| Autor: |
DOLLOFF, C. ANDREW, FLEBBE, PATRICIA A., THORPE, JOHN E. |
| Zdroj: |
Transactions of the American Fisheries Society; Jul1994, Vol. 123 Issue 4, p606-612, 7p |
| Abstrakt: |
The responses of salmonid fishes to the problems posed by marginal habitats are genetic exercises in population insurance. The costs increase as the risks increase, but the risks are met by a wide repertoire of biological capacities. The most general proximate response to adversity is behavioral: ontogenetic niche shifts are an acknowledgment that a series of environments becomes marginal for all salmonids during development. Physiological tolerances and developmental flexibility govern the timing of these movements. Such shifts are the product of natural selection in relatively predictable environments, but less predictable or catastrophic events are accommodated at a different genetic level. Low spatial flexibility is counteracted by temporal insurance, and vice versa. Thus, high homing precision is coupled with complex multiple-age structures, and simple age structuring is coupled with relatively high spatial straying. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
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