Hybridization and Back-Crossing in Giant Petrels (Macronectes giganteus and M. halli) at Bird Island,South Georgia,and a Summary of Hybridization in Seabirds

Hybridization in natural populations provides an opportunity to study the evolutionary processes that shape divergence and genetic isolation of species. The emergence of pre-mating barriers is often the precursor to complete reproductive isolation. However, in recently diverged species, pre-mating barriers may be incomplete, leading to hybridization between seemingly distinct taxa. Here we report results of a long-term study at Bird Island, South Georgia, of the extent of hybridization, mate fidelity, timing of breeding and breeding success in mixed and conspecific pairs of the sibling species, Macronectes halli (northern giant petrel) and M. giganteus (southern giant petrel). The proportion of mixed-species pairs varied annually from 0.4–2.4% (mean of 1.5%), and showed no linear trend with time. Mean laying date in mixed-species pairs tended to be later than in northern giant petrel, and always earlier than in southern giant petrel pairs, and their breeding success (15.6%) was lower than that of conspecific pairs. By comparison, mixed-species pairs at both Marion and Macquarie islands always failed before hatching. Histories of birds in mixed-species pairs at Bird Island were variable; some bred previously or subsequently with a conspecific partner, others subsequently with a different allospecific partner, and some mixed-species pairs remained together for multiple seasons. We also report the first verified back-crossing of a hybrid giant petrel with a female northern giant petrel. We discuss the potential causes and evolutionary consequences of hybridization and back-crossing in giant petrels and summarize the incidence of back-crossing in other seabird species.     

Monitoring of a Southern Giant Petrel Macronectes giganteus population on the Frazier Islands, Wilkes Land, Antarctica

Since 1956, Southern Giant Petrels on the Frazier Islands, East Antarctica, have been counted with different census techniques, sometimes varying within seasons and among islands, which hindered analysis of the data. Protective measures for the islands from 1986 onwards have increased the need for reliable long-term census data, but reduced the ways to collect these data. Published and unpublished data were re-examined, and population trends were reconstructed based on two relatively standardised techniques: the number of active chicks (AC) and the number of apparently occupied nests (AON) around hatching. AC-values from Nelly Island from 1959 to 1998 indicate substantial periodic fluctuations, but no consistent long-term change. Since the late 1970s, AC-values on the other two islands and AON-values suggest that the breeding population may have grown by 35%. This recent growth, however, is within the extent of periodic fluctuations observed in Southern Giant Petrel population that is stable over the long term.     

First Record of Undaria Pinnatifida (Laminariales, Phaeophyta) in Southern Patagonia, Argentina

The Japanese kelp Undaria pinnatifida was found on 7th September 2005 in Ría Deseado (Santa Cruz, Argentina). This invasive algae was registered from the lower intertidal to the upper levels of the subtidal zone. The sporophytes were fixed to slabs, gravel and rocks of variable sizes and were also present as epibionts of tunicates. The sporophytes total length ranged between 3 and 88 cm, with a mean of 28.75 cm in the intertidal and 38.3 cm in the subtidal. The density and biomass increased from the intertidal to the subtidal. The kelp population showed a higher number of small immature individuals in the intertidal than␣subtidal where the organisms were bigger and with more individual biomass. This first record of U. pinnatifida in Southern Patagonia extends its southern distribution limit in Argentina, showing progressive expansion in the southwestern Atlantic. More surveys must be conducted to understand the evolution of U. pinnatifida invasion and its impact on the native benthic community.     

Hardly hard-hearted: heart rate responses of incubating Northern Giant Petrels (Macronectes halli) to human disturbance on sub-Antarctic Marion Island

Guidelines for visitors to sub-Antarctic Marion Island recommend 15 and 100 m minimum approach distances for breeding Northern (Macronectes halli) and Southern (Macronectes giganteus) Giant Petrels, respectively. Using artificial eggs containing FM transmitters, we measured the heart rate responses of incubating Northern Giant Petrels to pedestrian approaches. The mean resting heart rate was 80 beats per minute. Heart rates increased upon the detection of a person approximately 40 m away, and continued to increase during the approach to 5 m. Maximum increases over resting heart rate in response to natural disturbances and human approach were 97 and 204%, respectively. Northern Giant Petrels appear at least as sensitive to human disturbance as their congenerics. While low-key disturbance is unlikely to affect this solitary breeder as severely as it would the colonial Southern Giant Petrel, improved protection from disturbance could be achieved by restricting human passage through breeding colonies of Northern Giant Petrels to defined paths.     

