Genetic variation of loci potentially under selection confounds species–genetic diversity correlations in a fragmented habitat
Bertin, A., Gouin, N., Baumel, A., Gianoli, E., Serratosa, J., Osorio, R. and Manel, S.
Positive species–genetic diversity correlations (SGDCs) are often thought to result from the parallel inﬂuence of neutral processes on genetic and species diversity. Yet, con-founding effects of non-neutral mechanisms have not been explored. Here, we investigate the impact of non-neutral genetic diversity on SGDCs in high Andean wetlands.We compare correlations between plant species diversity and genetic diversity (GD)calculated with and without loci potentially under selection (outlier loci). The study system includes 2188 specimens from ﬁve species (three common aquatic macroinvertebrate and two dominant plant species) that were genotyped for 396 ampliﬁed fragment length polymorphism loci. We also appraise the importance of neutral processes onSGDCs by investigating the inﬂuence of habitat fragmentation features. Signiﬁcant positive SGDCs were detected for all ﬁve species (mean SGDC = 0.52 0.05). While only a few outlier loci were detected in each species, they resulted in signiﬁcant decreases in GD and in SGDCs. This supports the hypothesis that neutral processes drive species–genetic diversity relationships in high Andean wetlands. Unexpectedly, the effects on genetic diversity GD of the habitat fragmentation characteristics in this study increased with the presence of outlier loci in two species. Overall, our results reveal pitfalls in using habitat features to infer processes driving SGDCs and show that a few loci potentially under selection are enough to cause a signiﬁcant downward bias in SGDC. Investigating confounding effects of outlier loci thus represents a useful approach to evidence the contribution of neutral processes on species–genetic diversity relationships.
Palabras claves: Community genetics, connectivity, habitat, high Andean wetlands, outlier loci,species–genetic diversity correlations.
Referencia APA: Bertin, A., Gouin, N., Baumel, A., Gianoli, E., Serratosa, J., Osorio, R. and Manel, S. (2017). Genetic variation of loci potentially under selection confounds species-genetic diversity correlations in a fragmented habitat. Molecular Ecology, 26(2), pp.431-443. dx.doi.org/10.1111/mec.13923
Rootstock effect on irrigated grapevine yield under arid climate conditions are explained by changes in traits related to light absorption of the scion
Bascuñán-Godoy, L., Franck, N., Zamorano, D., Sanhueza, C., Carvajal, D., & Ibacache, A.
The purpose of this study was to investigate the mechanisms underlying the effect of rootstocks on table grapevines grown under irrigated conditions in the arid North macro-zone of Chile.
Grapevine cv. Red Globe grafted onto three rootstocks (Harmony, Saint George and Salt Creek) were studied Structural and physiological parameters were monitored at different phenological stages under optimal production conditions.
An outstanding yield increment brought about by the rootstocks Harmony and Salt Creek was correlated with increased individual leaf and specific leaf area, pruning weight (proxy for total leaf area), photosynthesis per unit leaf mass, sugar in leaves and root carbon reserves. In addition, these high yielding rootstocks induced higher contents of light-harvesting chlorophyll a/b protein of photosystem II and total chlorophyll in the leaves of the scion. No correlations of yield with traits involved in water use (relative water content or instantaneous water use efficiency) were observed.
The effects of rootstocks on the light capture capacity of the scion directly affected carbon assimilation and storage and, accordingly, yield. Therefore, the identified traits are valuable targets for screening and selecting yield efficient rootstocks for irrigated table grape production in arid zones.
Palabras claves: Grapevine rootstock, Light capture, Photo synthesis, Pruning weight, Red Globe, Yield
Referencia APA: Bascuñán-Godoy, L., Franck, N., Zamorano, D., Sanhueza, C., Carvajal, D., & Ibacache, A. (2017). Rootstock effect on irrigated grapevine yield under arid climate conditions are explained by changes in traits related to light absorption of the scion. Scientia Horticulturae, 218, 284-292. http://dx.doi.org/10.1016/j.scienta.2017.02.034
Surface water quality in a sulfide mineral-rich arid zone in North-Central Chile: Learning from a complex past, addressing an uncertain future
Flores, M., Núñez, J., Oyarzún, J., Freixas, G., Maturana, H., & Oyarzún, R.
