Increasing the Understanding of Plant Invasions in Southern South America: First Symposium on Alien Plant Invasions in Chile

The first symposium on Alien Plant Invasions in Chile was held in southern Chile in November of 2002. Chile represents an interesting setting to study biological invasions because of its long history of introductions, and its high rate of endemisms that makes it more prone to invasions. However, little is known about plant invasions in Chile and the country lacks a clear policy on alien species. The speakers at the symposium discussed their research on several aspects of alien plant invasions in southern Chile and Argentina. They also elaborated a list of future challenges of plant invasion ecology for the area. The package of recommendations may be useful for other developing countries with similar state of knowledge of their flora and similar environmental and economic issues. We expect that this type of meeting will help to stimulate the scientific debate about invasion ecology and the development of coordinated research to answer local questions, while contributing to find generalities in plant invasion patterns and processes.     

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.     

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.     

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.     

Genetic structure of Cydia pomonella populations in Argentina and Chile implies isolating barriers exist between populations

The codling moth (Cydia pomonella (L.)) is an invasive pest of pome fruits introduced to the Americas in the 19–20^th centuries. This pest is widespread on both sides of the Andes range separating Argentina and Chile. We performed an analysis of the population genetic variability and structure of C. pomonella in Argentina and Chile using 13 microsatellite markers and sampled C. pomonella from apple as the main host plant along its distribution area (approx. 1,800 km). A total of 22 locations (11 from Chile and 11 from Argentina) were sampled. Significant genetic differentiation was observed among samples from Argentina and Chile (F_SC = 0.045) and between all localities (F_ST = 0.085). Significant isolation by distance (IBD) was found for each country and when samples from both sides of the Andes range were pooled, although a lower correlation coefficient was observed. The Mantel test showed that the geographic distance and highest altitude of the mountains between locations were significantly associated with the pairwise F_ST when samples from both sides of the Andes range were pooled. According to a Bayesian assignment test (STRUCTURE), samples from Argentina and Chile conformed to two distinct genetic clusters. Our results also suggest that the recent invasion of C. pomonella in the southernmost localities (Aysén Region in Chile and Santa Cruz Province in Argentina) originated in populations from the respective sides of the Andes range. Our results indicate a genetic exchange of C. pomonella within each country and significant genetic differentiation between countries, which could be explained by dispersal mediated by human activities related to fruit production within each country with little exchange between them. A possible explanation is that the Andes range could be a significant barrier for dispersal by flight, and quarantine barriers could prevent the movement of plant material or infested fruit between countries.     

Geographic mosaics of plant–soil microbe interactions in a global plant invasion

Aim Our aim in this study was to document the global biogeographic variation in the effects of soil microbes on the growth of Centaurea solstitialis (yellow starthistle; Asteraceae), a species that has been introduced throughout the world, but has become highly invasive only in some introduced regions. Location  To assess biogeographic variation in plant–soil microbe interactions, we collected seeds and soils from native Eurasian C. solstitialis populations and introduced populations in California, Argentina and Chile. Methods To test whether escape from soil‐borne natural enemies may contribute to the success of C. solstitialis, we compared the performance of plants using seeds and soils collected from each of the biogeographic regions in greenhouse inoculation/sterilization experiments. Results  We found that soil microbes had pervasive negative effects on plants from all regions, but these negative effects were significantly weaker in soils from non‐native ranges in Chile and California than in those from the non‐native range in Argentina and the native range in Eurasia. Main conclusions The biogeographic differences in negative effects of microbes in this study conformed to the enemy‐release hypothesis (ERH) overall, but the strong negative effect of soil biota in Argentina, where C. solstitialis is invasive, and weaker effects in Chile where it is not, indicated that different factors influencing invasion are likely to occur in large scale biogeographic mosaics of interaction strengths.     

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.     

