Background and aims: Acacia furcatispina belongs to the subgenus Aculeiferum. Currently, there are no studies in population genetics in this species. The aim of this work was to investigate the genetic diversity, population structure and spatial genetic structure at fne scale (SGS) in Argentinean sample sites by means of molecular markers. Materials and Metods: Two sample sites of A. furcatispina were studied with the AFLP technique. Three primer combinations were selected for this study. Results: The three primer combinations revealed a total of 121 AFLP bands. The percentage of polymorphic loci showed a mean value of 86.8 % and the mean heterozygocity was 0.33. The Bayesian analysis performed with software STRUCTURE detected three clusters (K= 3), corresponding one to Pasaje Pozo Zuni (PP) sample site and two for Cerro de la Gloria (CG) sample site, showing a subdivision of this last one (CG1 and CG2). The AMOVA showed that the great component of variability was represented within populations. The SGS detected significant structuration at short and middle distances in PP. Conclusions: Based on the results of the present work, we recommend to sample trees far apart 10 m to minimize the kinship between individuals. These results present the frst study in genetic diversity, population structure and spatial genetic structure at fne scale in A. furcatispina and all the analyses made here result of interest for management and conservation of this species.

Introduccion y objetivos: Acacia furcatispina, pertenece al subgénero Aculeiferum. Actualmente no hay estudios sobre la diversidad y estructura genética de esta especie. El objetivo de este trabajo fue estudiar la diversidad genética, estructura poblacional, y la estructura genética espacial a escala fna (SGS) en localidades argentinas de esta especie. Materiales y metodos: Se estudiaron dos localidades de la especie A. furcatispina mediante la técnica de AFLP. Se seleccionaron 3 combinaciones de cebadores. resultados: Con las combinaciones de cebadores seleccionadas, se revelaron un total de 121 bandas. El porcentaje de loci polimórficos presentó un valor medio de 86,8 % y la heterocigosis 0,33. El análisis bayesiano STRUCTURE mostró que los individuos analizados pertenecen a tres grupos genéticos (K= 3), uno correspondiente a la localidad Pasaje Pozo Zuni (PP) y dos, a Cerro de la Gloria (CG), subdividida en dos poblaciones (CG1 y CG2). El AMOVA indicó que la mayor parte de la variabilidad se encuentra contenida dentro de las poblaciones. El análisis SGS detectó estructuración local significativa a cortas y medianas distancias en la población PP. conclusiones: Basado en los resultados del presente trabajo, se recomienda muestrear árboles a más de 10 metros de distancia para minimizar el parentesco entre individuos. Estos resultados proveen el primer estudio acerca de la diversidad, estructura genética y estructura a escala espacial fna de Acacia furcatispina y todos los análisis realizados resultan de interés para el manejo y conservación de esta especie.

Bayesian clustering as implemented in STRUCTURE or GENELAND software is widely used to form genetic groups of populations or individuals. On the other hand, in order to satisfy the need for less computer-intensive approaches, multivariate analyses are specifically devoted to extracting information from large datasets. In this paper, we report the use of a dataset of AFLP markers belonging to 15 sampling sites of Acacia caven for studying the genetic structure and comparing the consistency of three methods: STRUCTURE, GENELAND and DAPC. Of these methods, DAPC was the fastest one and showed accuracy in inferring the K number of populations (K = 12 using the find.clusters option and K = 15 with a priori information of populations). GENELAND in turn, provides information on the area of membership probabilities for individuals or populations in the space, when coordinates are specified (K = 12). STRUCTURE also inferred the number of K populations and the membership probabilities of individuals based on ancestry, presenting the result K = 11 without prior information of populations and K = 15 using the LOCPRIOR option. Finally, in this work all three methods showed high consistency in estimating the population structure, inferring similar numbers of populations and the membership probabilities of individuals to each group, with a high correlation between each other.

Técnicas de análise por alozimas e DNA polimórfico aleatoriamente amplificado (RAPD) foram comparadas quanto a sua utilidade para estudos genéticos e taxonômicos em populações de Prosopis glandulosa e P. velutina. Isozimas e RAPD deram estimativas igualmente elevadas de variabilidade genética. A estrutura genética e a diferenciação foram analisadas pelo índice F DT não hierárquico de Wright (1978). Para todas as populações consideradas, ambos os marcadores produziram estimativas baixas do fluxo de genes (Nm < 1). Quando apenas as populações de P. glandulosa foram analisadas, os dados de isozima deram estimativas do fluxo gênico mais elevadas (Nm > 1), em concordância com o esperado para populações co-específicas. Contudo, com os dados de RAPD a redução esperada em F DT e o aumento em Nm não foram observados. A correlação entre F DT e as matrizes de distância geográfica (teste de Mantel) para todas as populações foi significante (P = 0,02) quando baseada em isozimas, mas não tanto (P = 0,33) quando baseada em RAPD. Não foram observadas associações significantes entre variáveis genéticas e geográficas ou climáticas. Dois sistemas isoenzimáticos (GOT e PRX) possibilitaram a distinção entre P. glandulosa e P. velutina, mas não foram detectadas por RAPD bandas diagnósticas para o reconhecimento de populações ou espécies aqui estudadas. Contudo, os marcadores de RAPD mostraram valores mais elevados para a diferenciação genética entre populações co-específicas de P. glandulosa e um coeficiente de variação menor do que aqueles obtidos a partir de isozimas.

