Genome analysis and biogeographic distribution of the earliest divergent Frankia clade in the southern hemisphere

Coriariaceae are a small plant family of 14-17 species and subspecies that currently have a global but disjunct distribution. All species can form root nodules in symbiosis with diazotrophic Frankia cluster-2 strains, which form the earliest divergent symbiotic clade within this bacterial genus. Studies on Frankia cluster-2 mostly have focused on strains occurring in the northern hemisphere. Except for one strain from Papua New Guinea, namely Candidatus Frankia meridionalis Cppng1, no complete genome of Frankia associated with Coriaria occurring in the southern hemisphere has been published thus far, yet the majority of the Coriariaceae species occur here. We present field sampling data of novel Frankia cluster-2 strains, representing two novel species, which are associated with Coriaria arborea and Coriaria sarmentosa in New Zealand, and with Coriaria ruscifolia in Patagonia (Argentina), in addition to identifying Ca. F. meridionalis present in New Zealand. The novel Frankia species were found to be closely related to both Ca. F. meridionalis, and a Frankia species occurring in the Philippines, Taiwan, and Japan. Our data suggest that the different Frankia cluster-2 species diverged early after becoming symbiotic circa 100 million years ago.

Exploring perceptions of extreme environments and extremophiles in Chilean schoolchildren: an ethnographic study

Chile is unique because of its diverse extreme environment, ranging from arid climates in the north to polar climates in Patagonia. Microorganisms that live in these environments are called extremophiles, and these habitats experience intense ecosystem changes owing to climate warming. Most studies of extremophiles have focused on their biotechnological potential; however, no study has examined how students describe extremophiles. Therefore, we were interested in answering the following question: How do schoolchildren living in extreme environments describe their environments and extremophiles? We performed an ethnographic study and analyzed the results of 347 representative drawings of participants aged 12-16 years from three schools located in the extreme environments of Chile San Pedro de Atacama (hyper-arid, 2,400 m), Lonquimay (forest, 925 m), and Punta Arenas (sub-Antarctic, 34 m). The social representation approach was used to collect data, and systemic networks were used to organize and systematize the drawings. The study found that, despite differences between extreme environments, certain natural elements, such as trees and the sun, are consistently represented by schoolchildren. The analysis revealed that the urban and rural categories were the two main categories identified. The main systemic networks were rural-sun (21,1%) for hyper-arid areas, urban-tree (14,1%) for forest areas, and urban-furniture (23,4%) for sub-Antarctic areas. When the results were analyzed by sex, we found a statistically significant difference for the rural category in the 7th grade, where girls mentioned being more rural than boys. Students living in hyper-arid areas represented higher extremophile drawings, with 57 extremophiles versus 20 and 39 for students living in sub-Antarctic and forest areas, respectively. Bacteria were extremophiles that were more represented. The results provide evidence that natural variables and semantic features that allow an environment to be categorized as extreme are not represented by children when they are focused on and inspired by the environment in which they live, suggesting that school literacy processes impact representations of their environment because they replicate school textbooks and not necessarily their environment.

Evidence of castrations in fleas of small mammals (Chiroptera and Rodentia) from Argentina

Morphological abnormalities in fleas seem to be common in nature and are under reported in Argentina. In this note, we describe anomalies in two males and one female of Alectopsylla unisetosa Mahnert (Ischnopsyllidae) and one of Polygenis sp. (Rhopalopsyllidae) male collected from small mammals in the provinces of Neuquen and Salta, Argentina. In all specimens, the anomalies were observed at the level of the genitalia recognized as partial castration. The structures mainly affected were the modified abdominal segments, the aedeagus (in male), and the spermatheca (in female). The present communication is the first one devoted exclusively to teratogenous fleas in Argentina.

Differential consumption of malic acid and fructose in apple musts by Pichia kudriavzevii strains

AIMS

To assess the capability of Pichia kudriavzevii strains isolated from wine, cider, and natural environments in North Patagonia to produce ciders with reduced malic acid levels.

METHODS AND RESULTS

Fermentation kinetics and malic acid consumption were assessed in synthetic media and in regional acidic apple musts. All P. kudriavzevii strains degraded malic acid and grew in synthetic media with malic acid as the sole carbon source. Among these strains, those isolated from cider exhibited higher fermentative capacity, mainly due to increased fructose utilization; however, a low capacity to consume sucrose present in the must was also observed for all strains. The NPCC1651 cider strain stood out for its malic acid consumption ability in high-malic acid Granny Smith apple must. Additionally, this strain produced high levels of glycerol as well as acceptable levels of acetic acid. On the other hand, Saccharomyces cerevisiae ÑIF8 reference strain isolated from Patagonian wine completely consumed reducing sugars and sucrose and showed an important capacity for malic acid consumption in apple must fermentations.

CONCLUSIONS

Pichia kudriavzevii NPCC1651 strain isolated from cider evidenced interesting features for the consumption of malic acid and fructose in ciders.

Ecological variation in invasive brown trout (Salmo trutta) within a remote coastal river catchment in northern Patagonia complicates estimates of invasion impact

Salmonids were first introduced into the Chilean fresh waters in the 1880s, and c. 140 years later, they are ubiquitous across Chilean rivers, especially in the southern pristine fresh waters. This study examined the brown trout (Salmo trutta) and native taxa ecology in two adjacent but contrasting rivers of Chilean Patagonia. During spring 2016 and spring-fall 2017 we examined the variation in benthic macroinvertebrate and fish community composition and characterized fish size structure, stomach contents, and stable isotopes (δ13 C and δ15 N) to understand population structure, fish diet, and trophic interactions between S. trutta and native taxa. The native Galaxias maculatus (puye) dominated the fish community (74% of abundance). S. trutta was less abundant (16% of survey catch) but dominated the fish community (over 53%) in terms of biomass. S. trutta showed distinct diets (stomach content analysis) in the two rivers, and individuals from the larger river were notably more piscivorous, consuming native fish with a relatively small body size (<100-mm total length). Native fishes were isotopically distinct from S. trutta, which showed a wider isotopic niche in the smaller river, indicating that their trophic role was more variable than in the larger river (piscivorous). This study provides data from the unstudied pristine coastal rivers in Patagonia and reveals that interactions between native and introduced species can vary at very local spatial scales.

Groundwater-surface water interactions in a semi-arid irrigated agricultural valley: A hydrometric and tracer-aided approach

The purpose of this study was to assess hydrological controls (e.g., rainfall, irrigation practices, river discharge, dam operation, evaporation) on surface (SW)- ground water (GW) interactions in an irrigated valley within semi-arid Patagonia Argentina (-65.49 W, -43.29 S). We combined different sampling designs (watershed/sub-watershed scales, longitudinal and monthly samplings) from 2015 to 2019 to investigate the temporal and spatial variation of hydrometrics, electrical conductivity (EC) and stable isotope composition of surface and ground water. Results showed that plant transpiration in the upper basin, evaporation in the middle basin and the reservoir dynamics modified water salinity and left an imprint in stable isotopes. Water tables in the irrigated valley were high (0.5-2 m level from soil surface) and presented higher salinity than river water. Groundwater salinity, temporal variation of water table levels and stable isotopes suggested that groundwater is subjected to evaporation, is recharged from field seepage and, at a lesser extent, from local rainwater. River salinity increased downstream of the irrigated valley during the whole study period (3 years), showing the effects of agriculture and urbanization. EC also responded to the opening and closing of irrigation channels. EC and daily discharge statistical analysis revealed that groundwater recharge the stream below a threshold discharge of 26 m.s-1; with river salinity increasing linearly as daily discharge decrease. This study illustrates the deep modifications that agricultural systems, mainly surface irrigation, produce on semiarid watersheds. Given that SW and GW components are currently not isolated and flow regulation and irrigation practices are playing a critical role in soil quality and river chemistry at low flow conditions, a conjunctive water management strategy must be implemented in order to prevent further land and water quality degradation.

Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences

Aucasaurus garridoi is an abelisaurid theropod from the Anacleto Formation (lower Campanian, Upper Cretaceous) of Patagonia, Argentina. The holotype of Aucasaurus garridoi includes cranial material, axial elements, and almost complete fore- and hind limbs. Here we present a detailed description of the axial skeleton of this taxon, along with some paleobiological and phylogenetic inferences. The presacral elements are somewhat fragmentary, although these show features shared with other abelisaurids. The caudal series, to date the most complete among brachyrostran abelisaurids, shows several autapomorphic features including the presence of pneumatic recesses on the dorsal surface of the anterior caudal neural arches, a tubercle lateral to the prezygapophysis of mid caudal vertebrae, a marked protuberance on the lateral rim of the transverse process of the caudal vertebrae, and the presence of a small ligamentous scar near the anterior edge of the dorsal surface in the anteriormost caudal transverse process. The detailed study of the axial skeleton of Aucasaurus garridoi has also allowed us to identify characters that could be useful for future studies attempting to resolve the internal phylogenetic relationships of Abelisauridae. Computed tomography scans of some caudal vertebrae show pneumatic traits in neural arches and centra, and thus the first reported case for an abelisaurid taxon. Moreover, some osteological correlates of soft tissues present in Aucasaurus and other abelisaurids, especially derived brachyrostrans, underscore a previously proposed increase in axial rigidity within Abelisauridae.

Four New Species of Pseudephedrus (Hymenoptera, Braconidae, Aphidiinae) from Chile with a Key to Species Identification

The following work consists of the description of four new species of the genus Pseudephedrus Starý (Aphidiinae), endemic to South America, associated with endemic callaphidid aphid hosts. The descriptions of the new species are based on new samples from Chile and Argentina. The new species described here are as follows: Pseudephedrus staryi sp.n., which is morphologically very close to the already described P. chilensis Starý, with clear apomorphies; P. pubescens sp.n., which presents a setose scutellum, P. flava sp.n. and P. patagonicus sp.n. which have distinct, very elongated, and crenulated petioles representing synapomorphies and probably form separate phylogenetic lineages within Pseudephedrus. All hosts are aphids from the genus Neuquenaphis Blanchard, with varying degrees of diet specialization. From our field and laboratory observations, we hypothesize that, since attempts to sample parasitoids using sweep nets were much more successful than sampling from collected aphids, and since we found mummified aphids only on the ground among the fallen leaves under the trees, Neuquenaphis aphids fall to the ground showing a dropping behaviour as a defence against natural enemies after being stung by parasitoids. This makes rearing from live aphids very unsuccessful and could help explain why it has been difficult to collect and describe species. We supplement the distribution of Pseudephedrus from South America and present a key for the identification of all species based on their morphology.

