Vertebrate invaders and their ecological impacts in Chile

The South American country of Chile has been subjected to relatively few invasions in historic times. In comparison to the ca 610 vertebrate species found in continental Chile, only 24 species (3.9%) have invaded the country. Except for two bird and two or three mammal species that expanded their range and crossed the Andean Ranges from Argentina, the remaining 20 species were all introduced, or aided, by humans. Of the 24 invader species that currently occur in Chile, 11 (46%) were first introduced in central Chile, two (8%) in the northern part of the country, nine (38%) in the southern part, and two (8%) in Juan Fernández Archipelago. For ten (42%) of those species there is no information about their effects on the native flora, vegetation, or fauna. For eight species (33%), the information regarding the effects of the invaders is anecdotal. For six species (25%), there is adequate quantitative documentation available on their effects. Of a total of seven convincingly repo rted cases, two involve positive effects (increase in the prey base for native predators) and five have negative effects, of which three are on native vegetation and the remaining two on native fauna.     

Non-random co-occurrence of native and exotic plant species in Mediterranean grasslands

Invasion by exotic species in Mediterranean grasslands has determined assembly patterns of native and introduced species, knowledge of which provides information on the ecological processes underlying these novel communities. We considered grasslands from Spain and Chile. For each country we considered the whole grassland community and we split species into two subsets: in Chile, species were classified as natives or colonizers (i.e. exotics); in Spain, species were classified as exclusives (present in Spain but not in Chile) or colonizers (Spanish natives and exotics into Chile). We used null models and co-occurrence indices calculated in each country for each one of 15 sites distributed along a precipitation gradient and subjected to similar silvopastoral exploitation. We compared values of species co-occurrence between countries and between species subsets (natives/colonizers in Chile; exclusives/colonizers in Spain) within each country and we characterised them according to climatic variables. We hypothesized that: a) the different coexistence time of the species in both regions should give rise to communities presenting a spatial pattern further from random in Spain than in Chile, b) the co-occurrence patterns in the grasslands are affected by mesoclimatic factors in both regions. The patterns of co-occurrence are similar in Spain and Chile, mostly showing a spatial pattern more segregated than expected by random. The colonizer species are more segregated in Spain than in Chile, possibly determined by the longer residence time of the species in the source area than in the invaded one. The segregation of species in Chile is related to water availability, being species less segregated in habitat with greater water deficit; in Spain no relationship with climatic variables was found. After an invasion process, our results suggest that the possible process of alteration of the original Chilean communities has not prevented the assembly between the native and colonizer species together.     

A re‐examination of the heritability of fertility in the British peerage

Abstract

The gene and phenotype frequencies for the ABO blood groups system were studied in two socioeconomically different subpopulations of Santiago, Chile. The data were taken from the maternity services and blood banks of two hospitals, one serving mainly low socioeconomic classes and the other serving middle and high socioeconomic groups. Results show a clear difference in gene and phenotype frequencies between the two subpopulations, a difference maintained in two generations (mothers and their children). These results reinforce other studies showing that socioeconomic forces have resulted in assortative mating and different genetic subpopulations in Chile.     

Human sociogenetics

In three cities of Chile (Santiago, Valparaiso, Valdivia) the A allele and phenotype (ABO blood group) are more frequent in the higher socioeconomic strata (SES) and the O allele and phenotype are in the lower ones. This constitutes a structured sociogenetic cline (SGC). The B allele and phenotypes (B+AB) present a rather erratic or contradictory distribution among SES. This SGC was also found in England. The standard interpretation of the origin and maintenance of this SGC in Chile is founded on socio-ethno-historic-cultural and drift factors followed by socioeconomic assortative mating that has occurred since the origin of Chileans by the admixture of Europeans and Amerindians. This interpretation is insufficient to explain the coincidence of the cline in England and Chile, and for some findings in Chile. 1) The A and Rh(-) frequencies of the highest SES in Chile are significantly higher than those found in Europeans. 2) The B gene and phenotypes (with AB) behave differently and in contradiction to the socio-ethno-cultural-historical process. 3) There is a significant interaction of the SGC with gender in Chile and England. There is not at present a putative relationship between ABO and psycho-social factors that could account for this sociogenetic interaction. This SGC seems to be present in societies with a hierarchical organization in relation to power, prestige, ownership, income and life style, and when sampling includes the most extreme SES. It has not been found in two samples from Ireland and in a sample from Chile taken from a public hospital, probably because those variables and conditions were not ascertained.     

