The ballad of banded killifish: Examining the invasion of a native transplant fish in the Great Lakes region

Biological invasions continue to accumulate globally, overwhelming the ability of researchers, managers, and policymakers to understand these invasions or effectively intervene. Identifying which non-native species have harmful impacts is critical to inform management interventions and policy decisions. In the United States, non-game fishes have been overlooked as potential invasive species because natural resource managers have historically emphasized game fish. I begin my dissertation by documenting a gap in the literature on these potentially overlooked invaders, particularly regarding their ecological impacts. I then focus on confirming the invasion of a non-game fish – Eastern Banded Killifish (Fundulus diaphanus diaphanus) – in Lake Michigan and connected waters. Beginning in the 21st century, a rapid increase in the collection of Banded Killifish around Lake Michigan prompted a question as to whether these new populations indicated the recovery of threatened, native Western Banded Killifish (F. d. menona), or the invasion of non-native Eastern Banded Killifish. I applied mitochondrial DNA (mtDNA) barcoding to confirm the introduction, establishment, and spread of Eastern Banded Killifish throughout Lake Michigan and connected waters. Specifically, Eastern Banded Killifish were associated with habitats within or connected to Lake Michigan and with higher water clarity, whereas Western Banded Killifish persisted at sites isolated from Lake Michigan and with lower water clarity. Given the large-scale habitat modifications of non-native dreissenid mussels in Lake Michigan – including increased water clarity – the association of Eastern Banded Killifish with higher water clarity may suggest that they were facilitated by the dreissenid mussel invasion. Hybridization and introgression between native and invasive taxa can have important, negative implications on native taxa, but the environmental factors that determine outcomes of hybridization and patterns in introgression are poorly known. After confirming that Eastern and Western Banded Killifish were co-occurring in numerous populations with mtDNA, I used restriction site-associated DNA sequencing and ecological niche models to assess hybridization and introgression between these subspecies. I found that the successful establishment of Eastern Banded Killifish and subsequent hybridization and introgression between Eastern and Western Banded Killifish could be explained by higher habitat suitability for Eastern Banded Killifish and the spread of Eastern Banded Killifish from their proposed point of introduction. Hybridization and introgression are ongoing threats to Western Banded Killifish by invasive Eastern Banded Killifish, and therefore the conservation of Western Banded Killifish in isolated locations should be prioritized. I subsequently assessed potential reasons behind the successful invasion of Eastern Banded Killifish by comparing diet composition and trophic niche breadth between Eastern and Western Banded Killifish using stable isotope and gut content metabarcoding analyses. I found that Eastern Banded Killifish may use habitats distinct from Western Banded Killifish because of a higher variance in littoral dependence and trophic position. Further, both stable isotope and gut content metabarcoding analyses showed an overlap in the diet composition and trophic position between the subspecies. I conclude with next directions for research in this study system. In particular, conservation management may be directed at isolated kettle lakes acting as refugia for Western Banded Killifish. Future research might prioritize whole genome sequencing of both Eastern and Western Banded Killifish to evaluate selection as well as morphologic scale counts and environmental DNA assays for monitoring the continued spread of Eastern Banded Killifish.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Hartman, Jordan Holtswarth

Contributors dc:contributor

• Larson, Eric R
• Suski, Cory D.
• Davis, Mark A
• Fuller, Becky C

• Banded Killifish
• Lake Michigan
• Mitochondrial Dna
• Restriction Site-associated Dna Sequencing
• Ecological Niche Models
• Stable Isotope Analysis
• Native Transplant
• Invasive Subspecies

Statement dc:rights

• © 2023 Jordan Holtswarth Hartman

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/122234

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F122234