Resource polymorphism and diversity of Arctic charr
Salvelinus alpinus in a series of isolated lakes
P. J. Woods*†‡§, D. Young, S. Sk´ ulason*, S. S. Snorrason†
and T. P. Quinn‡
*H´olar University College, H´aeyri 1, 551 Sauð´arkr´okur, Iceland, †University of Iceland, Sturlugata 7, Askja, 101 Reykjavík, Iceland, ‡University of Washington, Box 355020, Seattle, Washington 98195, U.S.A. and National Park Service, Lake Clark National Park and Preserve, Port Alsworth, AK 99653, U.S.A.
(Received 5 April 2012, Accepted 30 October 2012)
Morphological, dietary and life-history variation in Arctic charr Salvelinus alpinus were characterized from three geographically proximate, but isolated lakes and one large lake into which they drain in south-western Alaska. Polymorphism was predicted to occur in the first three lakes because
S. alpinus tend to become polymorphic in deep, isolated lakes with few co-occurring species. Only one morph was evident in the large lake and two of the three isolated lakes. In the third isolated lake, Lower Tazimina Lake, small and large morphs were found, the latter including two forms differing in growth rate. The small morph additionally differed from the two large forms by having
more gill rakers and a deeper body than same-sized individuals of the large morph, consuming more limnetic and fewer benthic resources, having a greater gonado-somatic index and maturing at a smaller size. The two large forms consumed only slightly different foods (more terrestrial insects were consumed by the medium-growth form; more snails by the high-growth form). Trends
in consumption of resources with body shape also differed between lakes. Variability in life history of S. alpinus in these Alaskan lakes was as broad as that found elsewhere. This variability is important for understanding lake ecosystems of remote regions where this species is commonly dominant.
© 2013 The Authors
Journal of Fish Biology © 2013 The Fisheries Society of the British Isles
Journal of Fish Biology (2013) 82, 569–587
doi:10.1111/jfb.12011, available online at wileyonlinelibrary.com
Key words: divergence; intraspecific