Nosocomial urinary infection due to Trichosporon asahii. First two cases in Chile

We present two cases of nosocomial urinary tract infection due to Trichosporon asahii in intensive care unit patients with bladder catheter from two hospitals in Santiago, Chile. Both patients had an several catheters and bacterial infections that required the use of antibiotic therapy. One strain showed in vitro resistance to amphotericin B. Both strains were susceptible to fluconazole, but presented MIC with dose-dependent susceptibility to ketoconazole and itraconazole. This is the first report showing T. asahii as urinary tract infection agent in Chile.     

Diarthrodella chilensis sp.n. und Rossopsyllus kerguelenensis quellonensis subsp.n. (Copepoda, Paramesochridae) von Chile

During a collecting trip to Chile, two species of Paramesochridae belonging to the genera Diarthrodella and Rossopsyllus were found. The new species D. chilensis is widely distributed on the coasts of central Chile. Up to now, the new subspecies R. kerguelenensis quellonensis is only known from Quellón, Island of Chiloé. The nominate subspecies R. kerguelenensis kerguelenensis Soyer, 1974 was described from the Kerguelen Archipelago.     

Is Anisakis simplex s.l. a biological marker for stock identification of Strangomera bentincki from Chile?

The absence of the larval Anisakis simplex s. l. in samples from central Chile but heavy infections in fish from southern localities suggest the existence of two stocks of Strangomera bentincki, one closely associated with the central coast of Chile (landing port San Antonio and Talcahuano, c. 33° 30′ S–36° 40′ S) and the other associated with southern Chile (landing port Puerto Montt, c. 41° 30′ S). Results confirm the usefulness of metazoan parasites, like A. simplex s. l. as biological markers.     

Tracking the origin of an invasive species: Drosophila subobscura in Argentina

Biological invasions are excellent opportunities to study the evolutionary forces leading to the adaptation of a species to a new habitat. Knowledge of the introduction history of colonizing species helps tracking colonizing routes and assists in defining management strategies for invasive species. The Palearctic species Drosophila subobscura is a good model organism for tracking colonizations since it was detected in Chile and western North America three decades ago and later on in the Atlantic coast of Argentina. To unravel the origin of the Argentinean colonizers two populations have been analysed with several genetic markers. Chromosomal arrangements and microsatellite alleles found in Argentina are almost similar to those observed in Chile and USA. The lethal allelism test demonstrates that the lethal gene associated with the O₅ inversions in Argentina is identical to that found in Chile and USA, strongly supporting the hypothesis that all the American colonizing populations originated from the same colonization event. A secondary bottleneck is detected in the Argentinean populations and the genetic markers suggest that these populations originated from the invasion of 80–150 founding individuals from Chile.     

AFLP analysis reveals a clonal population of Phytophthora pinifolia in Chile

Phytophthora pinifolia is the causal agent of the recently discovered needle disease of Pinus radiata in Chile, referred to as “Daño Foliar del Pino” (DFP). The genetic structure of the pathogen population is unknown, which hinders our understanding of its appearance and spread in Chile since 2004. In this study, a population of 88 cultures of P. pinifolia isolated from P. radiata at several localities in Chile was evaluated for genotypic diversity using amplified fragment length polymorphisms (AFLPs). Results of the AFLP analyses showed that the P. pinifolia population in Chile consists of two near identical genotypes but with no genetic differentiation based on geography, year of isolation or the part of the tree from which the isolates were obtained. Mating experiments did not lead to the production of gametangia suggesting that the organism is sterile. The fact that a single clonal genotype dominates the population of P. pinifolia in Chile supports the hypothesis that P. pinifolia was recently introduced into this country and that its impact is due to a new and susceptible host encounter.     

