Joint evolution of sex ratio and dispersal: conditions for higher dispersal rates from good habitats

We analyze models of evolution of sex ratio conditional on habitat quality and with sex specific dispersal. Previous analysis concluded that the main constraint on sex ratio is habitat choice and leads to overproduction of the most dispersing sex in low quality habitat. Here, we analyze three models with finite local populations and show that constraints on sex ratio can balance constraints on habitat choice. In the first model, dispersal rates are fixed. In the second, sex specific dispersal can evolve independently of the habitat quality. These models suggests that sex ratio evolution can lead to higher global dispersal rates (mean of male and female dispersal rates) from high quality habitats. In the last model dispersal evolves conditionally with both sex and habitat. Our models suggests that conditions for overproduction of the most dispersing sex in high quality habitat are frequent. The predictions of the models with evolving dispersal contrast with patterns generally described in nature. We discuss possible reasons of this difference.     

High-level Expression of Maize <Emphasis Type="Italic">γ</Emphasis>-zein Protein in Transgenic Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)

Primers were developed for 118 microsatellites isolated from grape (Vitis vinifera) genomic libraries enriched for (AC)n repeats. Only one microsatellite sequence matched other grape SSR-sequences in the GeneBank database. Genotyping was carried out in the parental lines and four offspring of two pseudo-test-cross populations, Cabernet Sauvignon x Seyval and Chardonnay x Bianca, and a further six other grape genotypes (V. vinifera Sultanina, Merlot, Syrah, Müller-Thurgau, Vitis Regent and V. riparia Gloire de Montpellier). A total of 108 microsatellites showed easily scorable alleles and 100 of them segregated according to a configuration suitable for mapping in either cross. A further 8 SSRs, although unsuitable for mapping in those crosses, showed polymorphism in the other genotypes tested. This set of markers was used, along with 75 microsatellites of other repeat-types, to fingerprint 46 offspring of the cross Chardonnay x Bianca. For each full-sib, individual heterozygosity and distance in repeat units between pairs of alleles at each locus (mean d²) were calculated as a tool for predicting highly outbred recombinant individuals. Six microsatellites with segregation ratios significantly distorted towards the lack of homozygous sibs were identified and mapped to linkage groups LG 3 and LG 5. Estimation of heterozygosity at genome-wide level and genotyping at loci for which homozygous sibs are discriminated against are discussed for marker-assisted background selection in outcrossing grapevines.     

Exploitation ecosystems in heterogeneous habitat complexes

Summary When the model of exploitation ecosystems by Oksanenet al. (1981) is re-analysed, using similar consumer-victim differential equations, but allowing dispersal between habitats differing in primary productivity, the relation between trophic dynamics and primary productivity turns out to be strongly dependent on the abundance relationships between different habitat types. In habitat complexes where a relatively productive habitat abounds, exploitation tends to spill over' to the barren habitat, whose trophic dynamics thus become to a high degree driven by the dynamics in the productive habitat and entirely different from the predictions of Oksanenet al. (1981). Conversely, in habitat complexes where the barren habitat overwhelmingly prevails, the spillover exploitation becomes strongly diluted. Consequently, local trophic dynamics within both habitats will behave approximately as predicted by the model of Oksanenet al. (1981).     

Genetic analysis of two wheat cultivars, ‘Sonalika’ and ‘WL 711’ for reaction to leaf rust (Puccinia recondita)

Summary Genetic analysis for leaf rust reaction of two widely adapted cultivars, Sonalika and WL 711, has been done using 21 near isogenic Lr lines and rust culture IL004 — avirulent on the two cultivars and all the Lr lines used. The segregation pattern in the F₂ generation indicated the presence of a recessive gene in Sonalika and of a dominant gene in WL 711. These genes in cultivars Sonalika and WL 711 have been identified as Lr 11 and Lr 13, respectively. Gene Lr 13 is no longer effective in WL 711 but it continues to give field resistance in the backgrounds of Chris, Prelude and Thatcher. There has been no significant change in the virulence spectrum of the leaf rust pathogen in India with the release of WL 711. High susceptibility of WL 711 seems to be due to the evolution of more aggressive forms of the pathogen to this cultivar. The gene Lr 11, which behaves as a recessive in Sonalika, was effective against leaf rust when this cultivar was released. The high susceptibility of Sonalika is probably due to an increase in the frequency of race 77 virulent on Lr 11. Lr 11 has shown a dominance reversal in the background of Sonalika. Present results suggest that interaction of resistance genes with the background genotype must be studied for their effective use in breeding programme.     

