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Citogeografia de cuatro especies de Polylepis (Rosacea) en el Ecuador: Informacion relevante para el manejo y conservación de los bosques andinos.

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... The next studies examining ploidy levels in Polylepis were conducted by Segovia-Salgado and colleagues on Ecuadorean species [27][28][29][30][31][32][33]. Using flow cytometric measures of nucleus mass, chromosome numbers, and guard cell lengths, of dozens of individuals of each species, they documented that many species have variable chromosome numbers and nucleus mass, suggesting reductions in chromosome numbers. ...
... However, numerous published counts differ notably from these values. For example, Caiza et al. [33] and Segovia-Salcedo & Quijia [32] reported chromosome counts of 59-77 for nine individuals of P. ochreata (as P. sericea) from Yanacocha, Ecuador. In this situation, it is unclear if these numbers reflect the difficulty of fully counting the tiny chromosomes, or whether they correspond to real values with would suggest triploidy and other intermediate chromosome levels as a result of aneuploidy and dysploidy. ...
... (5) What is the prevalence of aneuploidy and dysploidy in the genus? Studies in Ecuador [27][28][29][30][31][32][33] suggest that these occur in the genus, but data are inconclusive. (6) How does hybridization between ploidy levels induced by translocation and reforestation activities affect the population viability of species? ...
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The Andean tree genus Polylepis (Rosaceae) has recently been recognized to include polyploid species, but their occurrence within the genus is still incompletely known, especially in light of a forthcoming taxonomic treatment based on a narrow species concept including morphological, climatic and biogeographic distinctness that recognizes 45 species. We obtained guard cell measurements as proxies of ploidy level from 114 individuals of 33 species of Polylepis, including all species for which no previous measurements were available. In combination with previously published data, also on nucleus mass and chromosome counts, we infer that on current knowledge 19 (42%) species are probably purely diploid, 15 (33%) purely tetraploid, and one (2%) purely octoploid. The remaining eight (18%) species have mixed ploidy levels, with three (7%) being di- and tetraploid, two (4%) di- and hexaploid, and one each tetra- and hexaploid, tetra- and octoploid, and di-, tri-, tetra- and hexaploid. Based on our understanding of the evolutionary relationships in Polylepis, it would appear that polyploidy has originated at least about eight times independently in the genus, sometimes as autopolyploidy, sometimes as a result of interspecific hybridization, and sometimes in relation to cultivation. The taxonomic implications of the ploidy levels are complex, in some cases supporting species-level distinction and in others posing the question whether different ploidy levels within a species should better be treated as distinct species. Ploidy level needs to be taken into account for the conservation of the genus, as for example if different populations of a species have different ploidy levels, mixing these origins in reforestation schemes may lead to the formation of sterile hybrids. Guard cell measurement is a low cost and simple technique that can be readily used on both live and dried plant material for such applications, but it has limitations and further data on chromosome counts and nucleus mass are also needed to fully understand the evolution of ploidy levels in Polylepis and its implications.
... Morales, observación personal;Kessler 2006). Asimismo, investigaciones recientes mostraron que Polylepis presenta poliploidías (i.e., tiene más de dos juegos de cromosomas completos) y una capacidad de hibridación elevada (Schmidt-Lebuhn et al. 2006;Segovia-Salcedo et al. 2011;Segovia-Salcedo and Quijia-Lamiña 2014). Por ello, se considera que utilizar especies de Polylepis que no sean locales en los proyectos de reforestación es un riesgo para la diversidad genética de las poblaciones naturales. ...
