Experimental Analysis of Allocation during Larval Development in Ambystomatid Salamanders

We examined how variation in food availability and temperature influences patterns of energy allocation to growth, storage, metamorphosis, and reproduction in larval Ambystoma maculatum and A. tigrinum. In each species, an allocation vector consisting of metamorphic size, duration of larval period, fat body mass, and gonad mass was influenced by both food and temperature. Larvae grew rapidly at high food levels and high temperature, and delayed metamorphosis when grown at low temperature. High food levels resulted in larger fat bodies and decreased time to metamorphosis in A. tigrinum, and larger gonads in both species. The allocation vector collectively representing growth rate, storage, reproduction and metamorphosis differed between species: in A. maculatum, only the correlation between metamorphic size and fat body mass was significant, whereas all four variables were influenced in A. tigrinum. An interaction of food and temperature on the allocation vector was only detected for A. tigrinum. Our results indicate that interaction among allocation variables is stronger in some species than others and that these associations might be important in understanding life history variation between these species.