Specialized and generalized dispersal systems: where does ‘the paradigm’ stand?

I explore the specialization versus generalization paradigm in frugivory and seed dispersal. This view predicts that some tropical trees produce nutritious fruits adapted for use by a small coterie of specialized frugivores that provide reliable seed dissemination. Other tree species are expected to offer superabundant fruits of lower nutritional reward, relying instead on common opportunistic frugivores that are individually less reliable, but collectively disperse seeds effectively. Though widely referenced, many aspects of the paradigm are untested with tropical trees and avian frugivores, primarily because plant ecologists rarely determine whether specialist or generalist foragers are responsible for different patterns of seed distribution, while students of foraging behavior rarely determine the effects seed dispersal by different animals for survival of seeds or seedlings of specialist or generalist trees.Ecological paradigms provide alternative hypotheses, without evolutionary arguments. Keystone species have ecological effects disproportionate to their abundance; it is important for management considerations to know whether fruiting trees or frugivores serve as keystone mutualists in tropical forests. Alternatively, the extent to which vertebrate seed dispersers influence density-dependent seed, seedling, sapling, or adult mortality may have important consequences for spatial dispersion and population dynamics of tree species in tropical forests.     

Tetramethyl Rhodamine Methyl Ester (TMRM) is Suitable for Cytofluorometric Measurements of Mitochondrial Membrane Potential in Cells Treated with Digitonin

A new method for cytofluorometric analysis of mitochondrial membrane potential has been developed by using TMRM as a cationic, mitochondrial selective probe. The method is based on limited treatment of cultured cells with digitonin which permeabilises the plasma membrane and leaves mitochondria intact. The resulting signal of TMRM-stained cells thus represents only the probe accumulated in mitochondria. Fibroblasts and cybrids were used as a model cell systems and optimal conditions for digitonin treatment and staining by TMRM were described. The TMRM signal collapsed by valinomycin, KCN and antimycin A and FCCP titration was used to gradually lower and characterise the stability of . The method is suitable for sensitive measurement of in different types of cultured cells.     

Leaf thickness and carbon isotope composition in the Crassulaceae

Summary Measurements of leaf thickness and ¹³C value were obtained for twenty species and three intergeneric hybrids of the Crassulaceae. The data include plants growing in their native habitats and also in greenhouse cultivation. There is a strong relationship between leaf thickness and leaf ¹³C values. The plants with the thickest leaves of ca. 7 to 11 mm had ¹³C values ranging from -11.5 to -13.8. Plants with leaves that were thinner than 2.0 mm all had ¹³C values that were more negative than -23. Plants having intermediate leaf thickness possessed intermediate ¹³C values. The leaf tissue of four genotypes spanning the range of leaf thicknesses all exhibited a two-fold or greater nocturnal increase in titratable acidity. It appears that the differences in leaf thickness and ¹³C values among the tested species are genetically determined.     

Endogenous abscisic acid and 2-trans-abscisic acid in alternate bearing ‘Wilking’ mandarin trees

The relationship of abscisic acid (ABA) and 2-trans-abscisic acid (t-ABA) to alternate bearing has been examined in Wilking mandarin (Citrus reticulata Blanco) trees. Leaves, stems and buds of trees loaded with fruit (on trees) had 4.3, 6.0 and 2.2 fold higher ABA levels than the corresponding organs from off trees. Leaves had higher ABA levels than stems and buds in both on and off trees. t-ABA was non-detectable in Wilking leaf, stem and bud tissue. Amounts of t-ABA not exceeding 40% of the ABA content, were found in Shamouti and Valencia orange buds and in Wilking fruit peel.The elevated levels of ABA in on tree organs may reflect a stress imposed by the fruit overload.     

