• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 1
  • 1
  • Tagged with
  • 7
  • 7
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Population Structure and the Mating System of Loggerhead Turtles (Caretta caretta)

Nielsen, Janne Thoft 16 December 2010 (has links)
Studies of the maternally inherited mitochondrial DNA in loggerhead sea turtles (Caretta caretta) demonstrate that females are philopatric, returning to nest in the region where they hatched. Eleven genetic stocks of maternal lineages have been identified in the Atlantic Ocean. An analysis of the conventionally-used 380 bp of the mitochondrial control region of a sample of individuals from the genetic stock of loggerheads in Mexico (N = 175) revealed 13 haplotypes. When a longer sequence read of 815 bp was analyzed, 17 haplotypes were uncovered. In the genetic stock of loggerheads in northwestern Florida (N = 25), three haplotypes were identified with both control region sequence lengths. Based on the currently known distributions of the three long CC-A1 and CC-A2 haplotypes, two of each are unique to Mexico. This makes the longer sequence reads useful for stock identification. Within Mexico, there was evidence of significant population structuring between Cozumel and the northern region of the sampling area on mainland Mexico (pairwise ϕST = 0.1003, p = 0.0197), but not after Bonferroni correction. A direct comparison of female and male nuclear microsatellite genotypes indicated male-biased dispersal between Mexico and northwestern Florida. Within Mexico, microsatellite analysis indicated significant structuring of females between sampling years and between the northern and the southern region of the sampling area on the mainland. Consequently, this genetic stock, while perhaps not in equilibrium, shows signs of female natal homing. An analysis of clutches indicated that significantly more clutches in Mexico had multiple paternity compared to the northwestern Florida (66% and 23%, respectively). The frequency of multiple paternity was not correlated with female abundance, nest density or sex ratio of reproductively successful individuals. There was no evidence of females benefiting through increased reproductive success from multiple paternity. This is consistent with other studies of sea turtles.
2

Life history and reproductive fitness variation associated with the Y chromosome in Callosobruchus maculatus

Revenikioti, Maria January 2021 (has links)
In the seed beetle Callosobruchus maculatus, the female is the larger sex and the male is the smaller sex. However, males that are almost as large as females can also occur, which is due to a specific Y chromosome haplotype. This Y chromosome polymorphism is not expected since the Y chromosome does not recombine and has lost genetic variation as a consequence. Nevertheless, the Y chromosome manages to maintain this polymorphism. Thus, the questions asked are how this occurs and how the large male Y haplotype persists to exist since previous studies have shown how small males have the higher fitness. In this study, large males were from line SL3b Y and small males were from line SL1b Y. To answer the questions, two important measures of fitness were conducted, mating- and lifetime reproductive success, as well as lifetime-history traits of the SL1b Y and SL3b Y males. Males from line SL3b Y turned out to have a faster growth rate and a shorter development time compared to the SL1b Y males. Both the SL3b Y males with a shorter development time and the SL1b Y males with a longer development time had larger body sizes. Large males also showed to have heavier ejaculate weight and produced more offspring compared to the other male Y haplotype. However, neither of the males had higher pre-mating success. In conclusion, the two male Y haplotypes must coexist in nature since their traits are beneficial in different environments and circumstances.
3

Assessment of Test-Retest Reliability of the Reproductive Fitness Questionnaire by Survey of Mothers of Children with Juvenile Rheumatoid Arthritis and Best Friend Controls

Heald, Brandie Shantel 13 July 2006 (has links)
No description available.
4

Does arbuscular mycorrhiza symbiosis increase the capacity or the efficiency of the photosynthetic apparatus in the model legume Medicago truncatula?

Rehman, Ateeq ur January 2010 (has links)
<p>The Arbuscular mycorrhiza (AM) is an endosymbiont of higher plant roots. Most land plants and cultivated crops are concerned to AM symbiosis. This endosymbiosis is based on the mutual exchange of nutrients between plant and fungus. Therefore, AM symbiosis leads to an increased demand for photosynthetic products. The aim of this study was to investigate the pathway used by plants during AM symbiosis to increase photosynthetic performance. Therefore, we have carried out a systematic characterization of photosynthesis in Medicago truncatula (M. truncatula), which is a model legume. We observed colonization by the fungus in roots and that AM symbiosis increases the fresh and dry plant biomass. This could be attributed to an increase in both photosynthetic efficiency and capacity in AM plants. Consistent with these observations, AM symbiosis enhanced phosphorus uptake from the soil into roots, stems and leaves, as based on analyses of phosphorus content. Based on equal chl loading, no differences were found regarding D1, Lhcb1 and Lhcb2 protein content in four plant groups. This indicates similar ratio between chl and PSII proteins. Furthermore, AM symbiosis increases the amount of chlorophyll, steady state oxygen evolution activities, maximum quantum yield (Fv/Fm), and photosynthetic electron transport rate (about 5 fold). Nevertheless, photoprotection was not affected by AM symbiosis. We observed an increase in weight of seed/fruit and weight of seed/plant in AM plants (about 2 fold). Based on these results, we propose that AM symbiosis increases both the efficiency and the capacity of photosynthetic apparatus in the M. truncatula.</p>
5

Does arbuscular mycorrhiza symbiosis increase the capacity or the efficiency of the photosynthetic apparatus in the model legume Medicago truncatula?

