Streamflow elasticity, in a context of climate change, in arid Andean watersheds of north-central Chile
Barrera, C., Núñez Cobo, J., Souvignet, M., Oyarzún, J., & Oyarzún, R.
Based on a future temperature increase of 0.5°C and precipitation decrease of 25%, the climate elasticity of streamflow to precipitation and temperature changes in 12 Andean watersheds of the Coquimbo Region, north-central Chile, was assessed. Also, the possible relationships between this elasticity and specific physiographic characteristics of the watersheds (area, average elevation, slope distribution, terrain roughness, slope orientation, vegetation cover) were studied. Climate elasticity of streamflow ranged between 0 and 2.8. Watersheds presenting higher elevations, with a fairly well-balanced distribution of slope exposure tend to exhibit lower elasticity, which could be explained by the contribution of snowfall to the hydrological regime, more significant in those watersheds. Results should be considered when downscaling climate model projections at the basin scale in mountain settings. Finally, uncertainties in the approach, given by factors such as streamflow seasonality, data availability and representativeness and watershed characteristics, and therefore the scope of the results, are discussed.
Palabras claves: Streamflow elasticity, arid zone, Andes Mountains, climate change resilience
Taguatagua 1: New insights into the late Pleistocene fauna, paleoenvironment, and human subsistence in a unique lacustrine context in central Chile
Labarca, R., González-Guarda, E., Lizama-Catalán, A., Villavicencio, N.A., Alarcón-Muñoz, J., Suazo-Lara, F., Oyanadel-Urbina, P., Soto-Huenchuman, P., Salazar, C., Soto-Acuña, S., Buldrini, K.E.
The Laguna de Tagua Tagua has yielded two important late Pleistocene archaeological sites, Taguatagua 1 and Taguatagua 2, in which a clear early human exploitation of megafauna has been recorded. Particularly in Taguatagua 1 (TT-1), here re-dated around 12,600 cal yr BP, an abundant small faunal assemblage was also recovered, which had not been previously studied in detail. Here we report the first comprehensive taxonomic and taphonomic analysis of this site. We identified 28 different taxa, including mollusks, fish, anurans, reptiles, birds, marsupials, rodents, carnivores, gomphotheres, horses and cervids, making this the richest late Pleistocene site in Chile so far. Among these, sixteen taxa are new for the Chilean late Pleistocene. Birds are the richest group, with ten taxa, followed by rodents with eight taxa. Most of the species currently inhabit the area, but we identified some locally extirpated taxa, together with extinct taxa (exclusively megamammals). Taphonomic analysis suggests a very complex depositional scenario, mostly related to lake-level oscillations which covered and exposed a mainly natural deposited small faunal assemblage. So far, we detected human-made modifications exclusively in horse and cervid bones. Current habitat requirements of the extant fauna, as well as dietary reconstruction of extinct fauna, suggest a highly variable climate and vegetation during the formation of TT-1 since taxa with preferences from semiarid to humid/wooded environments were identified. These results can be related to the changes from cold/wet to dry/warm conditions documented during the Pleistocene - Holocene transition.
Palabras claves: Pleistocene, South America, Megafauna, Small fauna, Taphonomy, Paleoenvironment
Socio-environmental conflicts: An underestimated threat to biodiversity conservation in Chile
Carranza, D.M., Varas-Belemmi, K., De Veer, D., Iglesias-Müller, C., Coral-Santacruz, D., Méndez, F.A., Torres-Lagos, E., Squeo, F.A., Gaymer, C.F.
Biodiversity is vital in the functioning of ecosystems, but it’s permanently being threatened by anthropic impacts derived from productive activities. Thus, conservation has become a global challenge. In Chile, the dissociation between economic activities and conservation has triggered numerous socio-environmental conflicts in recent decades. This work explores how different projects that give rise to these conflicts can represent an underestimated threat to biodiversity.
