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The results of studies of the nature of science (NOS) as a factor that enhances students’ understanding of evolution have been inconclusive. Therefore, the main purpose of this study was to test the role of NOS instruction in enhancing students’ learning about evolution. We used a quasi-experimental design with pre- and post-tests to investigate the impact of teaching evolution with and without NOS in two classes with 15–16-year-old students, who were randomly assigned to these two classes. To measure their understanding of NOS and their acceptance and understanding of evolution, we used three different instruments that have been shown to generate reliable and valid inferences in comparable populations. The main results of this study were that, in the class in which the teaching of evolution included NOS instruction, the students’ understanding of NOS and their acceptance of evolution significantly improved. However, irrespective of the use of NOS instruction, both classes increased their understa...

Chinchilla chinchilla (Lichtenstein, 1830), a hystricomorph rodent of the family Chinchillidae, is a highland species that inhabits the Andean foothills of northern Chile and southern Bolivia, specifically the Antofagasta and Atacama regions in Chile and Potosi in Bolivia, at elevations of 3,500–5,000 m. It has a silky-soft pelage of extremely dense and long fur, the color of which is bluish, pearl, or brownish gray on the dorsum. The furry tail is covered with coarse hairs on the dorsal surface. C. chinchilla is distinguished from Lagidium and Lagotomus by its small size and differs from C. lanigera in its smaller rounded ears and a shorter tail. Although new populations were found recently, this species is considered “Critically Endangered” requiring continued protection by law and further research of its genetics and ecology.

La historia evolutiva de Homo sapiens ha sido modelada por múltiples factores sucesivos, los que son aquí revisados en el marco de teorías biológicas clásicas y modernas. Incluye adaptaciones reproductivas, metabólicas, cognitivas y sociales, que le permitieron conquistar la Tierra, proliferar en dos saltos poblacionales y modificar dramáticamente los biomas del planeta a escalas sin precedentes; emerge así una nueva época, el Antropoceno. Para explicar las causas mayores de esta odisea, describiremos algunos rasgos humanos relevantes en el marco de la teoría sintética de la evolución, sus consecuencias, y el surgimiento de diversos procesos: la revolución cognitiva, el poblamiento global, la domesticación, la tragedia de los comunes y la evolución cultural. Esta última exige un nuevo marco teórico más inclusivo: la teoría de construcción de nicho en ecología y la teoría sintética extendida, recientemente propuestas; la evolución es considerada entonces como un proceso interactivo organismo-ambiente, que incluye tanto herencias genética como no genéticas (cultural, material y ecológica). Las nuevas teorías integradoras muestran actualmente que la causa más relevante en la evolución humana ha sido la construcción sociocultural de múltiples nichos, expresados en una diversidad de culturas.

Chinchilla lanigera (Molina, 1782) y C. chinchilla (Lichtenstein, 1830): revisión de su distribución y nuevas observaciones Tanto Chinchilla chinchilla como C. lanigera estuvieron muy cerca de la extinción debido a la caza histórica y masiva de que fueron objeto, y que acabó con millones de ejemplares durante la primera parte del siglo veinte. Para determinar el rango de distribución de estas especies y localizar nuevas colonias, analizamos las publicaciones científicas, los informes técnicos, la información facilitada por personas residentes y los trampeos en vivo. Detectamos una nueva colonia silvestre de pequeño tamaño de C. lanigera en la región de Atacama, Chile. El estado de conservación de ambas especies sería de “en grave peligro de extinción”, ya que la distribución está muy fragmentada y la mayor parte de las colonias detectadas son pequeñas y están aisladas., Millions of Chinchilla chinchilla and C. lanigera were killed during the early twentieth century and they were nearly hunted to extinction. In order to establish the current range of distribution of these two wild species and to localize possible new colonies, we used the available scientific literature, technical reports, information from residents, and live trapping methods. Both species are ‘critically endangered’ since their current distribution is highly fragmented and all recognized colonies are small and isolated. We report a small new wild colony of C. lanigera in the Atacama region, Chile.

