Ecological and methodological drivers of species’ distribution and phenology responses to climate change

Climate change is shifting species’ distribution and phenology. Ecological traits, such as mobility or reproductive mode, explain variation in observed rates of shift for some taxa. However, estimates of relationships between traits and climate responses could be influenced by how responses are measured. We compiled a global data set of 651 published marine species’ responses to climate change, from 47 papers on distribution shifts and 32 papers on phenology change. We assessed the relative importance of two classes of predictors of the rate of change, ecological traits of the responding taxa and methodological approaches for quantifying biological responses. Methodological differences explained 22% of the variation in range shifts, more than the 7.8% of the variation explained by ecological traits. For phenology change, methodological approaches accounted for 4% of the variation in measurements, whereas 8% of the variation was explained by ecological traits. Our ability to predict responses from traits was hindered by poor representation of species from the tropics, where temperature isotherms are moving most rapidly. Thus, the mean rate of distribution change may be underestimated by this and other global syntheses. Our analyses indicate that methodological approaches should be explicitly considered when designing, analysing and comparing results among studies. To improve climate impact studies, we recommend that (1) reanalyses of existing time series state how the existing data sets may limit the inferences about possible climate responses; (2) qualitative comparisons of species’ responses across different studies be limited to studies with similar methodological approaches; (3) meta‐analyses of climate responses include methodological attributes as covariates; and (4) that new time series be designed to include the detection of early warnings of change or ecologically relevant change. Greater consideration of methodological attributes will improve the accuracy of analyses that seek to quantify the role of climate change in species’ distribution and phenology changes.     

Improved procedure for the anion-exchange isolation of urinary organic acids

DEAE-Sephadex equilibrated in 0.5 M triethylammonium acetate is suitable for the quantitative isolation of lactonisable organic acids. Mono-, di- and tricarboxylic acids can be eluted sequentially from DEAE-Sephadex by the use of 0.5 M triethylamine, 0.5 M triethylamine—0.1 M acetic acid, and 1.5 M pyridinium acetate.     

Abnormal deoxyribose metabolites in the urine of a child with a possible new inborn error of metabolism

The urinary extract of a child investigated because of strabismus was found to contain large amounts of a compound which was identified using gas chromatography/mass spectrometry as 2-deoxyerythropentono-1,4-lactone. This lactone has not been observed previously in urinary extracts. When ion-exchange chromatography was used to isolate the organic acids from urine, the major peaks obtained by gas chromatography were shown to be 2-deoxyerythropentonic acid, 2-deoxyerythropentono-1,5-lactone and 2-deoxyerythropentono-1,4,lactone. Another abnormal metabolite, 2-deoxyribitol, was also excreted by the patient although this compound could not be detected in the urine of normal children. It is proposed that these unusual compounds accumulate in the urine of this child as a result of a defect in the catabolism of 2-deoxyribose.     

A theoretical study of surfactant and liquid delivery into the lung

A computational study is presented for thetransport of liquids and insoluble surfactant through the lung airways,delivered from a source at the distal end of the trachea. Four distinct transport regimes are considered: 1)the instilled bolus may create a liquid plug that occludes the largeairways but is forced peripherally during mechanical ventilation;2) the bolus creates a deposited film on the airway walls, either from the liquid plug transport or fromdirect coating, that drains under the influence of gravity through thefirst few airway generations; 3) insmaller airways, surfactant species form a surface layer that spreadsdue to surface-tension gradients, i.e., Marangoni flows; and4) the surfactant finally reachesthe alveolar compartment where it is cleared according to first-orderkinetics. The time required for a quasi-steady-state transport processto evolve and for the subsequent delivery of the dose is predicted.Following fairly rapid transients, on the order of seconds,steady-state transport develops and is governed by the interaction ofMarangoni flow and alveolar kinetics. Total delivery time is ~24 hfor a typical first dose. Numerical solutions show that both transitand delivery times are strongly influenced by the strength of thepreexisting surfactant and the geometric properties of the airwaynetwork. Delivery times for follow-up doses can increase significantlyas the level of preexisting surfactant rises.

     

Chemo-attractant for the garter snake: characterization of vomeronasally-mediated response-eliciting components of earthworm wash--III

Heating a 0.1 N HCl solution of lyophilized garter snake, Thamnophis sirtalis, chemoattractant obtained from earthworm, Lumbricus terrestris, surface washings, in a boiling water bath, and separation by gel chromatography, gave two fractions, F2, of high molecular weight and containing all the chemoattractant activity, and F4, of low molecular weight. The activity is lost between 15 and 30 min of heating. A similarly treated 0.1 N NaOH solution of lyophilized washings gave no F2 fraction and an F4 fraction in increasing amount. All the chemoattractant activity is lost between 0 and 15 min. Separations were monitored by assays for protein and carbohydrate.     

Taste psychophysics based on a simulation of human drinking

Taste stimulation during human drinking is approximated by alternatestimulation of the tongue with a stimulus liquid and a secondliquid. Such stimulation produces no significant sensory adaptationof taste, in contrast to continuous stimulation with the stimulusliquid. The absence of a reduction over time in judged tasteintensity holds up under variations in flow duration of thetwo liquids (1 sec to 3 sec), stimulus compound NaCl or Na-saccharin),stimulus concentration (2 mM Nasaccharin; 100 mM-500 mM NaCl),or subjects (29). Pulsatile, alternating taste stimulus presentationrepresents a model of taste relevant to human drinking. ¹With the technical assistance of D. Baron and L. Snyder.     

Heterogeneity in the accessory olfactory system

The mammalian accessory olfactory bulb (AOB) is chemoarchitecturally heterogeneous in that it stains differentially with a number of markers; the receptor cells that project to the AOB are similarly heterogeneous. What is the significance of this heterogeneity? We have found that the AOB of the gray, short-tailed opossum, Monodelphis domestica, stains differentially with a number of 'markers': antibodies to olfactory marker protein (OMP) and the alpha subunit of the G protein Gi2, the lectin of Vicia villosa and NADPH-diaphorase. These markers stain the rostral AOB more strongly than the caudal AOB whereas, the G protein subunit G(o) alpha is located predominantly in the posterior subdivision of the AOB. This heterogeneity in the chemoarchitecture of the AOB may reflect a fundamental organizational dichotomy within the vomeronasal system that corresponds to a functional dichotomy. The vomeronasal sensory epithelium also exhibits a chemoarchitectural heterogeneity: receptor cells in the basal third are G(o) alpha-immunoreactive whereas the cells in the middle third are Gi2 alpha-immunoreactive. Tracing studies using WGA-HRP demonstrate that the neurons in the middle third of the vomeronasal sensory epithelium project their axons to the anterior AOB whereas those in the basal third appear to project to the posterior AOB.