The genetic divergence of prehistoric populations of the south-central Andes as established by means of craniometric traits

The peopling of the south-central Andean region can be determined by exploring a combination of cultural, economic, and biological factors that influence the structure of populations and determine particular dispersals of gene frequencies. Quantitative characters from 1,586 adult crania of both sexes from northern Chile, northwestern Argentina, and the Cochabamba valleys in Bolivia were analyzed employing multivariate statistical analyses. Biological distances, representing phenotypic variation between these regions and their subregions, were studied within a population genetics framework. An analysis of Mahalanobis D(2) distances establishes two principle directions of interaction: the first between the Cochabamba valleys and northern Chile, and the second between the Cochabamba region and northwestern Argentina. The Chile and Argentina regions are shown to be less related to each other than each is to the Bolivian region. A higher mean genetic divergence is found for the entire region (F(ST) = 0.195); with northwestern Argentina having the highest spatial isolation (F(ST) = 0.143) and northern Chile the lowest (F(ST) = 0.061). These results allow us to propose a populating model based on the dispersion of several lines from a common ancestral population similar to those who inhabited the Cochabamba valleys. These lines differentiated themselves in time and space according to the effective size and the rate of gene flow, eventually producing the human groups which inhabited the valleys of northern Chile and northwestern Argentina.     

Low genetic diversity of the successful invasive African clawed frog Xenopus laevis (Pipidae) in Chile

In Africa, the genus Xenopus presents cryptic species and diverse hybrids between species. It has been assumed that the invasive populations of this genus correspond to X. laevis and that they are derived from the subspecies that inhabits the Mediterranean Cape region of South Africa. In part, this is supported by the successful establishment of this species in several Mediterranean regions of the world. In Mediterranean Chile, Xenopus has invaded an area of about 21,000 km², with scarce attention to genetic aspects underlying its invasion. Using mitochondrial DNA sequences we determined that Xenopus laevis laevis from the Cape region of South Africa is the subspecies that invaded Chile. The analysis indicated that the invaders have low genetic diversity (only two haplotypes, compared to 10 in two localities of their native range), and that probably the invasion in Chile occurred only once. Landscape genetics revealed that factors such as aridity and elevation have determined the spread of the species, both from the ecological and genetic points of view. Our results show that the invasion of the African clawed frog in Chile has been successful for at least 30 years, in spite of low genetic variability, few events of introduction, low propagule pressure, and bottlenecks in the founding population.     

Origins and colonization history of pandemic Vibrio parahaemolyticus in South America

The dynamics of dissemination of the environmental human pathogen Vibrio parahaemolyticus are uncertain. The O3:K6 clone was restricted to Asia until its detection along the Peruvian coasts and in northern Chile in 1997 in phase with the arrival of El Niño waters. A subsequent emergence of O3:K6 strains was detected in austral Chile in 2004. The origin of these 1997 and 2004 population radiations has not yet been conclusively determined. Multiple loci VNTR analysis using seven polymorphic loci was carried out with a number of representative strains from Asia, Peru and Chile to determine their genetic characteristics and population structure. Asian and Chilean subpopulations were the most genetically distant groups with an intermediate subpopulation in Peru. Population structure inferred from a minimum‐spanning tree and Bayesian analysis divided the populations into two genetically distinct groups, consistent with the epidemic dynamics of the O3:K6 clone in South America. One group comprised strains from the original Asiatic population and strains arriving in Peru and Chile in 1997. The second group included the remaining Peruvian Strains and Chilean strains obtained from Puerto Montt in 2004. The analysis of the arrival of the O3:K6 clone at the Pacific coasts of South America has provided novel insights linking the origin of the invasion in 1997 to Asian populations and describing the successful establishment of the O3:K6 populations, first in Peru and subsequently in the South of Chile owing to a possible radiation of Peruvian populations.     

Araucnephia iberaensis n. sp., a neotropical black fly with a peculiar distribution (Diptera-Simuliidae)

Araucnephia Wygodzinsky & Coscarón is a Neotropical black fly genus in which only one species from Central Chile is known. Another species has now been found in Corrientes province on the eastern side of the Iberá tropical swamps of Argentina, on the western border of the mountainous region of southern Brazil. This new species, A. iberaensis, is herein described and illustrated and information on its bionomics is recorded. It is an interesting species because previous to its discovery no black fly genus or subgenus from Central Chile region has been found in tropical areas, because these two regions are separated by the Monte and Pampas realms. Similarly, no Brazilian genus or subgenus has crossed the Andes mountains to Chile. A comparison with other Neotropical, Nearctic, Ethiopian (Afrotropical) and Australian Prosimuliini (sensu Crosskey & Howard) showed Araucnephia to be a valid taxon most closely related to Araucnephioides (sympatric in Chile). Araucnephia also shows great affinities with Lutzsimulium from Southeast Brazil and Argentina and Paracnephia from South Africa.     

