Anas Georgica Research Articles

High-altitude adaptation is accompanied by strong signatures of purifying selection in the mitochondrial genomes of three Andean waterfowl.

Evidence from a variety of organisms points to convergent evolution on the mitochondria associated with a physiological response to oxygen deprivation or temperature stress, including mechanisms for high-altitude adaptation. Here, we examine whether demography and/or selection explains standing mitogenome nucleotide diversity in high-altitude adapted populations of three Andean waterfowl species: yellow-billed pintail (Anas georgica), speckled teal (Anas flavirostris), and cinnamon teal (Spatula cyanoptera). We compared a total of 60 mitogenomes from each of these three duck species (n = 20 per species) across low and high altitudes and tested whether part(s) or all of the mitogenome exhibited expected signatures of purifying selection within the high-altitude populations of these species. Historical effective population sizes (Ne) were inferred to be similar between high- and low-altitude populations of each species, suggesting that selection rather than genetic drift best explains the reduced genetic variation found in mitochondrial genes of high-altitude populations compared to low-altitude populations of the same species. Specifically, we provide evidence that establishment of these three Andean waterfowl species in the high-altitude environment, coincided at least in part with a persistent pattern of negative purifying selection acting on oxidative phosphorylation (OXPHOS) function of the mitochondria. Our results further reveal that the extent of gene-specific purifying selection has been greatest in the speckled teal, the species with the longest history of high-altitude occupancy.

Trans-Andean Crossing of Yellow-Billed Pintails (Anas georgica)

There is a gap in knowledge of dispersal and migration behavior for many South American waterfowl species. This study presents data describing the movements of three individual Yellow-billed Pintails (Anas georgica) tracked with GPS-satellite telemetry that migrated via a trans-Andean Mountains crossing from Chile to Argentina. The frequency of this dispersal suggests that it is not an unusual behavior for the species, showing a possible facultative migratory trait, using different flight paths for the Andean crossing. Finally, there is evidence suggesting that there may be a migratory pattern behind the movements of southern South American populations after breeding season.

Daily Movements of Non-Breeding Yellow-Billed Pintails (Anas georgica) in Central Chile

Between January-August 2017, the movements of 18 individual Yellow-billed Pintail (Anas georgica) were studied after capture at the Carampangue wetland in Central Chile and equipped with GPS transmitters. The goal was to describe the movements of the species in terms of the distance travelled at different times of the day. Approximately 80% of all movements detected within 6-h time intervals were shorter than 1 km (median = 0.35 km). A total of 36 (0.3%) flights of more than 50 km (max dispersal = 317 km) were recorded, performed by 10 of the individuals. The distribution of flights of different distances varied significantly during the day, with short movements (0-1 km) occurring more frequently than expected during daylight, flights 1-50 km of distance being significantly more frequent during twilight, and long distance (> 50 km) flights concentrated during the night. There was no evidence of birds preferentially selecting clear-sky nights for long-distance flights.

A morphometric analysis of the lungs of high-altitude ducks and geese.

We examined the morphology of the lungs of five species of high-altitude resident ducks from Lake Titicaca in the Peruvian Andes (yellow-billed pintail [Anas georgica], cinnamon teal [Anas cyanoptera orinomus], puna teal [Anas puna], speckled teal [Anas flavirostris oxyptera], and ruddy duck [Oxyura jamaicensis ferruginea]) and compared them with those of the high-altitude migratory bar-headed goose (Anser indicus) and the low-altitude migratory barnacle goose (Branta leucopsis). We then determined the relationship between mass-specific lung volume, the volume densities of the component parts of the lung, and previously reported hypoxia-induced increases in pulmonary O2 extraction. We found that the mass-specific lung volumes and the mass-specific volume of the exchange tissue were larger in the lungs of high-altitude resident birds. The bar-headed goose had a mass-specific lung volume that fell between those of the low-altitude species and the high-altitude residents, but a mass-specific volume of exchange tissue that was not significantly different than that of the high-altitude residents. The data suggest that the mass-specific volume of the lung may increase with evolutionary time spent at altitude. We found an inverse relationship between the percentage increase in pulmonary O2 extraction and the percentage increase in ventilation across species that was independent of the volume density of the exchange tissue, at least for the resident Andean birds.

Haemosporidian Parasites of Chilean Ducks: The Importance of Biogeography and Nonpasserine Hosts.

