Dulce Arias - Academia.edu (original) (raw)
Papers by Dulce Arias
Revista de Biología Tropical, 2012
The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a nat... more The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a native tree. With the aim to assess the levels of genetic variation and population structure, four wild populations of J. mexicana were studied in the Sierra de Huautla Biosphere Reserve, Morelos, Mexico. For this, DNA was extracted from 159 individuals and were amplified with six random primers using the Random Amplified Polymorphic DNA (RAPD). A total of 54 bands were obtained, of which 50 (92.6%) were polymorphic. The total genetic diversity found within the four populations was 0.451 when estimated by Shannon's index. An AMOvA analysis showed that 84% of the total genetic variation was found within populations and 16% was among populations. The UPGMA dendrogram showed that all individuals from one of the populations (Huaxtla) formed one distinct genetic group, while the rest of the individuals did not cluster according to population. A Mantel test did not show an association between genetic and geographical distances among populations (r=0.893, p=0.20). A Bayesian cluster analysis performed with STRUCTURE, showed that the most probable number of genetic groups in the data was four (K=4), and confirmed the distinctness of Huaxtla population. Our results showed that important genetic differentiation among populations can occur even at this small geographic scale and this has to be considered in conservation actions for this genetic resource.
This is an academic description of our collective visit to the Reserve of the Biosphere “Sierra d... more This is an academic description of our collective visit to the Reserve of the Biosphere “Sierra de Huautla” –REBIOSH– where we observed the rural reality with its geographic, social and cultural dimensions. The groups of women and men inhabitants of the region want to live, to work, to participate and to enjoy the development projects. The women are interested in the medicinal plants and their use to elaborate galenic products to resolve more common suffering. Before, the women did not wanted to use the furnaces that save firewood and diminish the contact with smoke, now they use the traditional tlecuil. The women feel the effects of the male migration, a common phenomenon because a lot of men have gone away to the north.
Journal of Heredity, 1994
Gandarillas H, 1969. Esterilidad genetica y citoplasmica en la quinua {Chenopodium quinoa). Turri... more Gandarillas H, 1969. Esterilidad genetica y citoplasmica en la quinua {Chenopodium quinoa). Turrialba (Costa Rica) 19:429-430. Gomez KA and Gomez AA, 1984. Statistical procedures for agricultural research. New York: Wiley.
Acta Botanica Mexicana, 1992
Novon: A Journal for Botanical Nomenclature, 2015
Abstract. A new species, Brongniartia yahualica Dorado & D. M. Arias (Fabaceae, Faboideae), e... more Abstract. A new species, Brongniartia yahualica Dorado & D. M. Arias (Fabaceae, Faboideae), endemic to a small area of the state of Jalisco (known as Altos Sur) on the border with Zacatecas, Mexico, is described and illustrated. It has an unusual floral morphology, including a long and pendant semitubular shape and the largest flowers in the genus. Its morphological affinities with B. tenuifolia Standl. are discussed, and habitat data are given.
Inventio, la génesis de la cultura universitaria en …, 2007
Theoretical and Applied Genetics, 1997
The development of transgenic plants has heightened concern about the possible escape of genetica... more The development of transgenic plants has heightened concern about the possible escape of genetically engineered material into the wild. Hybridization between crops and their wild relatives provides a mechanism by which this could occur. While hybridization has been documented between several crops and wild or weedy relatives, little is known about the persistence of cultivar genes in wild populations in the generations following hybridization. Wild and weedy sunflowers occur sympatrically with cultivated sunflowers throughout much of the cultivation range, and hybridization is known to occur. We surveyed two cultivarspecific RAPD markers in 2700 progeny in a naturally occurring population of wild Helianthus annuus over five generations following a single generation of hybridization with the cultivar. Moderate levels of gene flow were detected in the first generation (42% hybrids at the crop margin) and cultivar allele frequencies did not significantly decline over four subsequent generations. These results indicate that gene flow from cultivated into wild populations of sunflowers can result in the long-term establishment of cultivar alleles in wild populations. Furthermore, we conclude that neutral or favorable transgenes have the potential to escape and persist in wild sunflower populations.