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¿Cómo acercar la ciencia a la práctica de la restauración de bosques de Polylepis? Esta pregunta suscitó la discusión y reflexión entre un grupo de científicos académicos y practicantes de restauración que participamos en el simposio “Reforestación y Restauración de Ecosistemas de Polylepis: Experiencias y Perspectivas” durante el IV Congreso Internacional de Ecología y Conservación de Bosques de Polylepis. A través del dialogo observamos que existen diferentes experiencias prácticas relacionadas con la reforestación con especies de Polylepis, con distintos objetivos, grado de avance y de éxito, pero que en general cuentan con poca participación del sector académico. Para que los científicos colaboremos de una manera más efectiva con la restauración de estos bosques, tenemos que realizar investigaciones en áreas tanto de relevancia para la ciencia como para la práctica y compartir nuestros aportes con los practicantes. Aquí identificamos temas que consideramos prioritarios para el marco de trabajo de investigación en la restauración de los bosques de Polylepis de acuerdo a los sectores académicos y de practicantes. El sector académico considera que los principales vacíos de información en los que hay que trabajar se relacionan con aspectos ecológicos que abarcan desde la escala genética a la de paisaje, mientras que para el sector de los practicantes es necesario priorizar aspectos técnicos aplicables a su labor: selección del sitio, manejo de las especies en vivero y en campo e identificación de las barreras de establecimiento. Finalmente, sugerimos algunas estrategias de comunicación y cooperación directa en investigación para facilitar la colaboración entre científicos y practicantes de restauración y lograr juntos el objetivo de conservar y restaurar los ecosistemas de Polylepis.
... Morales, observación personal;Kessler 2006). Asimismo, investigaciones recientes mostraron que Polylepis presenta poliploidías (i.e., tiene más de dos juegos de cromosomas completos) y una capacidad de hibridación elevada (Schmidt-Lebuhn et al. 2006;Segovia-Salcedo et al. 2011;Segovia-Salcedo and Quijia-Lamiña 2014). Por ello, se considera que utilizar especies de Polylepis que no sean locales en los proyectos de reforestación es un riesgo para la diversidad genética de las poblaciones naturales. ...
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¿Cómo acercar la ciencia a la práctica de la restauración de los bosques de Polylepis? Esta pregunta suscitó la discusión y la reflexión entre un grupo de científicos académicos y practicantes de restauración que participamos del simposio "Reforestación y Restauración de Ecosistemas de Polylepis: Experiencias y Perspectivas" durante el IV Congreso Internacional de Ecología y Conservación de Bosques de Polylepis. El diálogo dentro del grupo nos permitió reconocer que existen diferentes experiencias prácticas relacionadas con la reforestación con especies de Polylepis, con distintos objetivos, grado de avance y de éxito, y, en general, poca participación del sector académico. Para que los científicos colaboremos de una manera más efectiva con la restauración de estos bosques, tenemos que realizar investigaciones tanto en áreas relevantes para la ciencia como para la práctica, y compartir nuestros aportes con los practicantes. En este artículo identificamos temas que consideramos prioritarios como guía para definir el marco de trabajo de investigación en la restauración de los bosques de Polylepis y los presentamos de acuerdo con su importancia para los sectores académicos y de practicantes. El sector académico considera que los principales vacíos de información en los que hay que trabajar se relacionan con aspectos ecológicos que abarcan desde la escala genética hasta la de paisaje. Mientras tanto, el sector de los practicantes sostiene que es necesario priorizar aspectos técnicos aplicables a su labor, como selección del sitio, manejo de las especies en vivero y en campo, e identificación de las barreras al establecimiento. Finalmente, sugerimos algunas estrategias de comunicación y cooperación directa en investigación para facilitar la colaboración entre científicos y practicantes de restauración, y para lograr juntos el objetivo de conservar y restaurar los ecosistemas de Polylepis.
... Morales, observación personal;Kessler 2006). Asimismo, investigaciones recientes mostraron que Polylepis presenta poliploidías (i.e., tiene más de dos juegos de cromosomas completos) y una capacidad de hibridación elevada (Schmidt-Lebuhn et al. 2006;Segovia-Salcedo et al. 2011;Segovia-Salcedo and Quijia-Lamiña 2014). Por ello, se considera que utilizar especies de Polylepis que no sean locales en los proyectos de reforestación es un riesgo para la diversidad genética de las poblaciones naturales. ...
