DISTRIBUTION OF ARION HORTENSIS S.S. AND ARION DISTINCTUS IN NORTHERN SWITZERLAND

The distribution of the sibling slug species Arion hortensiss.s. and Arion distinctus in Northern Switzerland is described.In the sampled area, both species were almost equally abundantand their distributions overlapped. Most of the sampled sitescontained both species. Arion hortensis s.s. is more commonin Switzerland than previously known, and its range extendsmore towards the east of Switzerland. Arion hortensis s.s. wasmore abundant in gardens than in the other habitats sampled.At sites where only A. distinctus occurred, the form with abipartite oviduct prevailed. At sites where both species werepresent, the form of A. distinctus with a tripartite oviductwas more common than the form with a bipartite oviduct. In captivity,one specimen of A. distinctus mated with one A. hortensis s.s.,as indicated by a spermatophore of A. distinctus that was found withinthe atrium of one A. hortensis s.s. A majority of the specimens couldby assigned to the correct species by their colouration, buta safe distinction between A. hortensis s.s. and A. distinctusis only possible using characters of the reproductive system. (Received 4 July 2000; accepted 19 September 2000)     

Characterization and physical mapping of ribosomal RNA gene families in Plantago

• Background and Aims The organization of rRNA genes incultivated Plantago ovata Forsk. and several of its wild allieswas analysed to gain insight into the phylogenetic relationshipsof these species in the genus which includes some 200 species. • Methods Specific primers were designed to amplify theinternal transcribed spacer (ITS1 and ITS2) regions from sevenPlantago species and the resulting fragments were cloned andsequenced. Similarly, using specific primers, the 5S rRNA genesfrom these species were amplified and subsequently cloned. Fluorescencein-situ hybridization (FISH) was used for physical mapping of5S and 45S ribosomal RNA genes. • Results The ITS1 region is 19–29 bp longer thanthe ITS2 in different Plantago species. The 5S rRNA gene-repeatingunit varies in length from 289 to 581 bp. Coding regions arehighly conserved across species, but the non-transcribed spacers(NTS) do not match any database sequences. The clone from thecultivated species P. ovata was used for physical mapping ofthese genes by FISH. Four species have one FISH site while threehave two FISH sites. In P. lanceolata and P. rhodosperma, the5S and 45S (18S-5·8S-25S) sites are coupled. • Conclusions Characterization of 5S and 45S rRNA geneshas indicated a possible origin of P. ovata, the only cultivatedspecies of the genus and also the only species with x = 4, froma species belonging to subgenus Psyllium. Based on the studiesreported here, P. ovata is closest to P. arenaria, althoughon the basis of other data the two species have been placedin different subgenera. FISH mapping can be used as an efficienttool to help determine phylogenetic relationships in the genusPlantago and show the interrelationship between P. lanceolataand P. lagopus.     

Nitzschia cylindroformis sp. nov., a common and abundant nanoplankton diatom of the eastern subarctic Pacific

A new species of diatoms, intermediate between Nitzschia cylindrus(Grun.) Hasle and Nitzschia pseudonana Hasle is described. Differencesin morphology of the three species are outlined. The new specieshas been recorded only between 37°N and 53°N in thePacific Ocean while N. cylindrus is bipolar and N. pseudonanais cosmopolitan in distribution.     