This study presents an analysis of up to 30 years of hydrological variables and selected water quality parameters (pH, SO4, Fe, Cu, and As) in the upper area of the Elqui River basin in North‐Central Chile. A correlation analysis determined statistically significant positive relationship for SO4‐Cu, Fe‐As, and Fe‐Cu. In terms of historical behaviour, no statistically significant
trends were detected for precipitation or temperature. In contrast, for flow, there is an overall decreasing pattern for the entire area of study, although only in one case this trend was statistically significant. Along with the aforementioned analysis, a characterization of the flow‐water quality relationships is considered for the time period analyzed. Although erratic behaviours were confirmed, a negative (i.e., inverse) flow‐concentration relationship was identified for SO4, a positive (i.e., direct) relationship for Fe, and undefined relationships for As and Cu were obtained.
From these analyses and based on previous studies on projections regarding climate change for the Andean region, and in particular for the upper Elqui zone, an estimation of the possible effects of the change in water regimes on water quality in the area of study is developed. It is likely that a decrease in surface flow, as a consequence of climate change could translate into improvements in water quality in terms of Fe and eventually As and Cu, but into an impairment in the case of
SO4. In any case, this is a complex situation that demands special attention in the face of industrial activities that could be developed in tributaries like the Claro River, which currently play an important role in depurating or diluting contaminants in the waters of the Elqui River. Finally, it should be noted that this study addresses an issue that goes beyond the local interest and could be used as a reference to compare other transitional environments containing sulphide ores or areas of hydrothermal alterations, which are considered to be highly vulnerable to climate change and variability.
Palabras claves: acid rock drainage, Andean river, arid zone, Coquimbo region
Referencia APA: Flores, M., Núñez, J., Oyarzún, J., Freixas, G., Maturana, H., & Oyarzún, R. (2016). Surface water quality in a sulfide mineral-rich arid zone in North-Central Chile: Learning from a complex past, addressing an uncertain future. Hydrological Processes, 31(3), 498-513. http://dx.doi.org/10.1002/hyp.11086
Shrub–ephemeral plants interactions in semiarid north-central Chile: Is the nurse plant syndrome manifested at the community level?.
Madrigal-González, J., Kelt, D., Meserve, P., Squeo, F., & Gutiérrez, J.
Models of plant–plant interactions suggest that nurse plants are critical for the maintenance of biodiversity and ecosystem functions in arid and semiarid lands. At the community scale, however, empirical support of this idea is limited and context-dependent. Following on a preliminary work which suggested that a dominant shrub in north-central Chile (Porlieria chilensis) had nurse plant effects, we tested the effects of this and two other shrubs (Adesmia bedwellii and Proustia cuneifolia) on community biomass production, species density, and species composition of ephemeral plants in the semiarid scrub of the Bosque Fray Jorge National Park (Chile) over four consecutive years. We tested for main and interactive effects of shrubs and precipitation on total biomass production and species density of ephemeral plant communities using Generalized Linear Mixed Models (GLMM). To analyze the effects of shrubs and precipitation on species composition we used Canonical Correspondence Analysis (CCA) and t-value biplot analysis. Total biomass production increased significantly with precipitation and was consistently lower beneath shrub canopies, particularly under A. bedwellii and P. chilensis. Although ephemeral plant species density generally was higher in open areas, differences between open and shrub canopy samples diminished with increasing precipitation. Finally, despite significant differences in ephemeral plant species composition between open areas and shrub canopies, we found no evidence of shrub species-specific effects. In conclusion, our results do not support a classical nurse plant syndrome in the semiarid scrub of the Bosque Fray Jorge National Park although shrubs can increase local diversity by favoring some ephemeral plant species that are absent in open areas.
Palabras claves: Ephemeral plant communities; Facilitation; Nurse plant syndrome; Precipitation; Semiarid scrub; Biomass production; Diversity.
Referencia APA: Madrigal-González, J., Kelt, D., Meserve, P., Squeo, F., & Gutiérrez, J. (2016). Shrub–ephemeral plants interactions in semiarid north-central Chile: Is the nurse plant syndrome manifested at the community level?. Journal Of Arid Environments, 126, 47-53.