Monoclonal antibody specific for α2→8-linked oligo deaminated neuraminic acid (KDN) sequences in glycoproteins. Preparation and characterization of a monoclonal antibody and its application in immunohistochemistry

Two particular types of sialoglycoproteins have been detected in fish: polysialoglycoproteins containing 28-linked polysialic acid (8Neu5Gc2) _n present in unfertilized Salmonidae fish eggs, and glycoproteins bearing oligo/polymers of deaminated neuraminic acids (KDN) found in the vitelline envelope of the eggs and ovarian fluid. We report the preparation and characterization of a monoclonal antibody specifically recognizing oligo/polymers of KDN sequences in glycoproteins and its application in immunohistochemistry. Fusion of spleen cells from a BALB/c mouse immunized with a KDN-rich glycoprotein (KDN-gp) containing (8KDN2) _n 6(KDN23Gal13GlNAc13) GalNAc1 residues, with mouse myeloma cells yielded a hybrid cell line producing a monoclonal antibody that bound to KDN-gp, but not to KDN-gp depleted of KDN residues. The specificity of the monoclonal antibody, designated mAb.kdn8kdn, was determined by an enzyme-linked immunosorbent assay using KDN-gp samples that varied in KDN content. These antigens were prepared by the selective removal of KDN residues from the native KDN-gp. The mAb.kdn8kdn reacted most strongly with the intact KDN-gp and less strongly with KDN-gp samples containing decreased numbers of KDN residues. The mAb.kdn8kdn was shown specifically to recognize the 28-linked oligo/polyKDN sequences, (8KDN2) _n , and to be able to distinguish specifically (8KDN2) _n chains from (8Neu5Ac2) _n and (8Neu5Gc2) _n chains. The antibody was used successfully for the immunohistochemical detection of reactive KDN epitopes in sections of paraffin embedded rat pancreas. Several controls verified the specificity of the immunohistochemical staining, thus providing the first demonstration of (8KDN2) _n sequences in a mammalian tissue. The mAb.kdn8kdn can now be used to search further for glycoconjugates containing (8KDN2) _n chains and will facilitate studies on their biosynthesis, intracellular localization and function.     

Scientists Prefer them Blind: The History of Hypogean Fish Research

The history of hypogean fish research has been strongly influenced by neo-Lamarckism (including orthogenesis) and typological thinking. Only in the last few decades neo-Darwinism has made any inroads in the research approach to this subject. The majority of the most distinguished and productive hypogean fish researchers have used their research subjects to confirm their own views on evolution rather than to use those subjects as a spring of knowledge to enrich mainstream biological thought. Of these views, I found that the most perversive of all is the notion of evolutionary progress that has led many researchers to envision hypogean fishes as prime examples of regressive evolution. I propose that the utilization of hypogean fishes for the study of convergent evolution should catapult these subjects of research into prime objects of evolutionary ideas.     

Simulated effects of fire,dispersal and spatial pattern on competition within forest mosaics

Simulations representing tree locations on a rectangular grid (cellular automaton) imply that spatial patterns associated with fire, seed dispersal, and the distributions of plants and resources affect forest dynamics profoundly. Simulated fires ignited at random locations in a uniform environment create non-uniform habitats and lead to patches dominated by different vegetation types. Short-range seed dispersal promotes vegetation clumping; fires cause these clumps to coalesce into vegetation zones separated by sharp borders, especially across an environmental gradient. In simulation of competition within vegetation mosaics, tree populations with a competitive advantage still require the intervention of fire to eliminate rivals. Also, the availability of local seed sources enables established tree populations to exclude invaders, but fires can trigger sudden changes in the composition of such systems. In models of simple succession systems, climax vegetation tends to displace pioneer vegetation, even under harsh fire regimes.     

Plant regeneration through culture of isolated microspores of Triticum aestivum L.