Phytogeography, Biology and Conservation of Western Australian Epacridaceae

The Epacridaceae of Western Australia comprise 181 named speciesdistributed in 17 genera. One hundred and seventy seven species(98% of the total) and ten genera are endemic to the region.within Western Australia, all members are confined to the south,with a bimodal pattern of species diversity centred on the sandplainsand uplands around the Stirling Ranges and Mount Lesueur.Leucopogon, the largest genus, reflects this pattern, however, speciesdiversity is greatest on the south coastal sandplains. All species are woody shrubs, mostly found on neutral or acidicsandy soils. Plants of at least 120 species are killed by fire;Astrolomacontainsthe only significant number of resprouting species. Althoughsome species are in flower every month every year, autumn/winterflowering is a common feature of many members of the family.All species are biotically pollinated. Bird pollination is foundin 18 species in six genera. The remaining species are insectpollinated. Bees are the major pollinators inLeucopogon, ConostephiumandColeanthera.Moths and butterflies are important pollinators inAndersonia,Leucopogon,LysinemaandStyphelia. Flies are minor pollinators of some speciesofAndersonia, LeucopogonandMonotoca. All species studied areprotandrous and outbreeding, with onlyCosmeliabeing capableof self pollination. Fruits are fleshy inAstroloma, Brachyloma,Croninia, in certain species ofLeucopogonandStypheliaand areanimal dispersed. Other genera have dry, dehiscent fruit withgravity or wind dispersed seeds. Many species have relatively narrow distribution ranges, 90species having ranges of over 300km, 54 species have rangesof 100–300km and 37 have ranges of less than 100km (andthere are many undescribed species in this group). The conservationstatus of many species is still poorly known. Dieback diseaseis a major threat to the family, and could cause the extinctionof several species in the wild. Western Australia; Epacridaceae; phytogeography; biology; pollination; dispersal; conservation; disease     

北京地区法医昆虫学研究I 嗜尸性甲虫物种多样性及其地区分异

本项研究系调查北京地区清河、密云、房山三地点与人尸体有关的鞘翅目昆虫,共采集标本878号,经鉴定隶属于13科26属38种,文中列出名录,其中6种为优势种,7种为三个地点都采到标本的普遍分布种。在种类组成上,各地点有明显的地区性差异：仅在清河发现的甲虫有11种(占总种数的40.O%),仅在密云发现的有2种(占15.4%),仅在房山发现的有11种(占52.4%)：房山的物种多样性指数(H’)是2.45,清河是1.72,密云是1.60。所以,房山种类组成比较特殊。根据此结果,特别是地区的差异,为判断异地移尸提供了基本数据。     

Sulfide Tolerance and Detoxification in Arenicola marina and Sipunculus nudus

SYNOPSIS. The lugworm Arenicola marina and the peanut worm Sipunculusnudus both inhabit intertidal flats. Sulfide concentrationsin the pore water of the sediment can be as high as 340 µMin the habitat of A. marina. Sulfide levels in the burrow waterand in the coelomic fluid increase during low tide. In contrast,S. nudus is only rarely exposed to sulfide. Neither A. marinanor S. nudus is able to exclude sulfide completely from itsbody. However, both worms accumulate only 15 to 40% respectivelyof the external sulfide concentration during hypoxic 1 mM sulfideincubations. During normoxia, sulfide accumulation is more thanten-fold lower than under hypoxic conditions in both species.When oxygen is available, sulfide is oxidized to thiosulfate.The oxidation rate is about 5 times higher in A. marina thanin S. nudus. A major component of sulfide oxidation is due tothe mitochondria of both species. Mitochondrial sulfide oxidationin the tissues of A. marina is insensitive to low cyanide andto high sulfide concentrations, but can be inhibited by salicylhydroxamicacid. The existence of an alternative terminal oxidase is suggested.When the sulfide level in the body of A. marina and S. nudusincreases above a toxic level, both species survive by switchingto an anaerobic metabolism.     

Competition and Coexistence Among Four Estuarine Species of Fundulus

Four sympatric species of Fundulus (F. heteroclitus, F. majalis,F. diaphanus, and F. luciae) are distributed along tidal heightand salinity gradients such that F. heteroclitus co-occurs witheach species, while the remaining species rarely occur together.Feeding habitats of all the species are similar, and food hasbeen shown to limit population size of F. heteroclitus. Thispaper examines whether competition is an important structuringforce within this guild by addressing two questions: 1) is thespatial separation exhibited by three of the species due tophysiological barriers or due to competitive exlusion? and 2)when F. heteroclitus occurs with other Fundulus species doescompetition for resources take place? Laboratory studies indicate that all four species are tolerantof a wide range of environmental conditions; available evidencesuggests that physiological barriers are an unlikely explanationfor spatial segregation among some members of this guild. Competitiveexclusion seems a likely alternate explanation, but is supportedonly by studies of diet overlap. Similarly, only inference fromdiet overlap is available to answer the second question. A fieldexperiment is presented here in which F. heteroclitus and F.majalis were placed in enclosures separately and together. Competitionbetween these species appears to be important, and similar fieldexperiments are recommended to investigate competitive interactionsamong other species pairs within the genus     