A new species of Notocotylus (Digenea: Notocotylidae) from the black-necked swan Cygnus melancorhyphus (Molina) of Argentina

Notocotylus cygni n. sp. is described here, taken from the intestine of the black-necked swan Cygnus melancoryphus (Molina) of Patagonia, Argentina. This new species differs from other members of the genus Notocotylus by having the genital pore anterior to the caecal bifurcation (located slightly posterior to oral sucker) and the unequal number and arrangement of ventral papillae (2-3 in the lateral rows and 10-12 in the median row). Phylogenetic analyses of the 28S and ITS1-5.8S ribosomal DNA (rRNA) sequences of the new species and other notocotylid trematodes available in GenBank indicate that N. cygni n. sp. is a sister taxon of Notocotylus fosteri Kinsella et Tkach, 2005, a trematode of the intestine of the rice rat Oryzomys palustris of Florida, United States. The new species differs from N. fosteri in the unequal number and arrangement of ventral papillae, number of uterine loops, size of the egg, definitive hosts (birds vs. mammals), and disparate environment and geographical distribution (freshwater environment in Patagonia vs. salt marsh in North America). This is the eighth species of Notocotylus reported from birds in Argentina, and the ninth species from the family Notocotylidae recorded in black-necked swans in South America.

Presence of Saccharomyces eubayanus in fermentative environments reveals a new adaptive scenario in Patagonia

Patagonia (Argentina and Chile) harbors the highest Saccharomyces eubayanus genomic diversity and its widest predominance in natural environments. In this work, S. eubayanus was isolated for the first time from a fermentative environment. This species was found dominating both a traditional apple chicha fermentation as well as feral apple trees in the Andean region of Aluminé (Argentina). S. eubayanus was the only Saccharomyces species found in the isolation substrates, although it coexisted with other non-Saccharomyces species. The absence of strong fermentative competitors of the Saccharomyces genus (like Saccharomyces uvarum or Saccharomyces cerevisiae) in the feral apples could promote the development and implantation of S. eubayanus in a spontaneous apple must fermentation. Phylogeographic analyses revealed a high intraspecific diversity in S. eubayanus, enabling the characterization of strains belonging to the genomic subpopulations PA1, PA2, and PB1 according to the sequences obtained for the intFR gene region. This result evidence that the studied sampling area represents a natural habitat for the species. Being a novel finding, studying the causes that allowed this species to prosper in a fermentative environment becomes essential. Hence, the physiological profile of the new isolates, including their ability to grow at different temperature, nitrogen, and ethanol concentrations was evaluated in comparison with a set of S. eubayanus strains previously isolated from natural environment and representing different genomic subpopulations. Greater physiological diversity was evidenced when strains isolated from both natural and fermentative environments were analyzed overall. Furthermore, no direct relationship between genomic population and physiological behavior was observed; on the opposite, strains appeared to exhibit similar behavior, primarily grouped by isolation origin.

Beetle mania: Understanding pond aquatic beetles diversity patterns through a multiple-facet approach

Ecological studies searching for drivers of biodiversity variation have frequently focused on taxonomic richness. However, more aspects of biodiversity, namely diversity facets can be considered to properly assess biotic-environment relationships. Here, we explore the environmental factors that could control the four biodiversity facets of aquatic Coleoptera from 93 regionally sampled Patagonian ponds. We also explore which are the ponds with high diversity values of all facets to prioritize them with a high conservation value. We fitted generalized additive models (GAM) to test relationships among environment (i.e., local and climatic variables) and aquatic beetles diversity facets (i.e., richness (SD), functional diversity (FD), phylogenetic diversity (PD), and local contribution to local beta diversity (LCBD). Climatic drivers were the most important predictors of beetle diversity facets, which exhibited linear and nonlinear responses. Thus, ponds from warmer Patagonia exhibited the highest values of SD and PD, whereas LCBD also peaked on colder sites suggesting that ponds under extreme temperatures sustain unique beetle assemblages. Moreover, ponds located in areas with higher precipitation variability exhibit the highest values of LCBD (i.e., unique assemblages). This result in addition to arid conditions in Patagonia prevailing since 16 m.y.a made us think that Patagonian beetle pond-dwellers are basally adapted to aridity. We calculated an index that summarizes the four facets patterns, to assign high conservation value to those ponds with higher index values. The relative importance of each facet varies from pond to pond. Hence, this multifaceteded approach not only allows us to identify priority areas for biodiversity conservation but also focuses on the importance of including multiple facets to understand biodiversity spatial patterns.

Genetic characterization and regional distribution of lymnaeid snails in northern Patagonia, Argentina

Lymnaeid snails serve as intermediate hosts for Fasciola hepatica (Linnaeus, 1758), the etiological agent of fasciolosis, which is a widespread livestock disease in Argentina. Determining their geographic distribution and identifying the snail species involved in the transmission of fasciolosis can provide crucial information for designing strategic control programs. In this context, this work aimed at genetically characterizing the species of lymnaeid snails collected in different water bodies of northern Patagonia, Argentina. To this end, 689 snails were collected in 12 sites in the provinces of Neuquén, Río Negro and Chubut, in areas where fasciolosis is endemic. According to the morphological characteristics of their valves, they were identified as Galba spp. Twenty-three of these specimens were further identified using the nuclear sequences of the internal transcribed spacers ITS-1 and ITS-2 and 18S rRNA. The results confirmed the identity of all the analyzed snails as Galba viatrix and provided evidence that studying the variable region V2 of the 18S rRNA gene is not enough to differentiate closely related species, as observed in lymnaeid snails. Both the fact that G. viatrix was the only species identified in the endemic area surveyed and previous evidence of the high prevalence of F. hepatica infestation in grazing animals in the region suggest that this species is the main intermediate host of F. hepatica. The correct identification of lymnaeid snail species has great importance to determine risk zones and develop appropriate control measures to reduce transmission, according to the different ecological characteristics of each species.

Novel B2 mitogenomes from Continental southern Patagonia's Late Holocene: New insights into the peopling of the Southern Cone

OBJECTIVES

The main aim of this study is to discuss the migratory processes and peopling dynamics that shaped the genetic variability of populations during the settlement of the Southern Cone, through the analysis of complete mitogenomes of individuals from southern Patagonia.

MATERIALS AND METHODS

Complete mitogenomes were sequenced through massively parallel sequencing from two late Holocene individuals (SAC 1-1-3 and SAC 1-1-4) buried in the same chenque at Salitroso Lake Basin (Santa Cruz province, Argentina). To evaluate matrilineal phylogenetic affinities with other haplotypes, maximum likelihood and Bayesian phylogenetic reconstructions were performed, as well as a haplotype median-joining network.

RESULTS

The mitogenomes were assigned to haplogroups B2 and B2b, exhibiting an average depth of 54X and 89X (≥1X coverage of 98.6% and 100%), and a high number of nucleotide differences among them. The phylogenetic analyses showed a relatively close relationship between the haplotype found in SAC 1-1-4 and those retrieved from a Middle Holocene individual from Laguna Chica (Buenos Aires province), and from a group of individuals from the Peruvian coast. For the SAC 1-1-3, no clear affiliations to any other haplotype were established.

DISCUSSION

The large divergence between the haplotypes presented in this study suggests either a highly variable founder gene pool, or a later enrichment by frequent biological contact with other populations. Our results underline the persistence of genetic signals related to the first waves of peopling in South America, suggesting that the regional settlement of the southern end of the continent has been much more complex than initially thought.

The ephemeral record: The role of opportunistic animal resources in the archaeology of Pampa and Patagonia

The acquisition of opportunistic animal resources by hunter-gatherers-such as scavenged carcasses-is a well-known subsistence strategy. It is frequently mentioned in the context of the history of early human evolution, but not regularly considered among the strategies utilized by more recent foragers of the Southern Cone of South America. Historical and ethnographic information presented here suggests that the use of opportunistic animal resources was a strategy used under a number of conditions but only partially documented in the archaeological literature. We also present archaeological evidence from four sites-Guardia del Río, Paso Otero 1, Ponsonby, and Myren-in different Pampean and Patagonian settings where relevant guanaco (Lama guanicoe) bone assemblages were recovered. These sites record minimal anthropic involvement, basically cut marks on some guanaco bones accompanied by few stone tools, that we interpret as evidence for access and use of water logged immobilized or recently dead animals. Archaeological evidence for the use of these scavenging strategies is difficult to obtain at large archaeological sites that usually result from multiple occupations, since the distinction between the acquisition of actively pursued versus opportunistic animal resources is not straightforward. One conclusion from our review is that the best places to find and recognize this evidence are archaeological sites resulting from ephemeral occupations. The inclusion of these sites gives us access to crucial and rarely documented evidence for the long-term survival of hunter-gatherers.

Climate change-related growth improvements in a wide niche-breadth tree species across contrasting environments

BACKGROUND AND AIMS

The vulnerability and responsiveness of forests to drought are immensely variable across biomes. Intraspecific tree responses to drought in species with wide niche breadths that grow across contrasting climatically environments might provide key information regarding forest resistance and changes in species distribution under climate change. Using a species with an exceptionally wide niche breath, we tested the hypothesis that tree populations thriving in dry environments are more resistant to drought than those growing in moist locations.

METHODS

We determined temporal trends in tree radial growth of 12 tree populations of Nothofagus antarctica (Nothofagaceae) located across a sharp precipitation gradient (annual precipitation of 500-2000 mm) in Chile and Argentina. Using dendrochronological methods, we fitted generalized additive mixed-effect models to predict the annual basal area increment as a function of year and dryness (De Martonne aridity index). We also measured carbon and oxygen isotope signals (and estimated intrinsic water-use efficiency) to provide potential physiological causes for tree growth responses to drought.