Artificial induction of sporulation in Lessonia (Phaeophyta, Laminariales)

The effects of three physical variables on sporulation, germination and gametophyte survival were evaluated on two species of Laminariales at Coquimbo, Chile (30° S). Parameters were evaluated using reproductive fronds of Lessonia nigrescens Bory and Lessonia trabeculata Villouta and Santelices with treatment variables including type of pre-rinse, dehydration, and temperature. Although the response was slightly different in the two species, it was found that pre-rinsing the blades with tap water produced marked sporulation without affecting germination and survival. Minor effects were observed with other variables, including positive effects of lower temperature and negative effects of longer dehydration periods. The high commercial value of these two species has promoted much interest in their artificial propagation in Chile. This revised version was published online in June 2006 with corrections to the Cover Date.     

Do climatically similar regions contain similar alien floras? A comparison between the mediterranean areas of central Chile and California

Aim Taxonomic comparisons of alien floras across climatically similar regions have been proposed as a powerful approach for increasing our understanding of plant invasions across scales. However, detailed comparisons between the alien biotas of climatically similar regions are scarce. This study aims to compare the taxonomic patterns of alien species richness in mediterranean‐type climate areas of central Chile and California, in order to better understand how climatically similar regions converge or diverge in terms of their alien flora. Location Central Chile and California, United States. Methods We compared the alien floras of the state of California in the United States and central Chile, considering within‐region variation and taxonomic composition up to the species level. To test for within‐region variation, administrative units and counties were grouped within seven latitudinal bands for each region. We tested for differences in the relative contributions of the various origins of the naturalized species to each region. We used a family naturalization index to establish which families had relatively higher numbers of naturalized species in each region. We evaluated the similarity, using cluster analyses with Jaccard’s similarity index, of alien taxa between regions and latitudinal bands using presence–absence matrices at the species, genus and family levels. We used principal components analysis to determine the presence of a compositional gradient including all latitudinal bands. Results We recorded 1212 alien plant species in California and 593 in central Chile, of which 491 are shared between the two regions. These figures include 25 species that are native to California and 37 that are native to Chile. A comparison between the alien floras of central Chile and California reveals three major trends: (1) higher naturalized species diversity for California than for Chile, at all taxonomic levels; (2) differences in the proportion of species according to origin, with America, Africa, Asia and Australia providing a larger number of species in California than in Chile; (3) segregation between regions in terms of taxonomic composition of their alien flora, and a rather weak differentiation within regions; and (4) a trend towards higher similarity between the alien floras of latitudinal bands associated with higher levels of human disturbances. Main conclusions The alien floras of central Chile and California are significantly different, but this difference diminishes in highly disturbed areas. Thus, the current high levels of species movement caused by globalization, together with increasing levels of anthropogenic disturbances, should reduce the differentiation of the alien floras in these regions, increasing overall biotic homogenization.     

Phylogenetic and biogeographic relationships of the mouse opossum Thylamys (Didelphimorphia,Didelphidae) in southern South America

Nucleotide sequence data from the mitochondrial cytochrome b gene were used to evaluate the phylogenetic relationships among mouse opossum species of the genus Thylamys. Based on approximately 1000 bp in five of the six species of the genus and including different localities for some of the species, we concluded that T. macrura from the subtropical forests of eastern Paraguay is the most primitive taxon. Subsequent radiation of the genus is explained mainly via founder effect speciation. This evolutionary scenario would account for the speciation of T. pusilla, T. venusta, T. pallidior, and T. elegans in the Chaco, southern Bolivia and northern Argentina, the Andean Altiplano, the Coastal Desert of Chile, and coastal Perú, respectively. Calibration of a molecular clock set the Pleistocene as the period for the differentiation of Thylamys species. The molecular results confirm the strong genetic connection between populations that inhabit the "pre-cordillera" of northern Chile (T. pallidior) and the canyons that run through the Atacama Desert to the lowlands in northern Chile. Our results confirm the occurrence of two Thylamys species in Chile, T. pallidior and T. elegans, within and south to the Atacama Desert, respectively.     