Amphipods, isopods and surface currents: a case for passive dispersal in the Bay of Fundy, Canada

Six species of isopods and 18 species of amphipods were collectedin the neuston of the Bay of Fundy and adjacent waters. Collectionswere made over a grid of stations covering 2.4x10⁴ km² duringthree spring, three summer and two autumn surveys. No isopodsand only five species of amphipods were found in spring surveys.Isopods and amphipods were diverse and plentiful in the neustonin summer and autumn. Dominant isopods were Idotea baltica andI.metallica, and dominant amphipods were Calliopius laeviusculusand Parathemisto gaudichaudi. Amphipods and isopods reach theneuston of the Bay of Fundy in three ways. Idotea metallica,the only euneustonic species present, was probably advectedinto the Bay of Fundy from southern waters in summer, and didnot appear to overwinter in the Bay. Most species, includingI.baltica, were collected with drifting littoral vegetation,and we suggest that transport by surface currents is an importantfactor in dispersal of some shoreline crustaceans. Midwaterplankton, such as Parathemisto gaudichaudi, reached the neustoneither by advection in upwelling waters or by an extension oftheir normal diel vertical distribution.     

GENETIC VARIATION IN SIX SPECIES OF SACOGLOSSAN OPISTHOBRANCHS

Genetic variation in allozymes of six species of Saco-glossa(Mollusca, Opisthobranchia) from Denmark was studied. Nine enzymesrepresenting 11 loci gave reactions that could be used to calculateallele frequencies. Elysia viridis, Limapontia capitata, L.de-pressa, Ercolania nigra, Alderia modesta and Calliopaea oophagaall showed very great variation both within and between species.Levels of polymorphism varied between 0.5 and 0.8, and levelsof observed heterozygosity were between 0.18 and 0.42. Interspecificidentity of alleles in polymorphic loci was only found betweenthe two species of Limapontia. Even in these two species geneticidentity (I) was very low (0.07) for congeneric species. Theresults are discussed in relation to habitat, fertility, developmenttype and geographic range of the species. (Received 28 February 1990; accepted 26 July 1990)     

Integrating conventional microscopy and molecular analysis to analyse the abundance and distribution of four Calanus congeners in the North Atlantic

Analysis of the demographic structure of Calanus species inthe North Atlantic presents particular difficulties due to theoverlapping spatial distributions of four main congeneric species(Calanus finmarchicus, Calanus helgolandicus, Calanus glacialisand Calanus hyperboreus). These species have similar morphologies,making microscopic discrimination only possible between someof the species at late copepodite or adult stages. However,molecular techniques now offer the possibility of screeningsignificant numbers of specimens and unambiguously identifyingthem to species, regardless of developmental stage. Unfortunately,the processing rate of specimens by molecular methods is stilltoo low to offer a realistic alternative to microscopy for analysisof samples from large field surveys. Here, we outline and testan approach involving the use of molecular methodology in conjunctionwith conventional microscopy to assess the species assignmentof developmental stage abundances of Calanus congeners. Ourstudy has highlighted many important methodological issues.First, it cannot be assumed that the species composition ishomogeneous across the development stages; applying proportionalspecies composition of adults to morphologically undistinguishableearlier development stages can result in error. The second importantconclusion is that prosome length may be a highly unreliablediscriminator of C. finmarchicus and C. glacialis.     

