A NEW HYBRID BETWEEN A BLUE WHALE, BALAENOPTERA MUSCULUS, AND A FIN WHALE, B. PHYSALUS: FREQUENCY AND IMPLICATIONS OF HYBRIDIZATION

Authors

  • Martine Bérubé,

    1. Department of Population Biology, Zoological Institute, University of Copenhagen, Universitetsparken 15, Copenhagen Ø, DK-2100, Denmark
    2. Department of Natural Resource Sciences, Macdonald Campus, MGill University, Ste-Anne de Bellevue, Quebec, H9X 3V9, Canada
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    • 1

      Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92717, U. S. A. E-mail: martine@newt.bio.uci.edu.

  • Alex Aguilar

    1. Department of Animal Biology, Faculty of Biology, University of Barcelona, 08071 Barcelona, Spain
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Abstract

A female hybrid between a fin (Balaenoptera physalus) and a blue whale (B. mnusculus) was caught in whaling operations in 1984 off northwestern Spain. Its coloration and body proportions were intermediate between those of a fin and a blue whale, although it was anomalously large (19.4 m) when compared to fin whales of similar age (4 yr). It was sexually immature, concomitant with its age but not its length if it were a fin whale. Molecular analyses revealed that the mother of the hybrid was a blue whale and the father a fin whale. Examination of data for the five fin-blue whale hybrids in the literature, plus other anecdotal reports, indicates that hybridization between these two species occurs in various geographic regions and is relatively frequent, notably in light of the absence of reported hybrids between other mysticetes. Either species may act as father or mother, and there does not appear to be a selection for a given sex among the hybrids. The reproductive capacity of these hybrids remains unknown, although incidence of reproductive impairment appears to be higher in hybrid males than in hybrid females.

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