Systematic Botany, 1991
1991] RIESEBERG ET AL.: HELIANTHUS 51 genus into four sections: Helianthus, Agrestes Schilling &a... more 1991] RIESEBERG ET AL.: HELIANTHUS 51 genus into four sections: Helianthus, Agrestes Schilling & Heiser, Ciliares Schilling & Heiser, and Divaricati Schilling & Heiser. Section He-lianthus includes 11 or 12 species that are out-crossing, self-incompatible, primarily annual, diploids with ...
Genetic Resources and Crop Evolution, 2010
Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoa... more Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this
hydra.fciencias.unam.mx
Esta publicación es el resultado principal del proyecto AP007. Se encuentra disponible para su co... more Esta publicación es el resultado principal del proyecto AP007. Se encuentra disponible para su consulta en el Centro de Documentación e Imágenes de la Conabio
Botany, 2008
Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species... more Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species in Mexico that form hybrids when they occur in mixed (sympatric) areas. In this study, we used chloroplast microsatellite haplotypes to infer phylogeographic patterns onto the genetic structure of populations of both parental species, thus defining probable colonization routes throughout Mexico. Haplotype diversity in seven hybrid zones and four allopatric sites with nonmixed (allopatric) populations of both putative parental species was analyzed. To determine the expansion and colonization routes for the two species, we carried out a nested clade phylogeographic analysis that would allow us to infer the haplotype correspondence to a phylogeographical approach. In spite of sharing many common populations, we determined that there is a different genetic historical colonization for Q. crassipes and for Q. crassifolia. Hybrid populations had the highest levels of genetic variation (Gv), Sh...
Canadian Journal of Botany, 2005
The population genetics of two hybridizing Mexican red oaks, Quercus affinis Schweid. and Quercus... more The population genetics of two hybridizing Mexican red oaks, Quercus affinis Schweid. and Quercus laurina Humb. & Bonpl., was investigated with 54 randomly amplified polymorphic DNA (RAPD) markers scored in 415 individuals from 16 populations representing the distribution area of the two species and a probable secondary hybrid zone. Genetic relationships among populations, depicted in a unweighted pair group method with arithmetic averaging (UPGMA) dendrogram, were largely incongruent with the morphological classification of populations as Q. affinis-like or Q. laurina-like that was obtained in previous studies. In contrast, the two main population clusters in the UPGMA dendrogram corresponded to the location of populations in two distinct geographical areas: southwestern and northeastern. A Mantel test confirmed a significant association between geographic and genetic distances among populations. Analyses of molecular variance (AMOVA) indicated that most genetic variation is contai...