PHYLOGENY OF THE GENUS ROSTANGA (NUDIBRANCHIA), WITH DESCRIPTIONS OF THREE NEW SPECIES FROM SOUTH AFRICA

Rostanga elandsia sp. nov., Rostanga aureamala sp. nov. andRostanga phepha sp. nov. are characterized by having the radulawith slender innermost lateral teeth, which lack denticles onthe inner side of the cusp and have a single denticle on theouter side. The outermost lateral teeth of these three speciesare elongate, but shorter than in other species of the genus.In addition, R. aureamala is the only species of the genus withrachidian teeth and R. phepha is unique within the genus Rostanga byvirtue of its white coloration with dark spots. A phylogenetic analysis shows that the three new species fromSouth Africa and Rostanga setidens (Odhner, 1939) are the sistergroup of the rest of the genus. The species from Japan and MarshallIslands (North Pacific Ocean) are basal in the sister cladecontaining the other species of Rostanga Bergh, 1879. The tropicalIndo-Pacific species of Rostanga are not monophyletic. The Atlanticand Eastern Pacific species form a monophyletic, derived clade,being the sister group of Rostanga australis Rudman & Avern,1989, which has a narrow range restricted to south eastern Australia.The widespread Indo-Pacific species Rostanga bifurcata Rudman& Avern, 1989, is the sister group of Rostanga dentacus Rudman& Avern, 1989, also widesprad in the tropical western Pacific. This phylogeny suggest s a viariant origin of the Sourth African, Atlantic-EasternPacific, and probably North Pacific species, whereas in thetropical Indo-Pacific most sister speceis are sympatric. (Received 16 May 1999; accepted 31 July 2000)     

Behavioral Adaptations of Terrestrial Isopods

In their response to environmental stimuli, terrestrial isopodsshow various trends that are correlated with their ecology andphysiology. With the transition from sea to the littoral zone (Ligia), orientationto light changes from positive to negative. Yet, since theseisopods are positively hygrokinetic even at very high humidities,their hygroreaction is of greater significance than their photoreaction. In isopods from mesic habitats (Oniscus, Porcellio, Armadillidium)photoreaction becomes of less significance than in littoralspecies, until in some species it reverts to positive (Armadillidium).Sometimes the positive photoreaction occurs only at high temperatures(Porcellio), a pattern of behavior correlated with thermoregulationby evaporative cooling. Similarly, in mesic species the responseto humidity becomes less significant than in littoral species,resuming importance mainly when the isopods become dehydrated(Armadillidium). Finally, in isopods from xeric habitats in semi-arid and desertregions (Armadillo, Venezillo), photoreaction is strongly negativeexcept in Hemilepistus at lower temperatures. All of these isopodsare positively hygrokinetic only at low humidities and are stronglynegatively thermoactive, indicating a drop in activity at hightemperatures. The photonegative response in these isopods isstronger than the hygroreaction.     

The foraging behavior of granivorous rodents and short-term apparent competition among seeds

The foraging behavior of a predator species is thought to bethe cause of short-term apparent competition among those preyspecies that share the predator. Short-term apparent competitionis the negative indirect effect that one prey species has onanother prey species via its effects on predator foraging behavior.In theory, the density-dependent foraging behavior of granivorousrodents and their preference for certain seeds are capable of inducing short-term apparent competition among seed species.In this study, I examined the foraging behavior of two heteromyidrodent species (family Heteromyidae), Merriam's kangaroo rats(Dipodomys merriami) and little pocket mice (Perognathus longimembris).In one experiment I tested the preferences of both rodent speciesfor the seeds of eight plant species. Both rodent species exhibiteddistinct but variable preferences for some seeds and avoidanceof others. However, the differences in preference appearedto have only an occasional effect on the strength of the short-term apparent competition detected in a field experiment. In anotherexperiment, I found that captive individuals of both rodentspecies had approximately equal foraging effort (i.e., timespent foraging) in patches that contained a highly preferredseed type (Oryzopsis hymenoides) regardless of seed density and the presence of a less preferred seed type (Astragalus cicer)in the patches. The rodents also harvested a large proportionof O. hymenoides seeds regardless of initial seed density;this precluded a negative indirect effect of A. cicer on O.hymenoides. But there was a negative indirect effect of O.hymenoides on A. cicer caused by rodents having a lower foragingeffort in patches that only contained A. cicer seeds than inpatches that contained A. cicer and O. hymenoides seeds. Theindirect interaction between O. hymenoides and A. cicer thusrepresented a case of short-term apparent competition thatwas non-reciprocal. Most importantly, it was caused by theforaging behavior of the rodents.     

