Kimberly L. Howland, William M. Tonn, and Ross F. Tallman ... William M. Tonn ..... ald, G. Niditchie, E. Pilarski, K. Reid, P. Taylor, B. Wakeford, and K. Wescott.
Arch. Hydrobiol. Spec. Issues Advanc. Limnol. 57, p.253-264, htly 2002 Biology and Management of Coregonid Fishes - 1999
The influence of genetic and environmental factors on egg development and juvenile growth in two life history
forms of inconnu (Sfenodus leucichthys) Kimberly L. Howland, William M. Tonn, and Ross
F.
Tallman
with 2 figures and 3 tables
Abstract: Freshwater and anadromous populations of a species often differ in life history traits that are associated with their dichotomous migratory pxttern. Although regularly used to suppoft life history theory, the relative contribr.rtions of environmental and genetic influences to such intraspecific heterogeneity are not commonly known. We used a "common garden experiment" to examine the influence of these factors on lif'e history difTerences of freshwater and anadromous inconnu (.Stenodus Leucichthys) from the Mackenzie River system, northwestern Canada. In the common environment, rate of egg development diff'ered among life history types whereas juvenile growth rates did not, indicating that the former is under a substantial degree of genetic control, but the latter is more strongly influenced by environmenta1 differences in nature. Differences in rates of egg development may have evolved to match different temperature regimes within spawning rivers. In contrast, observed differences in growth rate of freshwater and anadromous inconnu in the wild are probably a result of phenotypic plasticity to different local environments.
lntroduction Salmonids, as a group, show considerable intraspecific variability, commonly occurring as multiple life history forms or ecotypes. Such intraspecific variation can range from obvious morphological differences, such as dwarf and normal forms of lake whitefish, Coregonus cLupeaformis (FeNoEnsow 1964, BEnNercnpz & DoosoN 1990), and arctic char, Salvelinus aLpinus (Hrxlln & JorvssoN 1993), which co-exist within lakes, to more subtle differences in habitat use, migratory behavior, and life history traits. Examples here include the existence of benthic and pelagic forms of lake cisco, Coregonus artedi (e.g., LrNosev I 98 I ) and, in several species, the occurrence of both anadromous and landlocked/freshwater forms (e.g., arctic charr, brown trott, Salmo trutta, and Atlantic salmon, Sctlmo salar) (BenNxB 1980, McCenr 1980, JoNssoN 198s).
Addresses of the authors: Kimberly L. Howland & Ross F. Tallman, Freshwater Institute, Department of Fisheries and Oceans,501 University Crescent, Winnipeg, Manitoba, Canada, R3T 2N6. William M. Tonn, Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9. e-mail: howlandk@ dfb-mpo. gc.ca
0071
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O 2002 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart
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K.L. Howland et al.
Whitefishes, in parlicular, are known for their high phenotypic plasticity (BeHnr
