Phylogenetic Relationships of Empetraceae, Epacridaceae, Ericaceae, Monotropaceae, and Pyrolaceae: Evidence from Nuclear Ribosomal 18s Sequence Data

Recent studies of phylogenetic relationships have indicatedthat the traditional recognition of Epacridaceae and Empetraceaeas distinct from Ericaceae should be reevaluated. These studiesused morphological data and nucleotide sequence from the chloroplastencodedrbc L (rubisco, large subunit) gene. They indicated thatEricaceae as presently recognized are paraphyletic and shouldinclude Epacridaceae and Empetraceae, as well as Pyrolaceaeand Monotropaceae. A study of nuclear ribosomal 18s gene sequenceswas undertaken to test the hypothesis that Epacridaceae forma monophyletic derived group out of Ericaceae. The problematictaxaPrionotesandLebetanthuswere included because these taxahave been alternatively placed in Ericaceae and Epacridaceae.Representatives of the herbaceous (Pyrolaceae) and mycoparasitictaxa (non-chlorophyllous, Monotropaceae) were also includedin the study. Taxa that represented lineages peripherally relatedto Ericaceae and Epacridaceae were included in order to developa better understanding of the relationships and limits of Ericales.Parsimony analyses of 18s sequences and a combined analysisof 18s+rbcL sequences were performed. Results of these analysesindicate strong support for the recognition of a monophyleticEricaceae that includes Empetraceae, Epacridaceae, Pyrolaceae,and Monotropaceae. nr18s; Empetraceae; Epacridaceae; Ericaceae; Monotropaceae; Pyrolaceae; rbc L     

Modulation of the Adrenocortical Responses to Acute Stress in Arctic Birds: A Possible Ecological Basis

There is considerable evidence that the increases in circulatingcorticosterone levels following acute stress, such as suddenstorms, can trigger facultative behavioral patterns designedto maximize survival. During the breeding season, adrenocorticalresponses to aseasonal storms may trigger facultative behavioralpatterns resulting in temporary disruption of nesting. A renestingcycle often follows when conditions become favorable again.However, in arctic ecosystems the brief breeding season limitsthe capacity of most avian populations to renest, and yet springweather may be extreme. This led to the hypothesis that arcticbirds may down-regulate their sensitivity to acute stress (suchas severe storms) so that breeding can begin and be completedbefore the first storms of autumn (only 6–8 weeks later).To test this we have used the "stress-series protocol" thattakes advantage of the fact that capture, handling and restraintconstitutes a more-or-less equal stress among all vertebratespecies, and that corticosterone concentrations in small bloodsamples collected during the first hour post-capture indicatesensitivity of the hypothalamo-adenohypophysial- adrenal axisto acute stresses in general. Comparisons of the increases inplasma levels of corticosterone following capture in severaltaxa of arctic birds indicated that suppression of the adrenocorticalresponse to acute stress was not ubiquitous. Although some speciesdid show low amplitude responses of the circulating corticosteroneincrease during the stress series protocol, others did not,and some (especially males) showed an increase in sensitivityto acute stress. Additional hypotheses were suggested as follows:1) species with greater body mass have larger relative energyreserves and would be more able to resist acute stresses thansmaller energy reserves and would be more able to resist acutestresses than smaller species; 2) short-lived birds with anexpectancy of one or two breeding seasons should be more resistantto acute stress than long-lived birds that may have many attemptsat successful breeding; 3) resistance of the adrenocorticalresponse to stress is a function of the degree of parental careprovided by the individual (also takes into account sex differencesin parental investment). Correlations of the maximum corticosteronelevel and the ratio of maximum to minimum corticosterone levelsgenerated during the stress series protocol with body mass andlongevity were not significant. However, maximum corticosteronelevel was significantly lower in birds providing most parentalcare and almost significant for the ratio of maximum to minimumcorticosterone levels. These comparative data from free-livingarctic birds suggest an ecological basis for modulation of theadrenocortical responses to stress. In at least one species,up-regulation of the response appears to involve a change insensitivity to glucocorticosteroid feedback. Further investigationswill explore neuroendocrine mechanisms further in the lightof these ecological bases.     

The action of cyclic-AMP on GA3 controlled responses II. Similarities in the induction of barley endosperm ATPase activity by gibberellic acid and cyclic 3',5'-adenosine monophosphate

The effect of cyclic-AMP and GA3 on ATPase production in embryolessbarley half-seeds was examined. Similarities in the responseinduced by 5 mM cyclic-AMP and GA₃ were observed in (1) thetotal amount of ATPase produced, (2) the time course for therelease of ATPase, and (3) the effect of abscisic acid on ATPaseinduction by these compounds. Of a variety of adenine nucleotidesexamined only cyclic-AMP was found to promote high levels ofATPase activity. Some of the implications of these results arediscussed. (Received May 11, 1971; )     

Responses of litter arthropods to major natural or artificial ecological disturbances in mountain ash forest

Pitfall trapping was used in commercial Mountain Ash (Eucalyptus regnans) regrowth forest to study the effects on epigeal arthropods of high-intensity wildfire plus salvage logging, and of harvesting by clearfelling plus slash burning, followed by fire-induced natural or artificially established regeneration respectively. The study, the first of its kind in the Victorian Central Highlands, 60 km east of Melbourne, was based on 146 922 specimens of 30 ordinal or lower level taxa collected over a 3-year period. The abrupt replacement of the ecologically complex regrowth forest by ecologically much simpler even-aged regeneration caused appreciable instability among the litter-frequenting arthropods. An immediate decline in diversity occurred due to short-term boosts in activity of some common ‘major’ taxa (notably a species of seed-harvesting ant) and the suppression of other taxa. A broad mix of functionally diverse taxa reappeared within two years of regeneration, and all but three rarely trapped ‘minor’ taxa present in undisturbed 43–46 year old regrowth (‘control’) forest had returned within 5 years. Epigeal arthropods therefore appeared to be affected only over a short period relative to the nominal 80–150 year rotation of the E. regnans ecosystem. Research is needed at the species level to achieve a more precise assessment of arthropod responses to major ecological disturbances.     

