Evolutionary costs and benefits of a newly discovered symbiosis between the social amoeba Dictyostelium and bacteria

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dc.contributor.advisorStrassmann, Joan E.en_US
dc.contributor.advisorQueller, David C.en_US
dc.creatorBrock, Debra Lynn Adamsen_US
dc.date.accessioned2013-03-08T00:32:59Zen_US
dc.date.available2013-03-08T00:32:59Zen_US
dc.date.issued2012en_US
dc.description.abstractRecent work has shown that microorganisms are surprisingly like animals in having sophisticated behaviours such as cooperation, communication, and recognition, as well as many kinds of symbioses. Here we show first that the social amoeba Dictyostelium discoideum has a primitive farming symbiosis that includes dispersal and prudent harvesting of the crop. About one-third of wild-collected clones engage in husbandry of bacteria. Instead of consuming all bacteria in their patch, they stop feeding early and incorporate bacteria into their fruiting bodies. They then carry bacteria during spore dispersal and can seed a new food crop, which is a major advantage if edible bacteria are lacking at the new site. However, if they arrive at sites already containing appropriate bacteria, the costs of early feeding cessation are not compensated, which may account for the dichotomous nature of this farming symbiosis. We also observed farmer Dictyostelium discoideum clones carry bacteria that they do not use as food. We hypothesized that these bacteria may play a defensive role against other D. discoideum clones. In our second study, we investigated the impact of these bacteria-carrying farmers on non-farming D. discoideum clones. We found that the presence of farming clones reduces spore production in non-farmers. Furthermore, this effect increases with frequency of farming clones, demonstrating the vulnerability of non-farming clones to farmers though in this experiment we had not separated the effects of the farmer clone and the bacteria they carry. In our third study we exposed non-farmers to a filtered supernatant from the most common non-food carried bacterium, Burkholderia xenovorans . This supernatant is likely to carry whatever the bacteria are producing. We treated Dictyostelium clones at the beginning of the social stage and found that the supernatant enhanced spore production of farming clones and hurt spore production of non-farming clones. This study shows that the effects of the bacteria can be restricted to a filtered supernatant alone. This discovery of symbiosis of D. discoideum with bacteria, and its impact on social interactions among D. discoideum clones will provide a fertile ground for further experiments on the evolution of sociality.en_US
dc.format.extent114 p.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.callnoTHESIS ECOL. 2012 BROCKen_US
dc.identifier.citationBrock, Debra Lynn Adams. "Evolutionary costs and benefits of a newly discovered symbiosis between the social amoeba Dictyostelium and bacteria." (2012) Diss., Rice University. <a href="https://hdl.handle.net/1911/70212">https://hdl.handle.net/1911/70212</a>.en_US
dc.identifier.digitalBrockDen_US
dc.identifier.urihttps://hdl.handle.net/1911/70212en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectBiological sciencesen_US
dc.subjectSocial amoebaen_US
dc.subjectDictyostelium discoideumen_US
dc.subjectFarming symbiosisen_US
dc.subjectBurkholderia xenovoransen_US
dc.subjectMicrobiologyen_US
dc.subjectEvolution & developmenten_US
dc.titleEvolutionary costs and benefits of a newly discovered symbiosis between the social amoeba Dictyostelium and bacteriaen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentEcology and Evolutionary Biologyen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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