This dissertation addresses the related questions of how online communication technologies affect communication in science and, more broadly, how new ways of interaction in online spaces affect how texts enact genres. Genres have been usefully thought of as typified discursive responses to recurrent social exigences, and much recent work has shown that genres often work together in assemblages with other genres to address these exigences. Using the relatively well-articulated genre assemblage of science, the work reported here examines four online tools for post-publication feedback on and review of articles published in two scientific journals: the online-only, open-access journal "PLoS ONE,' published by the non-profit publisher Public Library of Science, and the long-standing journal "Science," published by the American Association for the Advancement of Science. The communication in these tools is examined using quantitative methods and qualitative rhetorical criticism as well as the perspective of actor-network theory. In order to explore the particular generic conventions associated with these forums, a coding scheme was developed to examine both the speech acts and the objects of discussion in these online communication tools, and the results from this were compared with the results of a survey of readers and authors in "PLoS ONE" to ascertain how these texts are used in the community of researchers in genetics and genomics. The textual analysis and the survey study indicate that the direct hyperlinking of the online feedback tools with the research articles in the journals has some effect on how we might perceive these texts as enacting genres. To account for the interactions afforded by online media the concept of the "genre ecosystem" is proposed, which combines the symbiotic nature of genre systems with the dynamism and decentralization of genre ecologies while retaining the distinctly rhetorical nature of genres that is sometimes obscured by characterizations based in cultural-historical activity theory. It is also suggested that the scientific research article, which has been characterized in actor-network theory as an "immutable mobile," may be fruitfully conceived as becoming in some senses a "mutable mobile," due to the ability of online texts to cluster in digital space. Studies of the evolution of the research article and other genres as mutable mobiles may then help us better understand other genre assemblages in online media. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]