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dc.contributor.advisor Strassmann, Joan E.
dc.creatorKalla, Sara Edith
dc.date.accessioned 2013-03-08T00:34:53Z
dc.date.available 2013-03-08T00:34:53Z
dc.date.issued 2011
dc.identifier.urihttps://hdl.handle.net/1911/70286
dc.description.abstract Dictyostelium discoideum serves as an ideal system to study social evolution because of the social stage of its lifecycle, where individuals aggregate to build a multicellular structure. However, much of its basic biology remains unknown and this limits its utility. I used three separate projects to fill these gaps. In my first project, I examined how speciation and genetic diversity affects kin discrimination using a related dictyostelid, Polysphondylium violaceum . I sequenced the ribosomal DNA of 90 clones of P. violaceum and found that P. violaceum is split into several morphologically identical groups. When allowed to cooperate in pairwise mixes, I found that some clones cooperated with others in their group, but in mixes between groups, clones did not cooperate. For my second project, I looked at whether D. discoideum has sex in natural populations. While sex has been observed in laboratory clones of D. discoideum , it is unclear whether sex occurs in natural populations, and sex can influence the evolution of traits. I used a dataset of microsatellites in 24 clones of D. discoideum to look for a decrease in linkage disequilibrium as a molecular sign of sex. Linkage disequilibrium is higher between physically close loci than between loci on different chromosomes. From this, I conclude that D. discoideum undergoes recombination in nature. Lastly, I used the genome sequence of D. discoideum to look at large scale patterns of evolution. Mutations tend to be biased towards A/T from G/C so, on average, mutations should lower the nucleotide content of sequences. The removal of these mutations, purifying selection, should preserve nucleotide content. I used the genomes of D. discoideum and Plasmodium falciparum identify classes of sequences that should be under different amounts of purifying selection and compared their nucleotide contents. In all cases, those sequences under more purifying selection had higher GC contents than sequences under less purifying selection. Looking at relative nucleotide content may thus serve as an indicator purifying selection. These three studies add insight on how cooperation works in dictyostelids as well as adding an understanding of how traits, social and otherwise, would evolve in this system.
dc.format.extent 122 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectBiological sciences
Dictyostelids
Cryptic species
Speciation
Evolution & development
dc.title Evolutionary Genetics of Dictyostelids: Cryptic Species, Sociality and Sex
dc.identifier.digital KallaS
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Ecology and Evolutionary Biology
thesis.degree.discipline Natural Sciences
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Kalla, Sara Edith. "Evolutionary Genetics of Dictyostelids: Cryptic Species, Sociality and Sex." (2011) Diss., Rice University. https://hdl.handle.net/1911/70286.


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