A new species of mountain viscacha, Lagidium ahuacaense, is described based on a specimen and a mitochondrial cytochrome b (cyt b) sequence obtained from a second individual from Cerro El Ahuaca, Loja Province, Ecuador. In several external and craniodental measurements, the new species differed significantly from the three congeneric species (greatest length of skull, basilar, nasal length, palatilar length, length of diastema, least interorbital breadth, breadth of rostrum and skull height). The cyt b sequence of the Ecuadorean viscacha differed by 14 exclusive nucleotide substitutions from all other sequences of Lagidium examined. Kimura 2-parameter (K2P) genetic distances of the Ecuadorean sequence were 8.1–11.0% to L. peruanum, 7.9–9.9% to L. viscacia and 9.7% to L. wolffsohni. The single known population of the newly described species may not comprise more than a few dozen individuals and warrants urgent conservation actions.

To test whether there are differences between living lineages of domestic guinea pigs Cavia porcellus, we studied 118 specimens from six breeds collected along six Andean countries as well as 15 from the wild cavy species (Cavia tschudii). The mean weight and body length of 15 adult wild cavies (295±31 g, 242±8.3 mm) were significantly smaller than 25 creole guinea pigs from Bolivia and Chile (639±157 g, 287±23.7 mm, respectively). Eighteen laboratory/pet guinea pigs (including the English Pirbright breed) were also smaller (900±173 g, 308±21 mm) than 25 improved ones from Peru (Tamborada breed, 1241±75.4 g, 317±12 mm) and Ecuador (Auqui breed, 1138±65.5 g, 307±8 mm). Similar size increases appeared in the first axis of a principal component analysis of six skeletal measurements, recovering 84% of total variation. Phylogenetic and haplotype analyses of complete cytochrome b gene sequences consistently joined all 22 domestic individuals (13 shared unambiguous substitutions, 100% bootstrap in 1000 replicates), probably from a single first ancient domestication in the western Andes. Six laboratory/pet sequences were also joined within a common branch (six shared substitutions, 96% bootstrap), probably from a documented European second phase. By contrast, those from improved Auqui joined a northern creole subgroup (one shared substitution, 84% bootstrap), and those from Nativa and improved Tamborada clustered together and with a southern creole subgroup (four shared substitutions, 86% bootstrap); this suggests at least two independent modern events during a more complex third phase, producing two improved guinea pigs selected for size and meat. Cavia tschudii sequences showed some unexpected geographic variation.

Molecular phylogenetic relationships were investigated in 6 species of Chinchillidae (Chinchilla lanigera, C. brevicaudata, Lagidium peruanum, L. viscacia, L. wolffsohni, and Lagostomus maximus), 1 species of Dinomyidae (Dinomys branickii), 1 of Abrocomidae (Abrocoma cinerea), and 1 of Octodontidae (Octodon degus) using the first 548 base pairs of the mitochondrial cytochrome-b gene. Maximum-parsimony and maximumlikelihood analyses consistently showed Chinchillidae as a robust clade and confirmed a close relationship with Dinomyidae. Both Chinchilla species differed at 22 sites, and 3 were nonsilent; average genetic distances were approximately 6%. Sequences from domestic C. lanigeraand wild C. brevicaudatashowed low levels of variation. Although all topologies obtained were congruent with current taxonomy, Lagidium exhibited large genetic distances (range 5.9‐8.9%), suggesting the existence of more than the 3 species currently recognized. Chinchillids are endemic South American rodents (Rodentia, Hystricognathi, Chinchillidae) and occur along the Andes. They include chinchillas (Chinchilla), mountain viscachas (Lagidium), and pampas viscachas (Lagostomus).