Article
¿Cómo acercar la ciencia a la práctica de la restauración de los bosques de Polylepis? Esta pregunta suscitó la discusión y la reflexión entre un grupo de científicos académicos y practicantes de restauración que participamos del simposio "Reforestación y Restauración de Ecosistemas de Polylepis: Experiencias y Perspectivas" durante el IV Congreso Internacional de Ecología y Conservación de Bosques de Polylepis. El diálogo dentro del grupo nos permitió reconocer que existen diferentes experiencias prácticas relacionadas con la reforestación con especies de Polylepis, con distintos objetivos, grado de avance y de éxito, y, en general, poca participación del sector académico. Para que los científicos colaboremos de una manera más efectiva con la restauración de estos bosques, tenemos que realizar investigaciones tanto en áreas relevantes para la ciencia como para la práctica, y compartir nuestros aportes con los practicantes. En este artículo identificamos temas que consideramos prioritarios como guía para definir el marco de trabajo de investigación en la restauración de los bosques de Polylepis y los presentamos de acuerdo con su importancia para los sectores académicos y de practicantes. El sector académico considera que los principales vacíos de información en los que hay que trabajar se relacionan con aspectos ecológicos que abarcan desde la escala genética hasta la de paisaje. Mientras tanto, el sector de los practicantes sostiene que es necesario priorizar aspectos técnicos aplicables a su labor, como selección del sitio, manejo de las especies en vivero y en campo, e identificación de las barreras al establecimiento. Finalmente, sugerimos algunas estrategias de comunicación y cooperación directa en investigación para facilitar la colaboración entre científicos y practicantes de restauración, y para lograr juntos el objetivo de conservar y restaurar los ecosistemas de Polylepis.
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We present a monograph of the high Andean tree genus Polylepis (Rosaceae), based on a species concept considering morphological, climatic and biogeographic distinctness as indicators of evolutionary independence. In total, we recognize 45 species of Polylepis , grouped in five sections. Polylepis sect. Sericeae is represented by 15 species in four subsections, P. sect. Reticulatae by seven species, P. sect. Subsericantes by three species, P. sect. Australes by two species and P. sect. Incanaee by three subsections with 18 species. We describe seven new species, one from Colombia ( P. frontinensis ), one from Ecuador ( P. simpsoniae ) and five from Peru ( P. acomayensis , P. fjeldsaoi , P. occidentalis , P. pilosissima and P. sacra ). Three species from Peru ( P. albicans , P. pallidistigma and P. serrata ) are re-instated as valid species. Two taxa from Bolivia ( P. incanoides and P. nana ) are elevated from subspecies to species rank. The morphology, habitat, distribution, ecology and conservation status of each species are documented. We also provide an identification key to the species of the genus and general introductions on taxonomic history, morphology, evolution, ecology and conservation.
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The species of the genus Polylepis are the most important trees of high altitude woodlands in the Andes, an area with great climatic variation from Venezuela to Argentina. In the humid climate of the Cajas Massif (southern Ecuador), four native Polylepis species form little known woodlands between 2800 and 4400 m a.s.l.: P. reticulata, P. incana, P. weberbaueri and P. lanuginosa (the latter, endemic to Ecuador). Morphological-functional traits of these species and of another introduced (P. racemosa), and attributes at the population and ecosystem levels relevant to understanding their local distribution and the effects of global change were studied. Leaf area decreases with altitude, showing P. lanuginosa one of the largest of the genus Polylepis (17.3 cm²). High stem water content (>55%) and low stem wood density of three species suggest an ecological response to primary production limitation due to cold and/or climatic aridity. Tree species diversity (Shannon index) is moderate in the woodlands of P. reticulata and P. incana and relatively high in P. lanuginosa ones, with maxima higher than 3 bits. Tree species diversity decreases non-linearly with increasing Polylepis tree density, always greater than 400 individuals/ha and frequently more than 1000 individuals/ha. Aboveground biomass is a very variable ecosystem attribute and remarkable in some woodlands (about 200 Mg C/ha). The diameter growth rate at breast height of P. reticulata after seven years is 1.2 mm/year, and the average carbon sequestration rate is 2.6±0.3 Mg C.ha⁻¹.year⁻¹, outstanding for a slow-growing genus. Polylepis woodlands conservation is pertinent to preserve threatened high Andean biodiversity and mitigate climate change by its ability to retain carbon in biomass.
