Occupation of the Antarctic continent by petrels during the past 35 000 years: Inferences from a 14C study of stomach oil deposits

Summary The dated material was taken from organic deposits occurring in snow petrel colonies of the Untersee Oasis, central Queen Maud Land, East Antarctica. These deposits have been formed by accumulation and solidification of stomach oil regurgitated by petrels over a long time period. Within the deposits the ¹⁴C ages tend to increase with depth. Local mixing and irregular ¹⁴C profiles are of minor importance. This confirms the suitability of such material for ¹⁴C dating. According to the ¹⁴C chronology the colonies near Lake Untersee have been continuously occupied at least during the past 8 kyr. Surprisingly old ages for three samples, namely 13.8, 18.4 and 33.9 kyr BP, suggest that breeding colonies must have been in the study area during the last glacial maximum. Information about the minimum age of moraines and the timing of local ice retreat can be obtained from a correlation between the oldest ¹⁴C age of the organic material accumulated on moraines and the altitude of the sample site.     

Trichomycetes living in the guts of aquatic insects of Misiones and Tierra del Fuego, Argentina

Fourteen species of Trichomycetes living in the guts of aquatic insects are reported from two provinces of Argentina, Misiones and Tierra del Fuego. Twelve of the species belong to the Harpellales and two are Amoebidiales. Five harpellid species are reported from Misiones in the extreme northeast of the country (Genistellospora homothallica, Harpella tica, Smittium culisetae, Smittium sp., Stachylina sp.) and seven are from Tierra del Fuego, the southern tip of South America (H. meridianalis, Glotzia sp., S. culicis, S. cellaspora, S. imitatum, Stachylina minima, Penella simulii). Insect hosts all were immature stages of Culicidae, Simuliidae, Chironomidae, Ceratopogonidae (Insecta: Diptera), and Ephemeroptera and Plecoptera. The lower diversity of Trichomycetes found at Misiones, which has a subtropical climate and rainforest vegetation, was due possibly to the warmer temperatures of the water (15-24 C), compared to the colder streams of Tierra del Fuego (9-15 C), with forests and steppes as typical vegetation.     

Extreme high lichen growth rates detected in recently deglaciated areas in Tierra del Fuego

The goals of this study were to accurately determine the annual growth rate of two key lichen species for lichenometric studies in Tierra del Fuego and to provide more information on recent glacial evolution in the southernmost mountain range of South America. The study site was located on recent moraines deposited in front of a terminus of Pia Glacier in the East Arm of Pia Bay, a fjord of the Beagle Channel. Lichenometric measurements were made of the maximum and minimum axes on the five largest thalli of Rhizocarpon geographicum and Placopsis perrugosa at selected localities in the recently deglaciated area. Average growth rates were estimated from dated surfaces to be 0.63 mm year⁻¹ for R. geographicum and of 9.0 mm year⁻¹ for P. perrugosa. However, maximum growth rate of individual thalli of P. perrugosa could be as high as about 20 mm year⁻¹ increase in diameter directly measured from comparison between pictures taken over a 2-year interval. Both species had an almost linear increase in diameter size with the age of the rock surfaces and the distance from the glacier. The rapid colonization and growth of the lichens is mirrored by the higher plants with ecesis for Nothofagus trees being estimated at 4 years and height growth elongation at 30 cm year⁻¹.     

Late and postglacial vegetation and fire history in Southern Patagonia and Tierra del Fuego