Lack of dietary iodine is associated with thyroid insufficiency and its dire consequences including cretinism, yet territories severely deficient in iodine are home to many species of wild animals. The premise of our work is that an adaptation must be in place in order to allow these animals to thrive. We collected phyllotine rodents of the genus Auliscomys from the Altiplanic region of North Chile, an area historically associated with goitre and other manifestations of iodine deficiency disorders. The iodide concentration in the stream water in this locality, at

Cavia tschudii Fitzinger, 1867 is a wild guinea pig species living in South America that according to the analysis of mitochondrial genes is the closest wild form of the domestic guinea pig. To investigate the genetic divergence between the wild and domestic species of guinea pigs from a cytogenetic perspective, we characterized and compared the C, G and AgNOR banded karyotypes of molecularly identified Cavia tschudii and Cavia porcellus Linnaeus, 1758 specimens for the first time. Both species showed 64 chromosomes of similar morphology, although C. tschudii had four medium size submetacentric pairs that were not observed in the C. porcellus karyotype. Differences in the C bands size and the mean number of AgNOR bands between the karyotypes of the two species were detected. Most of the two species chromosomes showed total G band correspondence, suggesting that they probably represent large syntenic blocks conserved over time. Partial G band correspondence detected among the four submetacentric chromosomes present only in the C. tschudii karyotype and their subtelocentric homologues in C. porcellus may be explained by the occurrence of four pericentric inversions that probably emerged and were fixed in the C. tschudii populations under domestication. The role of the chromosomal and genomic differences in the divergence of these two Cavia species is discussed.

La tribu Phyllotini es un grupo avanzado de 46 especies endémicas entre los Muridae de América del Sur que, estando adaptado a sus ambientes xéricos, parece haber tenido el Altiplano Sur como área de diferenciación original (Reig 1986). Esta hipótesis es puesta a prueba examinando la distribución geográfica y los datos citogenéticos de 35 especies, incluyendo la descripción de bandas G de Andinomys edax y Euneomys chinchilloides y su comparación con Phyllotis, bandas AgNOR y FISH para ADNr en siete especies, así como datos de electroforesis de proteínas (118 electroalelos en 12 especies) y de secuencias del gen para citocromo b en el ADNmt (407 pb en 14 especies). Todos los cariotipos resultaron cromosómicamente distintos, excepto dos en los que no se contó con bandas G. Se encontró una asociación general entre distribución altiplánica de las especies con estados de caracteres ancestrales (cromosomas telocéntricos, 2n altos, posiciones basales en las filogenias basadas en proteínas y secuencias de citocromo b), así como entre distribución no altiplánica y estados derivados. Se documentan aquí distintas combinaciones de brazos cromosómicos tipo Andinomys que se fusionarían para formar cromosomas metacéntricos en Euneomys y Phyllotis, y también una disminución del número de NORes estructurales en Auliscomys respecto de Loxodontomys, rasgos derivados que demuestran una diversificación hacia el sur y otra hacia el norte respectivamente, desde un centro en el Altiplano SurThe tribe Phyllotini is an advanced group of 46 endemic species among the Muridae of South America, that being adapted to its xeric environments, seems to have the Southern Altiplano as its original differentiation area (Reig 1986). This hypothesis is tested by examining the geographic distributions and cytogenetic data from 35 species, including the Andinomys edax and Euneomys chichilloides G band descriptions, its comparison with Phyllotis, AgNOR bands and rDNA FISH in seven species, as well as protein electrophoresis data (118 electro-alleles in 12 species) and cytochrome b gen sequences in the mtDNA (407 bp in 14 species). All karyotypes were chromosomically different, except in two cases with unknown G bands. A general association between altiplanic distribution of species with ancestral character states (telocentric chromosomes, high 2n, basal positions in phylogenies based on protein and cytochrome b gene sequences) was found, as well as between non-altiplanic distribution with derived states. Different combinations of Andinomys-like chromosomal arms that would have suffered centric fusions to form the metacentric chromosomes of Euneomys and Phyllotis, respectively, are documented here, and also a reduction of the number of structural NOR in Auliscomys compared to Loxodontomys, all derived features showing a diversification to the south and another to the north respectively, from a center in the southern Altiplano