Allozyme and random amplified polymorphic DNA (RAPD) techniques have been compared for their usefulness for genetic and taxonomic studies in Prosopis glandulosa and P. velutina populations. Isozymes and RAPDs yielded similarly high estimates of genetic variability. Genetic structure and differentiation were analyzed through non-hierarchical Wright's F DT. For all populations considered, both markers produced low gene flow (Nm < 1) estimates. When only P. glandulosa populations were analyzed, isozyme data yielded higher gene flow estimates (Nm > 1), in agreement with that expected for conspecific populations. However, in RAPD data the expected reduction in F DT and the increase in Nm were not observed. Correlation between F DT and geographical distance matrices (Mantel test) for all populations was significant (P = 0.02) when based on isozymes, but not so (P = 0.33) when based on RAPDs. No significant associations among genetic and geographical or climatic variables were observed. Two isoenzyme systems (GOT and PRX) enabled us to distinguish between P. glandulosa and P. velutina, but no diagnostic band for recognition of populations or species studied here were detected by RAPD. However, RAPD markers showed higher values for genetic differentiation among conspecific populations of P. glandulosa and a lower coefficient of variation than those obtained from isozymes.

The way in which genetic variability is distributed within and among populations depends on different factors, outstanding among these are the reproductive system and the adaptive strategy. Population structure, in turn, imposses restrictions to those evolutionary processes tending to a growing adaptation to the environment and/or specific differentiation. Studies on population structure were made for the Prosopis genus and the genetic differentiation was analyzed for 15 species of Algarobia, Strombocarpa and Monilicarpa Sections using isoenzyme techniques, RAPD, RFLP and DNA sequenciation. The linkage system was analyzed in 7 species of the Algarobia Section from data obtained from isoenzyme electrophoresis, which showed that although these species are mostly exogamous they can reach up to 28% of self-fecundation, with an average of 19%. This behaviour and the limited capacity for pollen and seed dispersal determine an excess of homozygotes in the populations. Except for P. kuntzei, Algarobia species are closely related, independently of their ploidy level and geographical distribution, and are not grouped according to series. Species in the Strombocarpa Section exhibit much lower variability than those in Algarobia. P. argentina (Monilicarpa Section) is the most distinctly differentiated of the species studied to date. Natural hybridation is frequent among species of the Algarobia Section. This phenomenon and the great similarity among these species make their recognition difficult. The results obtained using RFLP techniques in mitocondria and cloroplasts confirm the great affinity among Algarobia species, and provide evidence that they would have a common origin.

La forma en que se distribuye la variabilidad genética dentro y entre poblaciones depende de diferentes factores entre los que se puede mencionar el sistema reproductivo y la estrategia adaptativa. La estructura de las poblaciones, a su vez, establece restricciones a los procesos evolutivos tendientes a la adaptación creciente al ambiente y/o la diferenciación específica. Los marcadores bioquímicos y moleculares constituyen herramientas para evaluar la proporción de la diversidad genética en entidades de complejidad creciente. Esta información permite hacer inferencias acerca de los mecanismos evolutivos que podrían haber conducido al escenario actual. En el género Prosopis se realizaron estudios de estructura poblacional y se analizó la diferenciación genética en 15 especies de la Sección Algarobia, Strombocarpa y Monilicarpa utilizando las técnicas de isoenzimas, RAPD, RFLP y Secuenciación de ADN. En siete especies de la sección Algarobia se analizó, a partir de datos provenientes de electroforesis de isoenzimas, el sistema de apareamiento, pudiendo demostrarse que aunque éstas son mayormente exógamas, pueden presentar hasta un 28% de autofecundación, con un promedio del 19%. La variabilidad genética en especies de Algarobia es alta, pero tiende a ocurrir dentro de las poblaciones. Por esta razón con muestras de pocas poblaciones se cubre la mayor parte de la variación genética detectada por isoenzimas y por la técnica de RAPD. Con excepción de P. kuntzei, las especies de Algarobia son muy afines entre sí independientemente de su nivel de ploidía y distribución geográfica y las mismas no se agrupan de acuerdo con las series. En las especies estudiadas de la sección Strombocarpa la variabilidad es mucho menor que en Algarobia. Estas especies se diferencian mucho entre sí y se separan claramente de las de Algarobia. Finalmente P. argentina (secc. Monilicarpa) es la especie más diferenciada de las estudiadas hasta el presente. La hibridación natural es un hecho frecuente entre especies de la sección Algarobia. La técnica de RAPD ha permitido obtener bandas marcadoras de especie que podrían utilizarse para inferir los progenitores putativos de híbridos naturales. Finalmente los resultados obtenidos por las técnicas de RFLP de mitocondrias y cloroplastos, así como la de secuenciación de un fragmento de este último plástido han permitido estudios cladísticos que confirman la alta afinidad entre especies de Algarobia y brindan evidencias de que las mismas tendrían un origen común.