KEY RESULTS

We found unexpected improvements in growth during 1980-1998 in moist sites, while growth responses in dry sites were mixed. All populations, independent of site moisture, showed an increase in their intrinsic water-use efficiency in recent decades, a tendency that seemed to be explained by an increase in the photosynthetic rate instead of drought-induced stomatal closure, given that δ18O did not change with time.

CONCLUSIONS

The absence of drought-induced negative effects on tree growth in a tree species with a wide niche breadth is promising because it might relate to the causal mechanisms tree species possess to face ongoing drought events. We suggest that the drought resistance of N. antarctica might be attributable to its low stature and relatively low growth rate.

Fertile Goeppertella from the Jurassic of Patagonia: mosaic evolution in the Dipteridaceae-Matoniaceae lineage

Goeppertella has been postulated as a monophyletic group, whose precise position within the Gleichenoid families Dipteriaceae and Matoniaceae, remains poorly understood. Previously described Goeppertella specimens are based on frond fragments and its fertile morphology is represented by a few, poorly preserved specimens. We describe a new species based on the largest collection of fertile specimens known to date and discuss the evolutionary history of the genus based on the additional reproductive characters provided by the fossils described. Plant impressions were collected in Early Jurassic sediments of Patagonia, Argentina. The specimens were described, and silicone rubber casts were developed to examine in detail vegetative and reproductive features. The new species was compared with other Goeppertella species. Finally, a backbone analysis was performed in the context of a previously published combined matrix of Dipteridaceae, using the maximum parsimony criterion. The new species is described based on a combination of features that have not been previously reported. The vegetative morphology shows affinities with most fossil and extant Dipteriaceae, contrasting with the reproductive morphology which is more comparable with the scarce number of fossil dipteridaceous forms and it is more spread in the sister family, Matoniaceae. The backbone analysis indicates that the position of the new species vary among different positions among Dipteridaceae and Matoniaceae. Additional analyses, discriminating the signal of reproductive and vegetative character, are provided to discuss the base of this uncertainty. We consider Goeppertella as a member of the family Dipteridaceae since we interpret most shared features with Matoniaceae as plesiomorphic conditions for the family. In contrast, most shared features with Dipteridaceae represent apomorphies for the group. Thus, Goeppertella would represent an early diverging genus in Dipteridaceae, considering the venation characters as the most important in order to define the family.

Local adaptation to aridity in a widely distributed angiosperm tree species is mediated by seasonal increase of sugars and reduced growth

Trees in dry climates often have higher concentrations of total non-structural carbohydrates (NSC = starch + soluble sugars) and grow less than conspecifics in more humid climates. This pattern might result from growth being more constrained by aridity than the carbon (C) gain, or reflect local adaptation to aridity, since NSC fuel metabolism and ensure adequate osmoregulation through the supply of soluble sugars (SS), while low growth reduces water and C demands. It has been further proposed that C allocation to storage could come at the expense of growth (i.e., a growth-storage trade-off). We examined whether NSC and growth reflect local adaptation to aridity in Embothrium coccineum (Proteaceae), a species with an exceptionally wide niche. To control for any influence of the phenotypic plasticity on NSC and growth, we collected seeds from dry (500 mm year-1) and moist (> 2500 mm year-1) climates and grew seedlings in a common garden experiment for 3 years. We then compared NSC and SS concentrations and pools (i.e., total contents), and the biomass of seedlings at spring, summer, and fall. Seedlings from the dry climate had significantly lower biomass and similar NSC concentrations and pools than seedlings from moist climate, suggesting that reduced growth in arid environments does not result from a prioritization of C allocation to storage but it confers advantages under aridity (e.g., lower transpiration area). Across organs, starch and NSC decreased similarly in seedlings from both climates from spring onward. However, root and stem SS concentrations increased during the growing season, and these increases were significantly higher in seedlings from the dry climate. The greater SS accumulation in seedlings from the dry climate compared to those from the moist climate demonstrates ecotypic differentiation in the seasonal dynamics of SS, suggesting that SS underlie local adaptation to aridity. (298 words).

Re-examination of the Southern Hemisphere truffle genus Amylascus (Pezizaceae, Ascomycota) and characterization of the sister genus Nothoamylascus gen. nov

Amylascus is a genus of ectomycorrhizal truffles within Pezizaceae that is known from Australia and contains only two described species, A. herbertianus and A. tasmanicus. Species of Amylascus are closely related to truffles (Pachyphlodes, Luteoamylascus) and cup fungi (Plicariella) from the Northern Hemisphere. Here we reevaluate the species diversity of Amylascus and related taxa from southern South America and Australia based on new morphological and molecular data. We identify previously undocumented diversity and morphological variability in ascospore color, ascospore ornamentation, hymenial construction, epithecium structure and the amyloid reaction of the ascus in Melzer's reagent. We redescribe two Amylascus species from Australia and describe seven new Amylascus species, five from South America and two from Australia. This is the first report of Amylascus species from South America. We also describe the new South American genus Nothoamylascus as sister lineage to the Pachyphlodes-Amylascus-Luteoamylascus clade (including Amylascus, Luteoamylascus, Pachyphlodes, and Plicariella). We obtained ITS sequences of mitotic spore mats from Nothoamylascus erubescens gen. & sp. nov. and four of the seven newly described Amylascus species, providing the first evidence of mitotic spore mats in Amylascus. Additional ITS sequences from mitotic spore mats reveal the presence of nine additional undescribed Amylascus and one Nothoamylascus species that do not correspond to any sampled ascomata. We also identify three additional undescribed Amylascus species based on environmental sequences from the feces of two grounddwelling bird species from Chile, Scelorchilus rubecula and Pteroptochos tarnii. Our results indicate that ascomata from Amylascus and Nothoamylascus species are rarely collected, but molecular data from ectomycorrhizal roots and mitotic spore mats indicate that these species are probably common and widespread in southern South America. Finally, we present a time-calibrated phylogeny that is consistent with a late Gondwanan distribution. The time since the most recent common ancestor of: 1) the family Pezizaceae had a mean of 276 Ma (217-337 HPD); 2) the Amylascus-Pachyphlodes-Nothoamylascus-Luteoamylascus clade had a mean of 79 Ma (60-100 HPD); and 3) the Amylascus-Pachyphlodes clade had a mean of 50 Ma (38-62 HPD). The crown age of Pachyphlodes had a mean of 39 Ma (25-42 HPD) and Amylascus had a mean age of 28 Ma (20-37 HPD), falling near the Eocene-Oligocene boundary and the onset of the Antarctic glaciation (c. 35 Ma). Citation: Healy RA, Truong C, Castellano MA, et al. 2023. Re-examination of the Southern Hemisphere truffle genus Amylascus (Pezizaceae, Ascomycota) and characterization of the sister genus Nothoamylascus gen. nov. Persoonia 51: 125-151. doi: 10.3767/persoonia.2023.51.03.

Survival rates in the world's southernmost forest bird community

The Magellanic sub-Antarctic Forest is home to the world's southernmost avian community and is the only Southern Hemisphere analogue to Northern Hemisphere temperate forests at this latitude. This region is considered among the few remaining pristine areas of the world, and shifts in environmental conditions are predominantly driven by climate variability. Thus, understanding climate-driven demographic processes is critical for addressing conservation issues in this system under future climate change scenarios. Here, we describe annual survival patterns and their association with climate variables using a 20-year mark-recapture data set of five forest bird species in the Cape Horn Biosphere Reserve. We develop a multispecies hierarchical survival model to jointly explore age-dependent survival probabilities at the community and species levels in a group of five forest passerines. At the community level, we assess the association of migratory behavior and body size with survival, and at the species level, we investigate the influence of local and regional climatic variables on temporal variations of survival. We found a positive effect of precipitation and a negative effect of El Niño Southern Oscillation on juvenile survival in the white-crested Elaenia and a consistent but uncertain negative effect of temperature on survival in juveniles and 80% of adults. We found only a weak association of climate variables with survival across species in the community and no temporal trends in survival for any of the species in either age class, highlighting apparent stability in these high austral latitude forests. Finally, our findings provide an important resource of survival probabilities, a necessary input for assessing potential impacts of global climate change in this unique region of the world.

Intraspecific phylogeny of a Patagonian fescue: differentiation at molecular markers and morphological traits suggests hybridization at peripheral populations

BACKGROUND AND AIMS

Grasses of the Festuca genus have complex phylogenetic relations due to morphological similarities among species and inter-specific hybridization processes. Within Patagonian fescues, information concerning phylogenetic relationships is very scarce. In Festuca pallescens, a widely distributed species, the high phenotypic variability and the occurrence of interspecific hybridization preclude a clear identification of the populations. Given the relevance of natural rangelands for livestock production and their high degradation due to climate change, conservation actions are needed and knowledge about genetic variation required.

METHODS

To ravel out the intraspecific phylogenetic relations and to detect genetic differences, we studied 21 populations of the species along its natural geographic distribution by coupling both molecular (ITS and trnL-F markers) and morpho-anatomical analyses. Bayesian inference, maximum likelihood, and maximum parsimony methods were applied to assemble a phylogenetic tree, including other native species. The morphological data set was analysed by discriminant and cluster analyses.

KEY RESULTS

The combined information of the Bayesian tree (ITS marker), the geographic distribution of haplotype variants (trnL-F marker) and the morpho-anatomical traits, distinguished populations located at the margins of the distribution. Some of the variants detected were shared with other sympatric species of fescues.

CONCLUSIONS

These results suggest the occurrence of hybridization processes between species of the genus at peripheral sites characterized by suboptimal conditions, which might be key to the survival of these populations.

The first Gondwanan Euphorbiaceae fossils reset the biogeographic history of the Macaranga-Mallotus clade

PREMISE

The spurge family Euphorbiaceae is prominent in tropical rainforests worldwide, particularly in Asia. There is little consensus on the biogeographic origins of the family or its principal lineages. No confirmed spurge macrofossils have come from Gondwana.