Bet-hedging strategies of native and exotic annuals promote coexistence in semiarid Chile.
Jiménez, M., Gaxiola, A., Armesto, J., González-Browne, C., Meserve, P., & Kelt, D., Gutierrez, J.R., Jaksic, F.M.
Scientists are increasingly interested in the evolutionary responses of organisms to unpredictable, variable, and extreme climate changes. In semiarid environments, inter-annual variability in the frequency and amount of rainfall affects both the growth and recruitment of plant species, especially annuals. In these inherently variable environments, individual selection should favor demographic responses that spread the risk of mortality over time and enhance long-term reproductive success (i.e., bet-hedging strategies). However, the same processes that allow the persistence and recruitment of native species could facilitate the introduction and establishment of exotics. We assessed whether native and exotic annuals in semiarid Chile displayed similar or contrasting bet-hedging traits, and discuss mechanisms of coexistence of both types of species and their demographic variation under interannual rainfall variability driven by El Niño Southern Oscillation (ENSO). We analyzed a proxy of long-term fitness, i.e., the variability of seed density over 17 years, for the two most common native and two exotic annual plant species present in the study area. We experimentally tested whether the quality of the maternal environment (soil water supply in a given year) had an extended effect (e.g. the next year) on the proportion of seed germination or on the mean and/or variability of seed size and seed dormancy. Results showed that native and exotic species in this annual plant assemblage displayed contrasting bet-hedging strategies as evolutionary responses to variable rainfall. Although rainfall variability promotes the evolution of bet-hedging strategies, the nature of these strategies varies across species, presumably to minimize competitive exclusion. In semiarid Chile, the success of two exotic ephemerals that are components of a diverse community of native annual species seems to reflect bet-hedging germination strategies that complement rather than compete with those expressed in dominant natives.
Palabras claves: Bromus; Coexistence; Germination; Long-term fitness; Storage effect.
Referencia APA: http://dx.doi.org/10.1016/j.jaridenv.2015.10.014
Patterns in arthropod abundance and biomass in the semiarid thorn scrub of Bosque Fray Jorge National Park, north-central Chile: A preliminary assessment.
Meserve, P., Vásquez, H., Kelt, D., Gutiérrez, J., & Milstead, W.
In 2003, we initiated a sampling protocol for arthropods as part of long-term field experiment in a semiarid thorn scrub community in north-central Chile. We utilized pitfall and Malaise traps to sample terrestrial and volant arthropods, respectively. Inventories were conducted for 4 days and nights monthly. We posited that arthropod abundance and biomass would track environmental changes such as high rainfall often due to El Niño Southern Oscillations (ENSOs). Peaks in both abundance and biomass for terrestrial and volant arthropods were in similar months (spring–early summer; August–November); arthropods also tracked high rainfall years in 2004, 2006, and 2011, due mostly to increases in a few dominant groups, i.e., tenebrionid beetles (Coleoptera) in terrestrial sampling, and moths (Lepidoptera: Noctuidae, microlepidoptera) in aerial sampling. However, the same groups increased dramatically in 2008 which was a below-average rainfall year. Numerical decreases in late summer-fall months (January–April) were more abrupt for terrestrial arthropods than for volant ones. Both terrestrial and volant arthropods reached their lowest levels in winter months (June–July). Some evidence suggests long-term shifts in the composition of volant taxa. Arthropods likely are important prey items for insectivorous reptiles (i.e., lizards), birds, and an insectivorous small mammal, the elegant mouse opossum (Thylamys elegans), and future efforts are being directed towards examining the evidence for correlated changes in those consumers with arthropod abundance and biomass.
Palabras claves: Long-term studies; Climate change; Arthropods; Semiarid systems; Chile.
Referencia APA: Meserve, P., Vásquez, H., Kelt, D., Gutiérrez, J., & Milstead, W. (2016). Patterns in arthropod abundance and biomass in the semiarid thorn scrub of Bosque Fray Jorge National Park, north-central Chile: A preliminary assessment. Journal Of Arid Environments, 126, 68-75.
El Niño Southern Oscillation drives conflict between wild carnivores and livestock farmers in a semiarid area in Chile.