Two 17,000-yr-old peat bog records from low-elevation sites in Tierra del Fuego (Harberton, 54°54′S) and southern Patagonia (Río Rubens, 52°4′48″S) and one c. 14,000 cal yr BP record from the upper treeline in Tierra del Fuego (Paso Garibaldi, 54°43′S) were analyzed for pollen, charcoal, and plant macrofossils to reconstruct changes in regional and local vegetation, fire frequency, and bog hydrology, respectively. Past environmental changes in both lowland records and in the upper treeline record are interpreted in terms of variations in effective moisture. During the late-glacial period, effective moisture changes at both low and high-elevation sites were interpreted from comparable shifts between mesic herb-rich grasslands and arid Empetrum heath or shrub-grassland with abundant disturbance indicators. The late-glacial effective moisture changes were primarily driven by temperature changes. During the early Holocene, expansion of open Nothofagus woodlands in the lowlands in present-day areas of dense forest was related to a marked precipitation increase. However, precipitation must have remained highly variable with century-long periods of increased summer drought, as evidenced by repeated intervals when bogs dried out and fire frequency was high. Up-slope shifts of the Nothofagus forest — Andean tundra ecotone at 11,000 and 9000 cal yr BP also appear to reflect precipitation increases. Precipitation variability, however, must not have affected the upper treeline environments as no fires were recorded and the present-day Nothofagus forest had become established after 9000 cal yr BP. Upper treeline apparently was below present from 8000 to 7000 and 2500 to c. 400 cal yr BP. During those times low-elevation environments did not register change which suggests that the upper treeline may have been affected by lower temperatures. After c. 5000 cal yr BP fires became rare in the lowlands, suggesting a shift to an equable precipitation regime with only minor intervals of summer drought. No simultaneous change was recorded at the upper treeline. Thus, for the late-glacial and early Holocene the upper and lower treeline environments apparently responded similarly to primarily moisture changes. Only during the mid- and late Holocene environmental changes at high and low elevations differed, suggesting responses to different climate signals, precipitation in the lowlands and temperature at high elevation.     

Gastrointestinal helminths of Commerson's dolphins Cephalorhynchus commersonii from central Patagonia and Tierra del Fuego.

The stomachs and intestines of 9 Commerson's dolphins incidentally caught in trawl nets in central Patagonia and 23 stranded on beaches in Tierra del Fuego were surveyed for helminth parasites. A total of 267 individuals belonging to 4 species of parasites (1 nematode, 3 digeneans) were found in the dolphins from the first area: Anisakis sp. (larvae type 1 = A. simplex), Braunina cordiformis, Hadwenius sp. and Pholeter gastrophilus. In the Tierra del Fuego dolphins, 142 specimens belonging to 3 species (2 nematodes, 1 digenean, 1 cestode) were found: A. simplex, Hadwenius sp. and Strobilocephalus triangularis. Only 2 of the helminth species were shared in the 2 study areas, A. simplex and Hadwenius sp., and both were more common in central Patagonia. Among the species, A. simplex was most prevalent and abundant in both study areas. In Tierra del Fuego, adults of A. simplex appeared in only 1 host. Hadwenius sp., P. gastrophilus and S. triangularis are new host records for Commerson's dolphin. Species diversity and species richness were low in both study areas. Helminth communities were more diverse in central Patagonia (t = 1.97, df = 258, p < 0.05) and species richness was higher in central Patagonia (S = 4). No differences in diversity were observed between females and males of central Patagonia (t = 1.97, df = 139, p < 0.05) and between females of central Patagonia and Tierra del Fuego. The results may suggest some differences in habitat use, diet and sex between Commerson's dolphin populations in the 2 study areas.     

Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina

Vigna, M. S. & Kristiansen, J. 1995. Mallomonas fuegiana (Synurophyceae), a new species of silica scaled chrysophytes from Tierra del Fuego, Argentina. — Nord. J. Bot. 15: 439–442. Copenhagen. ISSN 0107–055X.
During the research project "Cryptogamic Flora of Tierra del Fuego", a new species of Mallomonas has been found. It is described here as M. fuegiana , and is placed in the section Torquatae , close to Mallomonas schwemmlii and M. dickii .     

How long can glacier foreland species live?

Age determinations provide information on longevity of the species and on their population structure. This knowledge is of particular interest for species involved in succession. On a glacier foreland of the Central Alps age determinations of six target species (Saxifraga oppositifolia, Oxyria digyna, Artemisia mutellina, Anthyllis vulneraria ssp. alpestris, Trifolium pratense ssp. nivale and Helianthemum grandiflorum) were carried out by means of herbchronology. The species were selected on three differently aged moraines in order to compare pioneer, early and late successional species. Pioneer species were expected to have young, invasive populations. This was suggested also for populations of late successional species growing towards the glacier front where they substitute the pioneer species. These hypotheses were only confirmed for the pioneer Saxifraga oppositifolia. The longest life span was found for Helianthemum grandiflorum on the oldest moraine. Plant size of all investigated individuals correlated with age. Significant differences where observed between the age of vegetative and generative individuals.     

