Evolución bajo domesticación y cambios en caracteres funcionales y estructurales de frutos y semillas de Cucurbita maxima subsp. maxima

Tesis presentada para optar al Grado de Doctor en Ciencias NaturalesFil: Martínez, Analía Beatriz Luján. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Peduncles and pericarps of Cucurbita maxima duch.: a contribution for the reconstruction of domestication process of cultivated squash in Northwest Argentina

El objetivo de este trabajo consistió en reconocer y evaluar las modificaciones biométricas que se dieron en pedúnculos y pericarpios de Cucurbita maxima (subsp. maxima y andreana) ligadas a un proceso de selección, cultivo y/o domesticación en el pasado prehispánico del Noroeste de Argentina. Por medio de la realización de cultivos experimentales -técnica que nos permite reproducir procesos de hibridación e introgresión bajo condiciones controladas- junto al estudio morfométrico de los ejemplares así obtenidos, al igual que de los arqueológicos, se pretende aportar a la comprensión del proceso de domesticación del zapallo criollo. Los resultados obtenidos constatan la presencia de formas silvestres, híbridas y domesticadas hace cerca de 2000 años AP e indican que los pedúnculos son mejores indicadores que los pericarpios para la detección de las mismas mediante caracteres biométricos. Estos resultados llevan a concluir que el flujo génico entre estas formas con diverso grado de manejo habría sido posiblemente alentado como mecanismo de diversificación sobre el cual luego operaría un proceso de selección antrópica, lo cual coincidiría con lo registrado para otros miembros del género, al igual que explicaría la gran diversidad de morfotipos domesticados presentes en los restos arqueobotánicos analizados.The aim of this paper is to recognize and assess biometrical modifications in peduncles and pericarps of squash or “zapallo criollo” (Cucurbita maxima subsp. maxima and andreana) which are bound to a process of selection, cultivation and/or domestication in the Prehispanic past at the Argentinean Northwest. It is intended to contribute to the understanding of the process of domestication of the creole pumpkin by carrying out experimental cultivation (a technique which allows to reproduce the processes of hybridization and introgression under controlled conditions) together with morphometric and archaeological studies of the samples obtained. Results confirm the presence of wild, hybrid and domesticated forms near of 2, 000 years BP and that peduncles are better indicators than pericarps to detect those forms through biometrical analysis. These results lead to the conclusion that gene flow among these forms, which underwent several ways of managing, could have been possibly encouraged as a mechanism of diversification on which a process of anthropic selection would later operate. This coincides with records of other members of the same genus and would also explain the great diversity of domesticated morphotypes found in archaeobotanical remains submitted to analysis.Facultad de Ciencias Naturales y Muse

Differences in seed dormancy associated with the domestication of <i>Cucurbita maxima</i> : Elucidation of some mechanisms behind this response

This work presents the results of physiological studies developed to understand modifications linked to the reduction of seed dormancy provoked by domestication processes. The experiments performed compared wild and domesticated Cucurbita subspecies and their hybrids developed by reciprocal crossings. Seeds of two accessions of the wild subspecies presented dormancy, but it was largely reduced in seeds from the domesticated genotype, and partially reverted in hybrids, especially in those obtained when the domesticated genotype was used as the mother plant. In addition, naked embryos of all subspecies did not display dormancy when incubation was performed at 28°C, but embryo germination was progressively reduced only in the wild genotype under decreasing incubation temperatures (22 and 16°C). In the embryos, abscisic acid (ABA) concentrations were similar in both domesticated and wild subspecies, whereas in the seed coat, it was threefold higher in the wild subspecies. The naked embryos from the wild subspecies were far more responsive to ABA than those from the domesticated subspecies. These results indicate that dormancy in the wild subspecies is imposed by the seed coat tissues and that this effect is mediated by their high ABA content and the sensitivity of the embryos to ABA. These physiological aspects were apparently removed by domestication along with the temperature-dependent response for germination.Instituto de Fisiología VegetalLaboratorio de Etnobotánica y Botánica AplicadaFacultad de Ciencias Naturales y Muse