Biogeography is known to have shaped the diversity and evolutionary history of avian haemosporidian parasites across the Neotropics. However, a paucity of information exists for the temperate Neotropics and especially from nonpasserine hosts. To understand the effect of biogeography in the temperate Neotropics on haemosporidians of nonpasserine hosts we screened ducks (Anseriformes) from central Chile for the presence of these parasites. Forty-two individuals of 4 duck species (Anas flavirostris, Anas georgica, Mareca sibilatrix, Spatula cyanoptera cyanoptera) were collected and assessed for haemosporidian parasite infections by real-time polymerase chain reaction screening and subsequent sequencing of the mitochondrial cytochrome b gene. Haemoproteus (subgenus Haemoproteus) and Plasmodium were detected in 2 host species, A. georgica and S. c. cyanoptera, with no Leucocytozoon found. Overall haemosporidian prevalence was low (14.2%), with the prevalence of Plasmodium (11.9%) being substantially greater than that of Haemoproteus (4.8%). Six haemosporidian cytochrome b lineages were recovered, 2 Haemoproteus and 4 Plasmodium, with all 6 lineages identified for the first time. In phylogenetic reconstruction, the Chilean Plasmodium lineages were more closely related to South American lineages from passerine birds than to known lineages from anseriforms. The subgenus Haemoproteus known from nonpasseriformes has never been identified from any anseriform host; however, we recovered 2 lineages from this subgenus, one from each A. georgica and S. c. cyanoptera. Further work is needed to determine if this presents true parasitism in ducks or only a spillover infection. The results of phylogenetic reconstruction demonstrate a unique evolutionary history of these Chilean parasites, differing from what is known for this host group. The unique geography of Chile, with a large part of the country being relatively isolated by the Atacama Desert in the north and the Andes in the east and south, would present opportunities for parasite diversification. Further work is needed to investigate how strongly the biogeographical isolation has shaped the haemosporidian parasites of this area. Our results add to the growing body of evidence that nonpasserine hosts support unique lineages of haemosporidian parasites, while also demonstrating the role of biogeography in haemosporidian parasite diversity in the temperate Neotropics.

Effects of the surrounding landscape on waterbird populations in estuarine ecosystems of central Chile

Waterbirds have high potential as bioindicators of the status and functioning of estuarine ecosystems, because they respond to multiple stress factors in a wide range of spatial scales. The objective of this study was to analyze the dependence of the population size of waterbird species with different degrees of association with waterbodies (High: HAW, Low: LAW) on attributes of the surrounding landscape. This was accomplished by long-term monitoring (2006–2015) of the populations of waterbirds in three estuaries of central Chile; the Itata, Mataquito, and Reloca Rivers. We acquired data on the composition and structure of the landscape for each site from satellite sensors (Landsat TM5, ETM + 7 and OLI 8), specifically the normalized difference moisture index (NDMI). We also obtained the covers of grassland and crops, bare soil and shrubland annually (summer) using a supervised classification. Using point-count data (2013–2015) from the landscape surrounding the Itata estuary, we compared the proportion of the population of different species present within and outside the wetland. The negative temporal correlation (p < 0.05) between the number of Yellow-billed pintails (Anas georgica) inside and outside the estuary strongly suggests the movement of individuals between these two habitats. We found that the abundance of many species in in the estuaries was affected by the variation of some landscape attributes. However, that proportion of LAW and HAW species showing such relationships did not differ significantly. The most important attributes of the landscape for waterbird populations were moisture (flooded sites) and vegetation photosynthetic vigor, shrubland cover. The growing use of waterbird population data as an environmental monitoring tool requires a deep understanding of the factors that drive the changes in both population numbers but also in the data describing the latter. This study highlights the importance of incorporating into waterbird population assessments information from both inside the waterbodies and from their surrounding landscapes.

New and noteworthy records of waterbirds from Paraguay

Previously unpublished new and noteworthy Paraguayan reports of Anatidae, Ardeidae, Podicipedidae and Rallidae are provided. The first documented records of Speckled Teal Anas flavirostris, Yellow-billed Pintail Anas georgica, Blue-winged Teal Anas discors and Red-gartered Coot Fulica armillata are detailed with a review of previous undocumented reports of the species. Additional records of a further five rarely-recorded waterbird species are also reported: Silvery Grebe Podiceps occipitalis, Great Grebe Podiceps major, Little Blue Heron Egretta caerulea, Cinnamon Teal Anas cyanoptera and Red Shoveler Anas platalea. The new additions add up to a total of 123 waterbird species documented to occur in Paraguay.

