986 resultados para Temporal Orientation, , , .
Resumo:
Feral pigs (Sus scrofa) are believed to have a severe negative impact on the ecological values of tropical rainforests in north Queensland, Australia. Most perceptions of the environmental impacts of feral pigs focus on their disturbance of the soil or surface material (diggings). Spatial and temporal patterns of feral pig diggings were identified in this study: most diggings occurred in the early dry season and predominantly in moist soil (swamp and creek) microhabitats, with only minimal pig diggings found elsewhere through the general forest floor. The overall mean daily pig diggings were 0.09% of the rainforest floor. Most diggings occurred 3-4 months after the month of maximum rainfall. Most pig diggings were recorded in highland swamps, with over 80% of the swamp areas dug by pigs at some time during the 18-month study period. These results suggest that management of feral pig impacts should focus on protecting swamp and creek microhabitats in the rainforest, which are preferred by pigs for digging and which have a high environmental significance.
Resumo:
Taustaa Kehityksellinen dysleksia (lukivaikeus) on erityinen lukemaan oppimisen vaikeus, johon liittyy usein mys vaikeuksia kirjoittamaan oppimisessa. Lukivaikeuden oletetaan useissa tapauksissa johtuvan vaikeudesta ksitell kielen nnerakenteita (fonologinen prosessointi). Tm poikkeavuus voi olla joko lukivaikeuden perimminen syy tai vaihtoehtoisesti ongelmat nteiden ksittelyss voivat heijastaa jotain viel perustavamman tason vaikeutta. Ers tllainen ehdotettu perustavan tasoin syy on poikkeavuus aistien toiminnoissa, erityisesti aistien aikatarkkuudessa. Aikatarkkuudella tarkoitetaan kyky ja rajoja siin, kuinka nopeasti esitetty aistitiedon virtaa henkil kykenee vastaanottamaan ja ksittelemn. Monet arjen toiminnot lukemisen rinnalla edellyttvt aistien erittin tarkkaa ajallista erottelukyky (esimerkiksi kuulo puheen ymmrtmisess, tunto pintamateriaalin tunnistamisessa). Aikatarkkuusvaikeuksien esiintyvyytt lukivaikeudessa on tutkittu aiemminkin, mutta yksimielisyyteen ei ole psty siit, onko kaikilla lukivaikeuksisilla nit ongelmia tai mihin aisteihin vaikeudet mahdollisesti rajoittuvat. Myskn ei tiedet, havaitaanko aikatarkkuuden ongelmia kaiken ikisill lukivaikeuksisilla vai vaihteleeko mahdollinen ongelmien kuva in mukana. Lisksi on epselv, kuinka aikatarkkuuden ongelmat itseasiassa ovat yhteydess kielen ksittelyn ja varsinaisen lukemisen vaikeuksiin. Tutkimussarjan aihe Tss tutkimussarjassa aikatarkkuutta tutkittiin kolmessa yksittisess aistissa, joita olivat tunto, nk ja kuulo, sek kolmessa aistien vlisess yhdistelmss, joita olivat audiotaktiilinen (kuulo-tunto), visuotaktiilinen (nk-tunto) ja audiovisuaalinen (nk-kuulo). Aikatarkkuutta arvioitiin kahdella eri menetelmll, jotta saataisiin lis tietoa siit, miss tietyss aikatarkkuuden osa-alueessa lukivaikeuksisilla mahdollisesti on vaikeuksia. Ensimmisess tehtvss tutkittavan tuli arvioida, ovatko esitetyt ei-kielelliset rsykkeet samanaikaisia vai eriaikaisia. Toisessa tehtvss koehenkiln tuli arvioida