METHODS

We describe the first Gondwanan macrofossils of Euphorbiaceae, represented by two infructescences and associated peltate leaves from the early Eocene (52 Myr ago [Ma]) Laguna del Hunco site in Chubut, Argentina.

RESULTS

The infructescences are panicles bearing tiny, pedicellate, spineless capsular fruits with two locules, two axile lenticular seeds, and two unbranched, plumose stigmas. The fossils' character combination only occurs today in some species of the Macaranga-Mallotus clade (MMC; Euphorbiaceae), a widespread Old-World understory group often thought to have tropical Asian origins. The associated leaves are consistent with extant Macaranga.

CONCLUSIONS

The new fossils are the oldest known for the MMC, demonstrating its Gondwanan history and marking its divergence by at least 52 Ma. This discovery makes an Asian origin of the MMC unlikely because immense oceanic distances separated Asia and South America 52 Ma. The only other MMC reproductive fossils so far known are also from the southern hemisphere (early Miocene, southern New Zealand), far from the Asian tropics. The MMC, along with many other Gondwanan survivors, most likely entered Asia during the Neogene Sahul-Sunda collision. Our discovery adds to a substantial series of well-dated, well-preserved fossils from one undersampled region, Patagonia, that have changed our understanding of plant biogeographic history.

Multixenobiotic defence mechanism in native and exotic freshwater snails as a biomarker for land uses-changes

Human activities such as agriculture and urbanization generate a large number of substances like personal care products, pharmaceutical compounds, and pesticides, which often reach aquatic environments and represent a threat to biodiversity. Many organisms have developed different evolutionary strategies to remove pervasive substances from their bodies, allowing them to persist even in polluted environments, and one of these is the multixenobiotic resistance (MXR) mechanism associated with the expression of membrane proteins like P-glycoprotein (P-gp). Numerous chemical compounds with diverse functions and structures can modulate this mechanism, which can be employed as a pollution biomarker. We examined the MXR activity in two species of snails that inhabit Patagonian freshwaters. Functional assay measurements of MXR were conducted on the native Chilina dombeiana and the exotic Physella acuta in stream reaches affected by anthropogenic impacts. Results indicated that at agricultural sites, C. dombeiana snails had a more active MXR system than organisms sampled at reference and moderately disturbed urban sites, whereas P. acuta snails from agricultural and highly disturbed urban sites showed better detoxifying activity than organisms from reference sites. Only in exotic snails, part of this activity was due to the action of P-gp. The most important environmental variables explaining MXR activity were ammonium, nitrate and nitrite, phosphates, and electrical conductivity. These results show the promise of measuring MXR activity in native and exotic snails, as a biomarker in the environmental monitoring of Patagonian freshwaters.

Honeydew production by the giant willow aphid (Tuberolachnus salignus, Hemiptera: Aphididae) and its effect on foraging yellowjackets (Hymenoptera: Vespidae)

BACKGROUND

Understanding the factors that promote the success of invasive species is important for managing biological invasions. Interactions between invasives and other species (e.g. competitors, pathogens, or predators), could favor or limit their success. In recent decades, yellowjacket wasps, including Vespula germanica and Vespula vulgaris, have successfully established in Patagonia. Additionally, the invasive willow Salix fragilis has invaded areas next to watercourses, which in turn are typically colonized by the giant willow aphid (GWA, Tuberolagnus salignus), an additional species characterized as a successful invader in many regions worldwide. Aphid exudate (honeydew) has been reported to be used as a carbohydrate source by social wasps. The aim of our study was to gain a better understanding of the infestation pattern of the GWA in north-western Patagonia, its effect on exudate availability and its relationship with yellowjacket foraging patterns. The study was conducted under the working hypothesis that the increase in the size of GWA colonies and resulting honeydew production, will fuel an increase in local Vespula spp.

RESULTS

We found that the aphid honeydew is produced in relatively high amounts in the region (estimated at 1517  ± $$ \pm $$  139 kg/ha/season), with strong indications that it is used by yellowjackets because of the significantly higher abundance levels of yellowjackets foraging on honeydew compared to nearby areas.

CONCLUSION

Given its effect on yellowjacket foraging behavior, the interaction of these three invasive species, willows, GWA and yellowjackets, needs to receive special attention to develop future environmentally-sound mitigation tools of these nuisance pest. © 2023 Society of Chemical Industry.

Marine debris and associated organic pollutants in surface waters of Chiloé in the Northern Chilean Patagonia (42°-44°S)

We report the occurrence of plastics and associated persistent organic pollutants (POPs) in surface waters from Northern Chilean Patagonia. A total of 200 particles were found during the conducted survey. The highest number of particles found was 0.6 item m^-3. We found that 53 % of the collected particles corresponded to plastic, with an average of 0.19 ± 0.18 item m^-3. Microplastics (68 %) were the dominant size found in the area, followed by macroplastics (18 %) and mesoplastics (14 %). Most plastic particles were white (55 %) while others were <10 % each. Black and light blue represented 9 %; red, dark blue, and other colors 7 %; and green 6 %. Fragments were the most frequent shape of plastic debris (38 %), followed by Styrofoam (30 %) and fiber (27 %). Higher PBDE levels were found in the central zone, and those were higher than DDT, PeCB, HCB, and PCB levels. This study is the first report on POP occurrence in marine plastic debris from Chiloé Sea in the Northern Chilean Patagonia.

[Microbial contaminants in bottled craft beer of Andean Patagonia, Argentina]

The brewing activity in Andean Patagonia plays a very important role in the region's economy, being microbial contamination one of the main problems in terms of quality. The presence of contaminant bacteria and wild yeasts in beer generate microbiological, physical and chemical changes that impact on its sensory attributes. However, few breweries establish criteria and policies to guarantee the quality of their products in a microbiological sense. The purpose of this work was to study for the first time the incidence of microbial contaminants in bottled craft beers from Andean Patagonia, identify the main microorganisms involved and establish relationships between contamination and the physicochemical variables of beer. We analyzed 75 beers from 37 breweries from 12 different Patagonian cities. Our results showed that 69.3% of the analyzed beer exhibited contaminant microorganism growth. Bacteria Levilactobacillus brevis and wild yeasts of Saccharomyces were the main microorganisms responsible for these contaminations. In addition, we found that microbial contamination had an impact on beer sensory profile and also that pH was correlated with the presence of lactic acid bacteria in beer, being an indicator of contamination for these bacteria. In conclusion, we observed that 8 out of 10 breweries studied showed contamination problems, highlighting the need to design prevention and control strategies in microbreweries.

Two new species of Phaeohelotium (Leotiomycetes: Helotiaceae) from Chile and their putative ectomycorrhizal status

Species of the genus Phaeohelotium (Leotiomycetes: Helotiaceae) are cup fungi that grow on decaying wood, leaves, litter, and directly on soil. Northern Hemisphere species are primarily found on litter and wood, whereas in the Southern Hemisphere the genus includes a mix of saprotrophs as well as taxa that grow on soil in association with ectomycorrhizal trees. The diversity of this genus has not been fully explored in southern South America. Here we describe two species from Chile, Phaeohelotium maiusaurantium sp. nov. and Ph. pallidum sp. nov., found on soil in Patagonian Nothofagaceae-dominated forests. We present macro- and micromorphological descriptions, illustrations, and molecular phylogenetic analyses. The two new species are placed in Phaeohelotium with high support in our 15-locus phylogeny as well as phylogenetic reconstructions based on the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene. Our ITS phylogeny places both Ph. maiusaurantium and Ph. pallidum in a well-supported subclade that includes ectomycorrhizal root tip samples from Australasia. Similar species can be separated from these new taxa based on morphological characteristics, biogeography, substrate, and sequence data. In addition, two unnamed species from Chilean Nothofagaceae forests (Phaeohelotium sp. 1 and Phaeohelotium sp. 2) are documented from scant collections and sequence data and await description until more material becomes available. Citation: Grupe II AC, Smith ME, Weier A, Healy R, Caiafa MV, Pfister DH, Haelewaters D, Quandt CA (2022). Two new species of Phaeohelotium (Leotiomycetes: Helotiaceae) from Chile and their putative ectomycorrhizal status. Fungal Systematics and Evolution 10: 231-249. doi: 10.3114/fuse.2022.10.10.

Urbanity as a source of genotoxicity in the synanthropic Kelp Gull (Larus dominicanus)

Increases in human population lead to an increase in urban wastes, which could affect wildlife in several ways. Urban pollutants can affect erythrocytes of birds generating morphological membrane and nuclear anomalies. The Kelp Gull (Larus dominicanus) is an opportunistic species, which take advantage of urban environments, thus being highly exposed to environmental pollution. In northeastern Patagonia, the dynamic of the waste management was transformed in the last decade and consequently, gulls changed their movements in response to changes in waste management systems. The food available to the seagulls went from being a mixture of urban/fishing discards until 2015, when this landfill closures, to being domestic urban offerings. In order of evaluating genotoxicity and changes in pollutants exposition due to these changes, we analyzed the frequencies of erythrocytes nuclear abnormalities and micronuclei (ENAs and MN respectively) in 58 blood smears from adults extracted during the non-breeding season in two periods in landfills with different waste compositions: a mixed landfill (ML) in 2013 before closure (n = 24) versus an urban landfill (UL) (n = 34) in 2021. We found that the Kelp Gull showed high values of abnormalities with an average of 151.5 /10,000 RBC in comparison with other seabird species. The bud and notched types of ENAs were the most prevalent abnormalities in both sites. We did not find significate differences in the overall abnormality frequency between sites, however we found significant higher frequencies in displaced and tailed types of ENAs in ML. We also found poikilocytosis, as seen previously in other animals exposed experimentally to pollutants such as metals and crude oil. Cellular abnormalities found in the Kelp Gull suggest an exposition of individuals to pollutants in foraging areas. The hemispheric distribution and the synanthropic characteristics of the species denote its importance as a suitable global monitor of genotoxicity.

