A Markov approach for describing post-fire succession of vegetation

Vegetation dynamics in the coastal area of the Seto Inland Sea region in Japan, where wild fires occur frequently, were described using a stationary Markov model. In this region, vegetation types ofMiscanthus-Pleioblastus grassland,Lespedeza-Mallotus scrub,Pinus-Rhododendron forest andCrassocephalum-Erechtites community have been identified, and these show cyclic succession under the influence of fires. The model uses parameters determining fire frequency and rate of successional change to analyze the effect of variation in these parameters on the areal ratio of each vegetation type at equilibrium and on the time taken for one vegetation type to succeed another (elapsed successional time). The effect of fire frequency differs between hypothetical habitats with high and low productivity. A policy for vegetation management in areas of high and low productivity is proposed. The advantages and limitations of applying Markov models to studies of vegetation succession are also discussed.     

Natural selection of allozyme polymorphisms: a microgeographic climatic differentiation in wild emmer wheat (Triticum dicoccoides)

Summary Allozymic variation in proteins encoded by 48 loci was analyzed electrophoretically in 1984 and 1985 in 137 individual plants of wild emmer wheat, Triticum dicoccoides, from a microsite in Yehudiyya, northeast of the Lake of Galilee, Israel. The test involved two climatic microniches in the open Tabor oak forest (1) sunny between trees and (2) shady under trees' canopies. Significant genetic differentiation at single-, two- and multilocus structures was found between neighboring climatic niches, which were only separated by a few meters. Our results suggest that allozyme polymorphisms in wild emmer wheat are partly adaptive, and differentiate primarily at the multilocus level by climatic factors presumably related to aridity stress.     

A review and update of animal toxicoses associated with fumonisin-contaminated feeds and production of fumonisins by Fusarium isolates

During the 1989 corn harvest season, numerous reports of equine leukoencephalomalacia (ELEM) outbreaks and a pulmonary edema (PPE) syndrome in swine from several regions of the United States were received by the National Veterinary Services Laboratories (NVSL), Ames, Iowa. Previous and concurrent research linked Fusarium moniliforme and fumonisin-contaminated feeds to both diseases. Chemical and mycological investigations revealed fumonisin B₁ (FB₁) concentrations of 20 to 360 ppm in suspect swine feeds and 8 to 117 ppm in suspect equine feeds. Nonproblem feeds contained concentrations below 8 ppm. Fusarium moniliforme and Fusarium proliferatum were isolated from both problem and nonproblem equine and swine feeds. When cultured on autoclaved corn, the F. moniliforme and F. proliferatum isolates produced respective FB₁ and fumonisin B₂ (FB₂) that range from less than 5 to more than 2450 ppm and less than 5 to more than 1000 ppm, respectively. Isolates from both problem and nonproblem feeds produced high levels (greater than 500 ppm) in culture. Reported here is a review of chemical and mycological data resulting from the study of several cases of PPE and ELEM.     

In situ hybridization as a rapid means to assess meiotic pairing and detection of alien DNA transfers in interphase cells of wide crosses involving wheat and rye

Summary The objectives of this study were to determine if biotin-labelled total genomic DNA of rye (Secale cereale L.) could be used to (i) preferentially label rye meiotic chromosomes in triticale and (ii) detect translocation stocks at interphase and/or early prophase by in situ hybridization. Welsh triticale, a wheat-rye segmental amphiploid, and Kavkaz wheat, a wheat-rye translocation were used. The results indicated that labelled chromosomes of rye and unlabelled chromosomes of wheat could be observed throughout all meiotic stages in the triticale. For Kavkaz wheat, the presence of the translocated 1RS chromosome arm of rye was detected at the interphase or very early prophase stage. Rapid assessment of feasibility of gene transfers and detection of alien DNA in somatic cells at the interphase stage by in situ hybridization allows for rapid decision-making and saves time and expense in plant breeding programs.Plant Research Centre Contribution No. 1276     

欺骗,契约,合作的ESS

动物竞争中的欺骗、契约、合作现象是极为常见的。本文就论述与此有关的ESS。一、欺骗某些动物竞争时信号a后跟随发生行为A,如一个体不出现A则为欺骗。欺骗是相对真实     

Phorbol ester receptors in cerebral cortex of cats with GM1 gangliosidosis

The pathogenesis of neuronal dysfunction in the gangliosidoses is poorly understood. Studies of the feline gangliosidoses and in vitro experiments implicate ganglioside inhibition of protein kinase C (PKC) in the pathogenesis of these neurological diseases. Therefore, in the present study, the binding of [³H]phorbol-12, 13 dibutyrate was measured to determine the levels of PKC in cerebral cortex of cats with GM₁ gangliosidosis (mutant) and age matched normal siblings. This binding of ([³H]PDB) to cerebral cortex homogenates in both normal and mutant cats was highly specific. The specificity of receptors was ascertained also from displacement studies using nonradioactive phorbol ester analogues to displace [³H]PDB bound to its receptors. In both mutant and normal cat brain, phorbol 12, 13-dibutyrate (PDB), 4--phorbol 12,13-didecanoate (-PDA) and 4--phorbol 12,13-dibenzoate (-PDBz) were highly potent (approximately to same degree) and effective in displacing [³H]PDB. On the other hand, 4- phorbol 12,13-diacetate (-PDA) was a weak displacer and 4--phorbol did not displace the bound [³H]PDB in either normal or mutant brain. Scatchard analysis of the binding data indicated a homogenous single class of binding sites in normal and mutant brain (Normal: K_d=1.42×10^–7 M, B_max=8.40 pmoles/mg protein. Mutant: K_d=1.60×10^–7 M, B_max=10.00 pmoles/mg protein). Sphingosine inhibited the binding to approximately the same extent in normal and mutant cortex. These studies demonstrate the presence of highly specific, homogenous, single type phorbol ester receptors in cerebral cortex of cats with GM₁ gangliosidosis which are qualitatively and quantitatively similar to normal cat brain.     

Anti-predatory autecology in the geometrid larvae of Larentia clavaria pallidata

It was suggested by Heinrich that cryptic, palatable caterpillars would adopt foliar foraging techniques which would reduce the chance of their being detected. I wished to test this hypothesis further and to determine the post-discovery tactics. I found that caterpillars of Larentia clavaria pallidat, contrary to expectations, usually rested on upper surfaces of young Althaea setosa leaves but moved to the undersides when exposed to higher light intensities. This species may be effectively concealed by older canopy leaves. These larvae usually responded to predator-like stimuli by assuming a deimatic s form but rarely dropped. Dropping may be infrequent partly because younger caterpillars could not easily relocate the foot plant. I discuss, briefly the implications of host-plant selection.     

The determination of fresh organic carbon weight from formaldehyde preserved macrofaunal samples

Methodologies are presented whereby the fresh organic carbon weight of formaldehyde preserved macrofaunal samples may be estimated. Length-organic carbon weight regressions were determined for the four numerically dominant bivalves in Narragansett Bay, Rhode Island (Nucula annulata, Yoldia limatula, Mulinia lateralis, and Pandora gouldiana) and one commercially important, but less abundant species (Mercenaria mercenaria). Constants were determined to convert the dry weight of preserved softbodied organisms (polychaetes, oligochaetes, amphipods, etc.) to fresh (unpreserved) organic carbon weight. These results can be used by investigators studying the energetics of benthic communities similar to those in Narragansett Bay.