Wheat microspores mechanically isolated from the anthers before culture and isolated from the anthers during the hole culture period in a chemically defined medium resulted in proembryos, embryos and finally plants. Of the four genotypes included, all responded with proembryos, and the two spring wheats Ciano and Walter gave rise to macroscopic embryos and plants. The frequency of embryo regeneration and the frequency of albino plants in both Ciano and Walter was in accordance with previously obtained results with anther culture derived material.Abbreviations 2,4-d 2,4-dichlorophenoxy acetic acid - NAA 1-naphthaleneacetic acid     

Influence of parthenogenetic reproduction on the genotypic constitution and evolutionary success of populations and species

The life cycle of Daphnia commonly includes parthenogenesis, sexual reproduction, and diapause. Although there are no genotypic transformations during diapause, it separates the clonal and pseudopanmictic states of the population. During parthenogenetic reproduction primarily polymorphic natural populations gradually degenerate into a mixture of a few clones. As resting eggs are usually produced sexually (= by means of sexual reproduction), after the diapause the vast diversity of individual genotypes normal for panmictic populations is observed. It is the competitive interactions between parthenogenetic clones which again eventually decrease the genotypic polymorphism. Forms in which the sexual process and diapause are rare (or species which are represented by parthenogenetic populations in one part of their area and by bisexual ones in another) demonstrate the most significant differences between clonal and panmictic populations.Parthenogenesis, apomixis and other kinds of reproduction without genetic recombination are widely spread in branchiopod crustaceans (Notostraca, Anostraca, Conchostraca, Cladocera) and in many other animals and plants. Moreover, reproduction without recombination plays an important role in evolution of faunas and floras. It is emphasized that non-recombinating races and species having high heterozygosity but a low level of genetic variation, enjoy short term advantages, but die out after change in the environment.     

Disulfide linked αoLH-gelonin conjugate failed to recombine with βoLH subunit to generate bioeffective hormonotoxin

Since, linking of ovine luteinizing hormone (oLH) to ribosome inactivating protein gelonin (in oLH-gelonin conjugate) occur via the alpha-subunit, oLH, an attempt has been made to develop a universal hormonotoxin for selective targeting to specific cells in the gonads. Four different molar ratios of oLH and N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP) were used to activate the epsilon amino (-NH₂) groups of oLH. The oLH-SPDP derivatives recombine to native beta subunit of oLH (oLH) and the purified recombinants retained substantial receptor binding, steroidogenic activity and immunoreactivity to native oLH. The disulfide linked oLH-S-S-gelonin conjugates prepared by SPDP method were purified by gel filtration chromatography and analysed by reverse-phase high performance liquid chromatography (RP-HPLC). In order to obtain specificity and bioeffectivity, the oLH-S-S-gelonin conjugates were allowed to recombine to native oLH and the recombination mixture was further purified by gel-filtration chromatography. The RP-HPLC analysis of these recombinants indicated that oLH-S-S-gelonin did not recombine to oLH. The failure of recombination may be due to the reasons. (i) The site of -NH₂ activation by SPDP may be different in the oLH than the native oLH. (ii) The activation site may be in close proximity to the annealing site which facilitates the recombination of -subunit but failured to reassociate to oLH-S-S-gelonin conjugate. (iii) The introduction of gelonin (30 kDa basic protein) might have induced some steric hinderence for oLH to recombine to the oLH site which might have been masked in oLH-S-S-gelonin conjugates. (Mol Cell Biochem120: 95–102, 1993)Abbreviations oLH ovine Luteinizing Hormone - oLH alpha subunit of oLH - oLH beta subunit of oLH - BSA Bovine Serum Albumin - DTT Dithiothreitol - RP-HPLC Reverse Phase High Performance Liquid Chromatography - TSH Thyroid Stimulating Hormone - FSH Follicle Stimulating Hormone - LH Luteinizing Hormone - eCG equine Chorionic Gonadotropin - DMEM Dulbecco's Modified Eagles Medium - HEPES 4-(2-Hydroxyethyl)-1 Piperazine Ethane Sulfonic acid - PAP Pokeweed Antiviral Protein - RIA Radioimmunoassay - hCG human Chorionic Gonadotropin - TRH Thyrotropin Releasing Hormone - CRF Corticotropin Releasing Factor - hPL human Placental Lactogen - TFA Trifluroacetic Acid - oLH-SPDP SPDP activated derivative of oLH     

