{ "133445-21873105": { "datetime_modified":"20250305T103136", "datetime_start":"20250317T143000", "datetime_end":"20250317T160000", "has_end_time":1, "date_start":"2025-03-17", "date_end":"2025-03-17", "time_start":"14:30:00", "time_end":"16:00:00", "time_zone":"America\/Detroit", "event_title":"Cecilia Howard Dissertation Defense", "occurrence_title":"", "combined_title":"Cecilia Howard Dissertation Defense: Unraveling Records of Time and Environment in Microbial Ecosystems from the Archean to Today", "event_subtitle":"Unraveling Records of Time and Environment in Microbial Ecosystems from the Archean to Today", "event_type":"Lecture \/ Discussion", "event_type_id":"13", "description":"Microbial ecosystems have shaped and been shaped by Earth\u2019s environments since the origin of life, and microbial sediments and rocks (\u201cmicrobialites\u201d) can both inform our understanding of the past and complicate our records of it. The sediment record of microbial ecosystems has the potential to preserve information about past climate, biology, mechanics, and more. However, separating individual processes from the complex amalgamation of information that typifies microbial sediments is a continuing challenge for microbial systems from the Archean to the modern. This dissertation investigates the impacts of environmental variations on microbial records at a range of spatial and temporal scales.\r\nIn Chapters 2 and 3, I focus on early records of life in the Archean and Paleoproterozoic, prior to the evolution of multicellularity. In Chapter 2, I use a literature review to determine how microbialite depositional environments change across nearly two billion years of the Archean and Paleoproterozoic. This chapter presents the first broad dataset to consider marine and tidal microbialites separately and also reveals the consistent presence of terrestrial microbialites from the earliest records of life. I find that the majority of microbialites formed in tidal environments and the proportion of terrestrially influenced microbialites increased during periods of craton development, suggesting that terrestrially derived nutrients were essential to early life. In Chapter 3, I use microCT scanning to measure and reconstruct 3.48 Ga microbialites, among the earliest accepted evidence of life. These measurements, along with a compilation of carbon and sulfur isotope data, suggest that the microbialites were formed by metabolically diverse communities in a high flow tidal environment, consistent with modeling of Archean tides.\r\nIn Chapter 4, I investigate microbialites from a lake in the hothouse climate of the Early Eocene (~50 Ma) using a mixture of morphological and geochemical analyses. This chapter considers how spatial and temporal differences influence microbialites, looking at single beds over 10\u201320 km distances and samples spanning 3 Ma. I find that microbialite morphology and chemistry records a mixture of large-scale information such as temperatures consistent with a hothouse environment and local conditions such as spring or stream influence and sediment sources, which manifests as lateral variability within beds. Additionally, comparison of atmospheric carbon dioxide reconstructions based on preserved carbon in the microbialites to past estimates supports low to moderate microbial growth rates throughout this time period.\r\nIn Chapter 5, I consider how sediments in a modern microbial ecosystem are influenced by climate change using a ten-year timeseries of sediment carbon and nitrogen data from an anoxic sinkhole in Lake Huron, which hosts a diverse microbial mat ecosystem. I integrate this sediment data with climate and lake chemistry parameters, finding that changes in ice cover lead to differences in sediment carbon in the following year. These results suggest that decreasing ice cover in the Great Lakes could lead to rapid but potentially ephemeral effects on sediment carbon.\r\nThe results in this dissertation exhibit the array of spatial and temporal scales at which microbial-environmental interactions occur, from local effects such as groundwater altering microbialite chemistry or carbon preservation to global climate and tectonics driving microbialite distribution. These findings can provide a framework for understanding the interactions between microbial ecosystems and their environment and emphasize the importance of environmental context for understanding microbialite records.", "occurrence_notes":null, "guid":"133445-21873105@events.umich.edu", "permalink":"http:\/\/events.umich.edu\/event\/133445", "building_id":"1000188", "building_name":"1100 North University Building", "campus_maps_id":"628", "room":"2540", "location_name":"1100 North University Building", "has_livestream":0, "cost":"", "tags":["Dissertation"], "website":"", "sponsors":[ { "group_name":"Earth and Environmental Sciences", "group_id":"3170", "website":"http:\/\/www.lsa.umich.edu\/earth" } ], "image_url":"https:\/\/events.umich.edu\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "styled_images":{ "event_thumb":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_thumb\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_large":"https:\/\/events.umich.edu\/media\/cache\/event_large\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_large_2x":"https:\/\/events.umich.edu\/media\/cache\/event_large_2x\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_large_lightbox":"https:\/\/events.umich.edu\/media\/cache\/event_large_lightbox\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "group_thumb":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_thumb\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "group_thumb_square":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_thumb_square\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "group_large":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_large\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "group_large_lightbox":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_large_lightbox\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_large_crop":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_large_crop\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_list":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_list\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_list_2x":"https:\/\/events.umich.edu\/media\/cache\/event_list_2x\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_grid":"https:\/\/events.umich.edu\/media\/cache\/event_grid\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_grid_2x":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_grid_2x\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_feature_large":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_feature_large\/media\/attachments\/2025\/03\/event_133445_original-1.jpg", "event_feature_thumb":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_feature_thumb\/media\/attachments\/2025\/03\/event_133445_original-1.jpg" }, "occurrence_count":1, "first_occurrence":21873105 } , "133501-21873169": { "datetime_modified":"20250306T131812", "datetime_start":"20250317T150000", "datetime_end":"20250317T170000", "has_end_time":1, "date_start":"2025-03-17", "date_end":"2025-03-17", "time_start":"15:00:00", "time_end":"17:00:00", "time_zone":"America\/Detroit", "event_title":"EEB Student Dissertation Defense \/\/ From Museums to Islands: How Species Interactions Affect Cryptic Traits", "occurrence_title":"", "combined_title":"EEB Student Dissertation Defense \/\/ From Museums to Islands: How Species Interactions Affect Cryptic Traits: Hayley Crowell", "event_subtitle":"Hayley Crowell", "event_type":"Workshop \/ Seminar", "event_type_id":"21", "description":"Hayley Crowell, EEB PhD student, presents their dissertation defense.\r\n\r\nSummary: Our understanding of ecology and evolution depends on organismal traits we can detect and quantify. Hidden (i.e., cryptic) traits, those not readily apparent or those obscured by variation in other traits, represent a challenge in that they can lead to incomplete or incorrect interpretations of pattern and process in phenotypic evolution. The study of ecological and evolutionary interactions among species is particularly sensitive to these challenges in trait detection and quantification because every organism uses other species to survive and reproduce. If organisms are using hidden traits to communicate and function, then we may be missing entire axes of variation crucial to our understanding of species interactions. Given that many organisms have vastly different sensory capabilities than humans, studying cryptic traits in the context of species interactions provides the opportunity to examine animal behavior and ecology from perspectives more relevant to the interacting species themselves. My dissertation combines museum methods, classroom experiences, phylogenetic comparative analyses, and field observations to investigate species interactions and their consequential effects on cryptic trait variation. This research provides a detailed exploration into the evolution of UV color in response to ecological variables, as well as integrative ways to use museums and teaching to further our understanding of broader trait evolution in response to species interactions.\r\n\r\nThis is a hybrid event. Join remotely: https:\/\/umich.zoom.us\/j\/93903023670\r\nMeeting ID: 939 0302 3670\r\nPasscode: umwelt", "occurrence_notes":null, "guid":"133501-21873169@events.umich.edu", "permalink":"http:\/\/events.umich.edu\/event\/133501", "building_id":"1005169", "building_name":"Biological Sciences Building", "campus_maps_id":"631", "room":"1010", "location_name":"Biological Sciences Building", "has_livestream":0, "cost":"", "tags":["eeb","Museum Of Zoology","Museum - Zoology","Graduate Students","Graduate School","Graduate","Free","evolutionary biology","evolution","environmental","Environment","Ecosystems","ecosystem","Ecology And Evolutionary Biology","Ecology & Biology","Ecology","Dissertation","department of ecology and evolutionary biology","biological science","biodiversity"], "website":"https:\/\/umich.zoom.us\/j\/93903023670", "sponsors":[ { "group_name":"Ecology and Evolutionary Biology", "group_id":"1190", "website":"" } ], "image_url":"https:\/\/events.umich.edu\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "styled_images":{ "event_thumb":"https:\/\/events.umich.edu\/media\/cache\/event_thumb\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_large":"https:\/\/events.umich.edu\/media\/cache\/event_large\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_large_2x":"https:\/\/events.umich.edu\/media\/cache\/event_large_2x\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_large_lightbox":"https:\/\/events.umich.edu\/media\/cache\/event_large_lightbox\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "group_thumb":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_thumb\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "group_thumb_square":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_thumb_square\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "group_large":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_large\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "group_large_lightbox":"https:\/\/events.umich.edu\/media\/cache\/resolve\/group_large_lightbox\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_large_crop":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_large_crop\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_list":"https:\/\/events.umich.edu\/media\/cache\/event_list\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_list_2x":"https:\/\/events.umich.edu\/media\/cache\/event_list_2x\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_grid":"https:\/\/events.umich.edu\/media\/cache\/event_grid\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_grid_2x":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_grid_2x\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_feature_large":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_feature_large\/media\/attachments\/2025\/03\/event_133501_original-1.jpg", "event_feature_thumb":"https:\/\/events.umich.edu\/media\/cache\/resolve\/event_feature_thumb\/media\/attachments\/2025\/03\/event_133501_original-1.jpg" }, "occurrence_count":1, "first_occurrence":21873169 } }