Data and Code for: Isotopic Niche Size of Coregonus artedi (sensu lato) Increases in the Presence of Mysis diluviana, Expanded Habitat Use and Phenotypic Diversity

<p>Post-glacial colonization of lakes in Algonquin Park, Ontario, Canada resulted in food webs with cisco (<i>Coregonus artedi</i> sensu lato) and either <i>Mysis</i> <i>diluviana</i> or <i>Chaoborus </i>spp. as the dominant diel migrator. <i>Mysis</i> as prey, its diel movements and benthic occupancy, are hypothesized to be key elements of ecological opportunity for cisco diversity in the Laurentian Great Lakes.  If correct, the hypothesis strongly implies that lakes with <i>Mysis</i> would have greater trophic niche size and drive greater adaptive radiation of cisco forms relative to lakes without <i>Mysis</i>. The dichotomy in diel migrator in Algonquin Park lakes was an opportunity to assess the isotopic niche size of cisco (δ¹⁵N and δ¹³C) and determine if niche size expands with <i>Mysis </i>presence. We found the presence of <i>Mysis</i> is necessary to expand isotopic niche size in our study lakes. The use of habitats not typically associated with the ancestral form of cisco (e.g., benthic habitats) and phenotypic diversity (blackfin and cisco) also continue to expand niche size in <i>Mysis</i>-based food webs. Partial ecological speciation based on a large niche space appears to be present in one lake (Cauchon Lake) where use of alternative habitats is the only real difference in cisco. The presence of blackfin expands niche space in Cedar and Radiant Lakes. This was not matched in Hogan Lake where niche space was relatively smaller with similar forms. Possible reasons for this discrepancy may be related to the asymmetric basin of Hogan Lake and whether the two forms overlap during cool and cold-water periods of the annual temperature cycle. By comparing trophic niche size among lakes with and without <i>Mysis</i> we conclude that <i>Mysis</i> provides a key ecological opportunity for cisco diversity in our study lakes and likely more widely.</p>