Surfing the tide: Homeward migration of sea trout (Salmo trutta) in a Patagonian river

This study evaluates the influence of marine and freshwater conditions on the timing of river entry and upstream migration of sea trout (Salmo trutta) in the Grande River of Tierra del Fuego, Patagonia. We analysed the in-river catch-and-release records from a group of fishing lodges that dominate the Grande River fishery during January-April 2008 (n = 5029 fish) as a function of environmental variables: tidal amplitude, stage in the lunar cycle, river discharge, and river water temperature along the homeward migration season. We discuss the value of the daily catch rate as an abundance index in the Grande river, then analyse the temporal structure of the tidal cycle in the Grande River estuary, a macro-tidal environment with a mean tidal amplitude of 5.7 m, and analyse the fit of a generalized additive model to trout catches on a daily basis in four sections along the river to identify the environmental variables that may affect trout abundance throughout the homeward migration. Fish catches in each section of the river were differentially affected by specific environmental variables: tidal amplitude had a positive and significant effect on catches in the lower river sections, whereas water temperature and river discharge significantly affected catches in upper sections (positive effect of temperature; negative effect of discharge). Catches in the lower section clearly reflect the river entry stage of the homeward migration, with a bi-modal shape significantly correlated with the tidal cycle. The first peak was composed mainly of larger multi-sea-winter trout that move upstream, whereas the second one had a wider range of fish lengths, including a large proportion of small and maybe nonreproductive trout that overwinter in the lower river. Based on our results, we conclude that the large tides in the Grande River estuary strongly affect the river entry timing of sea trout. The underlying mechanisms of this effect may be a combination of increased olfactory recognition and increased tidal transport modulated by the seasonal tidal cycle, which operates on trout during coastal migration to produce the pulses observed in the Grande River sea trout run. In the middle and upper sections of the river, where the tidal effect at river entry was dissipated as upstream migration progressed, trout catches increased with water temperature and decreased with river discharge, which may operate through their influence on in-river migration rate and abundance, but also through changes in catchability.

Biogeographic history of a large clade of ectomycorrhizal fungi, the Russulaceae, in the Neotropics and adjacent regions

The biogeography of neotropical fungi remains poorly understood. Here, we reconstruct the origins and diversification of neotropical lineages in one of the largest clades of ectomycorrhizal fungi in the globally widespread family Russulaceae. We inferred a supertree of 3285 operational taxonomic units, representing worldwide internal transcribed spacer sequences. We reconstructed biogeographic history and diversification and identified lineages in the Neotropics and adjacent Patagonia. The ectomycorrhizal Russulaceae have a tropical African origin. The oldest lineages in tropical South America, most with African sister groups, date to the mid-Eocene, possibly coinciding with a boreotropical migration corridor. There were several transatlantic dispersal events from Africa more recently. Andean and Central American lineages mostly have north-temperate origins and are associated with North Andean uplift and the general north-south biotic interchange across the Panama isthmus, respectively. Patagonian lineages have Australasian affinities. Diversification rates in tropical South America and other tropical areas are lower than in temperate areas. Neotropical Russulaceae have multiple biogeographic origins since the mid-Eocene involving dispersal and co-migration. Discontinuous distributions of host plants may explain low diversification rates of tropical lowland ectomycorrhizal fungi. Deeply diverging neotropical fungal lineages need to be better documented.

Anthropogenic microfibers are highly abundant at the Burdwood Bank seamount, a protected sub-Antarctic environment in the Southwestern Atlantic Ocean

Microplastics debris in the marine environment have been widely studied across the globe. Within these particles, the most abundant and prevalent type in the oceans are anthropogenic microfibers (MFs), although they have been historically overlooked mostly due to methodological constraints. MFs are currently considered omnipresent in natural environments, however, contrary to the Northern Hemisphere, data on their abundance and distribution in Southern Oceans ecosystems are still scarce, in particular for sub-Antarctic regions. Using Niskin bottles we've explored microfibers abundance and distribution in the water column (3-2450 m depth) at the Burdwood Bank (BB), a seamount located at the southern extreme of the Patagonian shelf, in the Southwestern Atlantic Ocean. The MFs detected from filtered water samples were photographed and measured using ImageJ software, to estimate length, width, and the projected surface area of each particle. Our results indicate that small pieces of fibers are widespread in the water column at the BB (mean of 17.4 ± 12.6 MFs.L^-1), from which, 10.6 ± 5.3 MFs.L^-1 were at the surface (3-10 m depth), 20 ± 9 MFs.L^-1 in intermediate waters (41-97 m), 24.6 ± 17.3 MFs.L^-1 in deeper waters (102-164 m), and 9.2 ± 5.3 MFs.L^-1 within the slope break of the seamount. Approximately 76.1% of the MFs were composed of Polyethylene terephthalate, and the abundance was dominated by the size fraction from 0.1 to 0.3 mm of length. Given the high relative abundance of small and aged MFs, and the oceanographic complexity of the study area, we postulate that MFs are most likely transported to the BB via the Antarctic Circumpolar Current. Our findings imply that this sub-Antarctic protected ecosystem is highly exposed to microplastic pollution, and this threat could be spreading towards the highly productive waters, north of the study area.

New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction

Giant carnivorous dinosaurs such as Tyrannosaurus rex and abelisaurids are characterized by highly reduced forelimbs that stand in contrast to their huge dimensions, massive skulls, and obligate bipedalism.^1,2 Another group that follows this pattern, yet is still poorly known, is the Carcharodontosauridae: dominant predators that inhabited most continents during the Early Cretaceous^3-5 and reached their largest sizes in Aptian-Cenomanian times.^6-10 Despite many discoveries over the last three decades, aspects of their anatomy, especially with regard to the skull, forearm, and feet, remain poorly known. Here we report a new carcharodontosaurid, Meraxes gigas, gen. et sp. nov., based on a specimen recovered from the Upper Cretaceous Huincul Formation of northern Patagonia, Argentina. Phylogenetic analysis places Meraxes among derived Carcharodontosauridae, in a clade with other massive South American species. Meraxes preserves novel anatomical information for derived carcharodontosaurids, including an almost complete forelimb that provides evidence for convergent allometric trends in forelimb reduction among three lineages of large-bodied, megapredatory non-avian theropods, including a remarkable degree of parallelism between the latest-diverging tyrannosaurids and carcharodontosaurids. This trend, coupled with a likely lower bound on forelimb reduction, hypothesized to be about 0.4 forelimb/femur length, combined to produce this short-armed pattern in theropods. The almost complete cranium of Meraxes permits new estimates of skull length in Giganotosaurus, which is among the longest for theropods. Meraxes also provides further evidence that carchardontosaurids reached peak diversity shortly before their extinction with high rates of trait evolution in facial ornamentation possibly linked to a social signaling role.

Tracking the exposure of a pelagic seabird to marine plastic pollution

We aimed to describe how debris originated from coastal cities and fisheries circulates and accumulates along the Argentine continental shelf and its potential interaction with southern giant petrels (SGP, Macronectes giganteus). We used tracking data of 31 SGPs (adults and juveniles) from Patagonian colonies. Lagrangian simulations of particles were released from coastal cities and fisheries. Oceanographic features together with plastic input generated a corridor of debris through the Argentine shelf with areas of high debris accumulation, exposing SGP to plastic consumption. During chick provisioning trips 93.9% of petrel's locations overlapped with areas of plastic accumulation. Although early developmental stages were more exposed to particles from cities, the exposure of petrels (all classes) to debris from fisheries was 10% higher than from cities. Measures to reduce debris from fisheries, would reduce plastic ingestion by giant petrels. Proper management of open sky dumpsters would reduce plastic consumption by chicks and juveniles.

Cunoniaceae infructescences from the early Eocene Laguna del Hunco flora, Patagonia, Argentina

PREMISE

Two distinct types of fossil infructescences from the early Eocene Laguna del Hunco flora, Chubut Province, Patagonia, Argentina, preserve features of the family Cunoniaceae. The goal of the study was to assess their affinities within Cunoniaceae and to interpret their evolutionary and biogeographical significance.

METHODS

Specimens were collected from the Tufolitas Laguna del Hunco, Huitrera Formation. They were prepared, photographed, and compared morphologically with similar extant and fossil fruits and infructescences using published literature and herbarium material.

RESULTS

The fruit and infructescence morphology place the fossil taxa within Cunoniaceae. They do not conform to any extant genus, supporting the erection of two new fossil genera. Racemofructus gen. nov. shares diagnostic features of the tribe Cunonieae, especially Weinmannia s.l., and exhibits two tribal morphological synapomorphies: a racemose inflorescence and a replum composed of a single column. Cunoniocarpa gen. nov. specimens are paniculate inflorescences with basipetally dehiscent, bicarpellate capsules that have persistent styles and calyces. Its replum morphology suggests an affinity to the tribe Caldcluvieae, particularly to the genus Ackama.

CONCLUSIONS

The new Patagonian fossils described herein constitute the oldest record of cunoniaceous capsules globally, supplementing a significant body of fossil evidence from pollen, wood, and reproductive structures from southern South America and Antarctica that suggests that the Cunoniaceae were diversified and widely distributed in the southern hemisphere by the early Eocene. Racemofructus and Cunoniocarpa are, respectively, the first fossil records from South America of reproductive structures with affinity to tribes Cunonieae and Caldcluvieae.

Trophodynamics of trace elements in marine organisms from cold and remote regions of southern hemisphere

Trace metals bioaccumulate in aquatic organisms and some of them biomagnify through food webs, posing a threat to the organisms or their human consumers. Although the trophodynamics of many trace metals is well known in the northern hemisphere, much less is known about metals in aquatic food webs from cold and remote coastal zones of the southern hemisphere. To fill this gap, we investigated the trophodynamics of Al, Co, Cr, Li, Mo, Ni, Sr, and V, which were measured in marine macroinvertebrates and fishes from inshore and offshore locations in each of the Chilean Patagonia and the Antarctic Peninsula area. In Patagonia, there was biodilution of these metals across the whole food web, while biomagnification of Li and Ni was significantly found across the lower food web at the offshore site. In Antarctica, significant biodilution of Al, Li, Ni, Mo, Sr and V occurred through the whole food web for the inshore site, but no tendency (biodilution or biomagnification) was found (p > 0.05) across the organisms at lower trophic levels for the offshore site. Our data suggest that the geographic location and species influences the trophodynamics of these trace elements and expand our understanding of metal fate in remote locations of the southern hemisphere.