Peduncles and pericarps of Cucurbita maxima duch.: a contribution for the reconstruction of domestication process of cultivated squash in Northwest Argentina

El objetivo de este trabajo consistió en reconocer y evaluar las modificaciones biométricas que se dieron en pedúnculos y pericarpios de Cucurbita maxima (subsp. maxima y andreana) ligadas a un proceso de selección, cultivo y/o domesticación en el pasado prehispánico del Noroeste de Argentina. Por medio de la realización de cultivos experimentales -técnica que nos permite reproducir procesos de hibridación e introgresión bajo condiciones controladas- junto al estudio morfométrico de los ejemplares así obtenidos, al igual que de los arqueológicos, se pretende aportar a la comprensión del proceso de domesticación del zapallo criollo. Los resultados obtenidos constatan la presencia de formas silvestres, híbridas y domesticadas hace cerca de 2000 años AP e indican que los pedúnculos son mejores indicadores que los pericarpios para la detección de las mismas mediante caracteres biométricos. Estos resultados llevan a concluir que el flujo génico entre estas formas con diverso grado de manejo habría sido posiblemente alentado como mecanismo de diversificación sobre el cual luego operaría un proceso de selección antrópica, lo cual coincidiría con lo registrado para otros miembros del género, al igual que explicaría la gran diversidad de morfotipos domesticados presentes en los restos arqueobotánicos analizados.The aim of this paper is to recognize and assess biometrical modifications in peduncles and pericarps of squash or “zapallo criollo” (Cucurbita maxima subsp. maxima and andreana) which are bound to a process of selection, cultivation and/or domestication in the Prehispanic past at the Argentinean Northwest. It is intended to contribute to the understanding of the process of domestication of the creole pumpkin by carrying out experimental cultivation (a technique which allows to reproduce the processes of hybridization and introgression under controlled conditions) together with morphometric and archaeological studies of the samples obtained. Results confirm the presence of wild, hybrid and domesticated forms near of 2, 000 years BP and that peduncles are better indicators than pericarps to detect those forms through biometrical analysis. These results lead to the conclusion that gene flow among these forms, which underwent several ways of managing, could have been possibly encouraged as a mechanism of diversification on which a process of anthropic selection would later operate. This coincides with records of other members of the same genus and would also explain the great diversity of domesticated morphotypes found in archaeobotanical remains submitted to analysis.Facultad de Ciencias Naturales y Muse

Study of a pilot plant for the recovery of metals from spent alkaline and zinc-carbon batteries with biological sulphuric acid and polithionates production

The recovery of Zn and Mn from spent alkaline and Zn-C batteries with a biohydro-metallurgycal process was studied in a pilot plant that consists in an air lift bio-reactor with a sulfur packed bed where Acidithiobacillus thiooxidans produces an acid-reducing medium; a leaching reactor where the acid-reducing medium is mixed with the battery powder and a recovery reactor where metals are recovered from the leaching liquor by electroly-sis. Results shows that with a 350 mM in proton me-dium produced in 12 days by Acidithiobacillus thiooxidans in the bio-reactor, an extraction of the 100% of Zn and 67% of the Mn present in the bat-tery powder was reached. The presence of polithionates in the medium produced in the bio-reactor allows the dissolution of the manganese. The solid remaining after bioleaching is a manganese oxide. The electrolysis of the leaching liquor pro-duced a cathodic deposit of metallic Zn and an an-odic deposit of a high surphase manganese oxide in one step at room temperature.Centro de Investigación y Desarrollo en Ciencias Aplicada

The study of human-plants interactions in Argentina: history of building of an interdisciplinary approach from Museo de La Plata (FCNYM-UNLP)

