Microgeographic differentiation among closely related species of Biomphalaria (Gastropoda: Planorbidae) from the Andean Altiplano

Direct development and water dependence entail limited vagility in freshwater fauna. In these organisms, the population structure is probably linked to restrictions imposed by the habitat. In this study we investigate the relative contribution of processes stimulating the divergence of populations of Biomphalaria costata (Biese, 1951) and Biomphalaria crequii (Courty, 1907), two freshwater snails occurring in two contiguous and fragmented closed basins from the Andean Altiplano using mitochondrial DNA (cytochrome c oxidase subunit I) sequences, shell morphometric and radular morphology. In order to clarify the species boundaries, a third allopatric species was included: Biomphalaria aymara Valdovinos & Stuardo, 1991. Molecular analyses recovered two distinct clades: one composed of B. aymara from the Isluga swamps and B. costata from Spring 1 in Salar de Carcote, the single spring occupied by this species, and another integrated by snails from 12 springs spread across the Salar de Carcote and the Salar de Ascotán assigned to B. crequii, originally described from the Salar de Ascotán. Unlike shell morphometrics, radular morphology was informative for distinguishing these species. The division of the lineages occurred in the Late Pleistocene. A subclade that includes snails from the southernmost springs in Salar de Ascotán suggests fragmentation of the distribution of B. crequii associated with landscape discontinuities. In addition to microvicariance signals, the private haplotypes scattered around both salt spans show that close‐range dispersal is a common biogeographic process in this species. As evolutionary units, the single isolated and restricted population of B. costata has a high priority for conservation. © 2013 The Linnean Society of London     

Landsat TM inventory and assessment of waterbird habitat in the southern <Emphasis Type="Italic">altiplano</Emphasis> of South America

The diverse set of wetlands in southern altiplano of South America supports a number of endemic and migratory waterbirds. These species include endangered endemic flamingos and shorebirds that nest in North America and winter in the altiplano. This research developed maps from nine Landsat Thematic Mapper (TM) images (254,300 km²) to provide an inventory of aquatic waterbird habitats. Image processing software was used to produce a map with a classification of wetlands according to the habitat requirements of different types of waterbirds. A hierarchical procedure was used to, first, isolate the bodies of water within the TM image; second, execute an unsupervised classification on the subsetted image to produce 300 signatures of cover types, which were further subdivided as necessary. Third, each of the classifications was examined in the light of field data and personal experience for relevance to the determination of the various habitat types. Finally, the signatures were applied to the entire image and other adjacent images to yield a map depicting the location of the various waterbird habitats in the southern altiplano. The data sets referenced with a global positioning system receiver were used to test the classification system. Multivariate analysis of the bird communities censused at each lake by individual habitats indicated a salinity gradient, and then the depth of the water separated the birds. Multivariate analysis of the chemical and physical data from the lakes showed that the variation in lakes were significantly associated with difference in depth, transparency, latitude, elevation, and pH. The presence of gravel bottoms was also one of the qualities distinguishing a group of lakes. This information will be directly useful to the Flamingo Census Project and serve as an element for risk assessment for future development.This revised version was published online in March 2005 with corrections to the issue cover date.     

Biomass allocation in herbaceous plants under grazing impact in the high semi-arid Andes

Among the plant traits that affect performance, vitality and herbivore resistance in rangeland vegetation, biomass partitioning ranks top, commonly outweighing processes at single leaves (e.g., photosynthesis, respiration). We explored the allometry of a broad sample of herbaceous species from two high elevation sites in the Andes in order to explain biomass partitioning under harsh climatic conditions and risk of biomass losses under strong camelid grazing pressure. We combined data from NW-Argentina and W-Bolivia from elevations between 4200 and 4250 m in a landscape dominated by tall Festuca orthophylla tussocks and a drought driven seasonality (rainfall only between November and March). Across 10–20 taxa per region we found less investment in leaves with a mean leaf mass fraction of only 11% and instead a massive storage in below-ground compartments (rhizomes, tap roots), particularly at the colder Argentinean site. Though grazing pressure was much greater in Bolivia, the foliage mass fraction was there larger than in Argentina. The inter-tussock space in these open, dry plains (‘pajonal’) was dominated by rosette forming species with a below-ground shoot apex and massive tap roots (70% of all species), rendering these species less sensitive to grazing and trampling. The storage organs of these species represented more than 50% of total biomass. Llamas, which represented the main vertebrate herbivore in these open plains at the Bolivian site, preferred non tap-root herbs and species with low leaf nitrogen concentration. Palatable forbs for llamas (22% of all species at the Bolivian site) only survived when nested (facilitated) in the rigid, tall Festuca orthophylla tussocks or thorny shrubs. In conclusion, these extremely high elevation rangeland herbs invest preferentially in structures for persistence (K-strategy) rather than maximizing carbon gain.     