A POLARLY FLAGELLATED MEMBER OF THE ENTEROBACTERIACEAE

SUMMARY: An organism which has been frequently isolated from the rhizosphere of plants of Lolium perenne (Perennial Rye-grass) is described; it has the typical morphology and flagellation of Pseudomonas but the biochemical reactions of Klebsiella.     

Plasma membrane H+-ATPase-dependent citrate exudation from cluster roots of phosphate-deficient white lupin

White lupin ( Lupinus albus L.) is able to grow on soils with sparingly available phosphate (P) by producing specialized structures called cluster roots. To mobilize sparingly soluble P forms in soils, cluster roots release substantial amounts of carboxylates and concomitantly acidify the rhizosphere. The relationship between acidification and carboxylate exudation is still largely unknown. In the present work, we studied the linkage between organic acids (malate and citrate) and proton exudations in cluster roots of P-deficient white lupin. After the illumination started, citrate exudation increased transiently and reached a maximum after 5 h. This effect was accompanied by a strong acidification of the external medium and alkalinization of the cytosol, as evidenced by in vivo nuclear magnetic resonance (NMR) analysis. Fusicoccin, an activator of the plasma membrane (PM) H⁺-ATPase, stimulated citrate exudation, whereas vanadate, an inhibitor of the H⁺-ATPase, reduced citrate exudation. The burst of citrate exudation was associated with an increase in expression of the LHA1 PM H⁺-ATPase gene, an increased amount of H⁺-ATPase protein, a shift in pH optimum of the enzyme and post-translational modification of an H⁺-ATPase protein involving binding of activating 14-3-3 protein. Taken together, our results indicate a close link in cluster roots of P-deficient white lupin between the burst of citrate exudation and PM H⁺-ATPase-catalysed proton efflux.     

The earliest stages of adaptation in an experimental plant population: strong selection on QTLS for seed dormancy

Colonizing species may often encounter strong selection during the initial stages of adaptation to novel environments. Such selection is particularly likely to act on traits expressed early in development since early survival is necessary for the expression of adaptive phenotypes later in life. Genetic studies of fitness under field conditions, however, seldom include the earliest developmental stages. Using a new set of recombinant inbred lines, we present a study of the genetic basis of fitness variation in Arabidopsis thaliana in which genotypes, environments, and geographic location were manipulated to study total lifetime fitness, beginning with the seed stage. Large‐effect quantitative trait loci (QTLs) for fitness changed allele frequency and closely approached 90% in some treatments within a single generation. These QTLs colocated with QTLs for germination phenology when seeds were dispersed following a schedule of a typical winter annual, and they were detected in two geographic locations at different latitudes. Epistatically interacting loci affected both fitness and germination in many cases. QTLs for field germination phenology colocated with known QTLs for primary dormancy induction as assessed in laboratory tests, including the candidate genes DOG1 and DOG6. Therefore fitness, germination phenology, and primary dormancy are genetically associated at the level of specific chromosomal regions and candidate loci. Genes associated with the ability to arrest development at early life stages and assess environmental conditions are thereby likely targets of intense natural selection early in the colonization process.     

Temporal Patterns of Territorial Behavior and Circulating Testosterone in the Lapland Longspur and Other Arctic Passerines

We studied territorial aggression in relation to circulatingtestosterone levels in free-living birds of four species innorthern Alaska. The Lapland longspur, Calcarius lapponicus,is an abundant breeding passerine on the arctic tundra. Unlikemany passerines at lower latitudes, male Lapland longspurs donot defend a "multiple-purpose territory" that serves to providenest sites, food and shelter. Rather, after arrival on the breedinggrounds, they perform aerial display flights over a looselydenned "nest area" for a very brief period of two days or so,showing tolerance of other males. This song display may be involvedin courtship. During this phase, male longspurs show a briefand pronounced peak in circulating testosterone levels, andare not aggressive toward simulated territorial intrusions (STIs).Males then "guard" their sexually receptive mates for aboutten days, during which they are highly aggressive toward STIs,but do not sing as much. During the next phase, incubation,the males become very tolerant of conspecific males. Their circulatingtestosterone levels decline to baseline levels, and they generallydo not sing or display aggression in response to STIs. Threeother passerines, the white-crowned sparrow, Zonotrichia leucophrysgambelii, American tree sparrow, Spizella arborea, and savannahsparrow, Passerculus sandwichensis, show patterns of territorialaggression typical of species studied at lower latitudes. Welldefinedterritories are defended for several weeks, during which thereis a prolonged peak in plasma concentrations of testosterone.These three species continue to sing and display aggressioneven late in the season, unlike the longspurs. The peak of testosteronein the longspurs occurs simultaneously with the peak in songdisplay, while in mid-latitude species it occurs with the peakin reproductive aggression. These data suggest that the interrelationshipof testosterone and aggression in Lapland longspurs may be differentfrom that of passerines with multiple-purpose territories, andmay be related to the constraints of breeding in the open arctictundra.