Gene Flow and Hybridization between Numerically Imbalanced Populations of Two Duck Species on the Subantarctic Island of South Georgia

Hybridization is common between species of animals, particularly in waterfowl (Anatidae). One factor shown to promote hybridization is restricted mate choice, which can occur when 2 species occur in sympatry but one is rare. According to the Hubbs principle, or "desperation hypothesis," the rarer species is more likely to mate with heterospecifics. We report the second of 2 independent examples of hybridization between 2 species of ducks inhabiting island ecosystems in the Subantarctic and South Atlantic Ocean. Yellow-billed pintails (Anas georgica) and speckled teal (Anas flavirostris) are abundant in continental South America, where they are sympatric and coexist in mixed flocks. But on South Georgia, an isolated island in the Subantarctic, the pintail population of approximately 6000 pairs outnumbers a small breeding population of speckled teal 300∶1. Using 6 genetic loci (mtDNA and 5 nuclear introns) and Bayesian assignment tests coupled with coalescent analyses, we identified hybrid-origin speckled teal alleles in 2 pintails on South Georgia. While it is unclear whether introgression has also occurred into the speckled teal population, our data suggest that this hybridization was not a recent event, but occurred some time ago. We also failed to identify unequivocal evidence of introgression in a much larger sample of pintails and speckled teal from Argentina using a 3-population "Isolation-with-Migration" coalescent analysis. Combined with parallel findings of hybridization between these same 2 duck species in the Falkland Islands, where population ratios are reversed and pintails are outnumbered by speckled teal 1:10, our results provide further support for the desperation hypothesis, which predicts that scarcity in one population and abundance of another will often lead to hybridization. While the South Georgia pintail population appears to be thriving, it's possible that low density of conspecific mates and inverse density dependence (Allee effect) may be one factor limiting the reproductive output of the speckled teal population, and this situation may persist unless speckled teal increase in abundance on South Georgia.

Late Pleistocene colonization of South Georgia by yellow-billed pintails pre-dates the Last Glacial Maximum

Aim Glacial cycles had a major influence on the distribution of high-latitude species, and while genetic consequences of these cycles have been well studied in the Circumpolar North, notably fewer studies have been undertaken in the Antarctic. Here, we use multilocus genetic data from the South Georgia pintail (Anas georgica georgica) as a proxy to study the presence and timing of ice-free refugia on South Georgia, a glaciated subantarctic island in the South Atlantic Ocean that has been the subject of intense geomorphological and palaeoenvironmental study. Location South Georgia. Methods Multilocus DNA sequence data from five nuclear loci and the mitochondrial DNA control region were analysed for South Georgia pintails (n = 60) and the neighbouring population of yellow-billed pintails (A. georgica spinicauda) in Argentina (n = 64). Population genetic structure and gene flow were examined using ΦST, assignment tests, and multilocus coalescent analyses. Results Isolation-with-migration (IM) analysis revealed that the South Georgia pintail population was founded by pintails dispersing from South America. Although the confidence intervals on divergence dates inferred from genetic data are generally wide and there may be time-dependency in rate calibrations, our analysis suggests that this founding event probably occurred c. 34,000 years ago, prior to the Last Glacial Maximum (LGM). Our findings further suggest that South Georgia pintails might have experienced a bottleneck coinciding with complete replacement of mitochondrial DNA prior to 8700 years ago following the final advance of glaciers. Main conclusions These findings suggest that ice-free refugia existed earlier in the chronology of deglaciation in contrast with earlier studies, but in agreement with observations that the plant community was also established on South Georgia prior to the end of the Pleistocene. Like other recent studies that have utilized genetic data to date dispersal and vicariance events in the Antarctic, our results provide a constraint on the extent of ice sheets, suggesting that past ice coverage on South Georgia through the LGM was overestimated.