Rehman, Ateeq ur January 2010 (has links)
The Arbuscular mycorrhiza (AM) is an endosymbiont of higher plant roots. Most land plants and cultivated crops are concerned to AM symbiosis. This endosymbiosis is based on the mutual exchange of nutrients between plant and fungus. Therefore, AM symbiosis leads to an increased demand for photosynthetic products. The aim of this study was to investigate the pathway used by plants during AM symbiosis to increase photosynthetic performance. Therefore, we have carried out a systematic characterization of photosynthesis in Medicago truncatula (M. truncatula), which is a model legume. We observed colonization by the fungus in roots and that AM symbiosis increases the fresh and dry plant biomass. This could be attributed to an increase in both photosynthetic efficiency and capacity in AM plants. Consistent with these observations, AM symbiosis enhanced phosphorus uptake from the soil into roots, stems and leaves, as based on analyses of phosphorus content. Based on equal chl loading, no differences were found regarding D1, Lhcb1 and Lhcb2 protein content in four plant groups. This indicates similar ratio between chl and PSII proteins. Furthermore, AM symbiosis increases the amount of chlorophyll, steady state oxygen evolution activities, maximum quantum yield (Fv/Fm), and photosynthetic electron transport rate (about 5 fold). Nevertheless, photoprotection was not affected by AM symbiosis. We observed an increase in weight of seed/fruit and weight of seed/plant in AM plants (about 2 fold). Based on these results, we propose that AM symbiosis increases both the efficiency and the capacity of photosynthetic apparatus in the M. truncatula.
6

Atributos florais e reprodutivos de syagrus coronata (mart) becc. como ferramentas para a conservação de uma palmeira endêmica do Brasil

BARBOSA, Camila Miranda 24 February 2016 (has links)
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-03-30T17:49:38Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Camila Miranda Barbosa.pdf: 2266282 bytes, checksum: 8e483f742cbf0b10a05321744d93decd (MD5) / Made available in DSpace on 2017-03-30T17:49:38Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação - Camila Miranda Barbosa.pdf: 2266282 bytes, checksum: 8e483f742cbf0b10a05321744d93decd (MD5) Previous issue date: 2016-02-24 / CNPQ / O licuri (Syagrus coronata) é uma palmeira que floresce e frutifica durante o ano inteiro, tendo grande importância ecológica e econômica, uma vez que fornece hábitat e alimento para diversos seres vivos, inclusive para a subsistência de populações humanas. Em populações nativas encontradas no Parque Nacional do Catimbau, a fenologia da espécie foi monitorada em quatro áreas (total de 120 indivíduos). Também foram identificados os visitantes florais, a composição química dos odores florais e a variação de temperatura das flores durante a antese, levando em consideração as fases reprodutivas (feminina e masculina), o sexo das estruturas reprodutivas (flores pistiladas e estaminadas) e o período do dia (manhã e noite). O fitness reprodutivo foi comparativamente analisado para polinização diurna vs noturna, entomófila vs anemófila. Amostras de odores florais foram coletadas através de “headspace” dinâmico a partir de flores pistiladas e estaminadas, bem como nas suas respectivas brácteas. O estudo da fenologia evidenciou duas áreas sazonais, enquanto duas outras produziram eventos contínuos de reprodução. A riqueza e abundância de visitantes florais foram maiores nas inflorescências masculinas que nas femininas. O fitness reprodutivo não mostrou diferença entre os tratamentos de polinização. Por sua vez, análises de odor floral demonstraram diferenças de compostos isolados nas brácteas e inflorescências, mas não entre as fases reprodutivas; a quantidade de odor emitido diferiu nas brácteas nas fases femininas e masculinas, mas não nas inflorescências, as quais apresentaram quantidades similares de compostos. Não foi evidenciado fenômeno de termogênese floral, nem ao longo do dia, nem entre as fases reprodutivas. Estratégias como o fornecimento de recursos em abundância e hábitat para visitantes florais, liberação diferenciada de odor e floração contínua, podem estar associadas à garantia do fluxo gênico dentro e entre populações dessa espécie de Syagrus. / Licuri (Syagrus coronata) is a palm tree that blooms and bears fruit throughout the year, having an ecological and economic importance, as it provides habitat and food for many living beings, including for the livelihoods of human populations. In native populations, found in Catimbau National Park, the phenology of species was monitored in four areas (total 120 individuals). Also flower visitors were identified, the chemical composition of floral scents and temperature variation of flowers at anthesis, taking into account the reproductive stages (male and female), sex of the reproductive structures (pistillate and staminate flowers) and the period the day (morning and evening). The reproductive fitness was comparatively analyzed for day vs. night pollinated and entomophilous vs anemophilus. Samples of floral odours were collected through "headspace" dynamic from pistillate and staminate flowers as well as in their respective bracts. The study of phenology showed two seasonal areas, while two others produced continuous reproductive events. The richness and abundance of floral visitors were higher in male than in female inflorescences. The reproductive fitness showed no difference between pollination treatments. In turn, floral odor analysis showed differences in isolated compounds in the bracts and flowers, but do not between the reproductive stage; the amount of odor emitted differed in the bracts in male and female phases, but not in inflorescences, which showed similar amounts of compounds. Floral thermogenesis phenomenon was not evidenced neither throughout the day nor between reproductive stages. Strategies such as providing abundant resources and habitat for floral visitors, differentiated release of odor and continuous flowering, may be associated with the guarantee of gene flow within and among populations of this species of Syagrus.
7