Bottom-up effects of woodland eutrophication: Interacting limiting nutrients determine herbivory frequency in northwestern Patagonia

Nutrient enrichment disrupts plant-animal interactions and ecosystem functioning globally. In woodland systems, the mechanisms of bottom-up turnover on plant-herbivore interactions remain understudied. Here, we performed a full-factorial field experiment to evaluate the interactive effects of nutrient addition (nitrogen, phosphorus, and/or potassium) on the assemblage of foliar herbivores and the interaction frequency with Berberis microphylla, a dominant shrub species in Patagonian woodlands. Additionally, we assessed whether these effects could be mediated by changes in vegetative traits and microhabitat characteristics (i.e., canopy cover) that may ultimately influence the foraging behavior of herbivores. The addition of nitrogen reduced the herbivory frequency by 41%, yet this effect was diluted in the presence of potassium. We found no effects of phosphorus addition. Our results suggest that the impact of multiple nutrient additions (N and K) on herbivory patterns could be mediated by changes in two important foliar traits, leaf size and leaf density. This study shows how multiple nutrient addition can change the magnitude of antagonistic plant-animal interactions in woodlands. Since herbivory by arthropods has a relevant role in net primary productivity, our results highlight the importance of buffering human-driven woodland eutrophication to maintain important ecological functions (e.g., herbivory) associated with antagonistic plant-animal interactions and avoiding ecosystem dysfunction.

Wood density relates negatively to maximum plant height across major angiosperm and gymnosperm orders

PREMISE

Wood density is a crucial plant functional trait related to plant life history strategies. Its ecological importance in small-stature growth forms (e.g., shrubs) has not been extensively examined. Given that hydraulic conduit dimensions vary positively with plant height and that there is a negative relationship between conduits' diameter and wood density, I hypothesized an also negative relationship between wood density and plant height. Knowing that bark and pith proportions are significant in small-diameter stems, I additionally disentangled the contribution of wood, bark, and pith to stem density.

METHODS

I determined density in small-diameter stems across 153 species spanning all major angiosperm and gymnosperm orders by considering a diversity of growth forms (trees, treelets, shrubs, vines, and hemiparasites). Stem cross sections were dissected to consider the densities of wood with bark and pith; wood with pith and without bark; wood with bark and no pith; and wood without bark and pith. Secondary growth was also measured.

RESULTS

Trees showed similar wood densities as non-self-supporting vines, and both showed significantly less dense wood than treelets, shrubs, and hemiparasites. General comparisons showed that wood was significantly denser than all other tissues, and these differences did not depend on growth form. Wood density was significantly and negatively related to growth rate and pith area proportions but not to bark thickness proportion.

CONCLUSIONS

An implicit negative relationship between maximum plant height and stem density emerges as a property of plants likely linked to hydraulic conductive size.

Relationships among Calibrachoa, Fabiana and Petunia (Petunieae tribe, Solanaceae) and a new generic placement of Argentinean endemic Petuniapatagonica

Calibrachoa Cerv., Fabiana Ruiz & Pav., and Petunia Juss. form a clade within tribe Petunieae (Solanaceae). Phylogenetic studies of Petunieae, either as part of a family-wide analysis or focusing on the genera Calibrachoa and Petunia, have either left Fabiana unsampled or included only a single species. These studies have found conflicting relationships among the three genera with all three possible topologies obtained. Petuniapatagonica (Speg.) Millán, originally described in the genus Nierembergia Ruiz & Pav., is morphologically distinct within Petunia and geographically disjunct from other members of the genus. For the first time, in this study we include multiple species of Fabiana, Calibrachoa, and Petunia, including P.patagonica. Using three chloroplast DNA regions and the nuclear gene GBSSI, or "waxy," our results provide strong support for a sister group relationship between Calibrachoa and Fabiana and for the placement of P.patagonica within Fabiana. Since there is already a species Fabianapatagonica Speg., we provide the new name Fabianaaustralis Alaria nom. nov. to replace Petuniapatagonica.

Livestock guarding dogs have minor effects on the parasite burden of wild carnivores

Livestock guarding dogs are increasingly used to reduce carnivore-livestock conflicts, but no information is available to determine any adverse effects that these dogs may have on the health of wild carnivores. We assessed differences in prevalence, richness and severity of parasites in chilla fox (Lycalopex griseus) populations associated with livestock guarding dogs, which were routinely dewormed. We also evaluated whether the parasite assemblages of herding dogs, which were not dewormed, and chilla foxes were more similar in the presence of livestock guarding dogs. Scats of L. griseus and herding dogs were collected and screened for parasite eggs in areas with and without livestock guarding dogs to determine differences in prevalence, richness, intensity and parasite aggregation. We did not find any association between livestock guarding dogs and differences in parasite richness or prevalence of parasites. The intensity of parasites was higher among foxes positive to parasites when LGDs were present. A lower proportion of foxes with low parasite burdens occurred in areas with LGDs compared to areas without LGDs, but this difference was not significant at the population level. Our findings show the need to continue studying the effects of livestock guarding dogs on the health of wildlife with larger sample sizes and more locations.