Threatened fishes of the world: <Emphasis Type="Italic">Trichomycterus chungaraensis</Emphasis> Arratia 1983 (Trichomycteridae)

Trichomycterus chungaraensis is an endemic and endangered fish from the south high Andean plateau; mainly due to its habitat total extension thus has been calculated to be 2,910 m² and inhabiting solely in Mal Paso stream, at the UNESCO Biosphere Reserve and Lauca National Park.     

A modern pollen rain study from the central Andes region of South America

Aim To provide a greater understanding of the modern pollen rain for the central Andes region of South America, thus laying the groundwork for future pollen studies and the derivation of pollen‐climate transfer functions and response surfaces. Location Peru, Bolivia and Chile. Methods Standard palynological techniques for surface soil sampling and discriminant analysis. Results Statistical analysis of the 40 surface samples revealed four palynologically distinct assemblages: (1) the Yungas on the eastern slopes of the Andes; (2) the puna grasslands of the Altiplano; (3) the Coastal Deserts to the west of the Andes; and (4) the Southern Bolivian Highlands. Main conclusions The Yungas group is characterized by high percentages of Urticaceae/Moraceae pollen and fern spores along with trace amounts of pollen from common zoophilous lowland taxa such as Piperaceae, Bignoniaceae and Malpighiaceae. The puna assemblage of the Altiplano is characterized by the dominance of grass (Poaceae) in combination with moderate frequencies of Asteraceae pollen, which tend to increase slightly towards the southern (drier) locations of the Altiplano. Lower percentages of grass pollen and the greater prevalence of Asteraceae, Solanaceae, and the Chenopodiaceae/Amaranthaceae families define the coastal deserts to the west of the Andes. Samples taken from the Southern Bolivian Highlands are characterized by the dominance of Solanaceae in the area, in combination with the pollen of other xerophytic taxa.     

Botanical origin and geographic differentiation of bee-pollen produced in high mountains from the Colombian eastern Andes

In the high mountains of the Colombian Eastern Cordillera (~2000–3000 m above sea level), at the Altiplano Cundiboyacense region and surroundings, beekeepers have specialised in pollen production with substantial harvests all year round. Despite this productive advantage, the knowledge about plants used by honeybees as pollen resources is still limited. Hence, the aim of this work was to identify the botanical origin of bee pollen from this region and to examine differences between five distinguished sub-regions: Sabana de Bogotá, Fúquene, Márquez, Tundama and Norte-Gutiérrez. By means of palynological analyses of 86 pollen samples produced between 2008 and 2010, we found a total amount of 126 pollen types, most of them belonging to the families Asteraceae and Fabaceae. Major pollen types correspond to the exotic taxa Hypochaeris radicata, Brassicaceae, Eucalyptus globulus, Trifolium repens, Trifolium pratense and the native taxa Quercus humboldtii and Weinmannia sp. Differences between sample groups from the five sub-regions were mainly associated to variations in pollen abundance and frequency of native plant species. This result highlights the potential for commercialising bee-pollen from the Colombian Eastern Cordillera with geographical origin differentiation, as well as the importance for beekeeping in promoting the conservation of the natural ecosystems from the region.     

