{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/109451"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/109451","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Partners in space: Discordant population structure between legume hosts and Rhizobium symbionts in their native range","abstract":"To understand the coevolutionary dynamics of an interaction, theory suggests that we must study how genetic variation in both partners is structured in space. This is because, in coevolution, the spatial distribution of genetic variation in one species can both determine its ability to locally adapt to a partner species and also serve as an agent of selection acting on that partner species. Plant-microbe symbioses are ecologically and economically important, but broad-ranging dispersal and dynamic genome structure in bacteria present unique challenges for understanding spatial genetic processes in these systems. Here we study the model rhizobium Ensifer meliloti using a hierarchically structured sample of 191 strains from 21 sites in the native range and compare its population genetic structure to that of its host plant Medicago truncatula. We find that two of the three elements of the tripartite Ensifer genome lack a pattern of isolation by distance. Overall genetic variation across the symbiont genome is less spatially structured than that of its host, and variation in the two species is uncorrelated, indicating comparatively higher levels of gene flow among sampling sites in these bacterial symbionts relative to host plants. Taken together our results suggest that the spatial structure of genetic variation is impacted differently by the environment in the host and in the three symbiont genomic elements. This could lead to differing responses to selection not only between the host and symbiont, but also between the elements of the symbiont genome.","abstract_html":"To understand the coevolutionary dynamics of an interaction, theory suggests that we must study how genetic variation in both partners is structured in space. This is because, in coevolution, the spatial distribution of genetic variation in one species can both determine its ability to locally adapt to a partner species and also serve as an agent of selection acting on that partner species. Plant-microbe symbioses are ecologically and economically important, but broad-ranging dispersal and dynamic genome structure in bacteria present unique challenges for understanding spatial genetic processes in these systems. Here we study the model rhizobium Ensifer meliloti using a hierarchically structured sample of 191 strains from 21 sites in the native range and compare its population genetic structure to that of its host plant Medicago truncatula. We find that two of the three elements of the tripartite Ensifer genome lack a pattern of isolation by distance. Overall genetic variation across the symbiont genome is less spatially structured than that of its host, and variation in the two species is uncorrelated, indicating comparatively higher levels of gene flow among sampling sites in these bacterial symbionts relative to host plants. Taken together our results suggest that the spatial structure of genetic variation is impacted differently by the environment in the host and in the three symbiont genomic elements. This could lead to differing responses to selection not only between the host and symbiont, but also between the elements of the symbiont genome.","abstract_has_math":false,"creators":["Riley, Alexander"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Plant Biology","degree_department":null,"school":null,"contributors":["Heath, Katy D","Marshall-Colon, Amy"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-03-05T21:38:24Z","date_published":"2021-03-05T21:38:24Z","updated_at":"2026-07-22T22:24:50Z","subjects":["coevolution, mutualism, symbiosis, horizontal gene transfer, multipartite genome"],"languages":["en"],"rights":["Copyright 2020 Alexander Riley"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/109451","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Heath, Katy D","Marshall-Colon, Amy"]},{"key":"dc:creator","label":"Author","values":["Riley, Alexander"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2021-03-05T21:38:24Z","2020-12-10","2020-12"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Plant Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["coevolution, mutualism, symbiosis, horizontal gene transfer, multipartite genome"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Alexander Riley"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/109451"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["To understand the coevolutionary dynamics of an interaction, theory suggests that we must study how genetic variation in both partners is structured in space. This is because, in coevolution, the spatial distribution of genetic variation in one species can both determine its ability to locally adapt to a partner species and also serve as an agent of selection acting on that partner species. Plant-microbe symbioses are ecologically and economically important, but broad-ranging dispersal and dynamic genome structure in bacteria present unique challenges for understanding spatial genetic processes in these systems. Here we study the model rhizobium Ensifer meliloti using a hierarchically structured sample of 191 strains from 21 sites in the native range and compare its population genetic structure to that of its host plant Medicago truncatula. We find that two of the three elements of the tripartite Ensifer genome lack a pattern of isolation by distance. Overall genetic variation across the symbiont genome is less spatially structured than that of its host, and variation in the two species is uncorrelated, indicating comparatively higher levels of gene flow among sampling sites in these bacterial symbionts relative to host plants. Taken together our results suggest that the spatial structure of genetic variation is impacted differently by the environment in the host and in the three symbiont genomic elements. This could lead to differing responses to selection not only between the host and symbiont, but also between the elements of the symbiont genome.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2021-03-04 without embargo terms","The student, Alexander Riley, accepted the attached license on 2020-12-09 at 16:30.","The student, Alexander Riley, submitted this Thesis for approval on 2020-12-09 at 16:37.","This Thesis was approved for publication on 2020-12-10 at 15:58.","DSpace SAF Submission Ingestion Package generated from Vireo submission #16103 on 2021-03-04 at 15:36:23","Made available in DSpace on 2021-03-05T21:38:24Z (GMT). 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This is because, in coevolution, the spatial distribution of genetic variation in one species can both determine its ability to locally adapt to a partner species and also serve as an agent of selection acting on that partner species. Plant-microbe symbioses are ecologically and economically important, but broad-ranging dispersal and dynamic genome structure in bacteria present unique challenges for understanding spatial genetic processes in these systems. Here we study the model rhizobium Ensifer meliloti using a hierarchically structured sample of 191 strains from 21 sites in the native range and compare its population genetic structure to that of its host plant Medicago truncatula. We find that two of the three elements of the tripartite Ensifer genome lack a pattern of isolation by distance. Overall genetic variation across the symbiont genome is less spatially structured than that of its host, and variation in the two species is uncorrelated, indicating comparatively higher levels of gene flow among sampling sites in these bacterial symbionts relative to host plants. Taken together our results suggest that the spatial structure of genetic variation is impacted differently by the environment in the host and in the three symbiont genomic elements. This could lead to differing responses to selection not only between the host and symbiont, but also between the elements of the symbiont genome.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2021-03-04 without embargo terms","The student, Alexander Riley, accepted the attached license on 2020-12-09 at 16:30.","The student, Alexander Riley, submitted this Thesis for approval on 2020-12-09 at 16:37.","This Thesis was approved for publication on 2020-12-10 at 15:58.","DSpace SAF Submission Ingestion Package generated from Vireo submission #16103 on 2021-03-04 at 15:36:23","Made available in DSpace on 2021-03-05T21:38:24Z (GMT). No. of bitstreams: 2 RILEY-THESIS-2020.pdf: 682544 bytes, checksum: fe7aabac82b2a8dc4bf4f84989119802 (MD5) LICENSE.txt: 4212 bytes, checksum: f3956ac74f627e445eda1b9670feb0b3 (MD5) Previous issue date: 2020-12-10"],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/109451"],"dc:language":["en"],"dc:rights":["Copyright 2020 Alexander Riley"],"dc:subject":["coevolution, mutualism, symbiosis, horizontal gene transfer, multipartite genome"],"dc:title":["Partners in space: Discordant population structure between legume hosts and Rhizobium symbionts in their native range"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Plant Biology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:50Z"}