The taxonomy, biogeography and host plant relationships of jumping plant-lice (Hemiptera: Psyllidae) associated with creosote bushes (Larrea spp., Zygophyllaceae)

Abstract.  The Neotropical genus Panisopelma (Psyllidae: Aphalaroidinae) is revised and its internal phylogeny analysed. The constituent species, including five new ones, are described and illustrated. Keys are provided for the adults and the last instar larvae. Eight species are associated with creosote bushes ( Larrea , Zygophyllaceae): five with L. nitida and three with L. divaricata . There is evidence that another three species, the larvae of which are unknown, also develop on L. divaricata . Seven species are restricted to Argentina, one to Bolivia and three to Chile. The cladistic analysis based on male, female and larval morphological characters yielded a single most-parsimonious tree. The species associated with L. nitida form a monophyletic clade, those on L. divaricata , by contrast, are paraphyletic. One clade with three species is restricted to Argentina, but three clades each contain a species from Argentina and Chile. Although a close association exists between Panisopelma and Larrea , there is no evidence for cospeciation, but rather an initial shift from an unknown host to L. divaricata and a second shift from L. divaricata to L. nitida . In three species pairs of Panisopelma , the distribution patterns suggest geographical vicariance between Argentina and Chile.     

Global Diversity and Conservation Priorities in the Cactaceae

The purpose of this paper was to analyze the diversity patterns of Cactaceae at a global scale, to identify those countries where conservation actions should be performed. In order to do this, the species richness and the number of endemic species for 34 American countries were determined. With these data, the relationship between the total number of species or the number of endemic species and the area of the countries were analyzed. In addition, a complementarity analysis was conducted to determine the most important countries for cactus conservation. Results showed that Mexico had the highest number of total and endemic species followed by Argentina, Bolivia, Brazil, and Peru, among others. There was a significant positive relationship between both, the total and endemic species, and the area of the countries. Despite this fact, the cactus diversity in Mexico, Argentina, Peru, Bolivia, Chile, and Costa Rica was higher than expected according to their area. Further, these countries also presented the highest proportions of endemic species. The complementarity analysis indicated that 24 countries are necessary to preserve all cactus species. However, 94% of all species could be preserved with only 10 countries. Considering the diversity patterns and the complementarity analysis, three important groups for cactus conservation were identified: (1) Mexico, Argentina, Peru, Bolivia, Chile, and Costa Rica, (2) Paraguay and Cuba, and (3) Brazil and USA. Conservation efforts should be focused on these countries in order to preserve cactus diversity.     

Good news from Latin America and the Caribbean: national and international restoration networks are moving ahead

Degradation of ecosystems is ongoing in Latin America but there is also a strong upswing in conservation and restoration efforts. SIACRE – the Ibero‐American and Caribbean Society for Ecological Restoration – is playing a key role in coordinating and promoting this trend at international, national, and subnational levels. In October 2014, SIACRE members organized the first national seminar on ecological restoration in Chile, with participants representing both academic and non‐academic sectors. This seminar served as the catalyst for this essay and was an historic event at the national level. Much work has been underway in the science and practice of restoration in Chile, but until now it has been fragmented. This first national seminar enabled helped the principal strengths and challenges that Chile has and must face in the transdisciplinary domain of ecological restoration. Since 2004, various meetings have been organized in the region, in order to communicate the importance of restoration, especially in Mexico, Cuba, Colombia, Brazil, and more recently in Chile and Argentina. Here we trace the history of national and subnational restoration networks in Latin America and the Caribbean, and of SIACRE, and then outline some goals and challenges for the coming years.     

Dioecy in Fitzroya cupressoides (Molina) I.M. Johnst. and Pilgerodendron uviferum (D. Don.) Florin (Cupressaceae)

The aim of this study was to determine the dioecious or monoecious condition of Fitzroya cupressoides and Pilgerodendron uviferum. The study area lies west of the Nahuel Huapi National Park in northern Patagonia (Argentina), where these species form mixed stands. One hundred individuals of each species were studied over three successive years. The nature and position in the crown of their reproductive organs were recorded. Results showed that both species are dioecious. This feature has been confirmed on trees of these species growing in other sites within their natural distribution area in Argentina and Chile.     