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... In Plant Speciation , Grant (1981) devoted five chapters (15% of the total text) to polyploidy, reflecting the importance of the topic both to the author and to plant biologists. We update Grant&apos;s (1981) coverage by highlighting some ...
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Afforestation is a common and widespread management practice throughout the world, yet its implications for the genetic diversity of native populations are still poorly understood. We examined the effect of Aleppo pine (Pinus halepensis) plantations on the genetic composition of nearby conspecific native populations. We focused on two native populations in Israel with different levels of isolation from the surrounding plantations and compared the genetic diversity of naturally established young trees within the native populations with that of local native adults, using nine nuclear microsatellite markers. We found that the genetic composition of the recruits was significantly different from that of local adults in both populations, with allelic frequency changes between generations that could not be ascribed to random drift, but rather to substantial gene flow from the surrounding planted Aleppo pine populations. The more isolated population experienced a lower gene-flow level (22%) than the less isolated population (49%). The genetic divergence between native populations at the adult-tree stage (F(st) = 0.32) was more than twice as high as that of the young trees naturally established around native adults (F(st) = 0.15). Our findings provide evidence for a rapid genetic homogenization process of native populations following the massive planting efforts in the last decades. These findings have important implications for forest management and nature conservation and constitute a warning sign for the risk of translocation of biota for local biodiversity.
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The Andean tree genus Polylepis (Rosaceae) is notorious for the high morphological plasticity of its species and the difficulty in their circumscription. The evolutionary mechanisms that have driven diversification of the genus are still poorly understood, with factors as diverse as ecological specialisation, reticulate evolution, polyploidisation and apomixis being proposed to contribute. In the present study, chromosome counts, flow cytometry and stomata guard cell size measurements were employed to document for the first time the presence of polyploidy in the genus and to infer ploidy levels for most species. Inferred ploidy levels show a clear progression from diploidy in cloud forest species to polyploidy (tetra- to octoploidy) in the morphologically and ecologically specialised incana group, indicating that polyploidisation may have played a major role in speciation processes and the colonisation of novel habitats during the Andean uplift. At least two species of Polylepis comprise populations with varying degrees of ploidy. More extensive studies are needed to obtain a better understanding of the prevalence and effects of intraspecific polyploidy in the genus.
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The importance of hybridization in plant speciation and evolution has been debated for decades, with opposing views of hybridization as either a creative evolutionary force or evolutionary noise. Hybrid speciation may occur at either the homoploid (i.e., between two species of the same ploidy) or the polyploid level, each with its attendant genetic and evolutionary consequences. Whereas allopolyploidy (i.e., resulting from hybridization and genome doubling) has long been recognized as an important mode of plant speciation, the implications of genome duplication have typically not been taken into account in most fields of plant biology. Recent developments in genomics are revolutionizing our views of angiosperm genomes, demonstrating that perhaps all angiosperms have likely undergone at least one round of polyploidization and that hybridization has been an important force in generating angiosperm species diversity. Hybridization and polyploid formation continue to generate species diversity, with several new allopolyploids having originated just within the past century or so. The origins of polyploid species-whether via hybridization between species or between genetically differentiated populations of a single species-and the immediate genetic consequences of polyploid formation are therefore receiving enthusiastic attention. The time is therefore right for a review of the role of hybridization in plant speciation.
Polyploidy in Plants. En: Gregory TR, editor. The Evolution of the Genome
  • Ja Tate
  • De Soltis
  • Ps Soltis
Tate JA, Soltis DE, Soltis PS. 2005. Polyploidy in Plants. En: Gregory TR, editor. The Evolution of the Genome. San Diego: Elsevier Academic Press, pp 371-426.