Abstract
Life history trade-offs are often hierarchical with decisions at one level affecting lower level trade-offs. We investigated trade-off structure in female side-blotched lizards (Uta stansburiana), which exhibit two evolved strategies: yellow-throated females are K-strategists and orange-throated are r-strategists. Corticosterone treatment was predicted to differentially organize these females' reproductive decisions. Corticosterone-treated yellow females suppressed reproduction but survived well, and augmented egg mass without decreasing clutch size. Conversely, corticosterone enhanced mortality and reproductive rates in orange females, and increased egg mass only after lengthy exposure. Corticosterone did not affect post-laying condition, suggesting that corticosterone increased egg mass through enhanced energy acquisition (income breeding). Corticosterone enhanced survival of lightweight females, but decreased survival of heavy females, introducing a foraging vs. predation trade-off. We conclude that rather than being a direct, functional relationship, observed trade-offs between offspring size and number represent evolved differences in hierarchical organization of multidimensional trade-offs, particularly in response to stress.
Original language | English |
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Pages (from-to) | 556-565 |
Number of pages | 10 |
Journal | Journal of Evolutionary Biology |
Volume | 21 |
Issue number | 2 |
Early online date | 3 Jan 2008 |
DOIs | |
Publication status | Published - Mar 2008 |
Keywords
- endocrine hormones
- income vs. capital breeding
- life history strategy
- offspring quantity vs. quality
- polymorphism
- predation vs. foraging
- r- vs. K-selection
- reptile
- stress
- survival vs. reproduction