del Centro de Información Bibliotecario y cuenta con la participación de investigadores nacionales e internaciones en las temáticas antes escritas, con el horario de 09h00 hasta las 18h00. Evento trascendental de actualización y fortalecimiento científico que reúne anualmente a científicos, profesionales y estudiantes del área de las ciencias biológicas y ciencias afines de todas las universidades del país en un espacio de integración, diálogo y divulgación de resultados de investigación.Item Metadata only Directional Changes in an Amazonian forestHernández Rentería, Consuelo Bethsabé; Valencia Reyes, Luis RenatoWe study population and functional changes in a large forest plot (25-ha) located in eastern Ecuador. Previous studies suggest that climate change affect species in different ways. For instance, secondary species may become more important in Amazonian forests. And the forest itself is supposed to experience frequent and intense droughts. If these is true, species less tolerant to drought are expected to become more common in more humid habitats, such as the humid valleys and will become less common in less humid areas, such as the hill tops and slopes. In this study we test these predictions. The plot was stablished in 1995. Since then, four censuses has been made. We present results of 12 years (divided in two intervals). We use functional traits such us maximum size, wood density, seed mass and specific leaf area to address these questions. We found that the forest is decreasing in wood density, maximum size and specific leaf area in the second time interval. In the two time intervals, the population of 5 and 6% of the species increased or decreased significantly (>6 times of the original population). Contrary to the expectations, species increased tenfold in (dry) ridges than in (wet) valleys by the second interval. Only two species, one in ridge and another in valley, increased systematically in both time intervals and no species decreased in both censuses. Our results suggest that the secondary species are becoming more important, but not that species are increasing in population in the humid valleys.Item Metadata only Disentangling the functional trait correlates of spatial aggregation in tropical forest trees(2018-12) Valencia Reyes, Luis Renato; Valencia Reyes, Luis RenatoEnvironmental filtering and dispersal limitation can both maintain diversity in plant communities by aggregating conspecifics, but parsing the contribution of each process has proven difficult empirically. Here, we assess the contribution of filtering and dispersal limitation to the spatial aggregation patterns of 456 tree species in a hyperdiverse Amazonian forest and find distinct functional trait correlates of interspecific variation in these processes. Spatial point process model analysis revealed that both mechanisms are important drivers of intraspecific aggregation for the majority of species. Leaf drought tolerance was correlated with species topographic distributions in this aseasonal rainforest, showing that future increases in drought severity could significantly impact community structure. In addition, seed mass was associated with the spatial scale and density of dispersal-related aggregation. Taken together, these results suggest environmental filtering and dispersal limitation act in concert to influence the spatial and functional structure of diverse forest communities.Item Metadata only Distribution and Community Assembly of Trees Along an Andean Elevational Gradient(2019) Pérez Castañeda, Álvaro Javier; Valencia Reyes, Luis Renato; Pérez Castañeda, Álvaro JavierHighlighting patterns of distribution and assembly of plants involves the use of community phylogenetic analyses and complementary traditional taxonomic metrics. However, these patterns are often unknown or in dispute, particularly along elevational gradients, with studies finding different patterns based on elevation. We investigated how patterns of tree diversity and structure change along an elevation gradient using taxonomic and phylogenetic diversity metrics. We sampled 595 individuals (36 families; 53 genera; 88 species) across 15 plots along an elevational gradient (2440-3330 m) in Ecuador. Seventy species were sequenced for the rbcL and matK gene regions to generate a phylogeny. Species richness, Shannon-Weaver diversity, Simpson's Dominance, Simpson's Evenness, phylogenetic diversity (PD), mean pairwise distance (MPD), and mean nearest taxon distance (MNTD) were evaluated for each plot. Values were correlated with elevation and standardized effect sizes (SES) of MPD and MNTD were generated, including and excluding tree fern species, for comparisons across elevation. Taxonomic and phylogenetic metrics found that species diversity decreases with elevation. We also found that overall the community has a non-random phylogenetic structure, dependent on the presence of tree ferns, with stronger phylogenetic clustering at high elevations. Combined, this evidence supports the ideas that tree ferns have converged with angiosperms to occupy the same habitat and that an increased filtering of clades has led to more closely related angiosperm species at higher elevations.Item Open Access Diversidad de semillas dispersadas por aves del interior del bosque tropical amazónico de Yasuní(PUCE - Quito, 2022) Herrera Cueva, Juan Francisco; Valencia Reyes, Luis RenatoLa ornitozoocoria juega un papel fundamental en la estructura y funcionamiento de los bosques tropicales megadiversos. Este es el caso de los bosques amazónicos del Parque Nacional Yasuní, donde conviven en promedio 670 especies de árboles y arbustos por hectárea y se han registrado más de 200 especies de aves frugívoras dentro del parque, dónde la dispersión de semillas es crucial. El presente estudio analizó la diversidad de semillas dispersadas por aves frugívoras que habitan el interior del bosque de terra firme entre hábitats (valles y colinas) y entre estaciones (de mayor y menor precipitación). Se encontró que cada ave puede dispersar en promedio 1,41 ± SD 0,85 especies de semillas por deposición. Los patrones de dispersión en valle o colina variaron con la estacionalidad. En la colina, durante la estación menos lluviosa, se encontró 115 % más especies de aves frugívoras que en el valle, mientras la estación lluviosa fue 30 % menos diversa en aves frugívoras. Igualmente, las semillas dispersadas diversificaron en la estación menos lluviosa fueron 2,2 veces más diversas que durante la estación de lluvias, donde se dio la dominancia de la planta Clidemia dimorfica. Las aves de la familia Pipridae dispersaron el 81 % de las especies de semillas registradas, siendo dominante Lepidothrix coronata. También, las bayas de Melastomataceae y Araceae fueron la dieta más frecuente (74 %). La repartición de nichos dietarios entre aves frugívoras evidencia una red compleja de interacciones que facilita la coexistencia de cientos de aves y especies de plantas en áreas relativamente pequeñas.
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