Morphological and genomic assessment of putative hybridization among deepwater ciscoes and between deepwater ciscoes and typical artedi in Lakes Michigan and Huron – Year 2

Amanda Ackiss (USGS, aackiss@usgs.gov), Yu-Chun Kao(USFWS), Andrew honsey (USGS), Randy Eshenroder (GLFC)

Although species diversity can be lost through hybridization (Mallet 2005; Seehausen 2006) and hybridization has been common among ciscoes (genus Coregonus, subgenus Leucichthys; Smith 1964; Todd and Stedman 1989; Eshenroder et al. 2016; Ackiss et al. 2020), the importance of hybridization to the loss of cisco diversity in Lakes Michigan and Huron during the mid-1900s remains unclear. Throughout the years, several studies addressed that the major loss of cisco diversity was associated with putative wide-scale hybridization events (Smith 1964; Todd and Stedman 1989; Eshenroder et al. 2016; Eshenroder and Jacobson 2020; Eshenroder et al. 2021; Kao et al. in revision). However, the morphological evidence supporting claims of wide-scale hybridization (Lake Michigan: Smith 1964; Lake Huron: Todd and Stedman 1989) was not based on a comprehensive analysis of morphological data. Neither has been there any genetic evidence supporting claims of wide-scale hybridization in both lakes. In this project, we carry out a comprehensive morphological and genomic assessment of the role of hybridization in the apparent loss of described forms of deepwater ciscoes (C. alpenae, C. hoyi, C. kiyi, C. reighardi, and C. zenithicus) and extirpation of typical artedi (C. artedi artedi) from Lakes Michigan and Huron during the mid-1900s. The proposed project will contribute to our understanding of the taxonomy of extant deepwater Ciscoes, which in Lake Huron was inferred to be a hybrid swarm comprising the five deepwater Ciscoes listed above (Eshenroder et al. 2016), but which continue to be reported as C. hoyi (Favé and Turgeon 2008). It also will contribute to our understanding of the negative effects of hybridization, which has implications for Cisco restoration in the Great Lakes. For example, if the deepwater Ciscoes of Lakes Michigan and Huron hybridized as readily as described by Smith (1964) and Eshenroder et al. (2016), the prospects of reintroducing C. kiyi from Lake Superior are poor as those introduced may hybridize with extant deepwater Ciscoes. In addition, our results will clarify the role of hybridization in shaping morphological and genetic diversity of extant Ciscoes in the Great Lakes (Eshenroder and Jacobson 2020).