Avian cholera in a southern giant petrel (Macronectes giganteus) from Antarctica

A southern giant petrel (Macronectes giganteus) was found dead at Potter Peninsula, King George Island, South Shetland, Antarctica. The adult male was discovered approximately 48 hr after death. Macroscopic and microscopic lesions were compatible with avian cholera and the bacterium Pasteurella multocida subsp. gallicida, serotype A1 was isolated from lung, heart, liver, pericardial sac, and air sacs. In addition, Escherichia coli was isolated from pericardial sac and air sacs. This is the first known report of avian cholera in a southern giant petrel in Antarctica.     

Increased litter decomposition rates of exotic invasive species Hieracium pilosella (Asteraceae) in Southern Patagonia,Argentina

Plant Ecology - Plant invasions can affect key ecosystem processes regulating carbon and nutrient balances, i.e., litter decomposition. Exotic herb Hieracium pilosella (hawkweed, Asteraceae)...     

Notes on Erysiphales (Ascomycetes) from Patagonia, Argentina

Fifteen Erysiphaceous taxa found on 20 host plant species in Patagonia are documented. A new species Oidium maculatae (type host: Viola maculata) is described. Berberis linearifolia, Buddleja globosa, Prosopis alpataco and Viola maculata, are new host plants for Erysiphales. Three new combinations on fungi and host plant species were founded: Erysiphe howeana – Fuchsia magellanica; E. patagoniaca – Nothofagus pumilio and N. antarctica. The genus Sawadaea and the species S. bicornis on Acer negundo and A. pseudoplatanus, are new records for South America. New host plants recorded for Argentina: Consolida ajacis, Galega officinalis and Plantago lanceolata. New host plants recorded for Patagonia: Galium aparine, Melilotus albus, Petunia × hybrida, Potentilla anserina, and Spiraea × bumalda. Oidium longipes is a new record for Argentina and Golovinomyces riedlianus is a new record for Patagonia.     

Environmental Niche Overlap between Common and Dusky Dolphins in North Patagonia,Argentina

Research on the ecology of sympatric dolphins has increased worldwide in recent decades. However, many dolphin associations such as that between common dolphins (Delphinus delphis) and dusky dolphins (Lagenorhynchus obscurus) are poorly understood. The present study was conducted in the San Matías Gulf (SMG) ecosystem (North Patagonia, Argentina) where a high diet overlap among both species was found. The main objective of the present work was to explore the niche overlap of common and dusky dolphins in the habitat and temporal dimensions. The specific aims were (a) to evaluate the habitat use strategies of both species through a comparison of their group attributes (social composition, size and activity), and (b) to evaluate their habitat preferences and habitat overlap through Environmental Niche modeling considering two oceanographic seasons. To accomplish these aims, we used a historic database of opportunistic and systematic records collected from 1983 to 2011. Common and dusky dolphins exhibited similar patterns of group size (from less than 10 to more than 100 individuals), activity (both species use the area to feed, nurse, and copulate), and composition (adults, juveniles, and mothers with calves were observed for both species). Also, both species were observed travelling and feeding in mixed-species groups. Specific overlap indices were higher for common dolphins than for dusky dolphins, but all indices were low, suggesting that they are mainly segregated in the habitat dimension. In the case of common dolphins, the best habitats were located in the northwest of the gulf far from the coast. In the warm season they prefer areas with temperate sea surface and in the cold season they prefer areas with relatively high variability of sea surface temperature. Meanwhile, dusky dolphins prefer areas with steep slopes close to the coast in the southwestern sector of the gulf in both seasons.     

Relevance of forage fish in the diet of Magellanic penguins breeding in northern Patagonia,Argentina

We quantified the trophic niche of Magellanic penguins (Spheniscus magellanicus) breeding and moulting in Golfo San Jorge, Argentina, through conventional stomach content and stable isotope analysis. A total of 112 adults were flushed during the early and late chick stages of 2011 and 2012 at Isla Vernacci Norte, and at least 15 prey taxa were found, including fishes, cephalopods, crustaceans and polychaetes. Overall, Argentine anchovy (Engraulis anchoita) showed the highest contribution in terms of importance by mass (68.1–85.3%, depending on chick stage and year), except for the old chick stage in 2011 when the shortfin squid (Illex argentinus) was the main prey consumed (56.0%). Based on carbon and nitrogen isotopic values from a total of 256 blood samples, corresponding to young and old chicks and to adults of both sexes sampled throughout the incubation, chick and moult stages at the above mentioned colony and years, Bayesian mixing model outputs showed that Argentine anchovy was always the main prey (48–86%). Bayesian mixing model outputs obtained from adults of both sexes and their chicks during the late chick stage of 2013 at Isla Vernacci Norte, Isla Tova and Isla Leones also showed that Argentine anchovy was the main prey consumed. This is the first comprehensive assessment of Magellanic penguin diet composition in northern Patagonia, quantifying the relative contribution of prey in the diet of adults and chicks at different stages of the annual cycle and years, and confirms the relevance of a forage fish such as the Argentine anchovy in its trophic ecology.     