Acosta-Jamett, G., Gutiérrez, J., Kelt, D., Meserve, P., & Previtali, M.
The warm phase of El Niño-Southern Oscillation (ENSO) events results in greatly elevated rainfall in north-central Chile, with dramatic effects on small mammals and vertebrate carnivore abundances. In ensuing cool phases of ENSO, plant cover decreases, followed by small mammal densities, in turn affecting the resource availability for their predators. Wild carnivores such as foxes are one of the main predators of small mammals; when the latter decline, foxes could exhibit functional responses, increasing their consumption of domestic livestock. To our knowledge, the influence of native prey abundance on livestock predation has not been assessed. We hypothesize that periods of scarce native prey increases conflicts between carnivores and farmers outside protected areas, especially during drought years. From 1990 to 2005 we used live trapping to determine monthly density of small mammals in a national park (Bosque Fray Jorge National Park, BFJNP) in north-central Chile; rainfall was also monitored. We calculated an index of predation as the number of sheep predated by foxes annually on one farm (encompassing ca. 45,000 ha) located in the vicinity of BFJNP. Path analysis was carried out to assess factors influencing sheep predation by wild foxes. Factors included precipitation and small mammal density. Small mammal density correlated positively with two years moving average of rainfall. Sheep predation by foxes increased after of two years of low rainfall. Our findings suggest that wild carnivores employ functional responses in response to varying prey availability, shifting from wild to domestic prey during periods of drought, which could have important conservation and management implications.
Palabras claves: Wild foxes; Livestock predation; Drought; Coquimbo region; Chile.
Referencia APA: Acosta-Jamett, G., Gutiérrez, J., Kelt, D., Meserve, P., & Previtali, M. (2016). El Niño Southern Oscillation drives conflict between wild carnivores and livestock farmers in a semiarid area in Chile. Journal Of Arid Environments, 126, 76-80.
Biotic interactions and community dynamics in the semiarid thorn scrub of Bosque Fray Jorge National Park, north-central Chile: A paradigm revisited.
Meserve, P., Kelt, D., Gutiérrez, J., Previtali, M., & Milstead, W.
In 1989, we initiated a long-term field experiment in a semiarid thorn scrub community in north-central Chile. We posited that biotic interactions, particularly predation, interspecific competition, and herbivory assumed a primary top-down role in affecting small mammals and annual plants here. Using a multi-factorial design we selectively excluded vertebrate predators (principally carnivores and raptors) and a large small mammal herbivore, the degu (Octodon degus), from replicated 0.56 ha exclosures located in a valley near the coast in Bosque Fray Jorge National Park. Evidence initially supported effects of predator exclusion on O. degus but not for other small mammals in the assemblage (e.g., Phyllotis darwini, Abrothrix olivaceus). Subsequent years of monitoring have documented that predation has temporary effects on degu numbers, but that populations of this and other small mammals are much more strongly influenced by environmental bottom-up factors (i.e., rainfall). Further, our experimental manipulation has provided no evidence for negative interspecific competition effects on numbers of any small mammal in this assemblage. Degu exclusions, however, have had negative indirect effects on exotic annuals; native annuals appear to outcompete exotics especially during drought years The effect is magnified in all-small mammal exclusions. Since about 2002, selective exclusions of lagomorphs and small mammals have resulted in changes in cover of some perennial shrubs. Also notable has been a fundamental shift in the small mammal composition following the last major El Niño Southern Oscillation (ENSO) event in 2000–2002; degus now comprise a majority of small mammal biomass in the assemblage, and their numbers have become more stable and less temporally variable. This appears to have been caused by a shift in rainfall periodicity from strong interannual fluctuations in response to periodic ENSOs, to a more equitable pattern with more consistent annual rainfall. This represents one of the first documented cases of system-wide biotic phase shifts to a relatively modest change in rainfall regime. This may be indicative of ongoing climate change in the Chilean semiarid region, and we expect that further changes in the community will occur if those trends continue.
Palabras claves: Long-term studies; Population; Community ecology; Small mammals; Chile.
