Arrival of Paleo-Indians to the Southern Cone of South America: New Clues from Mitogenomes

With analyses of entire mitogenomes, studies of Native American mitochondrial DNA (mtDNA) variation have entered the final phase of phylogenetic refinement: the dissection of the founding haplogroups into clades that arose in America during and after human arrival and spread. Ages and geographic distributions of these clades could provide novel clues on the colonization processes of the different regions of the double continent. As for the Southern Cone of South America, this approach has recently allowed the identification of two local clades (D1g and D1j) whose age estimates agree with the dating of the earliest archaeological sites in South America, indicating that Paleo-Indians might have reached that region from Beringia in less than 2000 years. In this study, we sequenced 46 mitogenomes belonging to two additional clades, termed B2i2 (former B2l) and C1b13, which were recently identified on the basis of mtDNA control-region data and whose geographical distributions appear to be restricted to Chile and Argentina. We confirm that their mutational motifs most likely arose in the Southern Cone region. However, the age estimate for B2i2 and C1b13 (11–13,000 years) appears to be younger than those of other local clades. The difference could reflect the different evolutionary origins of the distinct South American-specific sub-haplogroups, with some being already present, at different times and locations, at the very front of the expansion wave in South America, and others originating later in situ, when the tribalization process had already begun. A delayed origin of a few thousand years in one of the locally derived populations, possibly in the central part of Chile, would have limited the geographical and ethnic diffusion of B2i2 and explain the present-day occurrence that appears to be mainly confined to the Tehuelche and Araucanian-speaking groups.     

Distribution of Pyrethroid Resistant Populations of Triatoma infestans in the Southern Cone of South America

BackgroundA number of studies published during the last 15 years showed the occurrence of insecticide resistance in Triatoma infestans populations. The different toxicological profiles and mechanisms of resistance to insecticides is due to a genetic base and environmental factors, being the insecticide selective pressure the best studied among the last factors. The studies on insecticide resistance on T. infestans did not consider the effect of environmental factors that may influence the distribution of resistance to pyrethroid insecticides. To fill this knowledge gap, the present study aims at studying the association between the spatial distribution of pyrethroid resistant populations of T. infestans and environmental variables.Conclusions/SignificanceThe occurrence of these two groups concentrated over a particular region that coincides with the area where populations of the intermediate cytogenetic group were found might reflect the spatial heterogeneity of the genetic variability of T. infestans, that seems to be the cause of the insecticide resistance in the area, even on sylvatic populations of T. infestans, never before exposed to pyrethroid insecticides, representing natural and wild toxicological phenotypes. The strong linear relationship found between LD₅₀ and RR₅₀ suggest RR₅₀ might not be the best indicator of insecticide resistance in triatomines.     

Geographic patterns of craniofacial variation in pre-Hispanic populations from the Southern Cone of South America

In this study we analyzed the relationships and patterns of spatial variation from morphological cranial variability of 17 population samples representing the ancient inhabitants of the central territory of Argentina (archaeologically known as "Sierras Centrales") and other pre-Hispanic populations from different ecological and geographic regions of the Southern Cone of South America (Argentina and Uruguay), based on the analysis of 10 craniofacial measurements. Results obtained from D2 distances can be interpreted as evidence of a similar biological history for the populations that inhabited the Sierras Centrales and the population of Santiago del Estero. Matrix correlation analysis demonstrated that craniometric variation is significantly influenced by geography, suggesting that populations that lived at lower geographical distance share more biological similarity. Global spatial autocorrelation analysis suggests a clinal pattern for the biological variation, although Moran's I estimates calculated for each variable demonstrate that only nasal height and breadth show this spatial pattern of variation. Results from spatial regression techniques show a significant effect of altitude modeling nasal shape, in agreement with previous studies suggesting that nasal morphology is strongly influenced by environment variables.     

Trojan hosts: the menace of invasive vertebrates as vectors of pathogens in the Southern Cone of South America

Biological Invasions - Invasive alien species (IAS) can act as vectors for the introduction of pathogens in ecosystems and their transmission to threatened native species (TNS), leading to...     

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.     