Annotated catalogue of the Tachinidae (Insecta, Diptera) of Chile

The Tachinidae (Diptera) of Chile are catalogued and information is given on distributions, name-bearing types, synonyms, nomenclatural issues, and pertinent literature. The history of tachinid collectors in Chile and authors who have contributed to the systematic knowledge of Chilean tachinids is extensively reviewed. The classification has been updated and 122 genera and 264 species are recognised in Chile. There is a significant amount of endemism with 28 genera and 100 species known only from Chile. There are also 113 species with distributions shared only between Chile and Argentina, particularly in the southern portions of these countries comprising Patagonia. The catalogue is based on examination of the original descriptions of all nominal species and all other references known to us containing relevant taxonomic and distributional information, for a total of approximately 450 references. Many of the name-bearing types and other Chilean specimens housed in collections were examined. Taxa are arranged hierarchically and alphabetically under the categories of subfamily, tribe, genus, subgenus (where recognised), and species. Nomenclatural information is provided for genus-group and species-group names, including lists of synonyms (mostly restricted to Neotropical taxa) and name-bearing type data. Species distributions are recorded by country within the New World and by larger geographical divisions in the Old World. Additional information is given in the form of notes and references under valid names at the level of tribe, genus, and species. Two genera are newly recorded from Chile: Chaetoepalpus Vimmer & Soukup, 1940 (Tachinini) (also newly recorded from Argentina) and Patelloa Townsend, 1916 (Goniini). Four species are newly recorded from Chile or other countries: Lyphaornata Aldrich, 1934 (Chile); Chaetoepalpuscoquilleti Vimmer & Soukup, 1940 (Argentina and Chile); Phytomypteraevanescens (Cortés, 1967) (Argentina); and Xanthobasisunicolor Aldrich, 1934 (Chile). Eight species previously recorded from Chile are deemed to have been misidentified or misrecorded from Chile (known distributions in parentheses): Archytasincertus (Macquart, 1851) (Argentina, Brazil, Paraguay, Uruguay); Archytasseminiger (Wiedemann, 1830) (Brazil, Colombia); Goniacrassicornis (Fabricius, 1794) (Brazil, Peru, Venezuela, Middle America, West Indies, Nearctic); Lespesiaandina (Bigot, 1888) (Cuba); Lespesiaarchippivora (Riley, 1871) (widespread Nearctic and most of Neotropical); Neoethillaignobilis (van der Wulp, 1890) (Mexico, United States); Siphona (Siphona) geniculata (De Geer, 1776) (Palaearctic, Nearctic [introduced]); and Winthemiaquadripustulata (Fabricius, 1794) (Palaearctic, Nearctic, Oriental]. As First Reviser we fix Paratheresiarufiventris Townsend, 1929 as the senior homonym and Sarcoprosenarufiventris Townsend, 1929 as the junior homonym when the two are placed together in Billaea Robineau-Desvoidy, 1830; and we fix Mayophoriniaangusta Townsend, 1927 as the senior homonym and Metarrhinomyiaangusta Townsend, 1927 as the junior homonym when the two are placed together in Myiopharus Brauer & Bergenstamm, 1889. New replacement names are proposed for eight preoccupied names of Neotropical species (country of type locality in parentheses): Billaearufescens O'Hara & Wood for Sarcoprosenarufiventris Townsend, 1929, preoccupied in the genus Billaea Robineau-Desvoidy, 1830 by Paratheresiarufiventris Townsend, 1929 (Peru), nom. nov.; Billaeatriquetrus O'Hara & Wood for Sarcoprosenatriangulifera Townsend, 1927, preoccupied in the genus Billaea Robineau-Desvoidy, 1830 by Dexiatriangulifera Zetterstedt, 1844 (Peru), nom. nov.; Eucelatorianudioculata O'Hara & Wood for Eucelatorioideanigripalpis Thompson, 1968, preoccupied in the genus Eucelatoria Townsend, 1909 by Chetolyganigripalpis Bigot, 1889 (Trinidad), nom. nov.; Eucelatoriaoblonga O'Hara & Wood for Urodexodeselongatum Cortés & Campos, 1974, preoccupied in the genus Eucelatoria Townsend, 1909 by Exoristaelongata van der Wulp, 1890 (Chile), nom. nov.; Lespesiathompsoni O'Hara & Wood for Sturmiopsoideaobscura Thompson, 1966, preoccupied in the genus Lespesia Robineau-Desvoidy, 1863 by Eurigasterobscurus Bigot, 1857 (Cuba), nom. nov.; Myiopharuscharapensis O'Hara & Wood for Metarrhinomyiaangusta Townsend, 1927, preoccupied in the genus Myiopharus Brauer & Bergenstamm, 1889 by Mayophoriniaangusta Townsend, 1927 (Peru), nom. nov.; Myiopharusincognitus O'Hara & Wood for Stenochaetaclaripalpis Thompson, 1968, preoccupied in the genus Myiopharus Brauer & Bergenstamm, 1889 by Neoxynopsoideaclaripalpis Thompson, 1968 (Trinidad), nom. nov.; and Myiopharusrufopalpus O'Hara & Wood for Paralispepalpalis Townsend, 1929, preoccupied in the genus Myiopharus Brauer & Bergenstamm, 1889 by Myioxynopspalpalis Townsend, 1927 (Peru), nom. nov. New type species fixations are made under the provisions of Article 70.3.2 of the ICZNCode for three genus-group names: Parafabricia Brauer & Bergenstamm, 1894 (synonym of Archytas Jaennicke, 1867), type species newly fixed as Parafabriciaperplexa Townsend, 1931; Tachinodes Brauer & Bergenstamm, 1889 (synonym of Archytas Jaennicke, 1867), type species newly fixed as Juriniametallica Robineau-Desvoidy, 1830; and Willistonia Brauer & Bergenstamm, 1889 (synonym of Belvosia Robineau-Desvoidy, 1830), type species newly fixed as Willistoniaaldrichi Townsend, 1931. Lectotypes are designated for the following four nominal species, all described or possibly described from Chile: Echinomyiapygmaea Macquart, 1851 (a valid name in the genus Peleteria Robineau-Desvoidy, 1830); Goniachilensis Macquart, 1844 (a junior synonym of Goniapallens Wiedemann, 1830); Masiceraauriceps Macquart, 1844 (a valid name in the genus Lespesia Robineau-Desvoidy, 1863); and Prosopochoetanitidiventris Macquart, 1851 (a valid name in the genus Prosopochaeta Macquart, 1851). The following 27 new or revived combinations are proposed (distributions in parentheses): Blepharipezaandina Bigot, 1888 is moved to Lespesia Robineau-Desvoidy, 1863 as L.andina, nomen dubium (Cuba), comb. nov.; Camposodesevanescens Cortés, 1967 is moved to Phytomyptera Rondani, 1845 as P.evanescens (Argentina, Chile), comb. nov.; Ectophasiopsisypiranga Dios & Nihei, 2017 is moved to Trichopoda Berthold, 1827 and assigned to subgenus Galactomyia Townsend, 1908 as T. (G.) ypiranga (Argentina, Brazil), comb. nov.; Embiomyiaaustralis Aldrich, 1934 is moved to Steleoneura Stein, 1924 as S.australis (Argentina, Chile), comb. nov.; Eurigastermodestus Bigot, 1857 is moved to Lespesia as L.modesta (Cuba), comb. nov.; Eurigasterobscurus Bigot, 1857 is moved to Lespesia as L.obscura (Cuba), comb. nov.; Macropatelloatanumeana Townsend, 1931 is moved to Patelloa Townsend, 1916 as P.tanumeana (Argentina, Chile), comb. nov.; Masicerainsignis van der Wulp, 1882 is moved to Drino Robineau-Desvoidy, 1863 as D.insignis (Argentina, Chile), comb. nov.; Parasetigenahichinsi Cortés, 1967 is moved to Chetogena Rondani, 1856 as C.hichinsi (Chile), comb. nov.; Parasetigenaporteri Brèthes, 1920 and junior synonym Stomatotachinasplendida Townsend, 1931 are moved to Chetogena as C.porteri (Chile), both comb. nov.; Phoroceracalyptrata Aldrich, 1934 is moved to Admontia Brauer & Bergenstamm, 1889 as A.calyptrata (Argentina, Chile), comb. nov.; Poliopsauratus Campos, 1953 is moved to Admontia Brauer & Bergenstamm, 1889 as A.aurata (Chile), comb. nov.; Poliopsstriatus Aldrich, 1934 is moved to Admontia as A.striata (Argentina, Chile), comb. nov.; Ruiziellafrontosa Cortés, 1951 is moved to Chaetoepalpus Vimmer & Soukup, 1940 and placed in synonymy with C.coquilleti Vimmer & Soukup, 1940 (Argentina, Chile, Peru), comb. nov.; Ruiziellaluctuosa Cortés, 1951 is moved to Chaetoepalpus as C.luctuosus (Argentina, Chile), comb. nov.; Sarcoprosenaluteola Cortés & Campos, 1974 is moved to Billaea Robineau-Desvoidy, 1830 as B.luteola (Chile), comb. nov.; Sarcoprosenarufiventris Townsend, 1929 is moved to Billaea where it is a junior secondary homonym and is renamed B.rufescens O'Hara & Wood (Peru), comb. nov.; Sarcoprosenatriangulifera Townsend, 1927 is moved to Billaea where it is a junior secondary homonym and is renamed B.triquetrus O'Hara & Wood (Peru),comb. nov.; Saundersiaaurea Giglio-Tos, 1893 is moved to "Unplaced species of Tachinini" (Mexico), comb. nov.; Schistostephanaaurifrons Townsend, 1919 is moved to Billaea as B.aurifrons (Peru), comb. nov.; Siphoactiacharapensis Townsend, 1927 is moved to Clausicella Rondani, 1856 as C.charapensis (Peru), comb. nov.; Siphoactiaperegrina Cortés & Campos, 1971 is moved to Clausicella as C. peregrina (Chile), comb. nov.; Sturmiafestiva Cortés, 1944 is moved to Drino as D.festiva (Argentina, Chile), comb. nov.; Sturmiopsoideaobscura Thompson, 1966 is moved to Lespesia Robineau-Desvoidy, 1863, where it is a junior secondary homonym and is renamed L.thompsoni O'Hara & Wood (Trinidad), comb. nov.; Trichopodaarcuata Bigot, 1876 is returned to Trichopoda from Ectophasiopsis Townsend, 1915 and assigned to subgenus Galactomyia (Argentina, Chile), comb. revived; and Trichopodagradata Wiedemann, 1830 is returned to Trichopoda from Ectophasiopsis and assigned to subgenus Galactomyia (Argentina, Brazil, Uruguay), comb. revived. New or revived generic and specific synonymies are proposed for the following 14 names: Camposodes Cortés, 1967 with Phytomyptera Rondani, 1845, syn. nov.; Ectophasiopsis Townsend, 1915 with Trichopoda Berthold, 1827, subgenus Galactomyia Townsend, 1908, syn. nov.; Embiomyia Aldrich, 1934 with Steleoneura Stein, 1924, syn. nov.; Fabriciaandicola Bigot, 1888 with Peleteriarobusta (Wiedemann, 1830), syn. revived; Macropatelloa Townsend, 1931 with Patelloa Townsend, 1916, syn. nov.; Peleteriainca Curran, 1925 with Peleteriarobusta (Wiedemann, 1830), syn. revived; Poliops Aldrich, 1934 with Admontia Brauer & Bergenstamm, 1889, syn. nov.; Ruiziella Cortés, 1951 with Chaetoepalpus Vimmer & Soukup, 1940, syn. nov.; Ruiziellafrontosa Cortés, 1951 with Chaetoepalpuscoquilleti Vimmer & Soukup, 1940, syn. nov.; Sarcoprosena Townsend, 1927 with Billaea Robineau-Desvoidy, 1830, syn. nov.; Schistostephana Townsend, 1919 with Billaea, syn. nov.; Siphoactia Townsend, 1927 with Clausicella Rondani, 1856, syn. nov.; Stomatotachina Townsend, 1931 with Chetogena Rondani, 1856, syn. nov.; and Sturmiopsoidea Thompson, 1966 with Lespesia Robineau-Desvoidy, 1863, syn. nov.

Integrated biomarker response in Mytilus chilensis exposed to untreated urban discharges along the coast of Ushuaia Bay (Beagle Channel, Argentina)

The short-term effects of coastal untreated effluents from Ushuaia Bay, Beagle Channel, on the biochemical and physiological biomarkers of Mytilus chilensis were assessed. An integrated biomarker response (IBR) index was calculated as a helpful tool to represent the general stress of the experimental organisms. Cultured mussels were exposed during 96 h to three coastal sites impacted by sewage effluents. At the beginning (T₀) and every 24 h, mussels were subsampled from each site and different biochemical and physiological biomarkers were determined. There was no mortality registered in the experiments during the 96 h. However, biochemical and physiological biomarkers presented significant variations. Lipid peroxidation mean levels in mussels decreased in mantle and increased in digestive gland with respect to T₀ in almost all cases. Acetylcholinesterase activity was inhibited in all sites, reaching a maximal decrease of 35% with respect to T₀. Catalase remained stable and glutathione-S-transferase was activated. Oxygen consumption and ammonia excretion rates increased in organisms from two sites and, consequently, O:N ratio decreased, denoting a symptom of stress. IBR values showed the existence of different stress levels between exposed and unexposed mussels. These results exhibited an alteration of the general metabolism of mussels exposed for a short period of time to untreated coastal wastewater, suggesting the use of these organisms as early indicators of changes in the environmental quality of coastal waters of Ushuaia Bay.

Physiological, biochemical, and anatomical responses of Araucaria araucana seedlings to controlled water restriction

Water stress triggers acclimation responses and can damage plants, which varies by species and stress levels. Ongoing climate change is projected to result in longer and more intense water stress conditions leading to an alarming increase in drought-induced forest decline. The aim of this study was to evaluate the physiological responses of leaves and stem wood anatomy from Araucaria araucana pot-grown three-year old seedlings, a conifer tree from northwestern Patagonia. Plants were subjected to moderate and severe water restriction regimes and compared to well-watered controls. Severe water stress reduced relative leaf water content and triggered an accumulation of free proline in leaves, regardless of age. Epicuticular wax extrusions increased in apical leaf stomata while photosynthetic pigments decreased, resulting in differential oxidative damage. The concentration of phenolic compounds was not affected by water restrictions. Plants exposed to restricted water regimes showed diminished middle leaf biomass and expansion (~60% of total leaves), increased stem wood density, and experienced 7% and 30% mortality rates under moderate and severe water stress, respectively. Our findings suggest that under moderate water stress, analogous to short-term droughts, A. araucana seedlings activate physiological mechanisms that allow them to withstand short periods of drought, while more severe water stress and longer droughts can be severely harmful.