esitettyjen ei-kielellisten rsykkeiden esitysjrjestys. Molemmissa tehtviss mriteltiin millisekuntitasolla (sekunnin tuhannesosa) se esitysnopeus, jolla koehenkil kykeni arvioimaan rsykkeiden ajalliset suhteet oikein. Englanninkielinen demonstraatio aikatarkkuustehtvist lytyy internetist (http://www.helsinki.fi/hum/ylpsy/neuropsy). Itse aikatarkkuustehtvien lisksi tutkimussarjassa arvioitiin tutkimushenkiliden pttelykyky, kielellisi toimintoja ja lukemista. Tutkimushenkilt Tutkimuksiin osallistui 53 lukivaikeuksista ja 66 sujuvaa lukijaa, jotka oli jaettu kolmeen pikryhmn: lapset (8-12 vuotta), nuoret aikuiset (20-36 vuotta) ja ikntyneemmt aikuiset (20-59 vuotta). Ikntyneempien aikuisten ryhm oli edelleen jaettu ikvuosikymmenluokkiin, mik mahdollisti sen tutkimisen, vaikuttaako lisntyv aikuisik lukivaikeuksisten aikatarkkuuteen (20-29, 30-39, 40-49 ja 50-59 -vuotiaat). Tutkimussarjan tulokset Aikatarkkuuden ongelmat lukivaikeuksisilla olivat yleistyneit yli in, aistien ja tehtvien Lukivaikeuksiset kaikissa pikryhmiss (lapset, nuoret aikuiset, ikntyneemmn aikuiset) tarvitsivat samanikisi sujuvia lukijoita hitaamman esitystahdin, jotta he kykenivt arvioimaan ei-kielellisten rsykkeiden ajallisen esitystavan oikein. Tm aikatarkkuuden ongelma havaittiin lukivaikeuksisilla kaikissa aisteissa (tunto, kuulo, nk) ja niiden yhdistelmiss (audiotaktiilinen, visuotaktiilinen, audiovisuaalinen). Lukivaikeuksisten aikatarkkuusongelmat ilmenivt edelleen molemmissa tehtvtyypeiss (samanaikaisuuden ja jrjestyksen arvioinnissa). Aikatarkkuus ja sen ongelmat olivat yhteydess nteiden ksittelyyn Aikatarkkuus oli yhteydess nteiden ksittelykykyyn (fonologiseen prosessointiin), niin lapsilla kuin aikuisillakin, kaikissa aisteissa, niiden yhdistelmiss ja tehtvtyypeiss. Yhteys ei-kielellisen aikatarkkuuden ja kielellisten toimintojen vlill oli kuitenkin selkempi lukivaikeuksisilla kuin sujuvilla lukijoilla. Tm tarkoittaa, ett etenkin lukivaikeuksisilla ryhmtason huono aikatarkkuus oli yhteydess huonoon nteiden ksittelyyn (fonologiseen prosessointiin) ja pinvastoin. Suoraa yhteytt lukemisen ja aikatarkkuuden vlill ei kuitenkaan havaittu. Lisntyv aikuisik heikensi lukivaikeuksisten aikatarkkuutta suhteettoman paljon Tiedonksittelyn nopeuden on toistuvasti osoitettu hidastuvan normaalissa ikntymisess. Lisntyv aikuisik (20-59 -vuotiailla) heikensikin sek sujuvien ett lukivaikeuksisten aikatarkkuutta. Toisin sanoen, mit ikkmmst aikuisesta oli kysymys, sit hitaammin hnelle tuli esitt rsykkeet, jotta hn kykeni arvioimaan niiden ajalliset suhteet oikein. Tm ikn liittyv tavanomainen hidastuminen oli kuitenkin ylltten suhteettoman nopeaa lukivaikeuksisilla. Toisin sanoen, jo nuorilla lukivaikeuksisilla havaittu aikatarkkuuden vaikeus (ryhmero verrattuna sujuviin lukijoihin) ei pysynyt saman suuruisena, vaan ryhmien ero kasvoi aikuisin lisntyess. Tulosten merkitys Lukivaikeuden osoitettiin tss tutkimussarjassa olevan yhteydess yleistyneeseen vaikeuteen ksitell ajassa nopeasti muuttuvaa ei-kielellist aistitietoa (yli aistien ja niiden yhdistelmien, tehtvtyyppien, tutkittavien in). Tm osoittaa, ett lukivaikeus ei