Craniometric analysis in groups from tierra del Fuego/Patagonia and the peopling of the south extreme of the Americas

Five large craniometric samples from extinct tribes (Selk’nam, Kawéskar and Yámana) from Tierra del Fuego and from Patagonia have been analyzed through multivariate techniques. The purpose was to test the hypothesis of one or two different migration waves in the peopling of the south extreme of South America. A cluster analysis has been made, using the squared Euclidean distance as a measure of proximity, and the UPGMA and neighbor joining algorithms as a tree building method. The robustness of the branches has been assessed with bootstrap analysis through 100 random iterations of the original data set. Results show that, despite their cultural differences, the three hunter-gatherer groups. from Tierra del Fuego tend to cluster together, indicating a similar morphological pattern. This suggests that geographic distance (in latitudinal sense) is the main factor that influenced the differentiation of the human groups from Tierra del Fuego and Patagonia, from a single ancestral population.     

Microbial diversity in the snow,a moraine lake and a stream in Himalayan glacier

The microbial diversity and abundance in surface snow at different altitudes (5300 and 5504 m above sea level), a moraine lake and a glacial stream in the Yala Glacier on the southern slope of the Himalayas were investigated through a 16S rRNA gene clone library and flow cytometry approaches. Cell abundance in different habitats changed from 1.1 × 10⁴ to 25 × 10⁴ cells mL⁻¹, with the highest abundance in the moraine lake and the lowest abundance in the snow at 5504 m. Microbial communities in the snow were significantly different from those in the moraine lake and stream, although they were similar within snow and within the aquatic habitats. The two snow libraries were both dominated by Cyanobacteria, which accounted for about half of the total, followed by the Alphaproteobacteria and Firmicutes. The moraine lake and stream libraries were dominated by the Bacteroidetes and Betaproteobacteria, followed by the Actinobacteria. The results indicated that snow and water were highly diverse systems even in the same glacier. Microbial communities in the snow on the Yala Glacier were distinctly different from those in the East Rongbuk Glacier on the northern slope of Himalayas. However, microbes in the moraine lakes at two glaciers had similar community features. The snow habitat was easily affected by various environmental factors, while the aquatic habitats were comparatively stable in different glaciers.     

Historical ecology and current abundance of the translocated Chilla or Grey fox Lycalopex griseus on the large Tierra del Fuego Island shared by Argentina and Chile

In 1951, a batch of 24 young animals of both sexes of Chilla or Grey fox Lycalopex griseus from continental Magallanes region, Chile – and perhaps also from adjacent continental Argentina – were released at Onaisin (65 km ESE Porvenir town, 53°18′S) on Tierra del Fuego Island in southernmost South America, to control a European rabbit (Oryctolagus cuniculus) irruption that was considered detrimental to sheep (Ovis aries) ranching. Up to now, no attention has been paid to the temporal course of that introduction. Here we provide a historical account of the presence of foxes on the Tierra del Fuego Archipelago, starting with Charles Darwin account of 1839 until present. We also review the regulatory framework concerning hunting of those foxes and tally their culling for export of pelts. Finally, we provide estimates of the abundance of Chilla foxes on Tierra del Fuego Island for the period 1999–2007 and for 2021, and highlight their current spread. These translocated foxes have become an abundant and functional part of both steppe and forest ecosystems on the Fuegian archipelago, even though they are killed by hunters, without spatial, temporal, or numerical limits. We conclude that interesting scientific opportunities are being missed regarding the population genetics of a species that may have left founding effects and genetic bottlenecks in Tierra del Fuego, and perhaps some peculiar continental markers among the island population. We also raise the question whether this introduced native species may be deemed invasive, calling for research to determine its impact in its new environment.     

Propiedades tafonómicas de las asociaciones óseas de pinnípedos en la costa atlántica de la Isla Grande de Tierra del Fuego, Argentina

A preliminary comparative study of pinniped bone assemblages from Late Holocene archaeological sites and from present day deposits on the Atlantic coast of Isla Grande de Tierra del Fuego is presented. The aim is to assess the properties distinguishing bone accumulations of these marine mammals formed by human activity and those formed by natural processes. The evidence suggests that anthropic assemblages differ from natural ones in a number of properties, such as anatomical composition and integrity and of the age profile of the individuals represented, and they look alike in other respects, such as bone specimen fragmentation.     

