Dissertations / Theses on the topic 'Seed size and number'
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Goszka, Abigail R. "Seed Production and Seed Quality in Red Maple (Acer rubrum L.)." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1564752025178858.
Full textFreewalt, Keith. "Creation of a High Density Soybean Linkage Map, QTL Mapping and the Effects of Marker Number, Population Size and Significance Threshold on Characterization of Quantitative Trait Loci." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1402656287.
Full textEaston, Lyndlee Carol, and lyndlee easton@flinders edu au. "LIFE HISTORY STRATEGIES OF AUSTRALIAN SPECIES OF THE HALOPHYTE AND ARID ZONE GENUS FRANKENIA L. (FRANKENIACEAE)." Flinders University. Biological Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081124.105244.
Full textNdirangu, Christopher Mwangi. "Soybean seed yield and size as influenced by row spacing and seeding rate and seed-size heritability." Diss., This resource online, 1997. http://scholar.lib.vt.edu/theses/available/etd-10052007-143343/.
Full textBandekar, Neha Keshav. "Correlation of Neuron Size and Number with Brain Size in Bumblebees." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/612851.
Full textHobson, Jennifer M. "Spring seeding, seed size and seed pathology of North American ginseng (Panax quinquefolius L.)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ40417.pdf.
Full textNorem, Margaret A. "Box Number Two Arrives at the Svalbard Global Seed Vault." University of Arizona (Tucson, AZ), 2012. http://hdl.handle.net/10150/556792.
Full textLarios, Cárdenas Eugenio. "Seed size selection in the wild in Dithyrea californica." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/321321.
Full textRamirez, Herbert 1959. "Flower and seed size in barley (Hordeum vulgare L.)." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/291929.
Full textHughes, Rhiannon. "Determinants of seed size and yield in Arabidopsis thaliana." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519024.
Full textDickson, Ross L. "Seed production in Pinus radiata D. Don : Impact of climate and site on numbers of emergent female strobili." Thesis, University of Canterbury. Forestry, 1995. http://hdl.handle.net/10092/7190.
Full textCrumpton-Taylor, Matilda. "Starch granule number and size in Arabidopsis thaliana leaves." Thesis, University of East Anglia, 2010. https://ueaeprints.uea.ac.uk/25637/.
Full textYi, Minyoung Janet. "Variation in Egg Size and Number in Drosophila subobscura." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539626847.
Full textSquella, Fernando. "Ecological significance of seed size in mediterranean annual pasture legumes." Adelaide Thesis (Ph.D.) -- University of Adelaide, Waite Agricultural Research Institute, Department of Plant Science, 1992. http://hdl.handle.net/2440/21647.
Full textThesis (Ph.D.)--University of Adelaide, Faculty of Agricultural and Natural Resource Sciences, 1992
Metcalf, Daniel James. "Seed size, litter and regeneration in tropical rain forest trees." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336743.
Full textKemp, Ronelle. "Seed size and light requirements in southern Cape forest species." Thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/26128.
Full textGoselle, Obed Nanjul. "Genome size, cell nuclei number and endopolyploidy in human demodex." Thesis, Bangor University, 2013. https://research.bangor.ac.uk/portal/en/theses/genome-size-cell-nuclei-number-and-endopolyploidy-in-human-demodex(2bbaad63-376d-4123-b812-83f8c860acbc).html.
Full textSaha, Nilanjan. "Gap Size Effect on Low Reynolds Number Wind Tunnel Experiments." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35938.
Full textMaster of Science
Loehrlein, Marietta Margaret 1957. "Priming techniques and size characteristics of triploid and tetraploid watermelon seed." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276845.
Full textBoman, Jesper. "Genome size and phenotypic plasticity in the seed beetle, Callosobruchus maculatus." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-337280.
Full textHerat, Lakshman Gamini. "Effects of maturity and seed size on seed vigor and plant growth in snap bean (Phaseolus vulgaris L.)." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39885.
Full textPh. D.
Gnan, Sebastian Christopher. "Genetic and environmental effects on natural variation in Arabidopsis thaliana seed size." Thesis, University of Bath, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619284.
