Erick Alejandro García Trejo | Universidad Nacional Autónoma de México (original) (raw)

Papers by Erick Alejandro García Trejo

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

Evolutionary Ecology, 2013

Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a n... more Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a natural experimental setting in which to assess the dynamics of reproductive isolation. Secondary contact zones, in particular, present a partial separation of the original divergence mechanisms and the subsequent genomic architecture of reproductive isolation (or lack thereof). The spatial context of secondary contact and its consequent effect on dispersal play vital roles on the contact's outcome. In a hybrid complex between two towhee species in Mexico, Pipilo maculatus and Pipilo ocai, two major hybrid gradients provide natural replicates for comparison. However, genetic analyses demonstrate significant divergence between geographically separate parental populations of each species and divergence of populations within each hybrid zone. The two hybrid transects (Teziutlán and Transvolcanic) are distinct and evidence suggests Electronic supplementary material The online version of this article (

... 1996), especie considerada vulnerable por BirdLife International (2000) y Collar et al. (1994... more ... 1996), especie considerada vulnerable por BirdLife International (2000) y Collar et al. (1994), y se reportan 24 especies y su sensibilidad a la intervención humana en la Laguna Media Luna (Palacio-Núñez et al. 2000). Así mismo, resaltan los trabajos de Mellink et al. ...

ACTA ZOOLÓGICA MEXICANA (N.S.)

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el ... more Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos ...

Western Birds

We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or season... more We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or seasonally noteworthy records, 10 of which are supported with specimens. Specimens collected were deposited in the ornithological collection of the Museo de Zoología "Alfonso L. Herrera," Facultad de Ciencias, Universidad National Autónoma de México, in Mexico City.

The Condor, 2009

Resumen. El grupo de especies de Melanerpes carolinus está compuesto por cinco especies morfológi... more Resumen. El grupo de especies de Melanerpes carolinus está compuesto por cinco especies morfológicamente similares cuyos límites han sido poco claros. Particularmente, la relación de M. aurifrons con el resto del grupo es incierta. Examinamos las relaciones filogenéticas de este grupo y sus parientes cercanos usando secuencias de ADN mitocondrial. Para un total de 11 especies del género Melanerpes amplificamos 872 pb que incluían fragmentos de los genes ND2, ND3, COIII, y tRNAmet. Los árboles fueron construidos a partir de las secuencias combinadas usando los métodos de máxima verosimilitud e inferencia Bayesiana. Encontramos que M. aurifrons no es monofilético y se separa en dos clados diferentes, uno que incluye a las poblaciones tropicales (M. santacruzi) y otro formado por las poblaciones norteñas, el cual es el grupo hermano de M. carolinus. La especie caribeña M. superciliaris fue el taxón hermano del clado carolinus-aurifrons. El grupo en general parece haberse diversificado en varios linajes como respuesta a varios eventos vicariantes. De acuerdo con nuestros resultados, es altamente probable que los patrones biogeográficos y de especiación del grupo carolinus estén asociados con los ciclos glaciaresinterglaciares. Nuestros resultados sugieren que es necesario realizar una actualización taxonómica del complejo.

Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a n... more Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a natural experimental setting in which to assess the dynamics of reproductive isolation. Secondary contact zones, in particular, present a partial separation of the original divergence mechanisms and the subsequent genomic architecture of reproductive isolation (or lack thereof). The spatial context of secondary contact and its consequent effect on dispersal play vital roles on the contact’s outcome. In a hybrid complex between two towhee species in Mexico, Pipilo maculatus and Pipilo ocai, two major hybrid gradients provide natural replicates for comparison. However, genetic analyses demonstrate significant divergence between geographically separate parental populations of each species and divergence of populations within each hybrid zone. The two hybrid transects (Teziutlán and Transvolcanic) are distinct and evidence suggests allelic introgression both across the species boundary and between the two transects. Habitat corridors for dispersal represent functional connectivity hotspots where the two transects meet. Both habitat connectivity and genetic differentiation between geographically disparate parental populations appear to influence the dynamics of gene flow across the hybrid gradients. In southern sympatric populations (Mt. Orizaba and Oaxaca) where morphological evidence for hybridization is scarce, opposing species’ alleles appear to traverse through the hybrid zones rather than arising from cryptic local hybridization. These results illustrate the importance of environmentally mediated gene flow in the context of secondary contact as an important force influencing evolutionary trajectory.