ole ongelma, joka rajoittuu vain kielellisen materiaalin ksittelyn vaikeuksiin (nteiden ksittely, lukeminen, kirjoittaminen). Nyt havaitut vaikeudet eivt myskn rajoittuneet vain niihin aisteihin, jotka selkeimmin liittyvt lukemiseen (nk) ja puhuttuun kieleen (kuulo); Ongelmia esiintyi mys muissa aisteissa (tunto). Lukivaikeuksisten lukijoiden ryhmtasolla havaittu aikatarkkuuden ongelma ei kuitenkaan heijastunut yksiltasolle; Jokainen lukivaikeuksinen ei ollut huono aikatarkkuustehtviss. Nin ollen ei siis voida vitt, ett kaikkien lukivaikeuksisten nteiden ksittelyn tai lukemaan oppimisen vaikeudet voisivat selitty aistien toimintojen poikkeavuudella. Aikatarkkuuden ongelmat eivt olleet yhteydess varsinaiseen lukemiseen. Sek lukivaikeuksisilla lapsilla ett aikuisilla todettiin kuitenkin selke yhteys aikatarkkuuden ongelmien ja lukemaan oppimisen keskeisen ennakkoehdon, fonologisen prosessoinnin, vlill. Saattaa siis olla, ett synnynninen aistien toimintojen poikkeavuus vaikuttaa yksiln suoriutumiseen jo ennen varsinaista lukemaan oppimista, kun ne taidot kehittyvt (fonologinen prosessointi), joille myhempi lukemaan oppiminen perustuu. Iknnyttess havaittu lukivaikeuksisten suhteettoman nopea aikatarkkuuden heikkeneminen osoittaa, ett lukivaikeus ei voi olla ongelma, joka koskee vain lapsuusik, tai vaikeus, joka johtuu vain kehityksen viivstymst joka kurottaisiin in myt umpeen. Tulosten ymmrtmiseksi onkin muistettava kaksi seikkaa. Lukivaikeus on ensinnkin yhdistetty synnynnisiin, pieniin, poikkeavuuksiin aivojen rakenteissa ja toiminnoissa. Toisaalta tavanomaiseen ikntymiseen liittyy se, ett aivot kykenevt yh huonommin korjaamaan ja kiertmn (kompensoimaan) pieni vaurioita. Tmn perusteella tutkimussarjan tuloksista voidaan ptell, ett lukivaikeuksisten jo synnynnisesti heikentyneet aivojen kompensointimahdollisuudet eivt ole yht tehokkaita puskuroimaan ikntymisen tavanomaisia vaikutuksia kuin sujuvilla lukijoilla. Yllttv kuitenkin on, ett tm korostunut heikkeneminen havaittiin jo suhteellisen nuorilla, tyikisill, lukivaikeuksisilla, ennen 60 ikvuotta. Samanlaista iknnyttess korostuvaa vaikeutta ei lukivaikeuksilla kuitenkaan havaittu pttelyss, kielellisiss toiminnoissa tai itse lukemisessa. Vaikuttaakin siis silt, ett ne toiminnot, joita on harjaannutettu aktiivisesti, eivt heikkene kasvavan aikuisin myt yht suhteettomasti. Alkuperiset artikkelit Laasonen M, Tomma-Halme J, Lahti-Nuuttila P, Service E, and Virsu V (2000) Rate of information segregation in developmentally dyslexic children, Brain and Language, 75(1), 66-81. Laasonen M, Service E, and Virsu V (2001) Temporal order and processing acuity of visual, auditory, and tactile perception in developmentally dyslexic young adults, Cognitive, Affective, and Behavioral Neuroscience, 1(4), 394-410. Laasonen M, Service E, and Virsu V (2002) Crossmodal temporal order and processing acuity in developmentally dyslexic young adults, Brain and Language, 80(3), 340-354. Laasonen M, Lahti-Nuuttila P, and Virsu V (2002) Developmentally impaired processing speed decreases more than normally with age, NeuroReport, 13(9), 1111-1113.