Biotropica, 2007
Dioecy, the segregation of male and female structures among individuals, is widespread in tropica... more Dioecy, the segregation of male and female structures among individuals, is widespread in tropical plants, encompassing 10-30 percent of species in some sites. In many cases, interindividual sex separation is not complete, as individual plants, although nominally dioecious, may produce both types of reproductive structures. A common form of this sexual variation is the production of female structures in otherwise male individuals, commonly referred to as fruiting males. Here we report the existence of fruiting males in the dioecious tropical tree Jacaratia mexicana (Caricaceae). We show that fruiting males can constitute up to 45 percent of all males in some populations of a tropical forest in Southern Mexico. In order to determine the functional significance of fruiting males for the breeding system of J. mexicana, we compared the relative performance of male-and female-borne seeds. Our results show that seeds from fruiting males are three times less likely to germinate and survive than seeds from female trees. Based on relative seed fitness data, and sex ratios in natural populations, we estimate that 6-15 percent of the genes contributed by fruiting males to the next generation are transmitted via ovules, meaning that morphological variation in gender is at least partially accompanied by functional gender variation. Finally, our seed fitness estimates for fruiting males suggest that fruiting males will not replace female plants in natural populations. RESUMEN El dioicismo, la distribución de estructuras masculinas y femeninas en dos tipos de individuos, es un fenómeno ampliamente distribuido en especies tropicales, llegando a abarcar 10-30 por ciento de las especies en algunos sitios. En muchos casos la separación de los sexos entre individuos no es completa, y un mismo individuo puede producir estructuras reproductivas del sexo opuesto. Una forma común de esta variación en el género es la producción de estructuras femeninas en individuos machos, los que comúnmente se denominan machos fructíferos. En este trabajo describimos la existencia de machos fructíferos en elárbol tropical dioico Jacaratia mexicana (Caricaceae). Encontramos que los machos fructíferos pueden constituir hasta el 45 por ciento de todos losárboles macho en algunas poblaciones de un bosque tropical en el Sur de México. Con el objeto de determinar el significado funcional de los machos fructíferos de J. mexicana, comparamos el desempeño relativo de semillas originadas en individuos macho y hembra. Nuestros resultados muestran que las semillas provenientes de machos fructíferos germinan y sobreviven con una probabilidad tres veces menor que las semillas provenientes deárboles hembra. Basados en la adecuación relativa de las semillas, así como en las proporciones sexuales en poblaciones naturales, estimamos que 6-15 por ciento de los genes contribuidos por los machos fructíferos a la siguiente generación son transmitidos víaóvulos, lo que significa que al menos parte de la variación en el género a nivel morfológico es acompañada por variación a nivel funcional. Finalmente, nuestras estimaciones de la adecuación de los machos fructíferos, vía semillas, sugieren queéstos no remplazarán a las plantas femeninas en poblaciones naturales.
Western North American Naturalist, 2009
Genetic structuring at a fine scale in the russet-crowned motmot Genetic structuring at a fine sc... more Genetic structuring at a fine scale in the russet-crowned motmot Genetic structuring at a fine scale in the russet-crowned motmot ((Momotus mexicanus Momotus mexicanus) in a tropical dry forest in central Mexico) in a tropical dry forest in central Mexico
Theoretical and Applied Genetics, 1994
With the development oftransgenic crops, concern has been expressed regarding the possible escape... more With the development oftransgenic crops, concern has been expressed regarding the possible escape of genetically-engineered genes via hybridization with wild relatives. This is a potential hazard for sunflowers because wild sunflowers occur as weeds in fields where cultivated sunflowers are grown and hybridization between them has been reported. In order to quantify the potential for gene escape, two experimental stands of sunflower cultivars were planted at two sites with different rainfall and altitude profiles. Populations of wild plants were planted at different distances from each cultivar stand. An allele homozygous in the cultivar (6Pgd-3-a), but absent in the wild populations, was used as a molecular marker to document the incidence and rate of gene escape from the cultivar into the wild populations of sunflowers. Three-thousand achenes were surveyed to determine the amount of gene flow from the cultivated to the wild populations, The marginal wild populations (3 m from the cultivar) showed the highest percentage (27%) of gene flow. Gene flow was found to decrease with distance; however, gene flow occurred up to distances of 1000 m from the source population. These data suggest that physical distance alone will be unlikely to prevent gene flow between cultivated and wild populations of sunflowers.