Trophic Segregation of Small Carnivorans (Carnivora: Mustelidae and Mephitidae) from the Southern Cone of South America

Remarkable adaptations in the Carnivora have evolved as a way of dealing with feeding competition, accentuating hypocarnivorous or hypercarnivorous morphotypes. The Carnivora is a highly successful order with 47 living species in South America. Their history in South America is recent, and includes few lineages that arrived before the Panamanian bridge was completed (procyonids), and others that arrived later (felids, mephitids). Here, we evaluated the trophic segregation of small carnivorans (Conepatus chinga, Galictus cuja, Lontra provocax, Lyncodon patagonicus, and the introduced Neovison vison) from southern South America, using a geometric morphometric approach, i.e., Principal Component and Canonical Variate Analysis, to study shape variations and t-tests to study size variation. We also performed Canonical Phylogenetic Ordination to study the association between shape, size, diet, and phylogeny. We identified C. chinga as the most hypocarnivorous member of the guild, G. cuja, L. patagonicus, and N. vison as hypercarnivores, with L. provocax in an intermediate position. Semiaquatic habits segregate Lontra provocax, and partially N. vison, from other species. Significant differences in size were observed between all species pairs, except C. chinga and N. vison. Phylogeny accounts for a very important part of morphological variance, with cladogenetic events between mustelids and mephitids responsible for almost 55 % of it. The small carnivoran guild of southern South America is represented by species adapted to different feeding strategies, with C. chinga and L. provocax preying mainly on invertebrates, G. cuja and L. patagonicus specifically on small vertebrates, and the non-native N. vison with a highly diverse diet.     

The genus Lessonia Bory (Phaeophyta,Laminariales) in Southern Chile and Argentina

Study of Lessonia in southern Chile and Argentina indicates that it is represented there by three species: L. nigrescens Bory, L. flavicans Bory and L. vadosa Searles sp. nov. Plants of these three species have been confused with each other in the literature, but appear clearly separable. Lessonia nigrescens is distinguished from the others by its massive, solid holdfast and numerous stipes. In Lessonia flavicans and L. vadosa a single stipe arises from a branched holdfast. These two species are distinguishable from each other in details of blade morphology, anatomy, and ecology. The taxonomic status of plants in South America outside of the study area remains unresolved. Populations in the Falkland Islands and in northern Chile in particular are in need of further study.     

Dispersal of forest birds and trees along the Uruguay River in southern South America

The Uruguay River starts in Serra do Mar in Brazil runs through the Paranense forest and flows southward through grassland and savannas. It has a continuous gallery forest of 750 km from the southern border of the Paranense forest to the river mouth. The gallery forest extends for 100 km more along the Río de la Plata. 125 (68.7%) of the 182 species of forest birds recorded in the southern Paranense forest penetrate into the gallery forest of the Uruguay River and only 13 (7.1%) reach the end of the gallery forest (Punta Lara). The number of bird species is inversely correlated (r² = 0.942) with distance and the slope of the regression is 58.10. This means a decline in diversity with 32% of species lost per unit distance. A hundred and eighty forest tree species were recorded in the southern Paranense forest, of which 113 (62.8%) penetrate into the gallery forest of the Uruguay River, and 28 (15.6%) reach Punta Lara. The number of tree species is inversely correlated (r² = 0.976) with distance and the slope of the regression is ?45.62. This means a decline in diversity with 25% of species lost per unit distance. The Uruguay River enables the dispersal of many species of forest birds and trees from the rain forest, but species richness tends to decrease with increased distance from the source area. A clear association pattern was found for birds between size, diet, habitat use and distance reached into the gallery forest. Species of smaller body size, granivores, insectivores and those that use both the interior and exterior parts of the gallery forest advanced noticeably further along the river than larger species, carnivores, nectarivores or frugivores, and those that frequent only a part of the forest. Similarly, a clear association between dispersal mechanism, water dependence and distance reached into the gallery forest was found for trees. Species with vegetative reproduction, zoochorous species and riparian species advanced markedly longer distances along the river than, anemochorous species and non‐riparian species.     

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.     

Ecology and conservation of grassland birds in southeastern South America: a review

ABSTRACT The grasslands of southeastern South America (SESA), comprising one of the most extensive grassland ecosystems in the Neotropics, have been negatively impacted by the development of the livestock industry, arable agriculture, and forestry. SESA grasslands have a rich avifauna that includes 22 globally threatened and near‐threatened species, and many other species have suffered local population extinctions and range reductions. In addition to habitat loss and fragmentation, grassland birds in SESA are threatened by improper use of agrochemicals, unfavorable fire management regimes, pollution, and illegal capture and hunting. Studies to date have provided information about the distribution of grassland birds, the threats populations face, and the habitat requirements of some threatened species, but more information is needed concerning dispersal and migration patterns, genetics, and factors that influence habitat use and species survival in both natural and agricultural landscapes. There are few public protected areas in the region (1% of original grasslands), and many populations of threatened grassland birds are found on private lands. Therefore, efforts to preserve grassland habitat must reconcile the interests of land owners and conservationists. Current conservation efforts include establishment of public and private reserves, promotion of agricultural activities that reconcile production with biodiversity conservation, development of multilateral conservation projects across countries, and elaboration of action plans. Measures that result in significant losses to private land owners should include economic compensation, and use of economic incentives to promote agriculture and forestry in native grassland areas should be discouraged, especially in priority areas for grassland birds. Although more studies are needed, some actions, particularly habitat protection and improved management of public and private lands, should be taken immediately to improve the conservation status of grassland birds in SESA.     