We identified socio-environmental conflicts in Chile and their associated projects by carrying out an online review of 1035 news articles published between 2004 and 2018 using the key words “environmental conflict”. We selected articles describing a socio-environmental conflict between parties caused by a project or productive sector. Conflict-generating projects were classified by productive sector and capital origin. In addition, their geographical distribution with respect to High Conservation Value Areas (HCVAs, protected areas and priority sites for conservation) was determined.
A total of 283 projects were identified from 14 different productive sectors, most of them related to energy and mining, which threaten biodiversity and human well-being mainly due to pollution and habitat destruction. Chilean companies finance most of the projects, but international companies finance over half of the energy and mining projects. Moreover, 37 % of the projects were located within HCVAs either for the establishment of future protected areas or where protected areas are currently established. As countries make new efforts to maintain and recover biodiversity, it is contradictory not to consider the threats posed by conflict-generating projects to key areas for conservation, both in public policies and in spatial planning instruments.
Palabras claves: Threat to biodiversity, Socio-environmental conflict, Conflict-generating project, High Conservation Value Areas, Public policies
Geographic Variation of UV Stress Tolerance in Red Seaweeds Does Not Scale with Latitude Along the SE Pacific Coast
Véliz, K., Chandía, N., Bischof, K., Thiel, M.
Geographic variation of phenotypic traits affects the capacity of species to withstand and adapt to environmental stress. Here, we examined how geographic origin influences UV stress tolerance of the red seaweeds Chondracanthus chamissoi and Gelidium lingulatum distributed along the South‐East Pacific coast between 20° S and 42° S. Seaweeds from six (C. chamissoi) and five (G. lingulatum) populations were grown under common‐garden conditions and then exposed to consecutive UV stress events and essential biological traits (e.g., growth, photosynthetic responses, antioxidant capacity, and UV‐absorbing compounds) were analyzed. In C. chamissoi, a strong UV sensitivity occurred in populations from mid‐latitudes (27° S and 29° S) where the lowest recovery of maximum quantum yield (Fv/Fm; between 32.3% and 66.8% of control) and growth rate were observed. Likewise, the lowest amount of mycosporine‐like amino acids (MAAs) and a significant decrease in phycobilins were registered in these populations. In G. lingulatum, recovery of Fv/Fm ranged from 82.0% to 97.7% of control, and antioxidant activity, carotenoid, and MAA contents were positively influenced by UV exposure. The multivariate analysis indicated a significant influence of PAR, cloud cover, and UV index on physiological traits, depending on species. The ecotypic differentiation index (EDI) indicated a higher phenotypic variation in C. chamissoi (EDI = 0.10) than G. lingulatum (EDI = 0.03). This study shows that the spatial distribution of UV stress tolerance in the studied seaweeds does not follow linear latitudinal or central–edge gradients. Instead, among‐site variability of solar intensities driven by specific climatic conditions seems to act as driver of phenotypic variation.
Palabras claves: Ecotypic, differentiation, latitudinal gradient, photoinhibition, seaweeds, ultraviolet radiation
Small burrowing amphipods cause major damage in a large kelp
Gutow, L., Poore Alistair, G. B., Díaz Poblete, M. A., Villalobos, V., and Thiel, M.
Large herbivores such as sea urchins and fish consume a high proportion of benthic primary production and frequently control the biomass of marine macrophytes. By contrast, small mesograzers, including gastropods and peracarid crustaceans, are abundant on seaweeds but have low per capita feeding rates and their impacts on marine macrophytes are difficult to predict. To quantify how mesograzers can affect macrophytes, we examined feeding damage by the herbivorous amphipods Sunamphitoe lessoniophila and Bircenna sp., which construct burrows in the stipes of subtidal individuals of the kelp Lessonia berteroana in northern-central Chile, southeast Pacific. Infested stipes showed a characteristic sequence of progressive tissue degeneration. The composition of the amphipod assemblages inside the burrows varied between the different stages of infestation of the burrows. Aggregations of grazers within burrows and microhabitat preference of the amphipods result in localized feeding, leading to stipe breakage and loss of substantial algal biomass. The estimated loss of biomass of single stipes varied between 1 and 77%. For the local kelp population, the amphipods caused an estimated loss of biomass of 24–44%. Consequently, small herbivores can cause considerable damage to large kelp species if their feeding activity is concentrated on structurally valuable algal tissue.
