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Breeding Behavior of the Leaf-Frogs Phyllomedusa callidryas and Phyllomedusa dacnicolor in Mexico
William F. Pyburn
Vol. 1970, No. 2 (Jun. 1, 1970), pp. 209-218
Stable URL: http://www.jstor.org/stable/1441643
Page Count: 10
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Male Phyllomedusa callidryas begin calling from vegetation at breeding sites before the pools fill. When standing water accumulates gravid females come to the pools and are attracted by the calling males. In both P. callidryas and Phyllomedusa dacnicolor the female, after entering into amplexus, carries the male from his perch (leaf or stem) down into the pool where she takes water into her bladder. She then leaves the pool, climbs up into the vegetation and lays an egg clutch, usually on the upper surface of a leaf, releasing the water from her bladder over the eggs as they emerge. The embryos die if the female is deprived of water at the time of oviposition. The female returns to the pool and refills her bladder before laying each egg clutch. Her trip from the pool back into the vegetation is probably initiated by filling of the bladder. If an egg clutch is submerged when the embryos are in stage 20 or earlier the embryos become retarded and die before hatching. Most embryos submerged in stage 21 or later survive and hatch sooner than they would have hatched in air. The males of P. callidryas and P. dacnicolor are aggressive toward other males of their own kind during the breeding season. When an amplectant pair passes near the perch of an unattached male, the latter may attack the amplectant male, trying to dislodge him from the female's back. At the same time the attacking male tries to secure a position on the female. The struggles usually have one of two outcomes: either the attacking male is driven off, or the attacking male gains a position on the female's back with the original male, and thus both males may fertilize the eggs. Rarely, fights involve three or more males. P. dacnicolor has opposable toes. The males continue to call while in amplexus and aid in oviposition by pulling eggs and jelly from the female's vent. Observations on breeding behavior and nesting habits in different species of Phyllomedusa support, in general, ideas of relationships based on foot structure. Leaf-breeding appears to have evolved from the habit in pond breeders of attaching the eggs to emergent vegetation near the water surface.