Genetic variation in threshold reaction norms for alternative reproductive tactics in male Atlantic salmon, Salmo salar
Alternative reproductive tactics may be a product of adaptive phenotypic plasticity, such that discontinuous variation in life history depends on both the genotype and the environment. Phenotypes that fall below a genetically determined threshold adopt one tactic, while those exceeding the threshold...
| Published in: | Proceedings of the Royal Society B: Biological Sciences |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
The Royal Society
2008
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1098/rspb.2008.0251 https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2008.0251 https://royalsocietypublishing.org/doi/full-xml/10.1098/rspb.2008.0251 |
| Summary: | Alternative reproductive tactics may be a product of adaptive phenotypic plasticity, such that discontinuous variation in life history depends on both the genotype and the environment. Phenotypes that fall below a genetically determined threshold adopt one tactic, while those exceeding the threshold adopt the alternative tactic. We report evidence of genetic variability in maturation thresholds for male Atlantic salmon ( Salmo salar ) that mature either as large (more than 1 kg) anadromous males or as small (10–150 g) parr. Using a common-garden experimental protocol, we find that the growth rate at which the sneaker parr phenotype is expressed differs among pure- and mixed-population crosses. Maturation thresholds of hybrids were intermediate to those of pure crosses, consistent with the hypothesis that the life-history switch points are heritable. Our work provides evidence, for a vertebrate, that thresholds for alternative reproductive tactics differ genetically among populations and can be modelled as discontinuous reaction norms for age and size at maturity. |
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