Impedance Parameters in Relation to Phosphorus and Calcium Deficiencies in Subterranean Clover (Trifolium subterraneum L.)

Changes caused by separate calcium and phosphorus deficienciesin the impedance locus and associated parameters of petioleswere investigated. In samples of mixed ages the deficiencieswhere characterized by a significant change in 17 out of the18 parameters studied. Almost invariably the change caused byphosphorus deficiency was significantly greater than that causedby calcium deficiency. In a more detailed study of phosphorus deficiency it was foundthat there is often a significant interaction between age andparameter change. From the phase angle data it is concludedthat the plasma membrane ages more rapidly in deficient thanin non-deficient plants; nevertheless the physico-chemical compositionof the plasma membrane in newly formed cells is the same indeficient and non-deficient petioles of similar ages. A mathematicalinference that phosphorus deficiency causes a lessened potassiumuptake is confirmed experimentally.     

Effects of Rapidly and Slowly Permeating Osmotica on Macromolecule and Sucrose Synthesis

Metabolic effects induced by low water potentials were separatedfrom those induce by low turgor and hydration, by comparingresponses of plant cells to rapidly and slowly permeating osmotica. Metabolic processes selected for study were those which areclaimed to be very sensitive to water deficits. ‘Glucose-stimulated’respiration, and sucrose and starch synthesis, were measuredin Chlorella pyrenoidosa and protein synthesis in vacuolatedand non-vacuolated segments of Zea mays roots. Mannitol, a slowlypermeating osmoticum, stimulated sucrose synthesis and reducedrates of other metabolic processes, including starch and proteinsynthesis. In contrast, metabolism changed little during exposureto low water potentials induced by ethylene glycol, which rapidlypermeates cells. The experiments demonstrated that water and solute potentialsas low as—20 atm had only very small effects on metabolism,strongly suggesting that water deficits act principally viadecreases in turgor and hydration.     

Gibberellin Content of Spinach in Relation to Photoperiod

When spinach plants were transferred from short days to continuouslight a large temporary increase in gibberellin content occuredafter one day. Several days after transfer the gibberellin contentwas less than that of plants in short days. It is suggestedthat the increase in gibberellin stimulates cell division andthat subsequently the turnover of gibberellin is greatly increased.     

Phylogeny and evolution of Staphyliniformia and Scarabaeiformia: forest litter as a stepping stone for diversification of nonphytophagous beetles

The beetle series Staphyliniformia exhibits extraordinary taxonomic, ecological and morphological diversity. To gain further insight into staphyliniform relationships and evolution, we reconstructed the phylogeny of Staphyliniformia using DNA sequences from nuclear 28S rDNA and the nuclear protein‐coding gene CAD for 282 species representing all living families and most subfamilies, a representative sample of Scarabaeiformia serving as a near outgroup, and three additional beetles as more distant outgroups. Under both Bayesian inference (BI) and maximum likelihood inference (MLI), the major taxa within Staphyliniformia are each monophyletic: (i) Staphylinoidea, (ii) Hydrophiloidea s.l., and the contained superfamilies (iii) Hydrophiloidea s.s. and (iv) Histeroidea, although Staphylinoidea and Hydrophiloidea s.l. are not strongly supported by MLI bootstrap. Scarabaeiformia is monophyletic under both methods of phylogenetic inference. However, the relative relationships of Staphylinoidea, Hydrophiloidea s.l. and Scarabaeiformia differ between BI and MLI: under BI, Staphyliniformia and Scarabaeiformia were sister groups; under MLI, Hydrophiloidea s.l. and Scarabaeiformia were sister groups and these together were sister to Staphylinoidea. The internal relationships in Scarabaeiformia were similar under both methods of phylogenetic inference, with Cetoniinae, Dynastinae + Rutelinae, Hybosoridae, Passalidae, Scarabaeidae and Scarabaeinae recovered as monophyla. Histeridae comprised two major clades: (1) Abraeinae, Trypanaeine and Trypeticinae; and (2) Chlamydopsinae, Dendrophilinae, Haeteriinae, Histerinae, Onthophilinae, Saprininae and Tribalinae. The relationships among early‐divergent Hydrophiloidea differed between BI and MLI, and overall were unresolved or received only moderate to low nodal support. The staphylinoid families Agyrtidae, Hydraenidae and Ptiliidae were recovered as monophyletic; the latter two were sister taxa, and Staphylinidae + Silphidae was also monophyletic. Silphidae was placed within Staphylinidae in close relation to a subset of Tachyporinae. Pselaphinae and Scydmaeninae were both recovered within Staphylinidae, in accordance with recent analyses of morphological characters, although not always with recently proposed sister taxa. None of the four major groups of Staphylinidae proposed by Lawrence and Newton (1982) was recovered as monophyletic. Certain highly specialized staphyliniform habits and morphologies, such as abdominal defensive glands and reduced elytra, have arisen in parallel in separate lineages. Further, our analyses support two major transitions to an aquatic lifestyle within Staphyliniformia: once within Staphylinoidea (Hydraenidae), and once within Hydrophiloidea s.l. (Hydrophiloidea s.s.). On a smaller scale, the most common transition is from litter to subcortical or to periaquatic microhabitats and the next most common is from litter to carrion and to fungi. Overall, transitions to periaquatic microhabitats were the most numerous. The broad picture in Staphyliniformia seems to be a high level of evolutionary plasticity, with multiple possible pathways to and from many microhabitat associations, and litter as a major source microhabitat for diversification. In Scarabaeiformia, the most common transitions were from litter to foliage, with flowers to litter, litter to flowers, and litter to dung being next, and then litter to roots, logs or carrion. Litter is again the largest overall source microhabitat. The most common transitions were to foliage and flowers. It thus seems that the litter environment presents ecological and evolutionary opportunities/challenges that facilitate entry of Staphyliniformia and Scarabaeiformia into ‘new’ and different ecological adaptive zones.     

The adaptive significance of life history characters in selectedorders of marine brown maeroalgae

Life history charaeters. which are generally eonsidered to be of eritieal signifteanee in evolution, consist of various pheiiotypie trails eoneerned with growth and reproduetion. Suites ot life history charaeters are frequently referred to as ‘strategies’. These are hypotheses which attempt to explain the adaptive significance of particular suites of charaeters. This paper reviews life history charaeters of species belonging to various orders of brown algae (Phaeophyeeae) and diseusses their possible adaptive, significance, together with the extent to which they are eonsistent with opportunistie, stress tolerant and biotieally eompetent strategies. In general, speeies belonging to the same order have broadly similar suites of life history charaeters and, thus, to some degree they share eomparable adaptive strategies. For example. the Laminariales, Fueales and Durvillaeales inelude a high proportion of biotieally eompetent speeies. many ofthe Dietyotales appear to be stress tolerant, and the Eetoearpales are typieally opportunistie. The two heteromorphie generations of speeies in the Seytosiphonales are viewed as having divergent strategies, the erustose stages showing a greater degree of stress toleranee than the opportunislie ereet stages.