Resumo:
The membracid Aconophora compressa Walker, a biological control agent released in 1995 to control Lantana camara (Verbenaceae) in Australia, has since been collected on several nontarget plant species. Our survey suggests that sustained populations of A. compressa are found only on the introduced nontarget ornamental Citharexylum spinosum (Verbenaceae) and the target weed L. camara. It is found on other nontarget plant species only when populations on C. spinosum and L. camara are high, suggesting that the presence of populations on nontarget species may be a spill-over effect. Some of the incidence and abundance on nontarget plants could have been anticipated from host specificity studies done on this agent before release, whereas others could not. This raises important issues about predicting risks posed by weed biological control agents and the need for long-term postintroduction monitoring on nontarget species.
Resumo:
Management of the commercial harvest of kangaroos relies on quotas set annually as a proportion of regular estimates of population size. Surveys to generate these estimates are expensive and, in the larger states, logistically difficult; a cheaper alternative is desirable. Rainfall is a disappointingly poor predictor of kangaroo rate of increase in many areas, but harvest statistics (sex ratio, carcass weight, skin size and animals shot per unit time) potentially offer cost-effective indirect monitoring of population abundance (and therefore trend) and status (i.e. under-or overharvest). Furthermore, because harvest data are collected continuously and throughout the harvested areas, they offer the promise of more intensive and more representative coverage of harvest areas than aerial surveys do. To be useful, harvest statistics would need to have a close and known relationship with either population size or harvest rate. We assessed this using longterm (11-22 years) data for three kangaroo species (Macropus rufus, M. giganteus and M. fuliginosus) and common wallaroos (M. robustus) across South Australia, New South Wales and Queensland. Regional variation in kangaroo body size, population composition, shooter efficiency and selectivity required separate analyses in different regions. Two approaches were taken. First, monthly harvest statistics were modelled as a function of a number of explanatory variables, including kangaroo density, harvest rate and rainfall. Second, density and harvest rate were modelled as a function of harvest statistics. Both approaches incorporated a correlated error structure. Many but not all regions had relationships with sufficient precision to be useful for indirect monitoring. However, there was no single relationship that could be applied across an entire state or across species. Combined with rainfall-driven population models and applied at a regional level, these relationships could be used to reduce the frequency of aerial surveys without compromising decisions about harvest management.
Resumo:
Long-running datasets from aerial surveys of kangaroos (Macropus giganteus, Macropus [uliginosus, Macropus robustus and Macropus rufus) across Queensland, New South Wales and South Australia have been analysed, seeking better predictors of rates of increase which would allow aerial surveys to be undertaken less frequently than annually. Early models of changes in kangaroo numbers in response to rainfall had shown great promise, but much variability. We used normalised difference vegetation index (NDVI) instead, reasoning that changes in pasture condition would provide a better predictor than rainfall. However, except at a fine scale, NDVI proved no better; although two linked periods of rainfall proved useful predictors of rates of increase, this was only in some areas for some species. The good correlations reported in earlier studies were a consequence of data dominated by large droughtinduced adult mortality, whereas over a longer time frame and where changes between years are less dramatic, juvenile survival has the strongest influence on dynamics. Further, harvesting, density dependence and competition with domestic stock are additional and important influences and it is now clear that kangaroo movement has a greater influence on population dynamics than had been assumed. Accordingly, previous conclusions about kangaroo populations as simple systems driven by rainfall need to be reassessed. Examination of this large dataset has permitted descriptions of shifts in distribution of three species across eastern Australia, changes in dispersion in response to rainfall, and an evaluation of using harvest statistics as an index of density and harvest rate. These results have been combined into a risk assessment and decision theory framework to identify optimal monitoring strategies.
Resumo:
NMR studies of methyldichlorophosphine have been undertaken in the nematic phase of mixed liquid crystals of opposite diamagnetic anisotropies. The r structure is derived. The proton chemical-shift anisotropy has been determined from the studies without the use of a reference compound and without a change of experimental conditions. It is shown that the molecule orients in the liquid crystal with positive diamagnetic anisotropy in such a way that the C3 symmetry axis of the CH3P moiety is preferentially aligned perpendicular to the direction of the magnetic field, unlike other similar systems. This is interpreted in terms of the formation of a weak solvent-solute molecular complex. The heteronuclear indirect spin-spin coupling constants are determined. The sign of the two-bond JPH is found to be positive.