The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a nat... more The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a native tree. With the aim to assess the levels of genetic variation and population structure, four wild populations of J. mexicana were studied in the Sierra de Huautla Biosphere Reserve, Morelos, Mexico. For this, DNA was extracted from 159 individuals and were amplified with six random primers using the Random Amplified Polymorphic DNA (RAPD). A total of 54 bands were obtained, of which 50 (92.6%) were polymorphic. The total genetic diversity found within the four populations was 0.451 when estimated by Shannon's index. An AMOvA analysis showed that 84% of the total genetic variation was found within populations and 16% was among populations. The UPGMA dendrogram showed that all individuals from one of the populations (Huaxtla) formed one distinct genetic group, while the rest of the individuals did not cluster according to population. A Mantel test did not show an association between genetic and geographical distances among populations (r=0.893, p=0.20). A Bayesian cluster analysis performed with STRUCTURE, showed that the most probable number of genetic groups in the data was four (K=4), and confirmed the distinctness of Huaxtla population. Our results showed that important genetic differentiation among populations can occur even at this small geographic scale and this has to be considered in conservation actions for this genetic resource. Rev. Biol. Trop. 60 (1): 1-10. Epub 2012 March 01.
Genetic Resources and Crop Evolution, 2010
Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoa... more Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this study we reconstruct the phylogeographical patterns in populations of J. mexicana A. DC., in order to find differences between genetic variation among wild and cultivated populations utilizing chloroplast DNA and nuclear DNA sequences. We generate a Bayesian phylogenetic tree, to estimate the divergence time between clades using calibrated mutation rates. We also infer the demographic history of these populations using neutrality tests among wild and cultivated accessions. We identified higher levels of haplotype and nucleotide diversity for the cpDNA and ITS types in wild populations than in domesticated populations. These results indicate a reduction of genetic diversity derived from human selection on domestication traits. Neutrality test suggests population expansion detected by the significant negative values of Fu’s Fs in the cultivated populations of this specie. These process results in an excess of rare polymorphism with the fixation of certain advantageous mutation throughout time, this implication are in accordance with the role of the strong selection in the fruit traits of J. mexicana. The dated phylogeny constructed with BEAST program indicated a dispersion pattern for the J. mexicana ancestors across the South Pacific and South Eastern populations during the late Pliocene. Posterior dispersion and divergence in the clades from Central Mexico and North Pacific are in agreement with the episodes of mountain-building in different regions of Mexico.
Revista de Biología Tropical, 2012
The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a nat... more The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a native tree. With the aim to assess the levels of genetic variation and population structure, four wild populations of J. mexicana were studied in the Sierra de Huautla Biosphere Reserve, Morelos, Mexico. For this, DNA was extracted from 159 individuals and were amplified with six random primers using the Random Amplified Polymorphic DNA (RAPD). A total of 54 bands were obtained, of which 50 (92.6%) were polymorphic. The total genetic diversity found within the four populations was 0.451 when estimated by Shannon's index. An AMOvA analysis showed that 84% of the total genetic variation was found within populations and 16% was among populations. The UPGMA dendrogram showed that all individuals from one of the populations (Huaxtla) formed one distinct genetic group, while the rest of the individuals did not cluster according to population. A Mantel test did not show an association between genetic and geographical distances among populations (r=0.893, p=0.20). A Bayesian cluster analysis performed with STRUCTURE, showed that the most probable number of genetic groups in the data was four (K=4), and confirmed the distinctness of Huaxtla population. Our results showed that important genetic differentiation among populations can occur even at this small geographic scale and this has to be considered in conservation actions for this genetic resource.
This is an academic description of our collective visit to the Reserve of the Biosphere “Sierra d... more This is an academic description of our collective visit to the Reserve of the Biosphere “Sierra de Huautla” –REBIOSH– where we observed the rural reality with its geographic, social and cultural dimensions. The groups of women and men inhabitants of the region want to live, to work, to participate and to enjoy the development projects. The women are interested in the medicinal plants and their use to elaborate galenic products to resolve more common suffering. Before, the women did not wanted to use the furnaces that save firewood and diminish the contact with smoke, now they use the traditional tlecuil. The women feel the effects of the male migration, a common phenomenon because a lot of men have gone away to the north.