Seasonal and spatial distribution of stoneflies in the Chubut River (Patagonia, Argentina)

Longitudinal and seasonal distributions of Plecoptera species were examined along the Chubut River in the Patagonian Precordillera and Plateau, Argentina. Chubut River (>1000 km) is the largest river in the area and the hydrological regime is modified in the lower section by an artificial reservoir (Florentino Ameghino Dam). Quantitative samples were collected in 13 sites in the higher, middle, and lower sections of the river basin. Sites were visited four times during 2004, and a total of nine species and 5772 individuals were collected in the study. Plecoptera richness decreased dramatically from the headwaters to the mouth of the river system. Two species, Antarctoperla michaelseni and Potamoperla myrmidon, were able to live below the impoundment but they were not abundant. Notoperlopsis femina and A. michaelseni abundances were higher in summer than in the other seasons, while Limnoperla jaffueli peaked in spring. Species–environmental relationships were examined using Canonical Correspondence Analysis and six independent variables were identified as the major factors structuring stoneflies assemblages. First axis was highly related to environmental variables reflecting the hydro-geological and land use gradients in the basin (conductivity, total suspended solids, periphyton Chlorophyll a). Second axis was more related to variables that changed seasonally (wet width, water temperature and soluble reactive phosphate).     

AFLP characterization of natural populations of Berberis (Berberidaceae) in Patagonia, Argentina

 AFLP markers were used to analyse the intra- and interspecific relationships among 22 natural populations of 13 Patagonian species of Berberis and the relationships among the taxa belonging to homoploid and polyploid complexes. Seven primer combinations gave rise to 231 AFLP bands, of which 199 were polymorphic. Correspondence between AFLP data, morphological traits and seed protein bands was also assessed. The dendrogram inferred from AFLP fingerprints showed that, in general, populations of the same species formed closely related groups with high coefficients of similarity. Principal co-ordinates analysis showed two separate subgroups: (i) B. bidentata and their putative ancestors –B. darwinii and B. linearifolia– which form a homogamic group, and (ii) B. buxifolia, B. heterophylla and B. parodii– which could form a polyploid hybrid complex. Received March 21, 2001 Accepted September 11, 2001     

Fossil moonseeds from the Paleogene of West Gondwana (Patagonia,Argentina)

Premise of the Study

The fossil record is critical for testing biogeographic hypotheses. Menispermaceae (moonseeds) are a widespread family with a rich fossil record and alternative hypotheses related to their origin and diversification. The family is well‐represented in Cenozoic deposits of the northern hemisphere, but the record in the southern hemisphere is sparse. Filling in the southern record of moonseeds will improve our ability to evaluate alternative biogeographic hypotheses.

Methods

Fossils were collected from the Salamanca (early Paleocene, Danian) and the Huitrera (early Eocene, Ypresian) formations in Chubut Province, Argentina. We photographed them using light microscopy, epifluorescence, and scanning electron microscopy and compared the fossils with similar extant and fossil Menispermaceae using herbarium specimens and published literature.

Key Results

We describe fossil leaves and endocarps attributed to Menispermaceae from Argentinean Patagonia. The leaves are identified to the family, and the endocarps are further identified to the tribe Cissampelideae. The Salamancan endocarp is assigned to the extant genus Stephania. These fossils significantly expand the known range of Menispermaceae in South America, and they include the oldest (ca. 64 Ma) unequivocal evidence of the family worldwide.

Conclusions

Our findings highlight the importance of West Gondwana in the evolution of Menispermaceae during the Paleogene. Currently, the fossil record does not discern between a Laurasian or Gondwanan origin; however, it does demonstrate that Menispermaceae grew well outside the tropics by the early Paleocene. The endocarps’ affinity with Cissampelideae suggests that diversification of the family was well underway by the earliest Paleocene.     