Thidiazuron substitution for chilling requirement in three apple cultivars

Thidiazuron [(TDZ)N-phenyl-N-1,2,3-thidiazol-5-ylurea] at 750 M was applied to buds of apple trees to determine if it could substitute for the chilling requirement to induce bud break. Shoots of cv. Anna (low chill), Delicious cv. Redchief (medium chill), and Northern Spy (high chill) were untreated, treated with TDZ prior to chilling (before-chill), and treated with TDZ at various intervals after the accumulation of specific amounts of chilling (after-chill). Shoots were stored in a cold room at 4°C. TDZ applied prior to chilling reduced the chill unit (CU) requirement (1 CU = 1 h at 4°C) for the promotion of bud break on 1-year-old shoots of Anna and Northern Spy and 1- and 2-year-old wood of Delicious. TDZ applied after-chill promoted bud break only for Anna and buds on 2-year-old wood of Delicious. While accumulating CUs, untreated buds or buds treated with TDZ on 1-year Delicious and Northern Spy did not respond to the cold treatment even after 1848 h of CU accumulation. For all three cultivars, TDZ treatment was more effective in promoting bud break when applied before the initiation of chilling.The use of a company or product name does not constitute an endorsement by USDA or the University of Maryland nor imply approval to the exclusion of other suitable products.     

The inheritance of host plant resistance and its effect on the relative infection efficiency of Magnaporthe grisea in rice cultivars

The inheritance of host plant resistance and its effect on the relative infection efficiency for leaf blast was studied in the crosses IR36/CO39 (partially resistant × highly susceptible) and IR36/IR64 (both partially resistant). On the natural scale, gene action appeared multiplicative. After log transformation, additive effects described most of the genetic variation in the cross IR36/CO39, while additive and dominance effects were about equal in magnitude in the cross IR36/IR64. Dominance was towards increased resistance. No transgressive segregation occurred in the cross IR36/CO39. The number of genes that reduce lesion number was estimated to be zero in CO39 and five or more in IR36. The cross IR36/IR64 showed transgressive segregation in both directions, and IR36 and IR64 each contain at least one gene that is not present in the other cultivar. The heritabilities (narrow sense) in the F₂ were low (range 0.06–0.16), while narrow sense heritabilities based on F₃ lines were much higher (range 0.41–0.68). Lesion numbers in F₃ lines were reasonably correlated with those in F₅ progenies derived from the same F₂ plant (r was±0.6 in both crosses). Partial resistance can be effectively improved by selecting the most resistant plants from the most resistant F₃ lines.     

Basis of the Relationship between Ash Content in the Flag Leaf and Carbon Isotope Discrimination in Kernels of Durum Wheat

The relationship between ash content and carbon isotope discrimination () was studied in durum wheat (Triticum durum Desf.) grown in a Mediterranean region (Northwest Syria) under three different water regimes (hereafter referred to as environments). In two of these environments, 144 genotypes were cultivated under rain-fed conditions. In the third environment, 125 genotypes were cultivated under irrigation. Ash content was measured in the flag leaf about 3 weeks after anthesis, whereas was analysed in mature kernels. Total transpiration of the photosynthetic tissues of the culm contributing, from heading to maturity, to the filling of kernels was also estimated. Leaf ash content, expressed either on dry matter or leaf area basis or as total ash per blade, correlated positively (p< 0.001) with in the three environments. However, this relationship was not the result of a positive correlation across genotypes between and tissue water content. Moreover, only a small part of the variation in across genotypes was explained by concomitant changes in ash content. When all genotypes across the three environments were plotted, and ash content followed a non-linear relationship (r ² = 74), with tending to a plateau as the ash content increased. However, for the set of genotypes and environments combined, total ash content per leaf blade was positively and linearly related (r ² = 0.76) with the accumulated culm transpiration. The non-linear nature of the relationship between ash content and is sustained by the fact that culm transpiration also showed a non-linear relationship with kernel . Therefore, differences in leaf ash content between environments, and to a lesser extent between genotypes, seem to be brought about by variations in accumulated transpiration during grain formation.     