Genetic divergence analysis of the Common Barn Owl Tyto alba (Scopoli, 1769) and the Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile using COI sequence

In this paper new mitochondrial COI sequences of Common Barn Owl Tyto alba (Scopoli, 1769) and Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile are reported and compared with sequences from other parts of the World. The intraspecific genetic divergence (mean p-distance) was 4.6 to 5.5% for the Common Barn Owl in comparison with specimens from northern Europe and Australasia and 3.1% for the Short-eared Owl with respect to samples from north America, northern Europe and northern Asia. Phylogenetic analyses revealed three distinctive groups for the Common Barn Owl: (i) South America (Chile and Argentina) plus Central and North America, (ii) northern Europe and (iii) Australasia, and two distinctive groups for the Short-eared Owl: (i) South America (Chile and Argentina) and (ii) north America plus northern Europe and northern Asia. The level of genetic divergence observed in both species exceeds the upper limit of intraspecific comparisons reported previously for Strigiformes. Therefore, this suggests that further research is needed to assess the taxonomic status, particularly for the Chilean populations that, to date, have been identified as belonging to these species through traditional taxonomy.     

Molecular identification and phylogeny of Armillaria isolates from South America and Indo-Malaysia

Armillaria root rot is a serious disease, chiefly of woody plants, caused by many species of Armillaria that occur in temperate, tropical and subtropical regions of the world. Very little is known about Armillaria in South America and Southeast Asia, although Armillaria root rot is well known in these areas. In this study, we consider previously unidentified isolates collected from trees with symptoms of Armillaria root rot in Chile, Indonesia and Malaysia. In addition, isolates from basidiocarps resembling A. novae-zelandiae and A. limonea, originating from Chile and Argentina, respectively, were included in this study because their true identity has been uncertain. All isolates in this study were compared, based on their similarity in ITS sequences with previously sequenced Armillaria species, and their phylogenetic relationship with species from the Southern Hemisphere was considered. ITS sequence data for Armillaria also were compared with those available at GenBank. Parsimony and distance analyses were conducted to determine the phylogenetic relationships between the unknown isolates and the species that showed high ITS sequence similarity. In addition, IGS-1 sequence data were obtained for some of the species to validate the trees obtained from the ITS data set. Results of this study showed that the ITS sequences of the isolates obtained from basidiocarps resembling A. novae-zelandiae are most similar to those for this species. ITS sequences for isolates from Indonesia and Malaysia had the highest similarity to A. novae-zelandiae but were phylogenetically separated from this species. Isolates from Chile, for which basidiocarps were not found, were similar in their ITS and IGS-1 sequences to the isolate from Argentina that resembled A. limonea. These isolates, however, had the highest ITS and IGS-1 sequence similarity to authentic isolates of A. luteobubalina and were phylogenetically more closely related to this species than to A. limonea.     

Ecosystem engineering across ecosystems: do engineer species sharing common features have generalized or idiosyncratic effects on species diversity?

Aim  To integrate the effects of ecosystem engineers (organisms that create, maintain or destroy habitat for other species) sharing the same archetype on species diversity, and assess whether different engineer species have generalized or idiosyncratic effects across environmentally similar ecosystems.
Location  High-Andean habitats of Chile and Argentina, from 23° S to 41° S.
Methods  We measured and compared the effects of eight alpine plants with cushion growth-form on species richness, species diversity (measured as the Shannon–Wiener index) and evenness of vascular plant assemblages across four high-Andean ecosystems of Chile and Argentina.
Results  The presence of cushion plants always increased the species richness, diversity (measured as the Shannon–Wiener index) and evenness of high-Andean plant assemblages. However, while the presence of different cushion species within the same ecosystem controlled species diversity in the same way, these effects varied between cushion species from different ecosystems.
Main conclusions  Results consistently supported the idea that increases in habitat complexity due to the presence of ecosystem engineers, in this case cushion plants, would lead to higher community diversity. Results also indicate that effects of the presence of different cushion species within the same ecosystem could be generalized, while the effects of cushion species from different ecosystems should be considered idiosyncratic.     