Resumo:
In order to investigate the effect of long term recurrent selection on the pattern of gene diversity, thirty randomly-selected individuals from the progenitors (p) and four selection cycles (C0, C3, C6 and C11) were sampled for DNA analysis from the tropical maize (Zea mays L.) breeding populations, Atherton 1 (AT1) and Atherton 2 (AT2). Fifteen polymorphic Simple Sequence Repeat markers amplified a total of 284 and 257 alleles in AT1 and AT2 populations, respectively. Reductions in the number of alleles were observed at advanced selection cycles. About 11 and 12% of the alleles in AT1 and AT2 populations respectively, were near to fixation. However, a higher number of alleles (37% in AT1 and 33% in AT2) were close to extinction. Fisher's exact test and analysis of molecular variance (AMOVA) showed significant population differentiations. Gene diversity estimates and AMOVA revealed increased genetic differentiations at the expense of loss of heterozygosity. Population differentiations were mainly due to fixation of complementary alleles at a locus in the two breeding populations. The estimates of effective population at an advanced selection cycle were close to the population size predicted by the breeding method.
Resumo:
Purpose This study aims to use opportunity as a theoretical lens to investigate how the spatio-temporal and social dimensions of the consumption environment create perceived opportunities for consumers to misbehave. Design/methodology/approach Drawing on routine activity theory and social impact theory, the authors use two experiments to demonstrate that spatio-temporal and social dimensions can explain consumer theft in retail settings. Findings Study 1 reveals mixed empirical support for the basic dimensions of routine activity theory, which posits that the opportunity to thieve is optimised when a motivated offender, suitable target and the absence of a capable formal guardian transpire in time and space. Extending the notion of guardianship, Study 2 tests social impact theory and shows that informal guardianship impacts the likelihood of theft under optimal routine activity conditions. Originality/value The study findings highlight important implications for academicians and retail managers: rather than focusing on the uncontrollable characteristics of thieving offenders, more controllable spatio-temporal and social factors of the retail environment can be actively monitored and manipulated to reduce perceived opportunities for consumer misbehaviour.
Resumo:
Ehkisypainotteisuus karieksen hoidossa: iranilaishammaslkrien hoitovalinnat Karies aiheuttaa hampaiden kovan pinnan ja hammasluun sypymist, joka lopulta nkyy reikn. Ist riippumatta kariesvaara vaanii kaikkia hampaiden omistajia, vauvasta vaariin, ja lhes kaikilla aikuisilla on suussaan merkkej karieksesta. Karies etenee yleens hitaasti ja antaa siten aikaa ehkisevlle hoidolle. Tm etsikkoaika j usein kyttmtt, ja karieksen hoito painottuu reikien paikkaamiseen. Karies voitaisiin pit kurissa sen ehkisyyn kehitetyill monipuolisilla keinoilla. Hammaslkrit ovat avainasemassa, sill he tekevt kauaskantoisia valintoja hoidetaanko kariesta paikkaamalla vai valitaanko ehkisev hoito? Valintojen taustalla ovat hammaslkrin tietotaso, asenteet ja omat terveystavat sek potilaiden ja vastaanoton aiheuttamiksi koetut esteet. Tm kyselytutkimus selvitti karieksen hoitovalintoja ja niiden taustoja Iranissa. Kysymyslomakkeet jaettiin kahdessa hammaslkrien kongressissa Teheranissa (20042005) ja palautettiin nimettmin. Kysely kartoitti