To identify and characterize chilean samples of Trypanosoma cruzi and their association with hosts, the first 516 bp of the mitochondrial cytochrome b gene were sequenced from eight biological samples, and phylogenetically compared with other known 20 American sequences. The molecular characterization of these 28 sequences in a maximum likelihood phylogram (−ln L = 1255.12, tree length = 180, consistency index = 0.79) allowed the robust identification (bootstrap % >99) of three previously known discrete typing units (DTU): DTU IIb, IIa, and I. An apparently undescribed new sequence found in four new chilean samples was detected and designated as DTU Ib; they were separated by 24.7 differences, but robustly related (bootstrap % = 97 in 500 replicates) to those of DTU I by sharing 12 substitutions, among which four were nonsynonymous ones. Such new DTU Ib was also robust (bootstrap % = 100), and characterized by 10 unambiguous substitutions, with a single nonsynonymous G to T change at site 409. The fact that two of such new sequences were found in parasites from a chilean endemic caviomorph rodent, Octodon degus, and that they were closely related to the ancient DTU I suggested old origins and a long association to caviomorph hosts.

To investigate the phylogenetic relationships of living marsupials, morphometric and G-banded chromosome analyses were made in the Chilean species Dromiciops gliroides (Microbiotheria) and Thylamys elegans (Didelphimorphia). Chromosome arm lengths and patterns of G-bands were compared in at least eight bone marrow metaphase spreads in six and nine specimens, respectively. They were contrasted with those published for another 11 American and Australian genera. Three of six autosomal pairs (A1, A3, and C2) were uniquely shared by Dromiciops and some Australian species, being different in shape and G-banded patterns from those with similar total sizes in Thylamys and other South American didelphoid karyotypes. Such chromosomal correspondences suggest the past occurrence of at least three pericentric inversions. A table of character states constructed from chromosomal G-band comparisons is presented, showing that cytogenetic data agree with Szalay's (1982) hypothesis on the affinities of the South American Dromiciops with Australian marsupials.

Morphological variation in the glans penis of the six genera and most species of octodontid rodents was studied and compared to members of the Abrocomidae and Ctenomyidae. Most specimens of Octodon degus, O. lunatus, O. bridgesi, Octodontomys gliroides, Aconaemys fuscus , and A. sagei presented two spikes on each side at the bottom of the intromitent sac (2–2 pattern), although the number of spikes varies from 1–2 to 4–5. The largest variability in number of spikes was shown by Spalacopus cyanus , ranging from 1–1 to 4–5; although they were rather short. The 1–1 pattern characterized Tympanoctomys barrerae and Octomys mimax . This pattern was found in the species of the genera Abrocoma and Ctenomys , which belong to the related families Abrocomidae and Ctenomyidae. Our results support the view that the 1–1 pattern is ancestral and that other patterns are derived states. Within the octodontids, only Tympanoctomys barrerae and Octomys mimax showed the ancestral condition shared with Ctenomyidae and Abrocomidae. All other octodontid genera share the derived state 2–2 or modifications of it.

Two penile types, simple and complex, seem to distinguish North and South American cricetids; their origins were investigated by study of dissected and stained glans of 101 adult and young specimens. A simple penis with only a proximal baculum was found in Abrothrix longipilis and A. sanborni from Chile. In the North American Peromyscus eremicus , juvenile males displayed three small and transient pieces of cartilaginous tissues exactly where those of the complex penis are located. It is suggested that simplification of the baculum was produced independently in the two New World groups. A. longipilis also showed elongation of the glans, probably inducing the formation of a ventral cleft, os bending, and regression of the distal baculum and lateral sacs; strikingly, its proximal baculum ossified late, when third molars erupted. Since ossification and distal bacular differentiation in muroids usually are induced by testosterone much earlier, and testosterone-dependent glands also have been modified in simple-penis species, such delay might be a mechanism inducing elongation, with simplification a secondary heterochronic effect.