Journal of Heredity, 1994
Gandarillas H, 1969. Esterilidad genetica y citoplasmica en la quinua {Chenopodium quinoa). Turri... more Gandarillas H, 1969. Esterilidad genetica y citoplasmica en la quinua {Chenopodium quinoa). Turrialba (Costa Rica) 19:429-430. Gomez KA and Gomez AA, 1984. Statistical procedures for agricultural research. New York: Wiley.
Acta Botanica Mexicana, 1992
Novon: A Journal for Botanical Nomenclature, 2015
Abstract. A new species, Brongniartia yahualica Dorado & D. M. Arias (Fabaceae, Faboideae), e... more Abstract. A new species, Brongniartia yahualica Dorado & D. M. Arias (Fabaceae, Faboideae), endemic to a small area of the state of Jalisco (known as Altos Sur) on the border with Zacatecas, Mexico, is described and illustrated. It has an unusual floral morphology, including a long and pendant semitubular shape and the largest flowers in the genus. Its morphological affinities with B. tenuifolia Standl. are discussed, and habitat data are given.
Inventio, la génesis de la cultura universitaria en …, 2007
Theoretical and Applied Genetics, 1997
The development of transgenic plants has heightened concern about the possible escape of genetica... more The development of transgenic plants has heightened concern about the possible escape of genetically engineered material into the wild. Hybridization between crops and their wild relatives provides a mechanism by which this could occur. While hybridization has been documented between several crops and wild or weedy relatives, little is known about the persistence of cultivar genes in wild populations in the generations following hybridization. Wild and weedy sunflowers occur sympatrically with cultivated sunflowers throughout much of the cultivation range, and hybridization is known to occur. We surveyed two cultivarspecific RAPD markers in 2700 progeny in a naturally occurring population of wild Helianthus annuus over five generations following a single generation of hybridization with the cultivar. Moderate levels of gene flow were detected in the first generation (42% hybrids at the crop margin) and cultivar allele frequencies did not significantly decline over four subsequent generations. These results indicate that gene flow from cultivated into wild populations of sunflowers can result in the long-term establishment of cultivar alleles in wild populations. Furthermore, we conclude that neutral or favorable transgenes have the potential to escape and persist in wild sunflower populations.
Systematic Botany, 1991
1991] RIESEBERG ET AL.: HELIANTHUS 51 genus into four sections: Helianthus, Agrestes Schilling &a... more 1991] RIESEBERG ET AL.: HELIANTHUS 51 genus into four sections: Helianthus, Agrestes Schilling & Heiser, Ciliares Schilling & Heiser, and Divaricati Schilling & Heiser. Section He-lianthus includes 11 or 12 species that are out-crossing, self-incompatible, primarily annual, diploids with ...
Genetic Resources and Crop Evolution, 2010
Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoa... more Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this
hydra.fciencias.unam.mx
Esta publicación es el resultado principal del proyecto AP007. Se encuentra disponible para su co... more Esta publicación es el resultado principal del proyecto AP007. Se encuentra disponible para su consulta en el Centro de Documentación e Imágenes de la Conabio
Botany, 2008
Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species... more Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species in Mexico that form hybrids when they occur in mixed (sympatric) areas. In this study, we used chloroplast microsatellite haplotypes to infer phylogeographic patterns onto the genetic structure of populations of both parental species, thus defining probable colonization routes throughout Mexico. Haplotype diversity in seven hybrid zones and four allopatric sites with nonmixed (allopatric) populations of both putative parental species was analyzed. To determine the expansion and colonization routes for the two species, we carried out a nested clade phylogeographic analysis that would allow us to infer the haplotype correspondence to a phylogeographical approach. In spite of sharing many common populations, we determined that there is a different genetic historical colonization for Q. crassipes and for Q. crassifolia. Hybrid populations had the highest levels of genetic variation (Gv), Sh...
