PARENT SESSION
Oral Session #23: Animal Ecology: Behavior and Sociobiology. Presiding: P. Brunkow.
Tuesday, August 7, 2001. 8:00 AM to 11:45 AM. Hall of Ideas E.

Swim fast or grow fast: a fundamental trade-off in anuran tadpoles.

Arendt, Jeffrey¹, ¹

ABSTRACT- Swimming speed and growth rate are important components of fitness in anuran larval ecology. Larger and faster individuals tend to survive better than their smaller, slower competitors. However, recent work in fish suggests that there may be a trade-off between growth rate and swimming speed. I demonstrate that a similar trade-off exists in tadpoles of the American toad (Bufo americanus) and Western spadefoot toad (Scaphiopus hammondi). After determining the growth rates of individual tadpoles, I videotaped startle responses (at 30 frames/sec.) induced by touching the tail with a blunt probe. I estimated burst swimming speed from the first half second of each response. After controlling for size effects I found a negative correlation between growth rate and swimming speed in both species. Because these species represent one of the most primitive and one of the most derived families of anurans, I suspect this trade-off may be general for tadpoles as well as fish.

KEY WORDS: growth rate, burst swimming speed, trade-off, tadpole