hammaslkrien tietoja karieksen ehkisykeinoista ja asenteita ehkisy kohtaan sek koettuja esteit sen toteuttamisessa. Hoitovalintoja selvitettiin tarkasti kuvattujen esimerkkipotilaiden avulla. Kysely kartoitti mys hammaslkrien omat terveystavat: suun omahoidon, tupakoinnin ja hammaslkriss kynnin. Aineisto ksitti 980 iltn keskimrin 37-vuotiasta hammaslkri, joista 64 % oli miehi. Iranilaishammaslkrien tiedot karieksen ehkisyst olivat fluorihammastahnan merkityst lukuun ottamatta hyvt ja heidn asenteensa ehkisy kohtaan valtaosin mynteiset. Tst huolimatta 77 % heist olisi valinnut suuren kariesvaaran potilaalle hammaskiilteess olevan rein hoidoksi paikkauksen. Ehkisyhoidoksi tarjotuista 8:sta keinosta lhes kaikki hammaslkrit valitsivat suuren kariesvaaran potilaalle hoidoksi harjausopetuksen ja snnlliset hammastarkastukset, noin 80 % valitsi hampaiden puhdistamisen vastaanotolla ja ravintoneuvonnan, 70 % ohjeet fluorihuuhteluista kotona ja 53 % vastaanotolla tehtvn fluoriksittelyn. Potilaiden vastustavat mielipiteet arvioitiin suurimmaksi esteeksi ehkisevn hoidon toteuttamiselle. Hammaslkreist 59 % ilmoitti harjaavansa hampaansa kahdesti pivss; 76 % ei tupakoinut ja 56 % kertoi aina ehdottavansa tupakoivalle potilaalle tupakoinnin lopettamista. Hammaslkrien ehkisypainotteisuus karieshoidossa oli naisilla vahvempi kuin miehill. Tulosten perusteella voi ptell, ett Iranissa tulisi nykyist selvemmin suosia ehkisev linjaa karieksen hoitovalintoja tehtess ja hammaslkreit koulutettaessa. Potilastyss koettujen ehkisyhoidon esteiden syvllisempi ymmrtminen edesauttaisi niiden poistamisessa.
Resumo:
Fruit flies require protein for reproductive development and actively feed upon protein sources in the field. Liquid protein baits mixed with insecticide are used routinely to manage pest fruit flies, such as Bactrocera tryoni (Froggatt). However, there are still some gaps in the underpinning science required to improve the efficacy of bait spray technology. The spatial and temporal foraging behaviour of B. tryoni in response to protein was investigated in the field. A series of linked trials using either wild flies in the open field or laboratory-reared flies in field cages and a netted orchard were undertaken using nectarines and guavas. Key questions investigated were the fly's response to protein relative to: height of protein within the canopy, fruiting status of the tree, time of day, season and size of the experimental arena. Canopy height had a significant response on B. tryoni foraging, with more flies foraging on protein in the mid to upper canopy. Fruiting status also had a significant effect on foraging, with most flies responding to protein when applied to fruiting hosts. B. tryoni demonstrated a repeatable diurnal response pattern to protein, with the peak response being between 12:0016:00 h. Season showed significant but unpredictable effects on fruit fly response to protein in the subtropical environment where the work was undertaken. Relative humidity, but not temperature or rainfall, was positively correlated with protein response. The number of B. tryoni responding to protein decreased dramatically as the spatial scale increased from field cage through to the open field. Based on these results, it is recommend that, to be most effective, protein bait sprays should be applied to the mid to upper canopies of fruiting hosts. Overall, the results show that the protein used, an industry standard, has very low attractancy to B. tryoni and that further work is urgently needed to develop more volatile protein baits.