Se sintetizan la historia académica y las líneas de investigación surgidas luego de 60 años de estudios conjuntos entre dos unidades de investigación de la Facultad de Ciencias Naturales y Museo de la Universidad Nacional de La Plata. Éstos se vinculan con el surgimiento de la Etnobotánica como disciplina científica y el desarrollo de la Arqueobotánica a escala mundial y se inscriben en un proyecto marco que incluye sitios arqueológicos distribuidos en la Diagonal Árida argentina. La metodología utilizada surge principalmente de equipamientos y protocolos de trabajo ajustados en el seno del equipo y del armado de colecciones de referencia. Los resultados y discusión de cada línea temática se resumen en tres secciones: 1) domesticación, selección y cultivo; 2) prácticas asociadas al uso de pipas e incensarios; y 3) patrones de subsistencia y prácticas de gestión y procesamiento. Se demuestra la importancia de la interdisciplina y las vías multi-proxy de análisis en los abordajes arqueobotánicos.This article synthesizes the academic history and lines of research from 60 years of joint studies of two research unities at the Natural Sciences Faculty, La Plata University. Discussed are the emergence of Archaeobotany as a scientific discipline and its globalization. Within this framework, we include recent research at archaeological sites throughout the Argentine Arid Diagonal. Methodologies include the compilation of comparative collections and the development of field and laboratory protocols, along with complementary ethnobotanical and actualistic studies. Research results are summarized in three sections: 1) selection, cultivation and domestication; 2) the use of pipes and other combustibles; and 3) patterns of plant management, processing, and subsistence, including activity areas. The importance of interdisciplinary and multi-proxy analysis in archaeobotanical research is emphasized.Facultad de Ciencias Naturales y Muse

Modification of characters linked to <i>Cucurbita maxima</i> domestication. Using morphometry as a tool for identification

El objetivo de este trabajo consiste en reconocer patrones de variación morfométrica –mediante la aplicación de análisis multivariado para tamaño y formaen semillas de C. maxima que sean diagnósticos para formas domesticadas, silvestres e híbridas actuales, a fin de aplicarlos a la identificación de semillas arqueológicas. Para lograr este objetivo se midieron con calibre digital 1317 semillas de las formas antedichas y de nueve sitios arqueológicos de Argentina y Perú. Se exploró el patrón de variación entre las mismas en tamaño y forma mediante análisis multivariado. Se identificó una tendencia general hacia la disminución de la variabilidad en forma y tamaño a lo largo del tiempo, con una primera etapa donde se mantuvieron ejemplares híbridos, generándose nuevas formas y una segunda donde se mantuvieron los rasgos de momentos previos y el aumento del tamaño de las semillas.The aim of this paper is to recognize patterns of morphometric variation –through the application of multivariate analysis for size and shape- in C. maxima seeds, which are diagnostic for current domesticated, wild and hybrid forms, in order to be applied to the identification of archaeological seeds. In order to achieve this aim, 1317 seeds were measured with digital caliber corresponding to the former forms and to nine archaeological sites from Argentina and Peru; patterns of variation among them were explored in both size and shape, employing multivariate analysis. A general trend in time towards diminution of variability in size and shape was identified with a first stage in which hybrid forms were maintained and new shapes were generated and a second stage in which features of previous moments were maintained and the size of the seeds were increased.Facultad de Ciencias Naturales y MuseoInstituto de Fisiología VegetalLaboratorio de Etnobotánica y Botánica Aplicad

Modification of characters linked to <i>Cucurbita maxima</i> domestication. Using morphometry as a tool for identification

El objetivo de este trabajo consiste en reconocer patrones de variación morfométrica –mediante la aplicación de análisis multivariado para tamaño y formaen semillas de C. maxima que sean diagnósticos para formas domesticadas, silvestres e híbridas actuales, a fin de aplicarlos a la identificación de semillas arqueológicas. Para lograr este objetivo se midieron con calibre digital 1317 semillas de las formas antedichas y de nueve sitios arqueológicos de Argentina y Perú. Se exploró el patrón de variación entre las mismas en tamaño y forma mediante análisis multivariado. Se identificó una tendencia general hacia la disminución de la variabilidad en forma y tamaño a lo largo del tiempo, con una primera etapa donde se mantuvieron ejemplares híbridos, generándose nuevas formas y una segunda donde se mantuvieron los rasgos de momentos previos y el aumento del tamaño de las semillas.The aim of this paper is to recognize patterns of morphometric variation –through the application of multivariate analysis for size and shape- in C. maxima seeds, which are diagnostic for current domesticated, wild and hybrid forms, in order to be applied to the identification of archaeological seeds. In order to achieve this aim, 1317 seeds were measured with digital caliber corresponding to the former forms and to nine archaeological sites from Argentina and Peru; patterns of variation among them were explored in both size and shape, employing multivariate analysis. A general trend in time towards diminution of variability in size and shape was identified with a first stage in which hybrid forms were maintained and new shapes were generated and a second stage in which features of previous moments were maintained and the size of the seeds were increased.Facultad de Ciencias Naturales y MuseoInstituto de Fisiología VegetalLaboratorio de Etnobotánica y Botánica Aplicad