Palynological characterization of honeys from the Andean Patagonia (Chubut,Argentina)

The pollen content of 58 honey samples of Apis mellifera L. from the Andean region of Chubut (Argentinian Patagonia) was analyzed. The samples were provided by beekeepers between 1999 and 2004. Eighty‐eight pollen types were identified, 30 of them are not reported in Argentinian honeys. Identified types belong to 47 families, of which the most diverse were Asteraceae (15 pollen types), Fabaceae (13 pollen types), and Rosaceae (four pollen types). From the samples analyzed, 47% were monofloral and corresponded to the following taxa: Trifolium spp. (16%), Rosaceae (10%), Aristotelia chilensis (Molina) Stuntz (7%), Discaria‐Colletia (5%), Escallonia spp. (3%), Schinus patagonica (Phil.) I. M. Johnst. (2%), Phacelia secunda J. F. Gmel. (2%), Myrtaceae (2%). The results of this study show a high level of utilization of native flora by Apis mellifera. Four new types of monofloral honey were recognized: Aristotelia chilensis, Discaria‐Colletia, Phacelia secunda, and Schinus patagonica. The high representation of native flora distinguishes these honeys geographically.     

Fruit Mineral Contents of Six Wild Species of the North Andean Patagonia, Argentina

The fruit mineral contents (K, Ca, Ba, Br, Zn, Co, Cr, Fe, Na, Rb, Cs, and Sr) of four native and two exotic naturalized shrubs growing in different areas of the Andean Patagonian region of Argentina were investigated. Native species Berberis darwinii, Berberis microphylla (Berberidaceae), Aristotelia chilensis (Elaeocarpaceae) and Ribes magellanicum (Saxifragaceae) produce small berries while the fruits of the exotic species Rosa rubiginosa and Rosa canina (Rosaceae) are aggregates of aquenes. They are used to prepare jams, tea, liquors, and ice creams. Native shrub fruits had higher content of Br, Zn, Co, Cr, Fe, Mo, and Na than those of the exotic naturalized species. Rosa species showed the highest contents of Ca and Ba in their fruits (the mean content doubled those of the native plant fruits). The fruit nutrient content found in the studied species was similar or higher than other values reported for fruits of temperate and tropical species in the world.     

Population trends,distribution and conservation status of semi-domesticated reindeer (Rangifer tarandus) in China

The reindeer (Rangifer tarandus tarandus) is listed as a species of “least concern” on the Red List of Threatened Species of the World Conservation Union (IUCN). It is distributed in the northern part of China and semi-domesticated in the region. Here we present a comparison of the historical and current distribution and numbers of reindeer in China, as well as an assessment of the factors limiting population growth. Based on this information we explore potential protective measures for reindeer in China.The reindeer has been herded extensively by the Ewenki people, the only people to do so in China. Reindeer in China originated from the Wenduosenlin tundra highlands of Siberia. Capable of migrating more than 3000 km/year, the reindeer moved from the highlands to the Weitimu river during the 16th century and on to the Northeast area of China in 1654. Since 1957, 600 reindeer have settled in Qiqian in Inner Mongolia, and from 1965 more than 900 reindeer migrated from there to Mangui. In response to frequent flooding and a fluctuating reindeer population in the Mangui region, in 2003 the Ewenki people and more than 260 reindeer translocated from there to Aoluguya.Currently, eight meta-populations of reindeer comprising 773 individuals inhabit in the Arctic region of China. The reindeer population peaked in the 1970s at more than 1080 animals, but declined markedly from 1998 onwards mainly as a result of inbreeding, poaching, predation and tourism. The Chinese government's interest in wildlife protection is increasing, as evidenced by the introduction of wildlife protection laws and regulations, the importation of new reindeer varieties from Russia and the joining of the Association of World Reindeer Herders. However, natural reserves and national parks have still not been established within the reindeer's range in China to conserve this fragile population.     

Presence of Pleurotus ostreatus in Patagonia,Argentina

Specimens belonging to the genus Pleurotus were collected growing on fallen trunks of Araucaria araucana, a native tree with a poorly known mycoflora, which grows in Patagonia, Argentina. Fruitbodies were produced in culture on sawdust from an isolated strain. Interspecific pairing tests performed between mating types of Pleurotus from Patagonia and tester strains of P. pulmonarius and P. ostreatus showed the Patagonia strain to be 100% compatible with P. ostreatus and incompatible with P. pulmonarius. Dikaryons obtained on sawdust were fertile, since they were able to produce fruitbodies and viable spores. This is the first documented record of P. ostreatus from Argentina and the first gilled fungus found growing on Araucaria araucana.     