An alternative model for the early peopling of southern South america revealed by analyses of three mitochondrial DNA haplogroups

After several years of research, there is now a consensus that America was populated from Asia through Beringia, probably at the end of the Pleistocene. But many details such as the timing, route(s), and origin of the first settlers remain uncertain. In the last decade genetic evidence has taken on a major role in elucidating the peopling of the Americas. To study the early peopling of South America, we sequenced the control region of mitochondrial DNA from 300 individuals belonging to indigenous populations of Chile and Argentina, and also obtained seven complete mitochondrial DNA sequences. We identified two novel mtDNA monophyletic clades, preliminarily designated B2l and C1b13, which together with the recently described D1g sub-haplogroup have locally high frequencies and are basically restricted to populations from the extreme south of South America. The estimated ages of D1g and B2l, about ～15,000 years BP, together with their similar population dynamics and the high haplotype diversity shown by the networks, suggests that they probably appeared soon after the arrival of the first settlers and agrees with the dating of the earliest archaeological sites in South America (Monte Verde, Chile, 14,500 BP). One further sub-haplogroup, D4h3a5, appears to be restricted to Fuegian-Patagonian populations and reinforces our hypothesis of the continuity of the current Patagonian populations with the initial founders. Our results indicate that the extant native populations inhabiting South Chile and Argentina are a group which had a common origin, and suggest a population break between the extreme south of South America and the more northern part of the continent. Thus the early colonization process was not just an expansion from north to south, but also included movements across the Andes.     

Biology and phylogenetic relationships of Neophonus bruchi, an anomalous south Andean staphylinid (Coleoptera)

Abstract. The virtually unknown monotypic genus Neophonus Fauvel has been collected in several localities in south-central Chile; it was previously known only from the type locality in Argentina. Field observations of the adults on forest foliage and study of their gut contents suggest that they are mycophagous and eat primarily foliicolous fungi, a habit previously unknown in Staphylinidae. Their mouthparts and tarsi show morphological specializations apparently correlated with these habits. Larvae remain unknown. The phylogenetic relationships of the genus within the omaliine-group of Staphylinidae sensu lato are discussed.     

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.     

Genetic characterization of fall armyworm (Lepidoptera: Noctuidae) host strains in Argentina

Fall armyworm is a major economic pest throughout the Western Hemisphere. Previous studies of populations in the southern United States, Brazil, and the Caribbean demonstrated the existence of two morphologically identical but genetically distinct host strains that can only be distinguished using genetic markers, including polymorphisms in the mitochondrial Cytochrome Oxidase I (COI) gene and in the Z-chromosome linked Triose phosphate isomerase (Tpi) gene. The strains differ in some physiological and behavioral characteristics, most notably their preference for different plant hosts, but are capable of hybridizing in the laboratory and in the field. These traits suggest that the strains are in the process of divergence, which may or may not be hemispheric in scope. The objective of this study was to determine whether the two strains are present in Argentina. It was found that the strain-diagnostic haplotypes of the COI and Tpi genes subdivided the Argentina population into two major groups. Each group displayed biases in their distribution among different host plants that were generally consistent with expected strain behavior. The overall results indicated that Argentina fall armyworm exhibit similar genetics and behavior to populations in the rest of the hemisphere. In addition, the Argentina populations had comparable haplotype frequencies to those from Brazil and Texas, consistent with possible interactions with these fall armyworm groups, but appeared to have had minimal exchanges with those from Puerto Rico or Florida.     

Ecogeographic variation in seed fatty acids of Austrocedrus chilensis

Seed megagametophyte fatty acids were analyzed for proportional composition in 104 trees from 13 natural populations of Austrocedrus chilensis in Andean Chile and Argentina, using gas-liquid chromatography. A total of 15 fatty acids were identified from their methyl esters by GC retention times and by mass spectroscopy and included, as major compounds, oleic, linoleic, linolenic and cis-5,11,14,17-eicosatetraenoic acids. Multivariate analyses indicated a separation of xeric zone populations (mediterranean Chile and the Argentinean steppe ecotone) from mesic populations (Argentinean Lakes and southern range in Chilean rainforest). These differences were associated with a greater abundance of C20 unsaturated rated acids in the mesic group. Differentiation among mediterranean Chilean populations was relatively high, perhaps as a result of their disjunct distribution. There was no evidence for lower levels of within-population variation for these isolated northern populations.