Different responses of leaf and root traits to changes in soil nutrient availability do not converge into a community-level plant economics spectrum
Delpiano, C.A., Prieto, I., Loayza, A.P., Carvajal, D.E., & Squeo, F.A.
Spatial heterogeneity in soil can influence the distribution of plant communities because plants differ in their ability to acquire resources. In nutrient-poor soils, plants should bear traits that prioritize conservation of resources over growth, whereas the opposite is expected in nutrient-rich soils. A coordinated response to soil fertility, in which leaves and roots converge into the same strategy, would lead to a community-level plant economics spectrum (PEScom). Here, we examine how nutrient availability across different soil types shapes the functional structure of desert shrub communities and how much of this variation is explained by species turnover or intraspecific variability (ITV).
Palabras claves: Atacama Desert, Nutrient limitation, K limitation, Soil N:P ratio, Resource acquisition strategies, Leaf economics spectrum, Root economics spectrum
A tradeoff between fitness‐related traits mask facilitation in a semiarid ecosystem
Molina‐Montenegro, M.A., Baldelomar, M., Atala, C., Torres‐Díaz, C.
In stressful environments, a nurse plant can ameliorate harsh biotic and abiotic conditions for another plant species that grows within its canopy. This canopy can act as a barrier for herbivores, reducing damage to the protected plants inside, but it can also reduce access to pollinators possibly resulting in a tradeoff between survival and reproductive output. In a semi‐arid ecosystem, the shrub Porlieria chilensis acts as a nurse, increasing soil moisture, nutrients and reducing temperature inside its canopy compared to open areas. Flourensia thurifera is one of the beneficiary shrubs that can grow inside P. chilensis, where it shows increased survival and performance compared to open areas. However, growing inside P. chilensis’ canopy may reduce pollinator visit. We aim to evaluate the possible tradeoff between survival and reproduction in F. thurifera individuals growing inside and outside the canopy of P. chilensis. This was achieved through a field experiment were we measured survival, pollinator visits and seed output of F. thurifera plants growing inside and outside the canopy of P. chilensis. Flourensia thurifera individuals had a higher survival when growing within the canopy of P. chilensis and had lower pollinator visits and seed output compared to plants growing in open areas. Thus, we found a significant negative correlation between plant survival and seed output considering both conditions (inside or outside nurses), evidencing a tradeoff between these traits. The tradeoff evidenced here could have large impact at the population and community level. On one hand, this tradeoff could mask possible nurse effects in other species, since they could show a similar net fitness in both microhabitat (inside or outside nurses). Finally, we propose a theoretical model to assess the change in the shape of this tradeoff under future climatic conditions where temperature and precipitation are predicted to vary due to climate change.
Palabras claves: climate change, facilitation, Mediterranean ecosystem, nurse effect, pollination, tradeoff
Multiple late‐Pleistocene colonisation events of the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) reveal the recent arrival of native Antarctic vascular flora
Biersma, E.M., Torres‐Díaz, C., Molina‐Montenegro, M.A., Newsham, K.K., Vidal, M.A., Collado, G.A., Acuña‐Rodríguez, I.A., Ballesteros, G.I., Figueroa, C.C., Goodall‐Copestake, W.P., Leppe, M.A., Cuba‐Díaz, M., Valladares, M.A., Pertierra, L.R., Convey, P.