Malacofauna Cuaternaria del litoral norte de Santa Cruz (Patagonia, Argentina)

The molluscan content from three “marine terraces” (TM) preserved along 250 km of the Santa Cruz province provided 49 molluscan taxa (33 Gastropoda and 16 Bivalvia) and the first Quaternary records for Ataxocerithium pullum, Crepidula protea, C. aculeata, Adelomelon ferrusacii, Brachidontes rodriguezi, Aequipecten tehuelchus, Ostrea tehuelcha, and Solen tehuelchus. The mollusca assemblages suggest typical marine nearshore conditions similar to the adjacent modern littoral (Southwestern Atlantic), with mostly hard substrates, shallow and cold waters. The TMVI (+ 5-15 m a.s.l., ca. 8-1.2 ka A.P.) is mainly characterized by dominance of Brachidontes spp., Nacella spp. and Mytilus edulis, associated with Siphonaria lessoni. No evidence has been found for the TMVI of clear biotic responses or strong palaeobiogeographic effects during the time span of the Climatic Optimum (“Hypsithermal”, mid-Holocene) which has been documented for other coastal areas northward in Argentina, down to ca. 44-45° S. Scarce differences distinguish the TMV (+ 15-30 m a.s.l., ca. 108-137 ka A.P., MIS5?) and TMIV (+ 20-30 m a.s.l., ca. 242 ka A.P.) regarding the Holocene and the modern littoral. Within the TMV, Clausinella, Eurhomalea, Solen tehuelchus and Brachidontes cf. darwinianus (typically in warmer waters) are exclusive; in the TMIV, Trophon, Buccinanops, Brachidontes and Pectinidae are characteristic. Predominance of Trophon spp. (typically in cold Magallanic waters) in modern samples vs. scarcity or absence in the TM suggest slightly lower modern SST. Several taxonomic similitudes with the Pacific Sudamerican coast (e.g., Fissurella,Nacella, Tegula, Crepidula, Trochita, and Acanthina) could respond to cold currents helping cold-water immigrants to join southern Southamerican Atlantic after the opening of the Drake Passage.     

Major vegetation trends in the Tertiary of Patagonia (Argentina): A qualitative paleoclimatic approach based on palynological evidence

The patterns of Patagonian vegetation change suggest a strong relationship between the major thermal characters of the flora and the global paleoclimatic trends during Tertiary times. This conclusion was reached from the assessment of fossil pollen data from Patagonia throughout the Paleogene and Early Neogene periods and the subsequent comparison of palynological data to the global deep-sea oxygen isotope record. Four main time intervals were recognized based on the temporal distribution of selected angiosperm key taxa. (1) Paleocene to Early Eocene: presence of megatherm elements (e.g. Nypa, Pandanus), probably integrating mangrove communities in Patagonian lowlands. (2) Middle Eocene to Early Oligocene: rise to dominance of mesotherm and microtherm Nothofagus species. Megatherm taxa were well recorded at the beginning of this interval (e.g. Ilex) but were shown to disappear towards the end. (3) Late Oligocene to Middle Miocene: new increases of megatherm taxa such as palms, Cupania and Alchornea. First occurrences of mesotherm Asteraceae, represented by trailing Mutisieae, were reported. (4) Late Miocene: dispersal of meso-microtherm and arid adapted taxa (e.g. Ephedraceae and Asteraceae) across the non-Andean region of Patagonia. Microtherm Nothofagacean forests probably occurred on the higher rainfall regions of western Patagonia. The current vegetation was most likely reached during this last stage with the forest development under wetter conditions on the Andean sectors, and the steppe throughout the non-Andean region of Patagonia.     

Spatio-temporal overlap between the at-sea distribution of Southern Giant Petrels and fisheries at the Patagonian Shelf

The interactions between seabirds and fisheries pose significant threats for the seabird species such as incidental capture. In contrast, several species of seabirds meet part of their energetic requirements through the use of fisheries discards. Knowledge about the relationship between at-sea distribution of Procellariiformes and fisheries is a key tool in marine ecosystem management. We analysed the spatio-temporal relationship between the areas used by 16 satellite-tracked breeding adults of the Southern Giant Petrel and fisheries distribution and catch at the Patagonian Shelf. We also determined the time spent by adults in different marine jurisdictions. Results indicated a marked spatio-temporal association between birds and fisheries, mainly trawlers. The Southern Giant Petrels concentrated their foraging effort over Argentinean waters. The use of an abundant and predictable food source provided by the fisheries discards may be one of the factors affecting the dynamics of the Southern Giant Petrel populations in Patagonia, Argentina.