Distribution of blood groups among indians in South America. VI. In Paraguay

This paper on the distribution of hereditary factors in the blood of Indians in South America, reports the results of tests made on samples procured from Paraguayan Indians. Specimens from putatively full-blood persons were obtained from the following tribes: 88 Chamacoco, 36 Moro, 85 Chulupi, 207 Lengua, 100 Toba, 20 Yam Lengua, and 51 Guayaki, These 587 Samples were tested for factors in the A-B-O, M-N-S-s, P. Rh-Hr, Lutheran, Kell-Cellano, Lewis, Duffy, Kidd, and Diego systems. Serum samples were tested for haptoglobins and transferrins. He molysates, prepared from whole blood, were tested for hemoglobin types. The results are presented on appropriate tables as number and per cent of phenotypes for the various blood group antigens and their calculated allele frequencies. Locations of the populations from which blood samples were procured are listed on the tables and shown on a map (fig. 1). Of the 587 samples all except two Chamacoco belonged to group O. High frequencies are reported generally for M, s, P, R¹ (CDe), R² (cDE), k (100%) and Fy alleles in Paraguayn Indians. Low frequencies were generally reported for N, S, r (cde) and R° (cDe) alleles. There was a wide variation in frequencies for Di, Jk, and haptoglobin Hp¹. All tested for transferrins were classified as Tf C and all contained hemoglobin (A) as a major component. The following antigens were completely absent: Mi^a, Vw, p, P^k, r^y (CdE), K, and Le¹. Most notable is the unusual distribution of hereditary blood antigens among the Guayaki and Moro. The Guayaki had 100% P₁ and Fy^a; they were higher in R° (cDe), R¹ (CDe), and Jk^a; and lower in R² (cDE) and Hp¹ genes than other Indians; and Di was absent. The Guayaki differed from the other Indians also in having fair skin. The Moro were lower in the P¹ and Jk gene frequencies than is usually found in Amerinds, and the Di gene was absent. The Chamacoco also had an exceptionally low frequency for the P¹ gene (0.261).     

Coat Gene Profiles of Several Cat Populations in Cuba,Costa Rica,Colombia, Paraguay,Chile and Argentina,and Possible Genetic Origins of These Cat Populations

Until the present moment, only a scarce number of Latin American domestic cat populations have been studied from a population genetic standpoint. For this reason, the cat populations of La Havana (Cuba), San José (Costa Rica), Bogotá and Ibagué (Colombia), Asunción (Paraguay), Santiago (Chile) and Buenos Aires (Argentina) were sampled for several coat genes. The results obtained were as follows: (1) there was a strong genetic resemblence between several Hispanic American cat populations (especially, those of Buenos Aires, San José and the two Colombian populations studied) and those from South Western United States (California, Texas and Colorado), which adds suport to the suspicion that these populations probably have a common origin; (2) The cat population of Santiago (Chile), contrarily to the other Hispanic American populations studied, showed a strong genetic resemblance with some Anglo North American populations; and (3) The I (long hair) and d(dilution) alleles showed systematic higher frequencies in the Hispanic American populations than those observed in Spain. Although the Hispanic American populations were not identical to the current Spanish populations (with the exception of Asuncion), this historic genetic experiment was very different to that found for the British populations and their overseas colonies.     

First genotyping of Giardia lamblia from human and animal feces in Argentina, South America

The purpose of this study was to investigate the genotypes of Giardia lamblia from human and animal feces and their epidemiological and clinical characteristics in Argentina, South America. Seventy isolates, 60 from humans (adults and children), eight from dogs and two from cows were processed by polymerase chain reaction-restriction fragment length polymorphism. Data corresponding to demographic, socio-cultural and environmental variables and presence/absence of signs/symptoms were collected. The triosephosphate isomerase gene was amplified from 43 (71.66%) of the 60 human fecal samples. Among these, 3/43 (6.98%) were genotype AII and 40/43 (93.02%) were genotype B. Assemblage AII was detected in three children who lived together in a shantytown and they were oligosymptomatic and none had diarrhea. This genotype was not found in animals. Genotype B showed a high prevalence in both adults and children. It was also found in polysymptomatic people, many of whom presented diarrhea. It was also found only in one dog. The present study represents the first contribution to the knowledge of G. lamblia genotypes in Argentina.