Referencia APA: Meserve, P., Kelt, D., Gutiérrez, J., Previtali, M., & Milstead, W. (2016). Biotic interactions and community dynamics in the semiarid thorn scrub of Bosque Fray Jorge National Park, north-central Chile: A paradigm revisited. Journal Of Arid Environments, 126, 81-88.
Where does the water go? Understanding geohydrological behaviour of Andean catchments in south-central Chile.
Arumí, J., Maureira, H., Souvignet, M., Pérez, C., Rivera, D., & Oyarzún, R.
Upper Diguillín and Renegado are two neighbouring Andean basins of south-central Chile, with different specific discharges that cannot be explained solely by their difference in size. To address this issue, this study considers three separate but complementary approaches: (a) long-term analysis of rainfall and flow trends; (b) determination of hydrogeological properties at the watershed scale; and (c) analysis of the temporal evolution of groundwater storage. First, a trend test detected a statistically significant discharge decrease for Renegado in summer, unrelated to a coincidental precipitation trend, which seems to be associated with an increased use of water in that season related to tourism activity in the area. Second, there were no important differences in hydraulic conductivity or drainable porosity between the two study areas. However, it was found that there is a long-term negative trend in groundwater storage for Renegado; that is, water that contributes to the lower Diguillín streamflow through numerous springs.
Palabras claves: Basin-scale hydrology, Brutsaert analysis, trend analysis, baseflow.
Referencia APA: Arumí, J., Maureira, H., Souvignet, M., Pérez, C., Rivera, D., & Oyarzún, R. (2016). Where does the water go? Understanding geohydrological behaviour of Andean catchments in south-central Chile. Hydrological Sciences Journal, 1-12.
Twenty-five years of research in the north-central Chilean semiarid zone: The Fray Jorge Long-Term Socio-Ecological Research (LTSER) site and Norte Chico.
Armas, C., Gutiérrez, J., Kelt, D., & Meserve, P.
This special issue of the Journal of Arid Environments includes papers addressing diverse aspects of the abiotic and biotic environment of the Mediterranean semiarid drylands in north-central Chile (29–32°S, the Norte Chico), as well as a review and recent research findings on one of the longest-running field experiments in global drylands, the Fray Jorge Long-Term Socio-Ecological Research site (LTSER), located in Bosque Fray Jorge National Park. The Fray Jorge LTSER started in 1989 and has become a sentinel site for monitoring effects of resource variability, climate change, and extreme climatic events on diverse groups including plants, small mammals, and their predators, and more recently arthropods and songbirds. This special issue takes a multidisciplinary approach that includes reviews, new data, and research ideas grouped into two sections: (i) climate, vegetation and avifauna of the national park and semiarid drylands of north-central Chile, and; (ii) focal papers summarizing some of the research performed in Fray Jorge LTSER. This effort include the long-term monitoring of different aspects and components of the biotic community: e.g., soil microorganisms, shrub and ephemeral plant species, arthropods, native small mammals (including the main herbivores in the system), and their vertebrate predators; analysis of the interactions among these components across trophic levels; and finally, analyses of the biotic responses to rainfall, the main abiotic factor governing these communities. This special issue ends with a review of the research performed over 25 years on biotic interactions including predation, herbivory, and interspecific competition and community dynamics in the semiarid Fray Jorge LTSER ( Meserve et al., 2016a).
Referencia APA: Armas, C., Gutiérrez, J., Kelt, D., & Meserve, P. (2016). Twenty-five years of research in the north-central Chilean semiarid zone: The Fray Jorge Long-Term Socio-Ecological Research (LTSER) site and Norte Chico. Journal Of Arid Environments, 126, 1-6.
Vegetation of Bosque Fray Jorge National Park and its surrounding matrix in the Coastal Desert of north-central Chile.
Squeo, F., Loayza, A., López, R., & Gutiérrez, J.
Within its almost 9000 ha, Bosque Fray Jorge National Park (BFJNP) possesses a natural mosaic of vegetation formations dominated by thorn scrub (63.3% of the park) and scrub with cacti and other succulents (34.1%); these formations, whose plant covers are above 40%, are representative of the Coastal Desert vegetation. Additionally, BFJNP has 230 ha (2.6%) of a relict fog forest. This unique combination of vegetation formations, partly explains the high plant species richness of the park. We discuss the climatic and topo-edaphic factors associated with each type of vegetation formation.