Resumo:
A chitooligosaccharide specific lectin (Luffa acutangula agglutinin) has been purified from the exudate of ridge gourd fruits by affinity chromatography on soybean agglutininglycopeptides coupled to Sepharose-6B. The affinity purified lectin was found homogeneous by polyacrylamide gel electrophoresis, in sodium dodecyl sulphate-polyacrylamide gels, by gel filtration on Sephadex G-100 and by sedimentation velocity experiments. The relative molecular weight of this lectin is determined to be 48,000 1,000 by gel chromatography and sedimentation equilibrium experiments. The sedimentation coefficient (S20, w) was obtained to be 406 S. The Stokes radius of the protein was found to be 29 nm by gel filtration. In sodium dodecyl sulphate-polyacrylamide gel electrophoresis the lectin gave a molecular weight of 24,000 in the presence as well as absence of 2-mercaptoethanol. The subunits in this dimeric lectin are therefore held by non-covalent interactions alone. The lectin is not a glycoprotein and circular dichroism spectral studies indicate that this lectin has 31% -helix and no -sheet. The lectin is found to bind specifically to chitooligosaccharides and the affinity of the lectin increases with increasing oligosaccharide chain length as monitored by near ultra-violetcircular dichroism and intrinsic fluorescence titration. The values of G, and S for the binding process showed a pronounced dependence on the size of the oligosaccharide. The values for both and S show a significant increase with increase in the oligosaccharide chain length showing that the binding of higher oligomers is progressively more favoured thermodynamically than chitobiose itself. The thermodynamic data is consistent with an extended binding site in the lectin which accommodates a tetrasaccharide. Based on the thermodynamic data, blue shifts and fluorescence enhancement, spatial orientation of chitooligosaccharides in the combining site of the lectin is assigned.
Resumo:
Grazing by domestic livestock is one of the most widespread uses of the rangelands of Australia. There is limited information on the effects of grazing by domestic livestock on the vertebrate fauna of Australia and the establishment of a long-term grazing experiment in north-eastern Queensland at Wambiana provided an opportunity to attempt an examination of the changes in vertebrate fauna as a consequence of the manipulation of stocking rates. The aim was to identify what the relative effects of vegetation type, stocking rate and other landscape-scale environmental factors were on the patterns recorded. Sixteen 1-ha sites were established within three replicated treatments (moderate, heavy and variable stocking rates). The sites were sampled in the wet and dry seasons in 1999-2000 (T-0) and again in 2003-04 (T-1). All paddocks of the treatments were burnt in 1999. Average annual rainfall declined markedly between the two sampling periods, which made interpretation of the data difficult. A total of 127 species of vertebrate fauna comprising five amphibian, 83 bird, 27 reptile and 12 mammal species were recorded. There was strong separation in faunal composition from T-0 to T-1 although changes in mean compositional dissimilarity between the grazing stocking rate treatments were less well defined. There was a relative change in abundance of 24 bird, four mammal and five reptile species from T-0 to T-1. The generalised linear modelling identified that, in the T-1 data, there was significant variation in the abundance of 16 species explained by the grazing and vegetation factors. This study demonstrated that vertebrate fauna assemblage did change and that these changes were attributable to the interplay between the stocking rates, the vegetation types on the sites surveyed, the burning of the experimental paddocks and the decrease in rainfall over the course of the two surveys. It is recommended that the experiment is sampled again but that the focus should be on a rapid survey of abundant taxa (i.e. birds and reptiles) to allow an increase in the frequency of sampling and replication of the data. This would help to articulate more clearly the trajectory of vertebrate change due to the relative effects of stocking rates compared with wider landscape environmental changes. Given the increasing focus on pastoral development in northern Australia, any opportunity to incorporate the collection of data on biodiversity into grazing manipulation experiments should be taken for the assessment of the effects of land management on faunal species.
Resumo:
The authors are grateful to Professor K. P. Abraham for the provision of facilities and encouragement. One of us (PRR) acknowledges the award of a National Associateship by the UGC which facilitated a short-time visit to the Indian Institute of Science.
Resumo:
The endemic non-pathogenic Australian rabbit calicivirus RCV-A1 is known to provide some cross protection to lethal infection with the closely related Rabbit Haemorrhagic Disease Virus (RHDV). Despite its obvious negative impacts on viral biocontrol of introduced European rabbits in Australia, little is known about the extent and mechanisms of this cross protection. In this study 46 rabbits from a colony naturally infected with RCV-A1 were exposed to RHDV. Survival rates and survival times did not correlate with titres of serum antibodies specific to RCV-A1 or cross reacting to RHDV, but were instead influenced by the time between infection with the two viruses, demonstrating for the first time that the cross protection to lethal RHDV infection is transient. These findings are an important step towards a better understanding of the complex interactions of co-occurring pathogenic and non-pathogenic lagoviruses.