Canadian Journal of Botany, 2005
The population genetics of two hybridizing Mexican red oaks, Quercus affinis Schweid. and Quercus... more The population genetics of two hybridizing Mexican red oaks, Quercus affinis Schweid. and Quercus laurina Humb. & Bonpl., was investigated with 54 randomly amplified polymorphic DNA (RAPD) markers scored in 415 individuals from 16 populations representing the distribution area of the two species and a probable secondary hybrid zone. Genetic relationships among populations, depicted in a unweighted pair group method with arithmetic averaging (UPGMA) dendrogram, were largely incongruent with the morphological classification of populations as Q. affinis-like or Q. laurina-like that was obtained in previous studies. In contrast, the two main population clusters in the UPGMA dendrogram corresponded to the location of populations in two distinct geographical areas: southwestern and northeastern. A Mantel test confirmed a significant association between geographic and genetic distances among populations. Analyses of molecular variance (AMOVA) indicated that most genetic variation is contai...
Biotropica, 2007
Dioecy, the segregation of male and female structures among individuals, is widespread in tropica... more Dioecy, the segregation of male and female structures among individuals, is widespread in tropical plants, encompassing 10-30 percent of species in some sites. In many cases, interindividual sex separation is not complete, as individual plants, although nominally dioecious, may produce both types of reproductive structures. A common form of this sexual variation is the production of female structures in otherwise male individuals, commonly referred to as fruiting males. Here we report the existence of fruiting males in the dioecious tropical tree Jacaratia mexicana (Caricaceae). We show that fruiting males can constitute up to 45 percent of all males in some populations of a tropical forest in Southern Mexico. In order to determine the functional significance of fruiting males for the breeding system of J. mexicana, we compared the relative performance of male-and female-borne seeds. Our results show that seeds from fruiting males are three times less likely to germinate and survive than seeds from female trees. Based on relative seed fitness data, and sex ratios in natural populations, we estimate that 6-15 percent of the genes contributed by fruiting males to the next generation are transmitted via ovules, meaning that morphological variation in gender is at least partially accompanied by functional gender variation. Finally, our seed fitness estimates for fruiting males suggest that fruiting males will not replace female plants in natural populations. RESUMEN El dioicismo, la distribución de estructuras masculinas y femeninas en dos tipos de individuos, es un fenómeno ampliamente distribuido en especies tropicales, llegando a abarcar 10-30 por ciento de las especies en algunos sitios. En muchos casos la separación de los sexos entre individuos no es completa, y un mismo individuo puede producir estructuras reproductivas del sexo opuesto. Una forma común de esta variación en el género es la producción de estructuras femeninas en individuos machos, los que comúnmente se denominan machos fructíferos. En este trabajo describimos la existencia de machos fructíferos en elárbol tropical dioico Jacaratia mexicana (Caricaceae). Encontramos que los machos fructíferos pueden constituir hasta el 45 por ciento de todos losárboles macho en algunas poblaciones de un bosque tropical en el Sur de México. Con el objeto de determinar el significado funcional de los machos fructíferos de J. mexicana, comparamos el desempeño relativo de semillas originadas en individuos macho y hembra. Nuestros resultados muestran que las semillas provenientes de machos fructíferos germinan y sobreviven con una probabilidad tres veces menor que las semillas provenientes deárboles hembra. Basados en la adecuación relativa de las semillas, así como en las proporciones sexuales en poblaciones naturales, estimamos que 6-15 por ciento de los genes contribuidos por los machos fructíferos a la siguiente generación son transmitidos víaóvulos, lo que significa que al menos parte de la variación en el género a nivel morfológico es acompañada por variación a nivel funcional. Finalmente, nuestras estimaciones de la adecuación de los machos fructíferos, vía semillas, sugieren queéstos no remplazarán a las plantas femeninas en poblaciones naturales.