Phloem Mobility of Boron is Species Dependent: Evidence for Phloem Mobility in Sorbitol-rich Species

Boron is generally considered to be phloem immobile or to haveonly limited phloem mobility in higher plants. Evidence suggests,however, that B may be mobile in some species within thePyrus,Malus andPrunusgenera. These genera utilize sorbitol as a primarytranslocated photosynthate and it has been clearly demonstratedthat B forms stable complexes with sorbitolin vitro.In the researchpresented here we demonstrate, further, that B is freely phloemmobile inPyrus, MalusandPrunusspecies and suggest that thisis mediated by the formation and transport of B-sorbitol complexes. The pattern of B distribution within shoot organs and the translocationof foliar-applied, isotopically-enriched¹⁰B was studied in sixtree species. Results demonstrate that in species in which sorbitolis a major sugar (sorbitol-rich), B is freely mobile while inspecies that produce little or no sorbitol (sorbitol-poor) Bis largely immobile. The sorbitol-rich species used here werealmond [Prunus amygdalusB. syn.P. dulcis(Mill.)], apple (MalusdomesticaB.) and nectarine (Prunus persicaL. B. var.nectarinaM.),sorbitol-poor species included fig (Ficus caricaL.), pistachio(Pistacia veraL.) and walnut (Juglans regiaL.). In sorbitol-richspecies foliar applied¹⁰B was transported from the treated leavesto adjacent fruit and specifically to the fruit tissues (hull,shell or kernel) that developed during the experimental period.Whereas, foliar-applied¹⁰B was rapidly translocated out of leaves,only a small percentage of the¹¹B present in the leaf at thetime of foliar application was retranslocated. In sorbitol-richspecies, B concentrations differed only slightly between oldand young leaves while fruit tissue had significantly greaterB concentrations than leaves. In contrast, sorbitol-poor specieshad significantly higher B concentrations in older leaves thanyoung leaves while fruit tissue had the lowest B concentration.This occurred irrespective the source of plant B (soil, solutionor foliar-applied). In a subsequent experiment the growth ofapple trees in solutions free of applied B was maintained solelyby foliar applications of B to mature leaves. These resultsindicate that B is mobile in species that produce significantamounts of sorbitol. We propose that the mobility of B in thesespecies is mediated by the formation of B-sorbitol complexes. Almond; Prunus amygdalus ; apple; Malus domestica; nectarine; Prunus persica; fig; Ficus carica; pistachio; Pistacia vera; walnut; Juglans regia; boron; phloem mobility; deficiency; toxicity; inductively coupled plasma-mass; spectrometer     

An Overview of the Ecology of Antarctic Seals

Four species of seals occupy the pack-ice region of the oceanssurrounding the Antarctic Continent. These seals include thecrabeater (Lobodon cardnophagus), leopard (Hydrurga leptonyx),weddell (Leplonychotes weddellii), and ross (Ommatophoca rossii),and are true seals with special adaptations for living in thepack-ice region. Two other seal species, the southern elephantseal (Mirounga leonina) and the fur seal (Arctocephalus gazella)(the only eared seal of this region) generally occur furtherto the north and use land rather than ice during the periodof birth of young. This paper reviews the status of these species,and examines the generalecology of the four species that inhabitthe pack-ice zone. In general, the four species that occupythe pack-ice zone have specialized in habitats and habits sothat little overlap in dietsor habitat use exist among thesespecies. The exception is the interaction between the leopardand the crabeater which occupy the same regions and eat krill(Euphausia superba), particularly during the winter. The impactof the potential harvest of krill by man on these species isdiscussed. Further, the impact that recovery of the large baleenwhales that feedin this region during the summer is discussedwith regard to the changes that might occur as competition forkrill by the large vertebrate species increases.     