Seasonal Patterns in Aquatic Bird Counts at Five Andean Lakes of Ecuador

Seasonal (semestral) counts of aquatic birds at five Andean lakes in Ecuador (Colta, La Mica, Yambo, Yahuarcocha and San Pablo) were analyzed to detect trends in population size between 2004 and 2011. Trends of four abundant species (Ardea alba, Anas georgica, Fulica ardesiaca and Oxyura jamaicensis) and those of five functional groups (based upon body size and diet) were tested using generalized additive mixed modeling. In total, 19 bird species were consistently recorded over the whole period. The Andean Coot (F. ardesiaca) was found in highest densities (c. 3 birds per ha at Colta and Yambo). No significant trends were detected. However, the counts of functional groups exhibited a seasonal pattern (higher counts in February than in July), possibly due to lower resource availability in the dry season. Piscivorous species were relatively abundant at one lake (Yahuarcocha), which might be related to the introduction of Tilapiine cichlid fishes.

Erratum to: Ephemeral Aquatic Bird Assemblages in Estuarine Wetlands from South-Central Chile: Using an Intertidal Flat Habitat During the Austral Summer

The use of intertidal environments by aquatic birds is an important topic of study in the northern hemisphere, grouping baseline distributional descriptions to assess human–bird interactions during shellfish harvesting in soft substrates. However, patterns of tidal regime plus human and natural disturbances may differ in areas in the southern hemisphere. We studied the use of an intertidal flat by a temporary (i.e., ephemeral) assemblage of migratory and resident shorebirds and waterbirds in the Queule River Estuary (39° S), in south-central Chile, during the summers of 2003 and 2008. Migrant species such as Whimbrel Numenius phaeopus and resident Southern Lapwing Vanellus chinesis positively selected sandy substrates when feeding during both spring (periods with stronger tidal range) and neap tides (periods with weaker tides). The resident Yellow-billed Pintail Anas georgica only positively selected the muddy–sandy bottom during spring tides. The predominant activity of resident species was feeding during both tides, except for the Yellow-billed Pintail which rested during neap tides. We highlight the importance of microhabitats such as the intertidal flats system as feeding and resting areas for migratory and resident species. We also comment on their conservation and natural modification by mega-earthquake and tsunami effects that may result in the future destruction or generation of these key environments.

Avian Remains from Khonkho Wankane, an Urban and Ceremonial Center in the Southern Lake Titicaca Altiplano

The urban and ceremonial center Khonkho Wankane flourished in the southern Lake Titicaca Altiplano region during the Late Formative prior to the rise of Tiwanaku as a dominant urban center. This site yielded an avifaunal number of identified specimens (NISP) = 631, with a minimum of 26 taxa represented among 539 skeletal elements or fragments. A total of 92 egg shell fragments also were recovered. The avifauna inhabited two major ecological zones: Lake Titicaca, its margins/wetlands and other water margins; and the dry Altiplano grassland (or puna). Lake/wetland taxa include Phoenicopterus chilensis (Chilean flamingo), Nycticorax nycticorax (night heron) and multiple taxa in the Order Anseriformes (ducks, geese, etc.) including Chloephaga melanoptera (Andean goose), Anas georgica (yellow-billed pintail), A. flavirostris (speckled teal) and Oxyura jamaicensis (Andean ruddyduck). Also present are Fulica ardesiaca (Andean coot), Gallinago andina (puna snipe), Himantopus mexicanus (black-necked stilt) and Charadrius alticola (puna plover). Puna taxa include Nothoprocta cf. ornata (ornate tinamou), Nothura cf. darwinii (Darwin's nothura), Metropelia sp. (ground doves), Athene cunicularia (burrowing owl), and multiple Passeriformes (songbirds, etc.). Taxa with a cosmopolitan distribution include Falco cf. femoralis (aplomado falcon) and Tyto alba (barn owl). Taphonomic analysis indicates that the avifauna were used in ceremonial contexts, including multiple Falco cf. femoralis burials, and for dietary and possibly tool-making purposes. Other sources of introduction into the site deposits likely include natural mortality of taxa directly inhabiting the site area. These findings are compared to the avifauna recovered from the Formative site of Chiripa along the Lake Titicaca margin, which included a much higher proportion of lake bird fauna. At Khonkho Wankane, the importance of wetland avifauna may have been enhanced by the alteration of the local environment to include qochas, or artificial reservoirs/ponds, and continued despite reliance upon multiple domesticated plant and mammal species. Copyright © 2011 John Wiley & Sons, Ltd.