Full textFatihi, Abdelhak [Verfasser]. "Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana / Abdelhak Fatihi." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1044190582/34.
Full textSchutte, Brian J. "Biology and ecology of Ambrosia Trifida L. seedling emergence." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1181937971.
Full textHathaway, John Ellis. "Determining the Optimum Number of Increments in Composite Sampling." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/425.
Full textLönnberg, Karin. "Effects of seed size and habitat on recruitment patterns in grassland and forest plants." Doctoral thesis, Stockholms universitet, Botaniska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-82384.
Full textAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.
Swarner, Joyce Carroll. "Ordinal size scaling in preschool children." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184584.
Full textAlqurashi, Faris. "Extension of spray flow modelling using the drop number size distribution moments approach." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/extension-of-spray-flow-modelling-using-the-drop-number-size-distribution-moments-approach(9c11e7da-f583-492d-b6a9-29b6fee71438).html.
Full textStandley, William George. "THE EFFECT OF SEED SIZE ON RESEEDING IN THE PRESENCE OF HETEROMYIDS (RODENTS, PREFERENCE)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275316.
Full textBickers, Richard. "Effects of population size and density on seed production and recruitment in Scabiosa columbaria." Thesis, University of Sussex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436827.
Full textYehnjong, Petra Seka. "Paleozoic Seed Bank and Their Ecological Significance." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2316.
Full textChanyenga, Tembo Faera. "Effect of population size on viable seed output, seed rand and natural regeneration pattern of a tropical conifer Widdringtonia whytei-Rendle in Malawi." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85589.
Full textENGLISH ABSTRACT: Widdringtonia whytei is a tropical endemic, fire-adapted pioneer coniferous tree species within natural fire-fragmented Afromontane forest patches in a confined area on Mulanje Mountain in Malawi. Natural and anthropogenic fires within the surrounding fire-prone landscape, insect attacks, and uncontrolled harvesting of mature trees for timber threaten the survival of W. whytei. This study investigated the effects of population fragmentation on the reproductive biology of W. whytei, through four specific studies: effects of population size, tree size and crown position on viable seed output; seed rain variation among population sizes; effects of temperature and light on viability and germination of W. whytei seeds; and the influence of population size on natural regeneration patterns. The study was conducted during 2008 and 2009 on three sites using three W. whytei population sizes: small (≤10 reproductively mature cone-bearing W. whytei trees), medium (11-20 cone-bearing trees) and large (>20 cone-bearing trees). Data were collected using field and laboratory experiments and a review of secondary information. The effect of fragment size and crown position on viable seed output and seed rain pattern was tested with a nested linear mixed model. The influence of stem diameter (dbh) on viable seed output was tested using a separate data set. The variation in seed rain was explored with a generalised linear model (GLM) with a negative binomial link function. Variations in seed germination was analysed with a Weibull regression model. The influence of fragment size on seedling regeneration was tested with a GLM (binary logistic regression). Viable seed output from W. whytei cones was very low (23%) and was not affected by population size, tree diameter or crown position. W. whytei population size influenced seed rain with large fragments having higher seed rain densities. Number of dispersed seeds was generally very low and poorly dispersed. W. whytei cones are semiserotinous and depends on moderate to severe fires for heavy seedfall and wider dispersal. Such fires did not occur during the study period. Temperature is a critical factor for seed germination. Seeds germinate between 15 and 25°C with the optimum at ~ 20°C either under light or dark conditions. Regeneration density followed the seed rain pattern indicating that seed availability is a critical factor for regeneration. Regular cool fires outside the forest patches and along the edges during the hot dry season, and the thick litter layer and shady conditions inside forest patches, caused most of the seedling mortality. This study highlighted the difficulties W. whytei experiences with low output of viable seed, limited seed dispersal and low seedling regeneration in and around forest patches, i.e. factors important for conservation management of this species. It is recommended that gaps with diameter equal to canopy height and occasional spot fires would promote seed dispersal onto exposed mineral soil for rapid seedling establishment and subsequent population growth. Such natural fire disturbance events may show the true seed rain and seedling establishment patterns in this species.