THE BIOLOGY OF THE NORTHEASTERN PACIFIC TURRIDAE II. OENOPOTA

The habitat, diet, some reproductive and mortality factors forseveral shallow-water species of the boreal turrid genus Oenopotafrom the Puget Sound region were determined. All fed exclusivelyon tubicolous polychaetes. Oenopota fidicula was a dietary andhabitat generalise Oenopota elegans eats Schistocomus hiltoniand lives in areas of shell fragments. Oenopota excunata eatsTharyx multifilis and is a habitat generalist. Oenopota tabulataappears to be a dietary generalist, but lives only on or nearrocks. The widely-distributed species, O. levidensis, eats spionidpolychaetes, primarily Polydora species, or Owenia fusiformis,and is a habitat generalist. Feeding frequencies are low asare population densities; although O. levidensis sometimes exceeds15 animals m^–2. Crabs are major predators upon turridsin some areas, but mortality causes are generally obscure. Spawningwas observed in four species, but only O. elegans and O. levidensishad viable larvae. Development takes 13–15 weeks, 6–7weeks in a capsule and 6–7 weeks as planktonic veligers.There are no nurse eggs. Settling was not observed. ^*Present mailing address: Bamfield Marine Station Bamfield,B.C. VOR 1B0 CANADA (Received 30 May 1982;     

Leaf Survival and Evolution in Betulaceae

Studies on the changes in leaf number of 12 species of Betulaceaewere carried out by repeated observations during several years.The inner structure of the winter buds of these species wasalso examined. The periods of leaf emergence were long in Alnusand Betula, intermediate in Corylus and short in Ostrya andCarpinus. A heavy summer leaf fall is characteristic only ofthe Gymnothyrsus subgenus of Alnus. One lamina and two stipulesis the basic unit constituting the winter buds. Only the budsof Gymnothyrsus are composed of several of these units. In theAlnaster subgenus of Alnus, Betula and Corylus, there are oneor two scales that seem to have originated from the two stipulesremaining after reduction of the lamina. Eight and 24 scalesof similar origin were found in Ostrya and Carpinus respectively.A common ancestral species having the following primitive charactersis proposed: shoot constituted only of the equal-sized units,period of leaf emergence long, and leaf fall usually occurs.Alnus (Gymnothyrsus) is assumed to be the most primitive typeas it has many characters similar to those of the proposed ancestralspecies. Carpinus is assumed to be the most advanced group.The leaf survivorship curve is assumed to have changed fromthe primitive bell-shaped to an advanced trapezoid concurrentwith an increase in the number of bud scales. Betulaceae, Alnus, Betula, Carpinus, Corylus, Ostrya, leaf survival, leaf emergence, stipules, winter buds, evolution     

Phylogenetic Analysis and Karyotype Evolution in the Genus Clivia(Amaryllidaceae)

Phylogenetic relationships of five taxa of Clivia, one probablenew species plus four recognized species, and three outgroupspecies were studied using sequences of the nuclear ribosomal5S non-transcribed spacer and the internal transcribed spacer(ITS) of 45S rDNA. Analysis of the data sets separately generatedsome well-supported groupings and congruent phylogenies. Cliviaminiata and C. gardenii are closely related. ‘Robust Gardenii’,the putative new species, is a sister clade of this group. Clivianobilis is distantly related to these three taxa and C. caulescensoccupies an intermediate position between the two groups. Chromosomelocations and distribution patterns of the 5S nuclear ribosomalgene in the species of Clivia were investigated using fluorescenceinsitu hybridization (FISH). In all species, only one pair of5S rDNA signals was observed. These were located on the shortarm of chromosome 8, at the position of the interstitial C-bands.The phylogenies obtained from the DNA sequences together withthe chromosome data accumulated here and previously publishedinformation on the location of the 45S rDNA sites have beenused to postulate evolutionary trends in Clivia chromosomes.Copyright 2001 Annals of Botany Company Clivia, chromosome evolution, 45S and 5S rDNA, ITS, FISH, molecular phylogeny     