Gene Flow and Hybridization between Numerically Imbalanced Populations of Two Duck Species in the Falkland Islands

Interspecific hybridization is common in plants and animals, particularly in waterfowl (Anatidae). One factor shown to contribute to hybridization is restricted mate choice, which can occur when two species occur in sympatry but one is rare. The Hubbs principle, or “desperation hypothesis,” states that under such circumstances the rarer species is more likely to mate with heterospecifics. Here we report interspecific hybridization between two waterfowl species that coexist in broad sympatry and mixed flocks throughout southern South America. Speckled teal (Anas flavirostris) and yellow-billed pintails (Anas georgica) are abundant in continental South America, but in the Falkland Islands speckled teal outnumber yellow-billed pintails approximately ten to one. Using eight genetic loci (mtDNA and 7 nuclear introns) coupled with Bayesian assignment tests and relatedness analysis, we identified a speckled teal x yellow-billed pintail F1 hybrid female and her duckling sired by a male speckled teal. Although our sample in the Falkland Islands was small, we failed to identify unequivocal evidence of hybridization or introgression in a much larger sample from Argentina using a three-population “isolation with migration” coalescent analysis. While additional data are needed to determine if this event in the Falkland Islands was a rare singular occurrence, our results provide further support for the “desperation hypothesis,” which states that scarcity in one population and abundance of another will often lead to hybridization.

Gene Flow in the Face of Countervailing Selection: Adaptation to High-Altitude Hypoxia in the A Hemoglobin Subunit of Yellow-Billed Pintails in the Andes

When populations become locally adapted to contrasting environments, alleles that have high fitness in only one environment may be quickly eliminated in populations adapted to other environments, such that gene flow is partly restricted. The stronger the selection, the more rapidly immigrant alleles of lower fitness will be eliminated from the population. However, gene flow may continue to occur at unlinked loci, and adaptive divergence can proceed in the face of countervailing gene flow if selection is strong relative to migration (s > m). We studied the population genetics of the major hemoglobin genes in yellow-billed pintails (Anas georgica) experiencing contrasting partial pressures of oxygen in the Andes of South America. High gene flow and weak population subdivision were evident at seven putatively neutral loci in different chromosomal linkage groups. In contrast, amino acid replacements (Ser-beta13, Ser-beta116, and Met-beta133) in the betaA hemoglobin subunit segregated by elevation between lowland and highland populations with significantly elevated F(ST). Migration rates for the betaA subunit alleles were approximately 17-24 times smaller than for five unlinked reference loci, the alphaA hemoglobin subunit (which lacks amino acid replacements) and the mitochondrial DNA control region. The betaA subunit alleles of yellow-billed pintails were half as likely to be transferred downslope, from the highlands to the lowlands, than in the opposite direction upslope. We hypothesize that migration between the lowlands and highlands is restricted by local adaptation, and the betaA hemoglobin subunit is a likely target of selection related to high-altitude hypoxia; however, gene flow may be sufficiently high to retard divergence at most unlinked loci. Individuals homozygous for lowland alleles may have relatively little difficulty dispersing to the highlands initially but may experience long-term fitness reduction. Individuals homozygous for highland genotypes, in contrast, would be predicted to have difficulty dispersing to the lowlands if their hemoglobin alleles confer high oxygen affinity, predicted to result in chronic erythrocytosis at low elevation. Heterozygous individuals may have a dispersal advantage if their hemoglobin has a wider range of function due to the presence of multiple protein isoforms with a mixture of different oxygen affinities.

First record of Australapatemon burti and Paramonostomum pseudalveatum (Digenea) from Anas georgica (Aves, Anseriformes) in Chile

AbstractAn examination of specimens of Anas georgica Gmelin (Anatidae) from Región del Bio-Bio and Región del Maule, Chile, revealed the presence of two digenean species reported for the Holartic Region: Australapatemon burti (Miller, 1923) Dubois, 1968 (Strigeidae) and Paramonostomum pseudalveatum Price, 1931 (Notocotylidae). A. burti parasitized ducks from both regions and P. pseudalveatum parasitized only ducks from Región del Bio-Bio. The digeneans were mounted in toto, described and illustrated. The morphology and dimensions of specimens studied correspond with their original descriptions and new morphometrical data and morphological characters are given. The reports of A. burti and P. pseudalveatum in A. georgica represent a new host record and the first record of the genera Australapatemon Sudarikov, 1959 and Paramonostomum Lühe, 1909 from Chile.