Guanacos (Lama guanicoe) are the most important native herbivorous species in the South American steppes and the dominant ungulate in a fauna rich in rodents but poor in large mammal species. Between 2 and 4 subspecies are usually recognized within Lama guanicoe, based on subtle morphological differences and geographic distribution. To evaluate whether molecular variation is consistent with the latter hypotheses, we analyzed the complete cytochrome-b and partial control region mitochondrial DNA sequences of L. guanicoe from 22 localities in Peru, Bolivia, Argentina, and Chile. Sequence analyses of both genes support the monophyly of the species but failed to distinguish the occurrence of subspecies along the geographic range. Despite that, the northernmost populations (Peru and northern Chile) showed some degree of genetic differentiation with respect to southern representatives from Argentina, Bolivia, and rest of Chile. Analysis of genetic diversity also showed a strong signal of past low population size and a recent population expansion.

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275,000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22 degrees S) dry Andes 14-12,000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29 degrees S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts.

Evolutionary Medicine is an emergent basic science that offers new and varied perspectives to the comprehension of human health. The application of classic evolutionary theories (descent with modification, and natural selection) to the human organism, to its pathogens, and their mutual co-evolution, provides new explanations about why we get sick, how we can prevent this, and how we can heal. Medicine has focused mainly on the proximate or immediate causes of diseases and the treatment of symptoms, and very little on its evolutionary or mediate causes. For instance, the present human genome and phenotypes are essentially paleolithic ones: they are not adapted to modern life style, thus favoring the so-called diseases of civilization (ie: ateroesclerosis, senescence, myopia, phobias, panic attacks, stress, reproductive cancers). With the evolutionary approach, post-modern medicine is detecting better the vulnerabilities, restrictions, biases, adaptations and maladaptations of human body, its actual diseases, and its preventions.

Phylogeographic relationships were evaluated at the intraspecific level using nucleotide sequence data from the mitochondrial cytochrome b gene of representative specimens of ‘‘colilargo’’ (Oligoryzomys longicaudatus) from 31 localities, along its distributional range over a large part of the western Andes and southern Argentina. Based on approximately 1,000 base pairs (bp), we recognized a single species on both the Chilean and the Argentinean side as far as at least latitude 518S, rejecting the subspecific distinctiveness of longicaudatus and philippi. We thus placed the latter in full synonymy with O. longicaudatus as earlier studies proposed, and enlarged its range as far as Torres del Paine, about 518S. The occurrence of subspecies in this range is doubtful given the low sequence divergence values and the absence of significant associations between haplotypes and their geography. Additionally, we hypothesized that the entrance of this species into the Chilean side of the Andes mountains occurred through the Patagonian forests of southern Argentina, with further dispersal to the north from the south.b gene of representative specimens of ‘‘colilargo’’ (Oligoryzomys longicaudatus) from 31 localities, along its distributional range over a large part of the western Andes and southern Argentina. Based on approximately 1,000 base pairs (bp), we recognized a single species on both the Chilean and the Argentinean side as far as at least latitude 518S, rejecting the subspecific distinctiveness of longicaudatus and philippi. We thus placed the latter in full synonymy with O. longicaudatus as earlier studies proposed, and enlarged its range as far as Torres del Paine, about 518S. The occurrence of subspecies in this range is doubtful given the low sequence divergence values and the absence of significant associations between haplotypes and their geography. Additionally, we hypothesized that the entrance of this species into the Chilean side of the Andes mountains occurred through the Patagonian forests of southern Argentina, with further dispersal to the north from the south. Fil: Palma, R. Eduardo. Pontificia Universidad Católica de Chile; Chile Fil: Rivera Milla, Eric. University of Konstanz; Alemania Fil: Salazar Bravo, Jorge. Texas Tech University; Estados Unidos Fil: Torres Pérez, Fernando. Pontificia Universidad Católica de Chile; Chile Fil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina Fil: Marquet Iturriaga, Pablo Angel. Pontificia Universidad Católica de Chile; Chile Fil: Spotorno, Angel E.. Universidad de Chile; Chile Fil: Meynard, Andrés P.. Pontificia Universidad Católica de Chile; Chile Fil: Yates, Terry L.. University of New Mexico; Estados Unidos