Genetic Variability ofLepidium meyeniiand other AndeanLepidiumSpecies (Brassicaceae) Assessed by Molecular Markers

A phylogenetic survey based on similarity levels was performedfor 29 cultivated accessions of maca (Lepidium meyeniiWalp.)and 27 accessions of wild species ofLepidiumfrom Ecuador, Peruand Bolivia, with RAPD markers. Chromosome counts for each accessionwere also performed. The similarity tree matrix separated intwo main branches: cultivated and wild species. The similaritylevel among cultivated accessions was high (0.952 or higher)indicating a low level of polymorphism. Within the wild species,two main secondary branches could be resolved, of which onewas subdivided into two tertiary branches. Morphological evaluationof the wild species accessions within each main group identifiedthree wild species: (1)L. bipinnatifidum, consisting mostlyof tetraploids and a single octoploid accession; (2)L. kalenbornii,consisting only of tetraploid accessions; and (3)L. chichicara,consisting mostly of octoploid and a few tetraploid accessions.Clustering by principal coordinates analysis supported the resultsobtained by the similarity tree matrix. These results indicatethat none of the three wild species is related enough to beconsidered ancestral to the cultivatedL. meyenii. Three accessionsof intermediate position may be of hybrid origin. None of thewild species was found to be diploid, which suggests that polyploidyhas been an important adaptation to high altitude habitats inthese species.Copyright 1998 Annals of Botany Company Lepidum meyenii, Lepidium peruvianum, maca, DNA markers, phylogeny.     

The Interaction of Heat and Smoke in the Release of Seed Dormancy in Seven Species from Southwestern Western Australia

Exposure to high temperatures (40–60 °C) over severaldays to months (simulating summer soil conditions) or to extremelyhigh temperatures (80–120 °C) for periods rangingfrom minutes to several days (simulating the heat of an extremefire) promoted germination in five (including one legume species)of the seven species tested from southwestern Australia. Heat,a collective term for high temperature (HT) and extremely hightemperature (EHT), has previously been used to promote germinationin species with impermeable seed coats (many of which are legumes).If heat is found to promote germination in species with permeableseed coats, it could be of use in the release of dormancy forcommercial development of native plants. Here we report thatelevated storage temperatures (50 °C for 45 and 90 d or60 °C for 45 d) and EHT (100 °C for 3 h and 120 °Cfor 30 min) alone, and in addition to smoke, directly promotegermination of the refractory species Actinotus leucocephalus,Anigozanthos manglesii, Gompholobium knightianum, Loxocaryastriatus and Stylidium affine. Germination of Sowerbaea laxifloraseed was not improved with heat alone but was improved by thecombination of heat and smoke. Seed of Schoenus unispiculatusdid not germinate in response to any of the treatments. Interactionsbetween the effect of temperature, the duration of heat exposureor smoke were detected in all species. Whilst most species demonstratedan interaction between heat and time, not all species were affectedby smoke alone. This was illustrated by an interaction betweensmoke and HT found only in Actinotus leucocephalus, Anigozanthosmanglesii and Stylidium affine or smoke and EHT in A. manglesiiandS. affine . Smoke and exposure time to heat influenced thegermination of Actinotus leucocephalus,Anigozanthos manglesiiand L. striatus in response to HT and only S. affine appearedto demonstrate an interaction between smoke and EHT. The variationsfound in the interactions between treatments suggest that germinationevents occur over a range of conditions both spatially and temporallywhich may facilitate seedling survival and limit competitionbetween emergents. Copyright 2001 Annals of Botany Company Smoke, heat, fire, seedbank, seed dormancy, seed germination, Western Australia