Two gerbils of the Negev: A long-term investigation of optimal habitat selection and its consequences

Optimal foraging theory has entered a new phase. It is not so much tested as used. It helps behavioural ecologists discover the nature of the information in an animals brain. It helps population ecologists reveal coefficients of interaction and their patterns of density-dependent variation. And it helps community ecologists examine niche relationships. In our studies on two species of Negev desert gerbil, we have taken advantage of the second and third of these functions. Both these gerbils prefer semi-stabilized dune habitat, and both altered their selective use of this habitat and stabilized sand according to experimental changes we made in their populations. Their changes in selectivity agree with a type of optimal foraging theory called isoleg theory. Isoleg theories provide examples of dipswitch theories – bundles of articulated qualitative predictions – that are easier to falsify than single qualitative predictions. By linking behaviour to population dynamics through isoleg theory, we were able to use the behaviour of the gerbils to reveal the shapes of their competitive isoclines. These have the peculiar non-linear shapes predicted by optimal foraging theory. Finally, when owl predation threatens, the behaviour of Gerbillus allenbyi reveals the shape of their victim isocline. As has long been predicted by predation theory and laboratory experiments, it is unimodal.     

Status and habitat preferences of Uganda cheetahs: an attempt to predict carnivore occurrence based on vegetation structure

In this paper we examine whether the occurrence of cheetahs (Acinonyx jubatus) in Uganda can be predicted from habitat characteristics extracted from a vegetation map. We first established the status of the cheetah in Uganda through field-interviews that Gros conducted in 1990. Cheetahs occurred almost exclusively in the Karamoja region where we estimated 53–310 individuals. Based on 216 sightings, the average number of adults in all-adults sightings was 1.65 + SD 0.95 and the average number of cubs in family groups 2.5 + SD 1.65. Compared to Graham and Parker's 1965 East African survey, average adult group size was slightly smaller in 1990 and large family groups were rarer. Comparison with Gros 1990 survey showed considerably lower cub-to-adult ratio and percent of observations with cubs in Uganda than in Kenya. A Geographic Information System (GIS) analysis of vegetation structure in areas where cheetahs were observed and in those where none were reported suggested that cheetahs might favor habitats with 25–50% woody cover and grasses of medium height (50–100 cm). A discriminant analysis correctly classified 72.1% of used habitats and 70.4% of no-report habitats. A logistic regression analysis improved the correct allocation of used habitats by 2.2%. Either the discriminant function or the logistic regression, which require only four easily obtainable vegetation characteristics, may help to pinpoint suitable cheetah habitats for conservation purposes. Our approach could be adapted for analyzing habitat suitability for other species of carnivores.     

The systematics of Porphyra: character evolution in closely related species

Isozymes, vegetative and reproductive morphology, seasonality, vertical and geographic distributions and chromosomes were compared for six pairs of putative sibling species of Porphyra (P. abbottae/P. torta, P. fallax subsp. fallax/P. fallax subsp. conwayae, P. amplissima/P. cuneiformis, P. fucicola/P. leucostica, P. miniata/P. variegata, P. umbilicalis/P. umbilicalis) and among five species in a complex (P. brumalis, P. kurogii, P. linearis, P. pseudolinearis, and P. purpurea.) Geographic distribution and zymograms for certain proteins showed the greatest change between species pairs: only one pair of species had identical distributions, and most species pairs were disjunct; every species had a different allozyme for GOT-1, whereas all species had apparently identical proteins for phycoerythrin. Seasonality and habitat exhibited moderate differentiation: Northeast Pacific sibling species were characterized by a high intertidal winter species pairing with a mid intertidal spring species, whereas all but one of the other species pairs exhibited nearly identical vertical distributions and seasonalities. There were few changes in morphology: most species pairs had essentially identical morphologies and coloration and the same arrangement of reproductive cells. Chromosome numbers and karyotypes were identical for species pairs and in the species complex. These results provide evidence for different rates of evolution of different characters in the genus Porphyra.