AFRIKAANSE OPSOMMING: Widdringtonia whytei is ‘n tropiese endemiese, vuuraangepaste pionier naaldhoutagtige boomsoort binne die natuurlike vuurgefragmenteerde Afromontane woudkolle binne ‘n beperkte area op Mulanje berg in Malawi. Natuurlike en menslike vure binne die omringende vuurgeneigde landskap, insekaanvalle, en onbeheerde kap van volwasse bome vir hout bedreig die voortbestaan van W. whytei. Hierdie studie het die effek van populasiefragmentasie op die voortplantingsbiologie van W. whytei ondersoek, deur vier spesifieke studies: die effek van populasiegrootte, boomgrootte en kroonposisie op produksie van lewenskragtige saad; saadreënvariasie tussen populasiegroottes; die effek van temperatuur en lig op lewenskragtigheid en ontkieming van W. whytei saad; en die invloed van populasiegrootte op natuurlike verjongingspatrone. Die studie is gedurende 2008 en 2009 uitgevoer op drie groeiplekke met drie W. whytei populasiegroottes: klein (≤10 keëldraende (volwasse) W. whytei bome), medium (11-20 keëldraende bome) en groot (>20 keëldraende bome). Data is versamel in veld- en laboratorium eksperimente asook 'n oorsig van sekondêre inligting. Die invloed van populasie fragmentgrootte en kroonposisie van bome op saadproduksie en die saadreënpatroon is getoets met ‘n geneste liniêre gemengde model. Die invloed van boomstamdeursnee op die produksie van kiemkragtige saad is met ‘n aparte datastel getoets. Die variasie in saadreënpatroon is met 'n algemene liniêre model (GLM) met 'n negatiewe binomiese skakelfunksie getoets. Variasies in ontkiemingspersentasie van sade is met 'n Weibull regressiemodel ontleed. Die invloed van fragmentgrootte op saailingverjonging is met 'n algemene linêre model (binêre logistiese regressie) getoets. Produksie van lewenskragtige saad in W. whytei keëls was baie lag (23%) en was nie deur populasiegrootte, boomstamdeursnee of kroonposisie beïnvloed nie. W. whytei populasiegrootte het saadreën beïnvloed en groot fragmente het groter saadreëndigthede gehad. Die aantal verspreide sade was in die algemeen baie laag en swak versprei. W. whytei keëls is semi-saadhoudend (serotinous) en is afhanklik van matige tot intense vure vir massiewe saadvrystelling en wyer saadverspreiding. Sulke vure het nie gedurende die studieperiode voorgekom nie. Temperatuur is ‘n kritiese factor vir saadontkieming. Sade ontkiem goed tussen 15 en 25°C met die optimum rondom ~ 20°C onder beide lig en donker toestande. Fragmentgrootte het nie die saailingverjonging in W. whytei beïnvloed nie. Verjongingsdigtheid het die saadreënpatroon gevolg, wat daarop dui dat saadbeskikbaarheid ‘n kritiese factor is vir saailingverjonging. Gereelde koel vure buite die woudkolle en langs die woudrand gedurende die droë warm seisoen, en die dik lae blaarval (litter) en skadutoestande binne ‘n woud, het meeste van die saailingmortaliteit veroorsaak. Hierdie studie het die probleme beklemtoon wat W. whytei ondervind met die lae produksie van kiemkragtige saad, saadverspreiding en saailingverjonging binne en rondom die woudkolle, m.a.w. faktore wat belangrik is vir bewaringsbestuur van hierdie boomsoort. Die aanbeveling word gemaak dat kroonopeninge met ‘n deursnee gelyk aan minstens die kroonhoogte, en sporadiese kolbrande binne die woudkolle kan saadverspreiding op blootgestelde minerale grond vir vinnige saailingvestiging en gevolglike populasiegroei bevorder. Sodanige vuurversteuringsgeleenthede mag die werklike patrone in saadreën en saailingvestiging in hierdie species toon.
Babale, Aliyu. "The interplay of habitat and seed size on the shift in species composition in a fragmented Afromontane forest landscape: Implications for the management of forest restoration." Thesis, University of Canterbury. Biological Sciences, 2014. http://hdl.handle.net/10092/10055.