The Condor

The Red-bellied Woodpecker species group (Melanerpes carolinus and relatives) is composed of five... more The Red-bellied Woodpecker species group (Melanerpes carolinus and relatives) is composed of five morphologically similar species whose limits have been unclear. The relationship of the Golden-fronted Woodpecker (M. aurifrons) to the remainder of the group is particularly uncertain. We used mitochondrial DNA sequences to examine the phylogeny of this group and its close relatives. We sequenced 872 bp, including fragments of the genes for ND2, ND3, COIII, and tRNAmet, of 11 species of Melanerpes. We constructed trees from combined sequences by using the maximum likelihood and Bayesian inference approaches. We found that M. aurifrons is not monophyletic but rather consists of two clades, one comprising tropical populations (M. santacruzi), the other, consisting of northern populations, being sister to M. carolinus. The Caribbean species, M. superciliaris, is sister to the carolinus—aurifrons clade. The group as a whole appears to have diversified into multiple lineages in response to several episodes of vicariance, perhaps associated with glacial—interglacial cycles. As a result of these findings, major taxonomic changes in the group are needed.

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el ... more Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos norte y sur. Los análisis de atenuación y de PAE revelaron la existencia de tres grupos principales de áreas: uno ubicado en la sección sur, que comprende desde el este de Oaxaca hasta el sur de Chiapas; otro en la porción norte, abarcando desde el norte de Sonora hasta el norte de Nayarit y Jalisco; y un último para la porción central, desde el sur de Jalisco y el noroeste de Colima hasta el este de Oaxaca, así como la existencia de varios subgrupos al interior de estos. Palabras Clave: Biogeografía, oeste de México, avifauna, análisis de parsimonia de endemismos, regionalización.

We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or season... more We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or seasonally noteworthy records, 10 of which are supported with specimens. Specimens collected were deposited in the ornithological collection of the Museo de Zoologia "Alfonso L. Herrera," Facultad de Ciencias, Universidad National Aut6noma de M•xico, in Mexico City.

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

The current phylogenetic systematics comprises a "hard core" of fundamental concepts, t... more The current phylogenetic systematics comprises a "hard core" of fundamental concepts, together with several methods based on different optimality criteria such as parsimony, maximum likelihood and Bayesians that allow the analysis of molecular data. The resulting phylogenetic hypotheses modify the previous classifications, sometimes suggesting traditionally unthinkable relationships and, in turn, allow the analysis of different evolutionary processes and patterns. Training to understand and use these methods properly is not without its difficulties. Although the students of the second semester of the Bachelor's Degree in Biology taught at the Faculty of Sciences of the UNAM learn the rudiments of systematic phylogenetics, they have yet to explicitly incorporate molecular tools. The Bioinformatics and Molecular Systematics Practice Guide, whose coordinators kindly invited me to preface, is intended to fill this gap. In more than 50 practices, this guide allows you to le...

Evolutionary Ecology, 2013

Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a n... more Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a natural experimental setting in which to assess the dynamics of reproductive isolation. Secondary contact zones, in particular, present a partial separation of the original divergence mechanisms and the subsequent genomic architecture of reproductive isolation (or lack thereof). The spatial context of secondary contact and its consequent effect on dispersal play vital roles on the contact's outcome. In a hybrid complex between two towhee species in Mexico, Pipilo maculatus and Pipilo ocai, two major hybrid gradients provide natural replicates for comparison. However, genetic analyses demonstrate significant divergence between geographically separate parental populations of each species and divergence of populations within each hybrid zone. The two hybrid transects (Teziutlán and Transvolcanic) are distinct and evidence suggests Electronic supplementary material The online version of this article (

... 1996), especie considerada vulnerable por BirdLife International (2000) y Collar et al. (1994... more ... 1996), especie considerada vulnerable por BirdLife International (2000) y Collar et al. (1994), y se reportan 24 especies y su sensibilidad a la intervención humana en la Laguna Media Luna (Palacio-Núñez et al. 2000). Así mismo, resaltan los trabajos de Mellink et al. ...

ACTA ZOOLÓGICA MEXICANA (N.S.)

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el ... more Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos ...

Western Birds

We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or season... more We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or seasonally noteworthy records, 10 of which are supported with specimens. Specimens collected were deposited in the ornithological collection of the Museo de Zoología "Alfonso L. Herrera," Facultad de Ciencias, Universidad National Autónoma de México, in Mexico City.

The Condor, 2009

Resumen. El grupo de especies de Melanerpes carolinus está compuesto por cinco especies morfológi... more Resumen. El grupo de especies de Melanerpes carolinus está compuesto por cinco especies morfológicamente similares cuyos límites han sido poco claros. Particularmente, la relación de M. aurifrons con el resto del grupo es incierta. Examinamos las relaciones filogenéticas de este grupo y sus parientes cercanos usando secuencias de ADN mitocondrial. Para un total de 11 especies del género Melanerpes amplificamos 872 pb que incluían fragmentos de los genes ND2, ND3, COIII, y tRNAmet. Los árboles fueron construidos a partir de las secuencias combinadas usando los métodos de máxima verosimilitud e inferencia Bayesiana. Encontramos que M. aurifrons no es monofilético y se separa en dos clados diferentes, uno que incluye a las poblaciones tropicales (M. santacruzi) y otro formado por las poblaciones norteñas, el cual es el grupo hermano de M. carolinus. La especie caribeña M. superciliaris fue el taxón hermano del clado carolinus-aurifrons. El grupo en general parece haberse diversificado en varios linajes como respuesta a varios eventos vicariantes. De acuerdo con nuestros resultados, es altamente probable que los patrones biogeográficos y de especiación del grupo carolinus estén asociados con los ciclos glaciaresinterglaciares. Nuestros resultados sugieren que es necesario realizar una actualización taxonómica del complejo.

Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a n... more Hybridization can either reinforce or erode species boundaries; therefore, hybrid zones offer a natural experimental setting in which to assess the dynamics of reproductive isolation. Secondary contact zones, in particular, present a partial separation of the original divergence mechanisms and the subsequent genomic architecture of reproductive isolation (or lack thereof). The spatial context of secondary contact and its consequent effect on dispersal play vital roles on the contact’s outcome. In a hybrid complex between two towhee species in Mexico, Pipilo maculatus and Pipilo ocai, two major hybrid gradients provide natural replicates for comparison. However, genetic analyses demonstrate significant divergence between geographically separate parental populations of each species and divergence of populations within each hybrid zone. The two hybrid transects (Teziutlán and Transvolcanic) are distinct and evidence suggests allelic introgression both across the species boundary and between the two transects. Habitat corridors for dispersal represent functional connectivity hotspots where the two transects meet. Both habitat connectivity and genetic differentiation between geographically disparate parental populations appear to influence the dynamics of gene flow across the hybrid gradients. In southern sympatric populations (Mt. Orizaba and Oaxaca) where morphological evidence for hybridization is scarce, opposing species’ alleles appear to traverse through the hybrid zones rather than arising from cryptic local hybridization. These results illustrate the importance of environmentally mediated gene flow in the context of secondary contact as an important force influencing evolutionary trajectory.

The Condor

The Red-bellied Woodpecker species group (Melanerpes carolinus and relatives) is composed of five... more The Red-bellied Woodpecker species group (Melanerpes carolinus and relatives) is composed of five morphologically similar species whose limits have been unclear. The relationship of the Golden-fronted Woodpecker (M. aurifrons) to the remainder of the group is particularly uncertain. We used mitochondrial DNA sequences to examine the phylogeny of this group and its close relatives. We sequenced 872 bp, including fragments of the genes for ND2, ND3, COIII, and tRNAmet, of 11 species of Melanerpes. We constructed trees from combined sequences by using the maximum likelihood and Bayesian inference approaches. We found that M. aurifrons is not monophyletic but rather consists of two clades, one comprising tropical populations (M. santacruzi), the other, consisting of northern populations, being sister to M. carolinus. The Caribbean species, M. superciliaris, is sister to the carolinus—aurifrons clade. The group as a whole appears to have diversified into multiple lineages in response to several episodes of vicariance, perhaps associated with glacial—interglacial cycles. As a result of these findings, major taxonomic changes in the group are needed.

Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el ... more Se analizaron los patrones de riqueza y endemismo de la avifauna en el oeste de México, desde el norte de Sonora hasta el sureste de Chiapas. La región fue dividida en 24 transectos para ser usados como unidades de estudio, y los análisis desarrollados con base en registros de distribución puntual obtenidos de colecciones científicas y bibliografía y con la ayuda de un sistema de información geográfica. Para el reconocimiento de los patrones biogeográficos generales y la regionalización de la zona se utilizaron análisis de parsimonia de endemismos (PAE) y de tasas de recambio de especies, teniendo en cuenta una propuesta taxonómica alternativa para la avifauna mexicana. Se registró un total de 783 especies de aves terrestres, de las cuales 157 poseen alguna categoría de endemismo. Los datos sugieren que existe una tendencia al aumento de la riqueza de especies hacia el sur, mientras que la riqueza de endemismos es mayor hacia el centro del área de estudio y menor hacia los extremos norte y sur. Los análisis de atenuación y de PAE revelaron la existencia de tres grupos principales de áreas: uno ubicado en la sección sur, que comprende desde el este de Oaxaca hasta el sur de Chiapas; otro en la porción norte, abarcando desde el norte de Sonora hasta el norte de Nayarit y Jalisco; y un último para la porción central, desde el sur de Jalisco y el noroeste de Colima hasta el este de Oaxaca, así como la existencia de varios subgrupos al interior de estos. Palabras Clave: Biogeografía, oeste de México, avifauna, análisis de parsimonia de endemismos, regionalización.

We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or season... more We traveled to the Baja California Peninsula in April 2001, adding 11 biogeographically or seasonally noteworthy records, 10 of which are supported with specimens. Specimens collected were deposited in the ornithological collection of the Museo de Zoologia "Alfonso L. Herrera," Facultad de Ciencias, Universidad National Aut6noma de M•xico, in Mexico City.