Get access

Morphological differences between two ecologically similar sympatric fishes

Authors

  • I. P. Helland,

    Corresponding author
    1. Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, P.O. Box 850 119, D-12561 Berlin, Germany
    2. Department of Biology, University of Oslo, Centre for Ecological and Evolutionary Synthesis, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
    Search for more papers by this author
  • L. A. Vøllestad,

    1. Department of Biology, University of Oslo, Centre for Ecological and Evolutionary Synthesis, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
    Search for more papers by this author
  • J. Freyhof,

    1. Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, P.O. Box 850 119, D-12561 Berlin, Germany
    Search for more papers by this author
  • T. Mehner

    1. Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, P.O. Box 850 119, D-12561 Berlin, Germany
    Search for more papers by this author

Author to whom correspondence should be addressed at present address: Aquatic Ecology Department, Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway. Tel.: +47 73801400; fax: +47 73801401; email: ingeborg.helland@nina.no

Abstract

Morphological differentiation and microhabitat segregation of two ecologically similar populations of pelagic planktivorous fishes, Coregonus albula and the smaller Coregonus fontanae, were studied in Lake Stechlin (northern Germany). Both populations performed diel vertical migrations, although C. fontanae was always situated in deeper pelagic water than C. albula both during day and night. Landmark-based geometric morphometrics revealed that sympatric C. albula and C. fontanae differ in external morphology, with main differences found in head length and eye position, as well as in length and width of the caudal peduncle. Moreover, while C. albula has a similar morphology over all sizes, the shape of C. fontanae changes with size. Accordingly, the morphology of the two is most different at smaller size. Although the morphological differences may reflect adaptations to the slightly differing microhabitats of the two populations, there is no conclusive evidence that this correspondence between ecology and morphology is the main mechanism behind the coexistence of the closely related coregonids in Lake Stechlin.

Ancillary