Adaptive introgression as a resource for management and genetic conservation in a changing climate

Current rates of climate change require organisms to respond through migration, phenotypic plasticity, or genetic changes via adaptation. We focused on questions regarding species’ and populations’ ability to respond to climate change through adaptation. Specifically, the role adaptive introgression, movement of genetic material from the genome of 1 species into the genome of another through repeated interbreeding, may play in increasing species’ ability to respond to a changing climate. Such interspecific gene flow may mediate extinction risk or consequences of limited adaptive potential that result from standing genetic variation and mutation alone, enabling a quicker demographic recovery in response to changing environments. Despite the near dismissal of the potential benefits of hybridization by conservation practitioners, we examined a number of case studies across different taxa that suggest gene flow between sympatric or parapatric sister species or within species that exhibit strong ecotypic differentiation may represent an underutilized management option to conserve evolutionary potential in a changing environment. This will be particularly true where advanced‐generation hybrids exhibit adaptive traits outside the parental phenotypic range, a phenomenon known as transgressive segregation. The ideas presented in this essay are meant to provoke discussion regarding how we maintain evolutionary potential, the conservation value of natural hybrid zones, and consideration of their important role in adaptation to climate.     

Streamflow Forecasting Using Singular Value Decomposition and Support Vector Machine for the Upper Rio Grande River Basin

The current study improves streamflow forecast lead‐time by coupling climate information in a data‐driven modeling framework. The spatial–temporal correlation between streamflow and oceanic–atmospheric variability represented by sea surface temperature (SST), 500‐mbar geopotential height (Z₅₀₀), 500‐mbar specific humidity (SH₅₀₀), and 500‐mbar east–west wind (U₅₀₀) of the Pacific and the Atlantic Ocean is obtained through singular value decomposition (SVD). SVD significant regions are weighted using a nonparametric method and utilized as input in a support vector machine (SVM) framework. The Upper Rio Grande River Basin (URGRB) is selected to test the applicability of the proposed model for the period of 1965–2014. The April–August streamflow volume is forecasted using previous year climate variability, creating a lagged relationship of 1–13 months. SVD results showed the streamflow variability was better explained by SST and U₅₀₀ as compared to Z₅₀₀ and SH₅₀₀. The SVM model showed satisfactory forecasting ability with best results achieved using a one‐month lead to forecast the following four‐month period. Overall, the SVM results showed excellent predictive ability with average correlation coefficient of 0.89 and Nash–Sutcliffe efficiency of 0.79. This study contributes toward identifying new SVD significant regions and improving streamflow forecast lead‐time of the URGRB.     

Computer programs for calculating soil loss on a watershed basis

A series of computer programs designed to predict gross annual soil loss on a watershed basis by application of the Universal Soil Loss Equation (USLE) have been developed. The programs provide an easy-to-use, flexible, and standardized means of organizing base data and applying the USLE to large land areas. The programs can be used to assess and to evaluate the effects of changing land-use patterns and conservation practices on soil losses. Critical or problem areas can be readily identified. The USLE Computer Programs are a useful research tool for investigators involved in water quality management, 208 planning, or conservation research.The package of computer programs consists of three main components: data input, the Main Program, and the Totals Program. Input data include both field base data describing the watershed and corresponding values for the factors in the USLE. The Main Program calculates the average rate of soil loss (tons/ acre/yr) and the total soil loss (tons/yr) for the smallest subunit of the watershed identified as the soil unit. Also calculated is an RKLS factor, which is an indication of the erosive potential of a given soil type, slope, and slope length, under a particular rainfall regime. The Totals Program aggregates soil unit losses into progressively larger units, that is, field, farm, subwatershed, and watershed units. An example of the programs' versatility and use is presented.     

CLIMATE CHANGE IMPACTS UNCERTAINTY FOR WATER RESOURCES IN THE SAN JOAQUIN RIVER BASIN,CALIFORNIA1

ABSTRACT: A climate change impacts assessment for water resources in the San Joaquin River region of California is presented. Regional climate projections are based on a 1 percent per year CO₂ increase relative to late 20th Century CO₂ conditions. Two global projections of this CO₂ increase scenario are considered (HadCM2 and PCM) during two future periods (2010 to 2039 and 2050 to 2079). HadCM2 projects faster warming than PCM. HadCM2 and PCM project wetter and drier conditions, respectively, relative to present climate. In the HadCM2 case, there would be increased reservoir inflows, increased storage limited by existing capacity, and increased releases for deliveries and river flows. In the PCM case, there would be decreased reservoir inflows, decreased storage and releases, and decreased deliveries. Impacts under either projection case cannot be regarded as more likely than the other. Most of the impacts uncertainty is attributable to the divergence in the precipitation projections. The range of assessed impacts is too broad to guide selection of mitigation projects. Regional planning agencies can respond by developing contingency strategies for these cases and applying the methodology herein to evaluate a broader set of CO₂ scenarios, land use projections, and operational assumptions. Improved agency access to climate projection information is necessary to support this effort.     