Compared to BFJNP, the surrounding vegetation matrix shows evidence of changes in both the dominant vegetation and their plant covers; moreover, it is floristically depauperate relative to the park. This territory also includes agricultural land and plantations of non-native shrubs, as well as goat herding and small, inter-dispersed human settlements. Its main land cover types are: scrub (50%), scrub with succulents (34%), agricultural land (8%), secondary prairies (3.5%), and plantations of non-native shrubs (1.6%). Approximately 22% of this area presents high levels of anthropization. Additionally, two wind farms (217 wind turbines) have begun operating within the vicinity of BFJNP within the past two years.
BFJNP provides more than a mere representative sample of the current vegetation; it constitutes a remnant of the natural vegetation that once dominated the Coastal Desert before European colonization. Whereas the relict fog forest has been historically isolated, the desert vegetation is increasingly losing connectivity outside the park. We discuss the consequences of this isolation in terms of long-term maintenance of biodiversity. We argue that plant communities at BFJNP are the best available model for ecological restoration projects in this region of Chile.
Palabras claves: Plant diversity; Plant community; Land cover; Relict fog forest; Conservation.
Referencia APA: Squeo, F., Loayza, A., López, R., & Gutiérrez, J. (2016). Vegetation of Bosque Fray Jorge National Park and its surrounding matrix in the Coastal Desert of north-central Chile. Journal Of Arid Environments, 126, 12-22.
Rainfall, microhabitat, and small mammals influence the abundance and distribution of soil microorganisms in a Chilean semi-arid shrubland.
Aguilera, L., Armas, C., Cea, A., Gutiérrez, J., Meserve, P., & Kelt, D.
Patterns in rainfall and soil water availability are considered to be the main drivers governing arid and semiarid ecosystems. While the mechanisms by which water limits aboveground net primary production has been widely explored, few long-term studies have examined interactions between precipitation, soil resources, plant communities, and soil microbial communities; these may be critical to understanding soil biogeochemical cycles and above- and belowground interactions. We capitalized on a long-term biotic manipulation (exclusion of small mammal herbivores from replicate plots) and long-term variation in rainfall to assess how precipitation, small mammals, and shrub cover act directly and interactively to influence the spatial and temporal distribution of soil microorganisms, a key first step to understanding soil biogeochemical cycles. We measured the abundance of arbuscular mycorrhiza (AM), soil fungi, soil bacteria, and soil physicochemical characteristics over 10 consecutive years in a semiarid thorn scrub community in north–central Chile; we sampled two microhabitats (under shrub cover, and in open spaces between shrubs colonized by ephemeral plants), and in plots with or without the presence of native small mammals, the main herbivores in this environment. Annual rainfall ranged widely (11–356 mm) in this period and was the primary factor affecting abundance of AM root colonization and soil microbes. While the percentage of root length with AM was higher in dry compared to wet years, free-living soil bacteria and fungi were more abundant during wet years. All microorganisms were more abundant in the resource islands beneath the shrubs compared to open microhabitat between shrubs, although the relation between soil biota and the concentration of some particular nutrients was negative. These patterns were modulated by the presence of small mammals, which enhanced root colonization by AM fungi, particularly for ephemeral plants, but which were negatively associated with soil fungi abundance. The abundance of soil bacteria showed a more complex response to the presence of small mammals and was dependent on microhabitat and year. The spatial and temporal heterogeneity of soil resources and the activity of small mammals are important modulators of subterranean biotic responses to rainfall, the primary factor affecting soil microbiota abundance in this semiarid ecosystem.
Palabras claves: ENSO; LTSER; Plant-soil interactions; Mycorrhizal fungi; Soil filamentous fungi; Soil heterotrophic bacteria; Soil yeasts.
Referencia APA: Aguilera, L., Armas, C., Cea, A., Gutiérrez, J., Meserve, P., & Kelt, D. (2016). Rainfall, microhabitat, and small mammals influence the abundance and distribution of soil microorganisms in a Chilean semi-arid shrubland. Journal Of Arid Environments, 126, 37-46.