Full textMazibuko, Dickson Mgangathweni. "Phylogenetic relationships of Prosopis in South Africa : an assessment of the extent of hybridization, and the role of genome size and seed size in the invasion dynamics." Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71966.
Full textENGLISH ABSTRACT: Invasive alien plants have had diverse ecological and social impacts on recipient ecosystems and are a major problem for land managers. Successful management demands an understanding of the ecology of invading taxa. The invasive status and impacts are documented for Prosopis populations in South Africa. However, unresolved taxonomic issues, the extent of hybridization, the applicability of morphology as a species identification approach, and the role that some traits plays in the invasion success have not been studied. This creates a gap that hinders implementation of effective management policies. In this thesis I use a phylogenetic approach to determine the taxonomic make-up of invasive Prosopis populations in South Africa (Chapter 2) and compare the results to morphological identification (Chapter 3). I also look at seedling growth rates in the context of variation in genome size and seed size (Chapter 4). Almost all regions invaded by Prosopis are characterized by taxonomic uncertainty exacerbated by the ease of inter-specific hybridization. In Chapter 2 I aim to resolve taxonomic issues of invasive Prosopis populations in South Africa using a phylogenetic approach. In addition, I aim to unravel the extent of hybridization and the species involved in South Africa. Here, I found that Prosopis populations in South Africa comprise both reported and previously unreported species, indicating a need for a reassessment of the identity of invasive taxa. Hybridization is prevalent and all confirmed species are involved. These findings call for a rethink of legislation and management approaches, e.g. the selection of classical biological control agents. Overall the extent of hybridization indicates that Prosopis species in South Africa comprise a freely inter-breeding population typical of a syngameon. Proper morphological identification of invasive species is crucial for ecological studies and management of invasions. In Chapter 3, I use the total evidence approach to assess whether morphological approaches for identification are adequate for identifying Prosopis species in South Africa. I found that Prosopis taxa in South Africa cannot be reliably distinguished using existing morphological keys. This is likely due mainly to the proliferation of hybrids with a diverse morphology. Therefore, molecular tools are crucial for confirming any morphological identities and for determining the presence of any unreported species. Genome size and seed size have been reported to be associated with invasiveness in a number of plant groups, but not often in a system with multiple hybrids like Prosopis. In Chapter 4, I first investigate the relationship between genome size and seed size in invasive populations of Prosopis spp. in South Africa and secondly I investigate how genome and seed sizes influence germination and early growth. Here I found that genome size loses its distinctness, being diluted in hybridizing populations, but can still be used to assess hybridization events themselves. Large seed size seems to be important for invasiveness as it positively influences germination and early growth. This thesis confirms the taxonomic conundrum of Prosopis species in invasive ranges. This coupled with inadequacy of morphological identification calls for a global study involving native and invasive range taxa to clarify the existing confusions. In view of the presence of unreported Prosopis species in South Africa and extensive hybridization, a rethink of the current legislation and control is needed.
