Geographic and morphological variation in the presence and absence of the pelvic skeleton in the brook stickleback, Culaea inconstans (Kirtland), in Alberta and Saskatchewan
| Autor: | J S Nelson, F M Atton |
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| Rok vydání: | 1971 |
| Předmět: | |
| Zdroj: | Canadian Journal of Zoology. 49:343-352 |
| ISSN: | 1480-3283 0008-4301 |
| Popis: | Brook sticklebacks, Culaea inconstans (Kirtland), are known from 20 locations in Alberta and Saskatchewan in which a high proportion of the individuals lack all or part of the pelvic skeleton. These locations are interspersed and surrounded by other locations containing individuals with a normal pelvic skeleton. Individuals which lack the skeleton are of both sexes and are fertile in at least one of the lakes.Considerable variation exists between locations in the proportion of individuals with and without the pelvic skeleton. Morphological intermediates are known from most of the 20 locations and virtually all degrees of pelvic skeleton formation exist between its absence and its full development. Little or no gradation exists, however, in pelvic spine length between their absence and presence. Although the pelvic spines are the first part of the pelvic skeleton to appear during ontogeny, they are present only in intermediates with a virtually complete skeleton base. In addition, many intermediates are highly asymmetrical in their pelvic skeleton while development during the ontogeny of normal individuals is symmetrical.There is a greater tendency for individuals in which the pelvic skeleton is deficient to occur in lakes which lack an outlet rather than to occur in lakes with a permanent outlet. An unusually high proportion of the lakes with these aberrant individuals have been subject to fishery management activities (fish introduction and poisoning), but these disturbances are not causing the loss of the pelvic skeleton. |
| Databáze: | OpenAIRE |
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