Phylogenetic relationships and taxonomy of Altiplano populations of Biomphalaria (Gastropoda: Planorbidae): inference from a multilocus approach

Isolated closed basins provide a natural laboratory to study the differentiation among wild populations. Here we examined the phylogenetic relationships of the Southern Altiplano populations of Biomphalaria, a genus with medical importance, using nuclear (ITS1, ITS2) and mitochondrial (16S) ribosomal gene markers and a species of Helisoma as outgroup. Phylogenetic trees based on separate and combined analyses show that these populations form a particular lineage within Biomphalaria along with Biomphalaria peregrina (d'Orbigny, 1835) and Biomphalaria oligoza Paraense, 1974. The origin of this clade was estimated to have occurred in the middle Pleistocene. Molecular analyses showed that the nominal species Biomphalaria crequii ( Courty, 1907 ) from the Salar de Ascotán and Biomphalaria costata (Biese, 1951) from the Salar de Carcote, previously synonymized with Biomphalaria andecola (d'Orbigny, 1835) and B. peregrina, respectively, are distinct taxa. Molecular data did not resolve the relationship of Biomphalaria aymara Valdovinos & Stuardo, 1991 from the Isluga swamps to other Biomphalaria species, but confirm that the populations from the Lauca and Huasco basins may represent a distinct undescribed species of Biomphalaria from the Southern Altiplano. Snails examined for trematodes were found to be positive in some Altiplano localities. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 795–808.     

Parallel evolution in the major haemoglobin genes of eight species of Andean waterfowl

Theory predicts that parallel evolution should be common when the number of beneficial mutations is limited by selective constraints on protein structure. However, confirmation is scarce in natural populations. Here we studied the major haemoglobin genes of eight Andean duck lineages and compared them to 115 other waterfowl species, including the bar-headed goose ( Anser indicus ) and Abyssinian blue-winged goose ( Cyanochen cyanopterus ), two additional species living at high altitude. One to five amino acid replacements were significantly overrepresented or derived in each highland population, and parallel substitutions were more common than in simulated sequences evolved under a neutral model. Two substitutions evolved in parallel in the αA subunit of two (Ala-α8) and five (Thr-α77) taxa, and five identical βA subunit substitutions were observed in two (Ser-β4, Glu-β94, Met-β133) or three (Ser-β13, Ser-β116) taxa. Substitutions at adjacent sites within the same functional protein region were also observed. Five such replacements were in exterior, solvent-accessible positions on the A helix and AB corner of the αA subunit. Five others were in close proximity to inositolpentaphosphate binding sites, and two pairs of independent replacements occurred at two different α¹β¹ intersubunit contacts. More than half of the substitutions in highland lineages resulted in the acquisition of serine or threonine (18 gains vs. 2 losses), both of which possess a hydroxyl group that can hydrogen bond to a variety of polar substrates. The patterns of parallel evolution observed in these waterfowl suggest that adaptation to high-altitude hypoxia has resulted from selection on unique but overlapping sets of one to five amino acid substitutions in each lineage.     

High ENSO sensitivity in tree rings from a northern population of Polylepis tarapacana in the Peruvian Andes

Polylepis tarapacana is the highest-elevation tree species worldwide growing between 4000 and 5000 m a.s.l. along the South American Altiplano. P. tarapacana is adapted to live in harsh conditions and has been widely used for drought and precipitation tree-ring based reconstructions. Here, we present a 400-year tree-ring width (TRW) chronology located in southern Peru (17ºS; 69ºW) at the northernmost limit of P. tarapacana tree species distribution. The objectives of this study are to assess tree growth sensitivity of a northern P. tarapacana population to (1) precipitation, temperature and El Niño Southern Oscillation (ENSO) variability; (2) to compare its growth variability and ENSO sensitivity with southern P. tarapacana forests. Our results showed that this TRW record is highly sensitive to the prior summer season (Nov-Jan) precipitation (i.e. positive correlation) when the South American Summer Monsoon (SASM) reaches its maximum intensity in this region. We also found a positive relationship with current year temperature that suggests that radial growth may be enhanced by warm, less cloudy, conditions during the year of formation. A strong positive relationship was found between el Niño 3.4 and tree growth variability during the current growing season, but negative during the previous growth period. Growth variability in our northern study site was in agreement with other populations that represent almost the full range of P. tarapacana latitudinal distribution (~ 18ºS to 23ºS). Towards the south of the P. tarapacana TRW network there was a decrease in the strength of the agreement of growth variability with our site,with the exception of higher correlation with the two southeastern sites. Similarly, the TRW chronologies recorded higher sensitivity to ENSO influences in the north and southeastern locations, which are wetter, than the drier southwestern sites . These patterns hold for the entire period, as well as for periods of high and low ENSO activity. Overall, P. tarapacana tree growth at the north of its distribution is mostly influenced by prior year moisture availability and current year temperature that are linked to large-scale climate patterns such as the SASM and ENSO, respectively.