Ecological and environmental context shape the differential effects of a facilitator in its native and invaded ranges

Invasive species often exhibit disproportionately strong negative effects in their introduced range compared to their native range, and much research has been devoted to understanding the role of shared evolutionary history, or lack thereof, in driving these differences. Less studied is whether introduced species, particularly those that are important as facilitators in their native range, have persistent positive effects in their invaded range despite a lack of a shared evolutionary history with the invaded community. Here, we manipulated the density of a habitat-forming facilitator, the high intertidal acorn barnacle Balanus glandula, factorially with herbivore density in its native range (Bluestone Point, British Columbia, Canada) and invaded range (Punta Ameghino, Chubut Province, Argentina) to determine how this facilitator differentially affects associated species at these two locations. Given that high intertidal species at Punta Ameghino (PA) are evolutionarily naïve to barnacles, we predicted that the positive effects of B. glandula at PA would be absent or weak compared to those at Bluestone Point (BP). However, we found that B. glandula had an equally positive effect on herbivore biomass at PA compared to BP, possibly because the moisture-retaining properties of barnacle bed habitats are particularly important in seasonally dry Patagonia. Barnacle presence indirectly decreased ephemeral algal cover at BP by increasing grazer pressure, but barnacles instead facilitated ephemeral algae at PA. In contrast, B. glandula increased perennial algal cover at BP, but generally decreased perennial algal cover at PA, likely due to differences in dominant algal morphology. Though our experiment was limited to one location on each continent, our results suggest that shared evolutionary history may not be a prerequisite for strong facilitation to occur, but rather that the nature and strength of novel species interactions are determined by the traits of associated species and the environment in which they occur.

Gender dimorphism in the virulence of a dioecious mistletoe

Parasite virulence often differs between male and female hosts. However, less is known about how virulence might differ between male and female parasites. Here, I show that female plants of the dioecious mistletoe Misodendrum quadrifolium (Misodendraceae) grow larger than male plants. Correspondingly, females reduce the photosynthetic capacity of infected host branches more than males. Results indicate that in addition to playing an important role in determining host susceptibility to parasitism, gender can also play an important role in determining the virulence of dioecious parasites.

Upraising a silent pollution: Antibiotic resistance at coastal environments and transference to long-distance migratory shorebirds

Large amounts of antibiotics from different sources have been released into coastal environments, especially in high human-populated areas, but comprehensive studies of antibiotic footprint in wildlife are scarce. Here we assess occurrence of antibiotic resistant bacteria (ARB) and antibiotic resistance gene (ARG) both in sediments and gut microbiota of a long-distance migratory shorebird species in two coastal wetlands at a sparsely-populated area in Pacific Patagonian coasts with contrasting potential antibiotic sources, especially from aquaculture. We found 62% of sediment samples showing ARB, and ARGs similarly occurring in sediments at both bays. However multi-resistant ARB were found only at sediments in the bay surrounding aquaculture operations. An 87% of cloacal bird samples showed at least one ARB, with 63% being multi-resistant and some of them with a high potential pathogenicity. ARGs were present in 46% of the samples from birds, with similar multi-resistant frequencies among bays. Besides specific differences mainly associated to antibiotics used in salmon aquaculture that boosted ARB in sediments, ARB and ARGs occurrence was overall similar at two bays with contrasting main human activities, in spite of being a comparatively low human-populated area. Therefore, our results reinforce the idea that the antibiotic footprint may be widespread at a global scale and can extend beyond the geographical influence of antibiotic sources, especially at coastal environments where migratory shorebirds act both as reservoirs and potential spreaders of antibiotic resistance.

A decade later, reviewing floating marine debris in Northern Chilean Patagonia

Floating marine debris (FMD) were abundantly reported in the Northern Chilean Patagonia in 2009 where sea-based activities (mussel and salmon aquaculture) are responsible for most of them. Identifying the sources of FMD is important to take the necessary actions to diminish their abundance. In 2019 eleven transects were opportunistically conducted to evaluate the abundance, spatial distribution and composition of FMD in the same area, and to compare them with the previous study using the same methodology. FMD identified were classified into the same six categories from the previous study, however "Others" category were now the dominant one indicating that new pollutants have been increasing during the last decade. Inside the "others" category, plastics buoy and other floating devices, that normally are used by the salmon aquaculture, were the main items. Similarly than the previous study, styrofoam and domestic plastics were also the other most abundant items. In general, also, an increase in abundance compared with the previous study was found. The highest abundances were similarly found in the "Golfo de Corcovado" zone ranging from 50 to 230 items km^-2. Our results, as well as the previous study, confirm that sea-based activities are still responsible for the FMD found in the Northern Patagonia. To avoid the origin of this contamination it is urgent to implement public policies that effectively reduce FMD, and hold the aquaculture industries responsible.

Plant-plant co-occurrences under a complex land-use gradient in a temperate forest

Land-use generates multiple stress factors, and we need to understand their effects on plant-plant interactions to predict the consequences of land-use intensification. The stress-gradient hypothesis predicts that the relative strength of positive and negative interactions changes inversely under increasing environmental stress. However, the outcome of interactions also depends on stress factor's complexity, the scale of analysis, and the role of functional traits in structuring the community. We evaluated plant-plant co-occurrences in a temperate forest, aiming to identify changes in pairwise and network metrics under increasing silvopastoral use intensity. Proportionally, positive co-occurrences were more frequent under high than low use, while negative co-occurrences were more frequent under low than high. Networks of negative co-occurrences showed higher centralization under low use, while networks of positive co-occurrences showed lower modularity and higher centralization under high use. We found a partial relationship between co-occurrences and key functional traits expected to mediate facilitation and competition processes. Our results shows that the stress-gradient hypothesis predicts changes in spatial co-occurrences even when two stress factors interact in a complex way. Networks of negative co-occurrences showed a hierarchical effect of dominant species under low use intensity. But positive co-occurrence network structure partially presented the characteristics expected if the facilitation was an important mechanism characterizing the community under high disturbance intensity. The partial relationship between functional traits and co-occurrences may indicate that other factors besides biotic interactions may be structuring the observed negative spatial associations in temperate Patagonian forests.

Nitrogen dynamic in vitro using sludge of a sewage stabilization pond from Patagonia (Argentina)

A relevant and current aspect of wastewater treatment systems is related to the processes of the nitrogen cycle that results in its elimination in gaseous forms. In the present study, we report the first measurements of nitrate-reducing rate (NRR) at lab-scale, using the flow-through reactor technique with sludge of a sewage stabilization pond system located in Patagonia (Argentina). Sludge was collected from Inlet and Outlet areas, in winter and summer. The sludge was characterized by having high moisture content (>94%) and organic matter concentration greater than 37%. The nitrate reduction experimental dates fitted significantly to the Michaelis-Menten model, allowing the estimation of the parameters that regulate the NR kinetics. The maximum potential nitrate reduction rate (Rmax) showed great variability, registering a maximum of 131.6 μmol-N·gdw-1·h-1 (Outlet-Summer) and a minimum of 4.1 μmol-N·gdw-1·h-1 (Inlet-Winter). The lowest half saturation constant (Km) was recorded in the Inlet sludge during the winter (6.1 mg N-NO3-·L-1), which indicates a greater affinity for nitrate of this bacterial consortium. An unusually high activity of NR was registered, being higher with sludge from the Outlet zone and with summer temperature. In full-scale ponds, the NR activity could explain a relevant part of the nitrogen removal that involves the escape of gaseous forms.

Embryonic shell shape as an early indicator of pollution in marine gastropods

Gastropods shell shape has been proposed as a good indicator of environmental changes while geometric morphometric (GM) is a powerful tool to detect such changes. Shell shape pattern in adults of the marine gastropod Buccinanops deformis was proved to be correlated with imposex incidence and maritime traffic in populations of Patagonia. We explore through GM the shell shape variation of B. deformis intracapsular embryos in pre-hatching stages of development, in two populations with contrasting maritime traffic and imposex incidence. Embryonic shell shape from polluted and unpolluted areas was significantly different in apex, lateral, aperture and siphonal channel. The same shell shape pattern was observed previously in B. deformis adult specimens. Our results demonstrate that the embryonic shell shape is an early biomarker that could be used as a tool to detect the response to environmental pollution studying abundant egg capsules laid in the field but protecting reproductive adults.

The Bacterial Community of the Foliose Macro-lichen Peltigera frigida Is More than a Mere Extension of the Microbiota of the Subjacent Substrate

Lichens host highly diverse microbial communities, with bacteria being one of the most explored groups in terms of their diversity and functioning. These bacteria could partly originate from symbiotic propagules developed by many lichens and, perhaps more commonly and depending on environmental conditions, from different sources of the surroundings. Using the narrowly distributed species Peltigera frigida as an object of study, we propose that bacterial communities in these lichens are different from those in their subjacent substrates, even if some taxa might be shared. Ten terricolous P. frigida lichens and their substrates were sampled from forested sites in the Coyhaique National Reserve, located in an understudied region in Chile. The mycobiont identity was confirmed using partial 28S and ITS sequences. Besides, 16S fragments revealed that mycobionts were associated with the same cyanobacterial haplotype. From both lichens and substrates, Illumina 16S amplicon sequencing was performed using primers that exclude cyanobacteria. In lichens, Proteobacteria was the most abundant phylum (37%), whereas soil substrates were dominated by Acidobacteriota (39%). At lower taxonomic levels, several bacterial groups differed in relative abundance among P. frigida lichens and their substrates, some of them being highly abundant in lichens but almost absent in substrates, like Sphingomonas (8% vs 0.2%), and others enriched in lichens, as an unassigned genus of Chitinophagaceae (10% vs 2%). These results reinforce the idea that lichens would carry some components of their microbiome when propagating, but they also could acquire part of their bacterial community from the substrates.