Para investigar el origen y la divergencia de los cuyes domesticos Cavia porcellus (Linnaeus, 1758; Rodentia, Caviidae), secuenciamos el gen mitocondrial para citocromo b de 12 especimenes domesticos y 10 silvestres de seis especies, incluyendo las dos que se presumen como ancestro de la domestica: C. tschudii y C. aperea. Todos los analisis de maxima parsimonia y maxima verosimilitud agruparon a C. porcellus con C. tschudii (promedio de distancias K2P = 3,2 %); los mejores arboles tenian 609 pasos (CI = 0,796; Indice de Apoyo de Bremer (SI) = 28), y un _Ln = 4.419,52; con apoyos de remuestreo de 100 % y 97 % respectivamente. Dicho clado tambien aparecio en el analisis cladistico de los aminoacidos correspondientes, apoyado por tres sustituciones y 96 % remuestreo. Cuando el nodo de C. aperea fue forzado a unirse al de C. porcellus, estos arboles fueron consistentemente mas largos, menos probables y robustos, y con menos caracteres definitorios que el optimo. Todas las secuencias de C. porcellus se agruparon tambien en un nodo definido por 15 sustituciones. El subnodo con animales de mercados de ciudad, tiendas de mascota y laboratorios se caracterizo por cuatro sustituciones (una no silenciosa, SI = 7 y 91 % remuestreo). Los C. porcellus sudamericanos, llamados "criollos" por los criadores locales, son mas diversos. Probablemente, un clado del sur del Peru y Chile representa un linaje precolombino. La distancia K2P promedio entre C. tschudii y aperea fue mas bien grande, 7,7 %. Cavia aparecio como un nodo robusto (100 % remuestreo). Estos resultados indican que C. tschudii es la especie mas cercanamente relacionada a C. porcellus.

The complete mitochondrial (mt) genomes of five marsupial species have been sequenced. The species represent all three South American orders (Didelphimorphia, Paucituberculata, and Microbiotheria). Phylogenetic analysis of this data set indicates that Didelphimorphia is a basal marsupial lineage followed by Paucituberculata. The South American microbiotherid Dromiciops gliroides (monito del monte) groups with Australian marsupials, suggesting a marsupial colonization of Australia on two occasions or, alternatively, a migration of an Australian marsupial lineage to South America. Molecular estimates suggest that the deepest marsupial divergences took place 64-62 million years before present (MYBP), implying that the radiation of recent marsupials took place after the K/T (Cretaceous/Tertiary) boundary. The South American marsupial lineages are all characterized by a putatively non-functional tRNA for lysine, a potential RNA editing of the tRNA for asparagine, and a rearrangement of tRNA genes at the origin of light strand replication.