Ingestion of a medusa (Aegina citrea) by the nematocyst-containing ctenophore Haeckelia rubra (formerly Euchlora rubra): phylogenetic implications

The rare ctenophore Haeckelia rubra (formerly Euchlora rubra) has long been known to have nematocysts rather than colloblasts in its tentacles. Five specimens were collected in the San Juan Archipelago, Washington State, USA in 1980 and 1981, and their feeding behavior was observed in the laboratory. We found that H. rubra readily eats the tentacles of a medusa, Aegina citrea, whose nematocysts (apotrichous isorhizas) are nearly identical in morphology to the nematocysts of the ctenophore. When H. rubra was offered 16 other species of hydromedusae and 1 siphonophore in the laboratory, the ctenophores showed little or no tendency to ingest these potential prey items. In addition to its routinely positive response to A. citrea, the ctenophore could be induced by manipulation and starvation to accept and ingest bits of the bodies of 4 additional species of hydromedusae and 1 siphonophore. These results, combined with the histological and rearing experiments of other investigators, leave little doubt that the nematocysts in H. rubra are not endogenous, but are kleptocnidae similar to those nematocysts retained and subsequently used by some species of nudibranchs that feed on Cnidaria. A close phylogenetic link between the Cnidaria and the Ctenophora is most unlikely.     

Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed

In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions.     

Ammonium excretion in a temperate-reef community by a planktivorous fish,Chromis punctipinnis (Pomacentridae), and potential uptake by young giant kelp,Macrocystis pyrifera (Laminariales)

The blacksmith Chromis punctipinnis, an abundant planktivorous damselfish off southern California, USA, shelters along rocky reefs at night. While sheltered, blacksmiths excrete ammonium that could, in turn, be utilized by nearby benthic macrophytes. Laboratory experiments during the summer and fall of 1983 and 1984 indicate that ammonium excretion at night ranged from 18.1 mol h^-1 by a 8.5 g (dry) fish, to 89.1 mol h^-1 by a 27.3 g fish; excretion rates generally declined throughout the night. Field measurements at night indicate that ammonium concentrations were significantly higher in rocky crevices occupied by blacksmiths than in unoccupied shelters, and the ammonium level in one shelter dropped after a blacksmith was experimentally removed. Young kelp plants (Macrocystis pyrifera) are capable of taking up ammonium at night. Ammonium levels in chambers containing both a blacksmith and a young kelp plant were significantly lower than in chambers containing only a fish, and ammonium levels dropped in ammoniumspiked chambers that contained kelp plants. Nighttime ammonium uptake rates by young kelp plants, which averaged 1.6 mol g^-1 (dry) h^-1, were only slightly lower than those during the day. Daytime excretion by blacksmiths occasionally results in elevated ammonium levels in the water column. On two of six days, ammonium concentrations in midwater foraging aggregations were slightly but significantly higher than in upcurrent controls; since blacksmiths typically aggregate at the incurrent margin of kelp beds, the ammonium is swept downcurrent and may be utilized by large M. pyrifera that extend through the water column. Thus, the activities of blacksmiths may results in the importation of extrinsic, inorganic nitrogen to primary producers on temperate reefs.     

In situ diffusion experiment in granite: phase I

A program of in situ experiments, supported by laboratory studies, was initiated to study diffusion in sparsely fractured rock (SFR), with a goal of developing an understanding of diffusion processes within intact crystalline rock. Phase I of the in situ diffusion experiment was started in 1996, with the purpose of developing a methodology for estimating diffusion parameter values. Four in situ diffusion experiments, using a conservative iodide tracer, were performed in highly stressed SFR at a depth of 450 m in the Underground Research Laboratory (URL). The experiments, performed over a 2 year period, yielded rock permeability estimates of 2 x 10(-21) m(2) and effective diffusion coefficients varying from 2.1 x 10(-14) to 1.9 x 10(-13) m(2)/s, which were estimated using the MOTIF code. The in situ diffusion profiles reveal a characteristic "dog leg" pattern, with iodide concentrations decreasing rapidly within a centimeter of the open borehole wall. It is hypothesized that this is an artifact of local stress redistribution and creation of a zone of increased constrictivity close to the borehole wall. A comparison of estimated in situ and laboratory diffusivities and permeabilities provides evidence that the physical properties of rock samples removed from high-stress regimes change. As a result of the lessons learnt during Phase I, a Phase II in situ program has been initiated to improve our general understanding of diffusion in SFR.