Relationships between floristic gradients in a primary succession

Abstract. Correlations between five floristic gradients at small spatial extents (10 - 20 m) and one successional gradient over a larger spatial extent (1.5 km) are analysed. Floristic data (62 taxa) were sampled on five terminal moraines of known age deposited after the ‘Little Ice Age’ (1750–1930). The floristic gradients on the moraine ridges were sampled by two or three transects on each moraine, and the successional gradient by 114 plots on all moraines. The sequential orders of species were determined by constrained and unconstrained Correspondence Analysis. The similarities between species order on the successional gradient and the exposure gradients at the same age were tested against the null hypothesis of no correlation. The null hypothesis was rejected using both Monte Carlo permutation tests and Spearman's rank correlations, except on the oldest moraine. Here a closed canopy has developed, which eliminates the environmental variability associated with ridge morphology. The similarity between the successional gradient and the moraine-ridge gradients is attributed to variation in environmental severity, mainly caused by glacier wind and related factors such as temperature and moisture. Similarity was highest on the moraines in the middle of the glacier foreland, which have many successional stages present and have a relatively exposed relief. The distribution of growth/life-forms along gradients of small spatial extent are comparable to the successional gradient, but lichens, herbs and graminoids differ in their behaviour. The resemblance between species gradients at a small spatial extent and species gradients on a larger spatial extent is interpreted as an ecological self-similar pattern, where young and old substrate are linked to exposed-xeric and protected-mesic habitats, respectively.     

Pleistocene refugia and polytopic replacement of diploids by tetraploids in the Patagonian and Subantarctic plant Hypochaeris incana (Asteraceae, Cichorieae)

We report the phylogeographic pattern of the Patagonian and Subantarctic plant Hypochaeris incana endemic to southeastern South America. We applied amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and 32 populations, respectively, throughout its distributional range and assessed ploidy levels using flow cytometry. While cpDNA data suggest repeated or simultaneous parallel colonization of Patagonia and Tierra del Fuego by several haplotypes and/or hybridization, AFLPs reveal three clusters corresponding to geographic regions. The central and northern Patagonian clusters (∼38–51° S), which are closer to the outgroup, contain mainly tetraploid, isolated and highly differentiated populations with low genetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (∼51–55° S) contains mainly diploid populations with high genetic diversity and connected by high levels of gene flow. The data suggest that H. incana originated at the diploid level in central or northern Patagonia, from where it migrated south. All three areas, northern, central and southern, have similar levels of rare and private AFLP bands, suggesting that all three served as refugia for H. incana during glacial times. In southern Patagonia and Tierra del Fuego, the species seems to have expanded its populational system in postglacial times, when the climate became warmer and more humid. In central and northern Patagonia, the populations seem to have become restricted to favourable sites with increasing temperature and decreasing moisture and there was a parallel replacement of diploids by tetraploids in local populations.     

12. Bipolarity in the distribution of silica-scaled chrysophytes

An investigation of the chrysophyte flora of Tierra del Fuego (Argentina), 54–55 °S., has shown a high degree of similarity with the flora of climatically comparable regions on the northern hemisphere. All the Fuegian species (except two endemic to South America) also occur on the northern hemisphere—some are more or less cosmopolitan, others have pronounced bipolar distributions. Species in common with other Antarctic regions such as Tasmania are all cosmopolitan, and none of the interesting species originally described from Tasmania occur in Tierra del Fuego. Thus the Fuegian flora appears to be mainly climatically determined and a special Antarctic chrysophyte flora does not exist.     

Bryophyte-Cyanobacteria Associations during Primary Succession in Recently Deglaciated Areas of Tierra del Fuego (Chile)

Bryophyte establishment represents a positive feedback process that enhances soil development in newly exposed terrain. Further, biological nitrogen (N) fixation by cyanobacteria in association with mosses can be an important supply of N to terrestrial ecosystems, however the role of these associations during post-glacial primary succession is not yet fully understood. Here, we analyzed chronosequences in front of two receding glaciers with contrasting climatic conditions (wetter vs drier) at Cordillera Darwin (Tierra del Fuego) and found that most mosses had the capacity to support an epiphytic flora of cyanobacteria and exhibited high rates of N₂ fixation. Pioneer moss-cyanobacteria associations showed the highest N₂ fixation rates (4.60 and 4.96 µg N g⁻¹ bryo. d⁻¹) very early after glacier retreat (4 and 7 years) which may help accelerate soil development under wetter conditions. In drier climate, N₂ fixation on bryophyte-cyanobacteria associations was also high (0.94 and 1.42 µg N g⁻¹ bryo. d⁻¹) but peaked at intermediate-aged sites (26 and 66 years). N₂ fixation capacity on bryophytes was primarily driven by epiphytic cyanobacteria abundance rather than community composition. Most liverworts showed low colonization and N₂ fixation rates, and mosses did not exhibit consistent differences across life forms and habitat (saxicolous vs terricolous). We also found a clear relationship between cyanobacteria genera and the stages of ecological succession, but no relationship was found with host species identity. Glacier forelands in Tierra del Fuego show fast rates of soil transformation which imply large quantities of N inputs. Our results highlight the potential contribution of bryophyte-cyanobacteria associations to N accumulation during post-glacial primary succession and further describe the factors that drive N₂-fixation rates in post-glacial areas with very low N deposition.     