Genetic variability and interpopulational differentiation of Artemia strains from South America

Seven Artemia samples from three South American countries (Chile, Brazil, Peru) were studied by starch electrophoresis with the aim of comparing levels of genetic variation and genetic similarity to representative populations of A. franciscana (San Francisco Bay, California, USA) and A. persimilis (Buenos Aires, Argentina), which are species endemic to the New World. Based on the analysis of 22 loci, parameters measuring genetic variability were, for some populations, found to be among the highest reported for Artemia so far. The percentage of polymorphic loci varied from 31.8% (Piura, Peru; Buenos Aires) to 50% (Los Vilos and Salar de Atacama, Chile), while the observed heterozygosity varied from 0.025 (Piura) to 0.165 (Los Vilos, Chile). A dendrogram based on Nei's genetic distance (D) produced four major groups. The Argentinian form, A. persimilis; the San Francisco Bay strain together with samples from Brazil (Macau and Rio Grande do Norte) and Chile (Pichilemu and Salar de Atacama); two coastal populations from Chile (Los Vilos and Iquique) and the sample from Peru (Piura). These four groups have inter-group D values that are, in some cases, far above those normally associated with conspecific populations.     

Alien plants in southern South America. A framework for evaluation and management of mutual risk of invasion between Chile and Argentina

Most of the Chilean traffic exchange takes place along the border with Argentina. The road network between both countries facilitates the transport of alien plant species, raising the chance of new introductions of plant species and increasing the propagule pressure of already introduced plants. We used a modified version of the Australian Weed Risk Assessment method (AWRA) to analyze if alien plant species already present either exclusively in Chile or Argentina can be a potential source of risk for new alien species introduction and, specifically, which of the two countries poses a higher risk for its counterpart. We recorded 875 alien species of which 288 are exclusive to Chile, 283 are exclusive to Argentina, and 304 are shared by both countries. Considering the risk of new alien plants introductions, Chile presents a higher threat to Argentina than vice versa. Specifically, twenty-two alien species are exclusive to Chile, and are present on roadsides connecting both countries, hence they are regarded as a top risk for Argentina; a comparable top risk of alien species is absent from Argentinean roadsides. Both countries have a similar number of alien species being exclusive to one country, but are not present along roadsides (Chile 162; Argentina 186), which could represent a potential risk to the other country. The methodological approach proposed here may be a useful tool not only for screening potential new alien plant introductions, but also for the prioritization of eradication or control measures of those species already introduced.     

Comparative karyotypic analysis in the Alstroemeria hookeri Lodd. (Alstroemeriaceae) complex sensu Bayer (1987)

Alstroemeria L. (Alstroemeriaceae) is an American genus of monocots with two principal distribution centers in Chile and Brazil. In Chile, it is represented by about 32 species, most of them in central Chile, an area known for its high level of endemism. The "complex" Alstroemeriahookeri is endemic to Chile, where it is distributed from the Coquimbo to the Bío-Bío Region. We analyzed the karyotypes of 36 populations of this complex along its natural distribution. Ten metaphases per population were used for chromosome measurements. All analyzed subspecies presented a well defined asymmetric karyotype. The populations of A. hookeri subsp. hookeri collected in the coastal range of the Bío-Bío Region and the populations from the Central Valley of this Region (Pangal del Laja) presented striking morphological differences in the karyotype, mainly on chromosome 3. The population of A. hookeri subsp. recumbens from Pichicuy showed a polymorphism on chromosome 7, which differed from the other analyzed populations of this subspecies. Phenetic analysis suggested that A. hookeri subsp. cummingiana, which showed a more symmetrical karyotype and did not grow in sandy soil, should be alocated to A. cummingiana rather than considered as part of the hookeri complex.     

Exotic oniscideans (Crustacea: Isopoda) in coastal salt marshes: first record of the families Halophilosciidae and Platyarthridae in Continental Chile

We report two new exotic introduced isopods in Chile: Halophiloscia couchii of the family Halophilosciidae and Niambia capensis of the family Platyarthridae. This report provides first evidence of the presence of these species in the Southeastern Pacific. These species were found in several salt marshes and beaches spanning nearly 2000?km of the Chilean coast. With the data reported here, the percentage of exotic oniscidean isopods in Chile is 28%.