PARENT SESSION
Oral Session # 57: Evolutionary Ecology II: Animal.
Presiding: S Juliano
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 201.
Matrotrophic provisioning: A bet-hedging mechanism in mosquitofish?
Marsh-Matthews, Edie*,1, Brooks, Melody1, Deaton, Raelynn1, 1 University of Oklahoma, Norman, OK
ABSTRACT- Livebearing fishes in the genus Gambusia provision offspring both by production of large, yolky eggs and by mother-to-embryo transfer of nutrients (matrotrophy). We assayed nutrient transfer in Gambusia affinis and G. geiseri using radiolabeled leucine. In G. geiseri, matrotrophic provisioning was typically normally-distributed within broods. Provisioning to individual embryos was not a function of embryo size . In G. affinis, nutrient transfer was typically positively skewed within a brood, with higher levels of provisioning to larger embryos. In G. affinis, skewness was higher in broods at later stages and in broods with smaller median size of embryos. Differences between species in matrotrophic provisioning may reflect tactics evolved in environments that differ in predictability. Gambusia geiseri is restricted to high-discharge, constant-temperature springs, so matrotrophic provisioning may represent a tactic to optimize offspring quality. Gambusia affinis occupies a variety of habitats over its extensive range, including those with extreme and unpredictable conditions. Highly-skewed matrotrophic provisioning in G. affinis is consistent with a bet-hedging tactic to produce offspring of variable quality in unpredictable environments.
Key words: Gambusia geiseri, offspring quality, Gambusia affinis