Se describe una nueva especie de lagartija del norte de Chile, perteneciente al genero Liolaemus y adscrita al grupo montanus. Los ejemplares de la nueva especie fueron capturados en febrero de 1999 en los Farellones de Tara, Provincia del Loa, Region de Antofagasta. Esta difiere de las especies del subgrupo boulengeri en que carece de un parche de escamas alargadas en la parte femoral de la extremidad posterior. Difiere de las demas especies del grupo montanus por presentar un gran numero de escamas pequenas, lisas y redondeadas en la zona dorsal del cuerpo, y escamas cefalicas distintivas. De las especies con patron de escamacion similar, la nueva especie puede ser diferenciada por su moderado tamano, cola mas corta que la longitud cabeza-cloaca y patron de coloracion distintivo. Es de habitos psammofilos y se encuentra sobre los 4.000 m de altura. Se amplificaron y secuenciaron 1.775 pb de los genes mitocondriales ND1, ND2 y COI del holotipo, alotipo y un paratipo de la nueva especie. Fueron comparadas con dieciseis especies del genero Liolaemus, cuatro de ellas del grupo chiliensis y doce del grupo montanus. Ademas fue usado como grupo externo un ejemplar del genero Phymaturus. Las secuencias fueron alineadas y analizadas en los programas Clustal W, Mac Clade, PAUP y MEGA2. El numero de sitios variables filogeneticamente informativos fue de 453. La divergencia genetica de la nueva especie con las congenericas del grupo chiliensis fue entre 0,1780 y 0,1985 unidades K2P, mientras que con las especies del grupo montanus fue de 0,0676 y 0,0857 unidades K2P. Con respecto al analisis de Maxima Parsimonia, se detecto el arbol mas corto con 1.682 pasos y con un Indice de Consistencia de 0,68, con una topologia basicamente similar a la obtenida en Maxima Verosimilitud y Distancia. El analisis de componentes principales permite diferenciar a la nueva especie de otras seis del grupo montanus, principalmente por las medidas corporales, las que explican mas del 84 % de la varianza. Tanto el analisis morfologico como los datos moleculares muestran claramente que esta es una nueva especie

La tribu Phyllotini es un grupo avanzado de 46 especies endémicas entre los Muridae de América del Sur que, estando adaptado a sus ambientes xéricos, parece haber tenido el Altiplano Sur como área de diferenciación original (Reig 1986). Esta hipótesis es puesta a prueba examinando la distribución geográfica y los datos citogenéticos de 35 especies, incluyendo la descripción de bandas G de Andinomys edax y Euneomys chinchilloides y su comparación con Phyllotis, bandas AgNOR y FISH para ADNr en siete especies, así como datos de electroforesis de proteínas (118 electroalelos en 12 especies) y de secuencias del gen para citocromo b en el ADNmt (407 pb en 14 especies). Todos los cariotipos resultaron cromosómicamente distintos, excepto dos en los que no se contó con bandas G. Se encontró una asociación general entre distribución altiplánica de las especies con estados de caracteres ancestrales (cromosomas telocéntricos, 2n altos, posiciones basales en las filogenias basadas en proteínas y secuencias de citocromo b), así como entre distribución no altiplánica y estados derivados. Se documentan aquí distintas combinaciones de brazos cromosómicos tipo Andinomys que se fusionarían para formar cromosomas metacéntricos en Euneomys y Phyllotis, y también una disminución del número de NORes estructurales en Auliscomys respecto de Loxodontomys, rasgos derivados que demuestran una diversificación hacia el sur y otra hacia el norte respectivamente, desde un centro en el Altiplano Sur The tribe Phyllotini is an advanced group of 46 endemic species among the Muridae of South America, that being adapted to its xeric environments, seems to have the Southern Altiplano as its original differentiation area (Reig 1986). This hypothesis is tested by examining the geographic distributions and cytogenetic data from 35 species, including the Andinomys edax and Euneomys chichilloides G band descriptions, its comparison with Phyllotis, AgNOR bands and rDNA FISH in seven species, as well as protein electrophoresis data (118 electro-alleles in 12 species) and cytochrome b gen sequences in the mtDNA (407 bp in 14 species). All karyotypes were chromosomically different, except in two cases with unknown G bands. A general association between altiplanic distribution of species with ancestral character states (telocentric chromosomes, high 2n, basal positions in phylogenies based on protein and cytochrome b gene sequences) was found, as well as between non-altiplanic distribution with derived states. Different combinations of Andinomys-like chromosomal arms that would have suffered centric fusions to form the metacentric chromosomes of Euneomys and Phyllotis, respectively, are documented here, and also a reduction of the number of structural NOR in Auliscomys compared to Loxodontomys, all derived features showing a diversification to the south and another to the north respectively, from a center in the southern Altiplano