The Maritime Antarctic populations likely derived from two independent, late‐Pleistocene dispersal events. Both clusters shared haplotypes with sub‐Antarctic South Georgia, suggesting higher connectivity across the Southern Ocean than previously thought. The overall findings of multiple colonization events by a vascular plant species to Antarctica, and the recent timing of these events, are of significance with respect to future colonizations of the Antarctic Peninsula by vascular plants, particularly with predicted increases in ice‐free land in this area. This study fills a significant gap in our knowledge of the age of the contemporary Antarctic terrestrial biota. Adding to previous inferences on the other Antarctic vascular plant species (the grass Deschampsia antarctica), we suggest that both angiosperm species are likely to have arrived on a recent (late‐Pleistocene) time‐scale. While most major groups of Antarctic terrestrial biota include examples of much longer‐term Antarctic persistence, the vascular flora stands out as the first identified terrestrial group that appears to be of recent origin.
Palabras claves: Angiosperm, Antarctica, biogeography, dispersal, island, pearlwort, South America, Southern Ocean
Assessing the genetic diversity in Argopecten nucleus (Bivalvia: Pectinidae), a functional hermaphrodite species with extremely low population density and self‐fertilization: Effect of null alleles
Barros, J, Winkler, FM, Velasco, LA.
Argopecten nucleus is a functional hermaphroditic pectinid species that exhibits self‐fertilization, whose natural populations have usually very low densities. In the present study, the genetic diversity of a wild population from Neguanje Bay, Santa Marta (Colombia), was estimated using microsatellite markers, and the effect of the presence of null alleles on this estimation was assessed. A total of 8 microsatellite markers were developed, the first described for this species, and their amplification conditions were standardized. They were used to determine the genotype of 48 wild individuals from Naguanje Bay, and 1,010 individuals derived from the offspring of 38 directed crosses. For each locus, the frequencies of the identified alleles, including null alleles, were estimated using the statistical package Micro‐Checker, and the parental genotypes were confirmed using segregation analysis. Three to 8 alleles per locus with frequencies from 0.001 to 0.632 were detected. The frequencies of null alleles ranged from 0.10 to 0.45, with Ho from 0.0 to 0.79, and He from 0.53 to 0.80. All loci were in H‐W disequilibrium. The null allele frequencies values were high, with lower estimations using segregation analysis than estimated using Micro‐Checker. The present results show high levels of population genetic diversity and indicate that null alleles were not the only cause of deviation from H‐W equilibrium in all loci, suggesting that the wild population under study presents signs of inbreeding and Wahlund effect.
Palabras claves: Caribbean Sea, inbreeding, microsatellite, scallop, segregation analysis
Induced Systemic Resistance by a Plant Growth-Promoting Rhizobacterium Impacts Development and Feeding Behavior of Aphids
Serteyn, L.; Quaghebeur, C.; Ongena, M.; Cabrera, N.; Barrera, A.; Molina-Montenegro, M.A.; Francis, F.; Ramírez, C.C.
The effects of microorganisms on plant-insect interactions have usually been underestimated. While plant growth-promoting rhizobacteria (PGPR) are known to induce plant defenses, endosymbiotic bacteria hosted by herbivorous insects are often beneficial to the host. Here, we aimed to assess whether PGPR-induced defenses in broad bean plants impact the pea aphid, depending on its genotype and the presence of endosymbionts. We estimated aphid reproduction, quantified defense- and growth-related phytohormones by GC-MS, and measured different plant growth and physiology parameters, after PGPR treatment. In addition, we recorded the feeding behavior of aphids by electropenetrography. We found that the PGPR treatment of broad bean plants reduced the reproduction of one of the pea aphid clones. We highlighted a phenomenon of PGPR-induced plant defense priming, but no noticeable plant growth promotion. The main changes in aphid probing behavior were related to salivation events into phloem sieve elements. We suggest that the endosymbiont Hamiltonella defensa played a key role in plant-insect interactions, possibly helping aphids to counteract plant-induced resistance and allowing them to develop normally on PGPR-treated plants. Our results imply that plant- and aphid-associated microorganisms add greater complexity to the outcomes of aphid-plant interactions.
Palabras claves: Acyrthosiphon pisum; Bacillus amyloliquefaciens; electropenetrography; Hamiltonella defensa; interactions; plant growth-promoting rhizobacteria (PGPR); Vicia faba