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The Evolutionary Impact of Humans on Freshwater Fishes

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dc.contributor.authorZarri, Liam
dc.contributor.chairFlecker, Alexanderen_US
dc.contributor.committeeMemberMcIntyre, Peteren_US
dc.contributor.committeeMemberTherkildsen, Ninaen_US
dc.date.accessioned2025-01-14T20:01:23Z
dc.date.issued2024-08
dc.description188 pagesen_US
dc.description.abstractWhile ecological and evolutionary time have historically been thought to operate at different rates, strong selection has recently been recognized to cause the convergence of these timescales through rapid evolution. Since the industrial revolution, intensive habitat alteration and heightened species mortality have induced strong selection in many wild populations and accelerated extinction rates. This biodiversity crisis is particularly critical for freshwater fishes, which constitute roughly 25% of all known vertebrates yet occupy a tiny and heavily altered slice of Earth’s surface area. However, many species show rapid recent trait change that suggests that they might be adapting to the anthropogenic pressures caused by the sixth mass extinction. Because trait heritability has historically been challenging to estimate in the wild, it is largely unknown whether widespread trait changes are plastic and thus reversible, or heritable and encoded into the genome. Therefore, I blend field ecology with high-throughput genomic sequencing to explore the potential for rapid evolution in freshwater fishes arising from habitat alteration and accelerated mortality. First, I conducted a systematic review, field study, and landscape genetic analysis to explore the evolutionary impacts of habitat alteration arising from river dams. Large dams on mainstem rivers can catalyze plastic trait change ranging from morphology and migration patterns, to chemosensory and behavior patterns. However, tributary dams may be a more severe conservation concern than mainstem dams when small non-migratory fish populations are impounded. Next, I genotyped thousands of archived and field-captured smallmouth bass (Micropterus dolomieu) to explore the evolutionary underpinnings of rapid trait change arising from heightened anthropogenic mortality. I found that a decades-long effort to eradicate bass from Adirondack lakes caused rapid evolutionary change towards early growth and maturation, contributing to an unexpected expansion of the bass population. A comparison of disturbed versus natural lakes suggests that anthropogenic removals also altered reproductive life-history strategies, spawning locations, and spawn timing in nesting bass. In conclusion, freshwater fish populations can persist in a changing environment through both plastic and heritable trait changes acting in concert.en_US
dc.description.embargo2025-09-03
dc.identifier.doihttps://doi.org/10.7298/qcqh-tp20
dc.identifier.otherZarri_cornellgrad_0058F_14535
dc.identifier.otherhttp://dissertations.umi.com/cornellgrad:14535
dc.identifier.urihttps://hdl.handle.net/1813/116637
dc.language.isoen
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 International*
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectFisheriesen_US
dc.subjectFreshwater fishen_US
dc.subjectInvasive speciesen_US
dc.subjectLandscape geneticsen_US
dc.subjectLife-history evolutionen_US
dc.subjectRapid evolutionen_US
dc.titleThe Evolutionary Impact of Humans on Freshwater Fishesen_US
dc.typedissertation or thesisen_US
dcterms.licensehttps://hdl.handle.net/1813/59810.2
thesis.degree.disciplineEcology and Evolutionary Biology
thesis.degree.grantorCornell University
thesis.degree.levelDoctor of Philosophy
thesis.degree.namePh. D., Ecology and Evolutionary Biology

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