The Consequences of Within-Year Timing of Breeding in Ambystoma maculatum

Abstract

Embryonic and adult mortality, as a function of within-year timing of breeding, was studied in the spotted salamander, Ambystoma maculatum. Separate groups of salamanders bred at three different times in 1978 between 26 January and 28 March. Embryonic survival associated with the earliest breeding salamanders (wave 1) was very low (23%) compared to the later two waves (93% and 98%). The number of eggs per egg mass was greater in wave 1 egg masses than in wave 2 or 3 egg masses. Adult mortality caused by a pond freeze occurred among the earliest breeding salamanders (wave 1). Adults killed by the freeze had significantly larger snout-vent lengths than did survivors. It was concluded that withinyear variation in timing of breeding can have a major effect on reproductive