Western North American Naturalist, 2009
Genetic structuring at a fine scale in the russet-crowned motmot Genetic structuring at a fine sc... more Genetic structuring at a fine scale in the russet-crowned motmot Genetic structuring at a fine scale in the russet-crowned motmot ((Momotus mexicanus Momotus mexicanus) in a tropical dry forest in central Mexico) in a tropical dry forest in central Mexico
Theoretical and Applied Genetics, 1994
With the development oftransgenic crops, concern has been expressed regarding the possible escape... more With the development oftransgenic crops, concern has been expressed regarding the possible escape of genetically-engineered genes via hybridization with wild relatives. This is a potential hazard for sunflowers because wild sunflowers occur as weeds in fields where cultivated sunflowers are grown and hybridization between them has been reported. In order to quantify the potential for gene escape, two experimental stands of sunflower cultivars were planted at two sites with different rainfall and altitude profiles. Populations of wild plants were planted at different distances from each cultivar stand. An allele homozygous in the cultivar (6Pgd-3-a), but absent in the wild populations, was used as a molecular marker to document the incidence and rate of gene escape from the cultivar into the wild populations of sunflowers. Three-thousand achenes were surveyed to determine the amount of gene flow from the cultivated to the wild populations, The marginal wild populations (3 m from the cultivar) showed the highest percentage (27%) of gene flow. Gene flow was found to decrease with distance; however, gene flow occurred up to distances of 1000 m from the source population. These data suggest that physical distance alone will be unlikely to prevent gene flow between cultivated and wild populations of sunflowers.
The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a nat... more The tropical dry forest is a greatly endangered ecosystem, from which Jacaratia mexicana is a native tree. With the aim to assess the levels of genetic variation and population structure, four wild populations of J. mexicana were studied in the Sierra de Huautla Biosphere Reserve, Morelos, Mexico. For this, DNA was extracted from 159 individuals and were amplified with six random primers using the Random Amplified Polymorphic DNA (RAPD). A total of 54 bands were obtained, of which 50 (92.6%) were polymorphic. The total genetic diversity found within the four populations was 0.451 when estimated by Shannon's index. An AMOvA analysis showed that 84% of the total genetic variation was found within populations and 16% was among populations. The UPGMA dendrogram showed that all individuals from one of the populations (Huaxtla) formed one distinct genetic group, while the rest of the individuals did not cluster according to population. A Mantel test did not show an association between genetic and geographical distances among populations (r=0.893, p=0.20). A Bayesian cluster analysis performed with STRUCTURE, showed that the most probable number of genetic groups in the data was four (K=4), and confirmed the distinctness of Huaxtla population. Our results showed that important genetic differentiation among populations can occur even at this small geographic scale and this has to be considered in conservation actions for this genetic resource. Rev. Biol. Trop. 60 (1): 1-10. Epub 2012 March 01.
Genetic Resources and Crop Evolution, 2010
Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoa... more Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this study we reconstruct the phylogeographical patterns in populations of J. mexicana A. DC., in order to find differences between genetic variation among wild and cultivated populations utilizing chloroplast DNA and nuclear DNA sequences. We generate a Bayesian phylogenetic tree, to estimate the divergence time between clades using calibrated mutation rates. We also infer the demographic history of these populations using neutrality tests among wild and cultivated accessions. We identified higher levels of haplotype and nucleotide diversity for the cpDNA and ITS types in wild populations than in domesticated populations. These results indicate a reduction of genetic diversity derived from human selection on domestication traits. Neutrality test suggests population expansion detected by the significant negative values of Fu’s Fs in the cultivated populations of this specie. These process results in an excess of rare polymorphism with the fixation of certain advantageous mutation throughout time, this implication are in accordance with the role of the strong selection in the fruit traits of J. mexicana. The dated phylogeny constructed with BEAST program indicated a dispersion pattern for the J. mexicana ancestors across the South Pacific and South Eastern populations during the late Pliocene. Posterior dispersion and divergence in the clades from Central Mexico and North Pacific are in agreement with the episodes of mountain-building in different regions of Mexico.