Taxonomy, variation, and relationships in the Hordeum parodii group (Poaceae)

The Hordeum parodii group contains three species, viz. H. parodii Covas (6x), H. tetraploidum Covas (4x), and H. fuegianum Bothmer, Jacobsen, et Jørgensen, sp. nov. (4x). The former two species mainly occur in C and S Argentina, while H. fuegianum is native to Tierra del Fuego. All three species are probably of alloploid origin. Morphological, isoenzyme variation and cytogenetic data are presented.     

Human colonization of the central territory of Argentina: design matrix models and craniometric evidence

In this study we test several hypotheses about the peopling of the central territory of Argentina, archaeologically known as Sierras Centrales, by testing the association between four alternative models of the peopling of the area and cranial morphological variation through distance and matrix correlation analyses. Our results show that the ancient inhabitants of Sierras Centrales demonstrated close morphological similarities with the Patagonian and Tierra del Fuego populations. Moreover, the correlation and partial correlation analyses suggest that the peopling of the Sierras Centrales most likely took place as a migratory wave proceeding from the present area of Northeastern Argentina, and continued southward to Patagonia and Tierra del Fuego.     

First Quaternary fossil record of Polyplacophorans from southern South America

A diverse assemblages of well-preserved polyplacophoran shell plates is present in Holocene marine deposits along the Beagle Channel, Tierra del Fuego (54°S). They represent the first fossil Quaternary report of polyplacophorans from southern South America. The taxa include Callochiton puniceus (Couthouy MS, Gould), Plaxiphora aurata (Spalowsky), Plaxiphora sp., Tonicia atrata (Sowerby), Tonicia calbucensis Plate, Tonicia chilensis (Frembly), and Tonicia lebruni de Rochebrune. The presence of these taxa in a transitory area between the Atlantic and the Pacific oceans suggests that, in the recent past, the Beagle Channel acted as a path that facilitated faunal dispersion between the two oceans. These records also show an apparent stability of these faunas over a period of several thousand years (from ca. 7500 years BP to present).     

Mitochondrial DNA variation and population structure of Commerson’s dolphins (<Emphasis Type="Italic">Cephalorhynchus commersonii</Emphasis>) in their southernmost distribution

The Commerson’s dolphin, Cephalorhynchus commersonii, is found in shallow waters of the continental shelf off the eastern coast of South America between 40°S and 56°S. This species is taken incidentally in artisanal gillnet fisheries, especially along the shallow coastline of northern Tierra del Fuego and southern Patagonia. The biological importance of by-catch is likely to be underestimated if the boundaries of subpopulations are not properly defined. Here, we report on the sequence variation of the mitochondrial DNA control region of the Commerson’s dolphin from five areas defined in Tierra del Fuego, Argentina and Chile, to provide a preliminary assessment of population structure where conservation efforts are most needed. A 466 bp fragment of the mitochondrial DNA control region was sequenced from 196 samples of skin, teeth and bone, defining 20 haplotypes from 17 polymorphic sites. Nucleotide (π = 0.40%) and haplotype (h = 0.807) diversity were low compared to some other odontocete populations, but similar to that of other species of this genus. Genetic differentiation evaluated through analyses of molecular variance (AMOVA) showed significant overall differences among areas within Tierra del Fuego (Φ _ST  = 0.059, P < 0.01). An analysis of sex-specific population structure suggested that the dispersal rates of both females and males are low, indicative of females displaying greater site fidelity. The results from mtDNA control region sequences alone revealed significant differentiation among studied areas, which should be considered as independent management units. We recommend that the impact of localized gillnet mortalities should be managed on a local scale in these areas of Tierra del Fuego.