AFRIKAANSE OPSOMMING: Uitheemse indringer plante het grootskaalse ekologiese en sosiale impakte op die ekosisteme wat hulle indring en stel 'n groot uitdaging vir bestuurders van natuurlike hulpbronne. Suksesvolle bestuur en bestryding van indringer plante verg deeglike kennis oor hulle ekologie. Die indringer status en impakte van Prosopis populasies in Suid Afrika is reeds voorheen beskryf. Nieteenstaande, die problematiese taksonomie, die omvang van hibridisasie, die waarde van morfologiese identifikasie, en die rol wat sekere eienskappe speel in die sukses van hierdie groep is nog nie bestudeer nie. Daar is dus 'n gaping in kennis wat die effektiewe beheer van die groep in Suid Afrika belemmer. In hierdie tesis pas ek 'n filogenetiese benadering toe om die taksonomiese verwantskappe van Prosopis populasies in Suid Afrika te bepaal (Hoofstuk 2) en vergelyk my resultate met morfologiese identifikasie sleutels (Hoofstuk 3). Ek ondersoek ook saailing groei tempos in die konteks van variasie in genoom en saad groote in die groep (Hoofstuk 4). Bykans alle areas in Suid Afrika waar Prosopis voorkom word gekenmerk deur taksonomiese onsekerheid, verder bemoeilik deur die gemak waarmee spesies vrylik hibridiseer. Ek vind dat beide bekende en voorheen-onbeskryfde Prosopis spesies in Suid Afrika aangetref word en beklemtoon die behoefte om die identiteit van spesies in die land te hersien. Hibridisasie kom algemeen voor tussen alle spesies teenwoordig in Suid Afrika. Hierdie bevindinge beklemtoon dat wetgewing en beheermaatreêls hersiening benodig, byvoorbeeld in die toepassing van biologiese beheer. In samevatting kom dit voor asof hibridisasie gelei het tot 'n vrytelende Prosopis groep in Suid Afrika, tipies van 'n singameon. Ordentlike morfologiese identifikasie van indringer spesies is belangrik in enige ekologiese studie en die implementering van doeltreffende beheermaatreëls. In Hoofstuk 3 gebruik ek ʼn ‘totale bewys’ benadering om vas te stel of morfologiese eienskappe alleenlik genoegsaam is om Prosopis spesies in Suid Afrika korrek te kan identifiseer. Ek vind dat spesies nie geloofwaardig geïdentifiseer kan word nie, heel moontlik as gevolg van wydverspreide hibridisasie tussen alle spesies teenwoordig in die land. Genoom en saad groote is voorheen geassosieer met die indringer aard van verskeie plant groepe. In Hoofstuk 4 ondersoek ek die verwantskap tussen genoom en saad groote. Tweedens bepaal ek die invloed van genoom en saad groote op ontkieming en vroeë groei eienskappe van Prosopis. My bevindinge toon dat, terwyl die kenmerklikheid van genoom groote verloor word as gevolg van hibridisasie, dit steeds hibridisasie gebeurtenisse per se kan identifiseer. Groot sade het ook ʼn positiewe invloed op die ontkieming en vroeë groei eienskappe van Prosopis. Die tesis bevestig die taksonomiese onduidelikheid van indringer Prosopis taksa in Suid Afrika. Tesame met die onakkuraatheid van morfologiese sleutels beklemtoon my bevindinge die behoefte vir ʼn dringende wêreldwye studie op indringer en inheemse populasies van Prosopis om taksonomiese onsekerhede op te klaar. Die identifikasie van nuwe spesies in Suid Afrika beklemtoon ook die behoefte om huidige wetgewing en beheer van die groep in die land te hersien.
Amarillo-Suárez, Angela Rocío. "INFLUENCES OF HOST SIZE AND HOST QUALITY ON HOST USE IN A SEED-FEEDING BEETLE." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_diss/352.
Full textWhite, Merlin M. "Assessment of copepod development in relation to genome size and 18S rDNA copy number." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24996.pdf.
Full textChristians, Julian Kenneth. "The physiological basis of intraspecific variation in egg size, quality and number in birds." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0010/NQ61631.pdf.
Full textCook, Casey Lee. "Seeding rate and seed size as management techniques for ryegrass (Lolium Multiflorum, Lam) in winter wheat." Texas A&M University, 2002. http://hdl.handle.net/1969.1/2284.
Full textMendes, Calebe Pereira [UNESP]. "Patch size, shape and edge distance influences seed predation in a keystone palm in tropical rainforests." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/122104.
