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  • 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

Bumblebees in a region of northwestern Scania: Is species number correlated to the number of flowering angiosperms and does gene flow occur between four locations?

Dahlgren, Linnea January 2014 (has links)
Pollination, one of our ecosystem services, is considered to be in critical condition due to a worldwide reduction in pollinators and their biodiversity. As the agricultural landscape becomes more and more intense, the pollinators lose important food and living resources.     In temperate ecosystems, bumblebees (Bombus spp) are an important group of wild pollinators, and as with pollinators in general, they are declining in both abundance and richness, in Sweden as well as other countries.      The purpose of this study was to see if bumblebee species number of a location is linked to the location’s number of flowering angiosperm species in northwestern Scania when examining eight locations, and to see if gene flow existed between four chosen locations.        The result of this study suggests that it is not possible to tell from the flowering angiosperm species how many bumblebee species that will be abundant, but that it might be possible to tell the number of bumblebee individuals. With the number of bumblebee species, the abundant Fabaceae species was more important than the total number of flowering angiosperms of the location. The number of abundant Fabaceae species was strongly correlated to the bumblebee diversity index of the locations, indicating that it is a group of flowers closely linked to bumblebees.      To see if gene flow occurred between the chosen locations, mtDNA sequences were compared in neighbor joining trees. The result showed that though some tendencies of isolation existed, gene flow seemed to occur in general between the locations in that fragmented and human dominated landscape of northwestern Scania.
2

An Extended Study On The Alu Insertion Polymorphisms In Anatolian Human Population

Sekeryapan, Ceran 01 September 2005 (has links) (PDF)
In the present study, for estimating the Central Asia contribution to the Anatolia, nine Alu insertion polymorphisms (ACE, PV92, FXIIIB, APO, A25, B65, TPA25, D1, HS4.32 ) in 100 individuals from Anatolia were examined. Alu insertion frequency for these loci were calculated as 0,410 / 0,220 / 0,579 / 0,963 / 0,067 / 0,667 / 0,390 / 0,427 / and 0,637 respectively and they were found to be in Hardy-Weinberg equilibrium (p&lt / 0,05). Observed insertion frequencies of each loci were compared with those of the previous observations (Din&ccedil / , 2003 / Comas et al., 2004) and it was found that the present study results were not different than those obtained by Comas et al. (2004). Thus, these two data were pooled (N = 143) and used to examine genetic relationships between populations from Eurasia and Africa. Pairwise Fst statistics indicated that there is higher genetic similarity between Anatolia and all of the Balkans and some of the Caucasian populations. Neighbor Joining (NJ) tree based on Reynold&rsquo / s genetic distances and Principal Component Analysis (PCA) both grouped the Anatolian populations with Balkans and some of the Caucasian populations and show clear differentiation of Asian populations from the Anatolian population. The relative genetic contribution of Central Asian genes to the current Anatolian gene pool was quantified using Admix analysis, considering for comparison populations of Balkans (Greek, Romania, Albania and Hungarian) and Central Asia (Uighur, Uzbeks, Tajicks, Kazaks, Kyrgyzes, Dungans). Estimates suggest roughly 28 % contribution from Asia to Anatolia in concordance with the previous estimation (Benedetto et al., 2001).
3

Alu Insertion Polymorphisms In Anatolian Turks

Dinc, Havva 01 September 2003 (has links) (PDF)
In the present study / ten autosomal human-specific Alu insertion polymorphisms / ACE, APO, A25, B65, D1, FXIIIB, HS4.32, HS4.69, PV92 and TPA25 were analyzed in approximately 100 unrelated individuals from Anatolia. Alu insertion polymorphisms offer several advantages over other nuclear DNA polymorphisms for human evolution studies. The frequencies of the ten biallelic Alu insertions in Anatolians were calculated and all systems were found to be in Hardy-Weinberg equilibrium (p&gt / 0.05). By combining the results of this study with results of previous studies done on worldwide populations, the genetic distance (Nei&rsquo / s DA) between each pair of populations was calculated and neighbor joining trees were constructed. In general, geographically closer populations were found to be also genetically similar. Principal component analysis (PCA) was performed and Anatolia was found to be in the European cluster. As a result of PCA / it was concluded that FXIIIB, PV92 and ACE were the variables contributing the most to the explanation of the variation between the populations. Additionally / canonical variates analysis (CVA) concluded that the most discriminative markers for the groups of populations were PV92, D1, ACE and HS4.32. Pair-wise Fst values were also calculated between Anatolians and some of the populations for which the data was available. It was concluded that, Anatolians have non-significant pair-wise Fst values with Swiss and French Acadian populations. Lastly, heterozygosity vs. distance from centroid graph was constructed and it was found that Anatolians and India-Hindu had exactly the expected heterozygosity value predicted by the model of Harpending and Ward (1982).
4

Microbial Community Structure and Interactions in Leaf Litter in a Stream

Das, Mitali 13 April 2006 (has links)
No description available.

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