Modification of characters linked to <i>Cucurbita maxima</i> domestication. Using morphometry as a tool for identification

El objetivo de este trabajo consiste en reconocer patrones de variación morfométrica –mediante la aplicación de análisis multivariado para tamaño y formaen semillas de C. maxima que sean diagnósticos para formas domesticadas, silvestres e híbridas actuales, a fin de aplicarlos a la identificación de semillas arqueológicas. Para lograr este objetivo se midieron con calibre digital 1317 semillas de las formas antedichas y de nueve sitios arqueológicos de Argentina y Perú. Se exploró el patrón de variación entre las mismas en tamaño y forma mediante análisis multivariado. Se identificó una tendencia general hacia la disminución de la variabilidad en forma y tamaño a lo largo del tiempo, con una primera etapa donde se mantuvieron ejemplares híbridos, generándose nuevas formas y una segunda donde se mantuvieron los rasgos de momentos previos y el aumento del tamaño de las semillas.The aim of this paper is to recognize patterns of morphometric variation –through the application of multivariate analysis for size and shape- in C. maxima seeds, which are diagnostic for current domesticated, wild and hybrid forms, in order to be applied to the identification of archaeological seeds. In order to achieve this aim, 1317 seeds were measured with digital caliber corresponding to the former forms and to nine archaeological sites from Argentina and Peru; patterns of variation among them were explored in both size and shape, employing multivariate analysis. A general trend in time towards diminution of variability in size and shape was identified with a first stage in which hybrid forms were maintained and new shapes were generated and a second stage in which features of previous moments were maintained and the size of the seeds were increased.Facultad de Ciencias Naturales y MuseoInstituto de Fisiología VegetalLaboratorio de Etnobotánica y Botánica Aplicad

Multidisciplinary studies in <i>Cucurbita maxima</i> (squash) domestication

Plant domestication is a complex process in which natural and cultural factors play important roles delimiting evolutionary pathways of plants under cultivation. In order to deal with and understand the changes generated during this process, multi-disciplinary research is required, especially when a full picture of the domestication history of a taxon is to be assessed. We present here some advances in the study of Cucurbita maxima (squash) domestication from an integrated perspective, including experimental, morphometric and archaeobotanical approaches, which are discussed in the light of new data from physiological analyses. Modern material includes plants obtained from experimental fields, derived from crosses between domesticated (C. maxima ssp. maxima) and spontaneous/wild forms (C. maxima ssp. andreana), resulting in F1 and F2 generations. The archaeobotanical material includes remains recovered from sites in southern Peru and northwest Argentina ranging in date from 3,000 to 800 bp. Morphological and anatomical analyses were conducted on seeds, pericarps and peduncles (the stem of the flower or fruit) for reconstructing squash size and shape evolution under domestication. The results suggest the presence of hybrid forms, mainly from the earlier sites, but also from more recent ones. As expected, a linear evolutionary pathway was not found. Diversity and multiple crossings seem to have been a constant in squash cultivation over time, emphasising the role of gene flows between domestic and wild variants in the domestication process. Finally, we hypothesize the possible linkage between past gene flow and different dormancy patterns as part of management practices, allowing the maintenance of squash populations adapted to different environmental conditions.Instituto de Fisiología VegetalLaboratorio de Etnobotánica y Botánica Aplicad