Full textA predação de sementes é um importante tipo de processo ecológico, que afeta a abundância, diversidade e distribuição de espécies vegetais. Uma vez que esse processo ecológico depende da presença, abundancia e comportamento dos predadores de sementes, o que é afetado pelas características da paisagem, o processo de predação de sementes também acaba sendo afetado pelas características da paisagem. A maioria dos estudos em paisagens antrópicas não levam em conta as diferentes escalas em que esse processo opera. Aqui, nós avaliamos como a estrutura da paisagem afeta a predação de sementes de uma palmeira espécie-chave (Syagrus romanzoffiana) em 13 paisagens que variam em cobertura florestal, número e tamanho de fragmentos na Mata Atlântica brasileira. Nós observamos que a predação total de sementes é explicada pelo tamanho, forma e distância até a borda do fragmento. A predação de sementes pelo principal vertebrado predador de sementes (esquilos) também é relacionada com o tamanho e forma dos fragmentos, e eles interagem com os invertebrados de modo que a predação de sementes por estes é explicada principalmente pela predação por esquilos e pela distância até a borda mais próxima. Por sua vês, roedores não arborícolas são mais correlacionados com a quantidade de habitat na paisagem, predando mais sementes em paisagens com menos de 30% de habitat. Nossos resultados indicam que a predação de sementes de Syagrus romanzoffiana é mais afetada por variáveis do fragmento do que por variáveis da paisagem, e que o tamanho, a forma do fragmento e o efeito de borda são melhores preditores da predação de sementes dessa espécie-chave do que a quantidade de habitat na paisagem. Nossos resultados também ressaltam que a geometria do fragmento, uma variável negligenciada na maioria dos estudos, é importante para sistemas ecológicos
Seed predation is an important kind of ecological process that affect the abundance, diversity and distribution of plant species. Since this ecological process depends on the presence, abundance and behavior of seed predators, what it is affected by the landscape characteristics, the process of seed predation becomes also affected by the landscape characteristics. Most of studies on seed predation in human-modified landscapes do not take into account the different scales in which this process operates. Here we evaluate how landscape structure affects seed predation in a palm (Syagrus romanzoffiana) that provide a keystone resource to the frugivory community in 13 landscapes that vary in forest cover, fragment number and size in the Brazilian Atlantic forest. We found that the overall seed predation is explained by the fragment size, shape and the distance to the edge. Seed predation by the dominant vertebrate seed predator (squirrels) is also related with the fragment size and shape, and they interact with the invertebrates in such way that the invertebrate seed predation is mainly explained by the squirrel predation and by the distance to the edge. In turn, seed predation by terrestrial rodents is correlated with the habitat amount in the landscape, preying upon more seeds in landscapes with less than 30% of habitat. Our results indicate that the Syagrus romanzoffiana seed predation is more affected by the fragment variables than by landscape ones, and that patch size, shape and edge effect are more important predictors of seed predation of this palm than habitat amount in the landscape. Our results also highlights that the fragment geometry, a neglected variable in most of studies, is importance to ecological systems
Mendes, Calebe Pereira. "Patch size, shape and edge distance influences seed predation in a keystone palm in tropical rainforests /." Rio Claro, 2014. http://hdl.handle.net/11449/122104.
Full textCoorientador: Milton Cezar Ribeiro
Banca: Paulo Roberto Guimarães Junior
Banca: Marco Aurelio Pizo Ferreira
Resumo: A predação de sementes é um importante tipo de processo ecológico, que afeta a abundância, diversidade e distribuição de espécies vegetais. Uma vez que esse processo ecológico depende da presença, abundancia e comportamento dos predadores de sementes, o que é afetado pelas características da paisagem, o processo de predação de sementes também acaba sendo afetado pelas características da paisagem. A maioria dos estudos em paisagens antrópicas não levam em conta as diferentes escalas em que esse processo opera. Aqui, nós avaliamos como a estrutura da paisagem afeta a predação de sementes de uma palmeira espécie-chave (Syagrus romanzoffiana) em 13 paisagens que variam em cobertura florestal, número e tamanho de fragmentos na Mata Atlântica brasileira. Nós observamos que a predação total de sementes é explicada pelo tamanho, forma e distância até a borda do fragmento. A predação de sementes pelo principal vertebrado predador de sementes (esquilos) também é relacionada com o tamanho e forma dos fragmentos, e eles interagem com os invertebrados de modo que a predação de sementes por estes é explicada principalmente pela predação por esquilos e pela distância até a borda mais próxima. Por sua vês, roedores não arborícolas são mais correlacionados com a quantidade de habitat na paisagem, predando mais sementes em paisagens com menos de 30% de habitat. Nossos resultados indicam que a predação de sementes de Syagrus romanzoffiana é mais afetada por variáveis do fragmento do que por variáveis da paisagem, e que o tamanho, a forma do fragmento e o efeito de borda são melhores preditores da predação de sementes dessa espécie-chave do que a quantidade de habitat na paisagem. Nossos resultados também ressaltam que a geometria do fragmento, uma variável negligenciada na maioria dos estudos, é importante para sistemas ecológicos