Fekunditet hos honor av Drosophila melanogaster med en potentiell sexuellt antagonistisk gen : En fördjupande studie inom experimentell validering av en potentiell sexuellt antagonistisk gen hos Drosophila melanogaster / Fecundity in females of Drosophila melanogaster with a potentially sexually antagonistic gene : An in-depth study on experimental validation of a potentially sexually antagonistic gene in Drosophila melanogaster

Lindh, Sara January 2022 (has links)
Sexual conflicts arise when there is a difference in how females and males of a species or population achieve their maximum reproductive fitness. In intralocus sexual conflicts, alleles at a given locus are exposed to conflicting, or antagonistic, selection pressures. Based on a Genome-wide association study on sexually antagonistic genes in Drosophila melanogaster (fruit flies), the aim of this study was to investigate whether the candidate gene CG3598 exhibits sexually antagonistic effects on fitness between the 2 identified alleles of the gene. The study was performed on females from a Canton-S population of D. melanogaster who, by genetic manipulation through CRISPR Cas9, carried one of the 2 alleles of the CG3598. 6 excision lines of females had allele 1 and 5 excision lines had allele 2. The females were mated with "wild type" males from a Canton-S population in mediums prepared with about 6 mg of live dry yeast, after which the females were moved to separate mediums to lay their eggs. After 12 days, the adult offspring were counted and statistical calculations were performed on the average number of offspring per female for each line and allele. An Independent sample t-test showed that the females’ average fecundity did not differ between alleles (p = 0.059) and a Nested ANOVA analysis indicated that the average fecundity for each line within each allele differed (p = 0.023). Due to the fact that similar studies have found the same result, it may be necessary to investigate and possibly change the experimental design of the method to enable competition between females with different genetic conditions in order to observe a difference in fertility based on the females' ability to compete. / Sexuella konflikter uppstår när det finns en skillnad i hur honor och hanar i en art eller population uppnår sin maximala reproduktiva fitness. Vid intralocus sexuella konflikter utsätts alleler vid ett givet locus för motstridiga, eller antagonistiska, selektionstryck. Baserat på en Genome-wide association study om sexuellt antagonistiska gener hos Drosophila melanogaster (bananflugor) syftade denna studie till att undersöka huruvida genkandidaten CG3598 uppvisar sexuellt antagonistiska effekter på fitness mellan de 2 identifierade allelerna av genen. Undersökningen utfördes på honor från en CantonS-population av D. melanogaster som genom genmodifiering av CRISPR Cas9 bar en av de olika alleler av genen CG3598. 6 linjer av honor bar allel 1 och 5 linjer bar allel 2. Honorna parades med ”wild type”-hanar från en CantonS-population i rör preparerade med ca 6 mg levande torrjäst, varpå honorna förflyttades till separata rör för att lägga sina ägg. Efter 12 dagar räknades de vuxna avkommorna och statistiska beräkningar utfördes på det genomsnittliga antalet avkommor per hona för respektive linje och allel. Ett oberoende t-test visade att honornas genomsnittliga fekunditet inte skiljde sig mellan alleler (p=0,059) och en Nested ANOVA-analys indikerade att genomsnittlig fekunditet för varje linje inom respektive allel skiljde sig (p=0,023). Då även liknande studier funnit samma resultat kan det vara nödvändig att studera och eventuellt förändra den experimentella designen av metoden för att möjliggöra konkurrens mellan honor med olika genetiska förutsättningar för att kunna observera en skillnad i fekunditet baserat på honornas förmåga att konkurrera.

Page generated in 0.0693 seconds