Es revisada la biologia basica de los roedores potencialmente reservorios de hantavirus en Chile. La taxonomia y sistematica de cinco especies de roedores Muridae endemicos, el orizomino Oligoryzomys longicaudatus (reservorio primario), los akodontinos Abrothrix longipilis y Abrothrix olivaceus, y los filotinos Loxodontomys micropus y Phyllotis darwini, son puestas al dia con recientes modificaciones, asi como sus caracteres externos, distribucion geografica, habitat, etologia, alimentacion, ecologia y reproduccion. Especial atencion se da a las relaciones filogeneticas entre especies de roedores sus grupos, asi como con aquellas correspondientes a sus hantavirus huespedes, Una asociacion entre la evolucion de ambos grupos parece emerger, sugiriendo co-evolucion entre las especies de roedores virus. Esta importante hipotesis deberia ser puesta a prueba. Son discutidas otras relaciones entre especies de roedores y sus huespedes virales

Tympanoctomys barrerae, a desert specialist member of the family Octodontidae, until now thought to be conservative, and ancestral to South American hystricognath rodents, presents the highest diploid chromosome number (2n = 102) known in a mammal. Unexpectedly, its karyotype was found to be composed mainly of metacentric to sub-metacentric chromosomes. Mechanisms by which such a karyotype may have been derived are discussed.

The various rises of the Andes from Miocene to Pleistocene times have isolated a substantial portion of the South American continent, producing conditions that resulted in the emergence of two new high altitude life zones: the northern Paramos and the southern altiplano. We examine here the conditions prevailing in the altiplano now, and how they can be related to the present distributional patterns of its flora and fauna. We also describe how such conditions might have influenced the development of permanent human settlements, particularly through the emergence of agriculture and the domestication of the region’s animals, either as beasts of burden, or sources of food, or both.

Phyllotis darwini vaccarum and Phyllotis darwini darwini live contiguously in Central Chile, the former in the high Andes and the latter in the Central Valley and on the coast. All individuals examined of both kinds had 38 chromosomes of similar shape, but P. d. vaccarum always showed large paracentromeric C-bands on all chromosomes, whereas P. d. darwini showed none or only small ones. Fifty-six pairings between the two forms were made in the laboratory. They resulted in 23 hybrids produced by four P. d. vaccarum females and four P. d. darwini females. A higher incidence of aggression and mortality was observed in the cross-pairings, as well as a lower incidence of birth (14.3%), and a lower mean litter size (2.9), in comparison with 117 pairings within forms (65.0% and 4.2%, respectively). C-banded hybrid metaphases showed 19 chromosomes with large paracentromeric C-bands and 19 with none or only small ones. In the G-banded hybrid karyotypes, it was possible to identify eight chromosome pairs with total correspondence of band patterns, five pairs with correspondence only at their long arms, and 10 autosomes and the X chromosomes with no correspondence at all. Hybrids were completely sterile; adults had incomplete germinal lines and a lack of differentiated gametes in their gonads. These results, and the presence of individuals of both chromosomal forms in the same trap line with no traces of mixing, provide strong evidence of complete genetic isolation of the two forms; that is, they should be considered as separate species. Further considerations suggest the existence of gene flow between vaccarum and the other Andean forms living in northern Chile, and probably with those from southern Chile; the oldest species-group name available for all of these is xanthopygus .

A new subspecies of Agastopsylla nylota is described from Chile. The other 4 taxa belonging to this genus are briefly discussed, and a revised key to both sexes, where these are known, is presented.