Abstract: Seed predation is an important kind of ecological process that affect the abundance, diversity and distribution of plant species. Since this ecological process depends on the presence, abundance and behavior of seed predators, what it is affected by the landscape characteristics, the process of seed predation becomes also affected by the landscape characteristics. Most of studies on seed predation in human-modified landscapes do not take into account the different scales in which this process operates. Here we evaluate how landscape structure affects seed predation in a palm (Syagrus romanzoffiana) that provide a keystone resource to the frugivory community in 13 landscapes that vary in forest cover, fragment number and size in the Brazilian Atlantic forest. We found that the overall seed predation is explained by the fragment size, shape and the distance to the edge. Seed predation by the dominant vertebrate seed predator (squirrels) is also related with the fragment size and shape, and they interact with the invertebrates in such way that the invertebrate seed predation is mainly explained by the squirrel predation and by the distance to the edge. In turn, seed predation by terrestrial rodents is correlated with the habitat amount in the landscape, preying upon more seeds in landscapes with less than 30% of habitat. Our results indicate that the Syagrus romanzoffiana seed predation is more affected by the fragment variables than by landscape ones, and that patch size, shape and edge effect are more important predictors of seed predation of this palm than habitat amount in the landscape. Our results also highlights that the fragment geometry, a neglected variable in most of studies, is importance to ecological systems
Mestre
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Full textStuart, Joseph Scott 1971. "Observational constraints on the number, albedos, size, and impact hazards of the near-Earth asteroids." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/49805.
Full textIncludes bibliographical references (p. 132-144).
This work provides a statistical description of the near-Earth asteroids (NEAs) in terms of number, orbital parameters, reflectance spectra, albedos, diameters, and terrestrial and lunar collision rates. I estimate the size and shape of the NEA population using survey data from the Lincoln Near-Earth Asteroid Research project including more than 1300 NEA detections. The NEA population is more highly inclined than previously estimated and the total number of NEAs with absolute magnitudes (H) brighter than 18 is 1227 +170/-90. The absolute magnitude and orbital parameter distributions for the NEAs are combined with reflectance spectra and albedo measurements. I obtain a debiased estimate of the fraction of NEAs in each of 10 taxonomic complexes, and a debiased average albedo for each. The number of NEAs larger than 1 km is 1090 +/- 180. Next, I determine the impact frequency, collision velocity distribution and collision energy distribution for impacts of NEAs into the Earth and Moon. Globally destructive collisions ([approx.] 1021 J) of asteroids 1 km or larger strike the Earth once every 0.60 +/- 0.1 Myr on average. Regionally destructive collisions with impact energy greater than 4x1018 J ([approx.] 200 m diameter) strike the Earth every 47,000 +/- 6,000 years. The rate of formation of craters expected from the NEAs is found to be in close agreement with the observed number of craters on the Earth and Moon.
(cont.) These results combine the largest set of NEA discovery statistics from a single survey, the largest set of physical data on NEAs, and corrections for observational bias. The result is a comprehensive estimate of the total NEA population in terms of orbital parameters, absolute magnitudes, albedos, and sizes. This improved description of the NEAs will help us to plan surveys to find and study the remaining undiscovered NEAs, to connect the NEAs to their origins in the main-belt, to connect the NEAs to meteorite samples, to compare the lunar and terrestrial cratering record to the current population of potential impactors, and to understand the magnitude of the NEA impact hazard to the Earth's biosphere.
by Joseph Scott Stuart.
Ph.D.
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Full textMadhavan, Sharmila. "Screening of HvNAM-B1 gene polymorphism, grain nutrient content and seed size in 80 Scandinavian barley cultivars." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69079.
Full textJones, Trevor A. "The effects of seed size on seedling growth response to elevated CO¦2 in four conifer species." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62346.pdf.
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